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Niu ZR, Wu JH, Tan YJ, Luo DJ, Xu X. [Erdheim-Chester disease initially discovered at extraskeletal locations: a clinicopathological analysis of four cases]. Zhonghua Bing Li Xue Za Zhi 2024; 53:364-369. [PMID: 38556820 DOI: 10.3760/cma.j.cn112151-20230911-00160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/02/2024]
Abstract
Objective: To investigate the clinicopathological features of Erdheim-Chester disease (ECD) initially diagnosed at extraskeletal locations. Methods: Clinical and pathological data of four cases of ECD diagnosed initially in extraskeletal locations were collected at Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, from January 2013 to June 2023. BRAF V600E gene was detected by reverse transcription polymerase chain reaction (RT-PCR). Pertinent literatures were reviewed. Results: Four ECD patients included two males and two females ranging in ages from 2 years 11 months to 69 years. The lesions located in the lung (two cases), central nervous system (one case), and the testicle (one case) were collected in the study. One patient had occasional fever at night, one had nausea and vomiting, and two were asymptomatic. Radiologically, the two pulmonary ECD showed diffuse ground-glass nodules in both lungs, and the lesions in central nervous system and testicle both showed solid masses. Microscopically, there were infiltration of foamy histiocyte-like cells and multinucleated giant cells in a fibrotic background, accompanied by varying amounts of lymphocytes and plasma cells. The infiltration of tumor cells in pulmonary ECD was mainly seen in the subpleural area, interlobular septa, and perivascular and peribronchiolar areas. The fibrosis was more pronounced in the pleura and interlobular septa, and less pronounced in the alveolar septa. Immunohistochemical staining showed that all tumor cells expressed CD68, CD163 and Fa; one case showed S-100 expression; three cases were positive for BRAF V600E; all were negative for CD1α and Langerin. RT-PCR in all four cases showed BRAF V600E gene mutation. Conclusions: Extraskeletal ECD is often rare and occult, and could be easily misdiagnosed, requiring biopsy confirmation. The radiologic findings of pulmonary ECD is significantly different from other types of ECD, and the histopathological features of pronounced infiltration in the subpleura area, interlobular septa, perivascular and peribronchiolar areas can be helpful in the differential diagnosis from other pulmonary diseases. Detection of BRAF V600E gene mutation by RT-PCR and its expression by immunohistochemical staining are also helpful in the diagnosis.
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Affiliation(s)
- Z R Niu
- Department of Pathology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - J H Wu
- Department of Pathology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Y J Tan
- Department of Pathology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - D J Luo
- Department of Pathology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - X Xu
- Department of Pathology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
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Li H, Chng CB, Zheng H, Wu MS, Bartolo PJDS, Qi HJ, Tan YJ, Zhou K. Self-Healable and 4D Printable Hydrogel for Stretchable Electronics. Adv Sci (Weinh) 2024; 11:e2305702. [PMID: 38263891 PMCID: PMC10987146 DOI: 10.1002/advs.202305702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2023] [Revised: 11/21/2023] [Indexed: 01/25/2024]
Abstract
Materials with high stretchability and conductivity are used to fabricate stretchable electronics. Self-healing capability and four-dimensional (4D) printability are becoming increasingly important for these materials to facilitate their recovery from damage and endow them with stimuli-response properties. However, it remains challenging to design a single material that combines these four strengths. Here, a dually crosslinked hydrogel is developed by combining a covalently crosslinked acrylic acid (AAC) network and Fe3+ ions through dynamic and reversible ionically crosslinked coordination. The remarkable electrical sensitivity (a gauge factor of 3.93 under a strain of 1500%), superior stretchability (a fracture strain up to 1700%), self-healing ability (a healing efficiency of 88% and 97% for the mechanical and electrical properties, respectively), and 4D printability of the hydrogel are demonstrated by constructing a strain sensor, a two-dimensional touch panel, and shape-morphing structures with water-responsive behavior. The hydrogel demonstrates vast potential for applications in stretchable electronics.
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Affiliation(s)
- Huijun Li
- Singapore Centre for 3D Printing, School of Mechanical and Aerospace EngineeringNanyang Technological University50 Nanyang AvenueSingapore639798Singapore
| | - Chin Boon Chng
- Department of Mechanical Engineering, College of Design and EngineeringNational University of Singapore9 Engineering DriveSingapore117575Singapore
| | - Han Zheng
- Singapore Centre for 3D Printing, School of Mechanical and Aerospace EngineeringNanyang Technological University50 Nanyang AvenueSingapore639798Singapore
| | - Mao See Wu
- Singapore Centre for 3D Printing, School of Mechanical and Aerospace EngineeringNanyang Technological University50 Nanyang AvenueSingapore639798Singapore
| | - Paulo Jorge Da Silva Bartolo
- Singapore Centre for 3D Printing, School of Mechanical and Aerospace EngineeringNanyang Technological University50 Nanyang AvenueSingapore639798Singapore
| | - H. Jerry Qi
- School of Mechanical EngineeringGeorgia Institute of TechnologyAtlantaGA30332USA
| | - Yu Jun Tan
- Department of Mechanical Engineering, College of Design and EngineeringNational University of Singapore9 Engineering DriveSingapore117575Singapore
- Centre for Additive ManufacturingNational University of SingaporeSingapore117602Singapore
| | - Kun Zhou
- Singapore Centre for 3D Printing, School of Mechanical and Aerospace EngineeringNanyang Technological University50 Nanyang AvenueSingapore639798Singapore
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Anwar Ali HP, Zhao Z, Tan YJ, Yao W, Li Q, Tee BCK. Dynamic Modeling of Intrinsic Self-Healing Polymers Using Deep Learning. ACS Appl Mater Interfaces 2022; 14:52486-52498. [PMID: 36346733 DOI: 10.1021/acsami.2c14543] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The properties of self-healing polymers are traditionally identified through destructive testing. This means that the mechanics are explored in hindsight with either theoretical derivations and/or simulations. Here, a self-healing property evolution using energy functional dynamical (SPEED) model is proposed to predict and understand the mechanics of self-healing of polymers using images of cuts dynamically healing over time. Using machine learning, an energy functional minimization (EFM) model extracted an effective underlying dynamical system from a time series of two-dimensional cut images on a self-healing polymer of constant thickness. This model can be used to capture the physics behind the self-healing dynamics in terms of potential and interface energies. When combined with a static property prediction model, the SPEED model can predict the macroscopic evolution of material properties after training only on a small set of experimental measurements. Such temporal evolutions are usually inaccessible from pure experiments or computational modeling due to the need for destructive testing. As an example, we validate this approach on toughness measurements of an intrinsic self-healing conductive polymer by capturing over 100 000 image frames of cuts to build the machine learning (ML) model. The results show that the SPEED model can be applied to predict the temporal evolution of macroscopic properties using few measurements as training data.
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Affiliation(s)
- Hashina Parveen Anwar Ali
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore117575, Singapore
- Biomedical Engineering & Materials Group, School of Engineering, Nanyang Polytechnic, 180 Ang Mo Kio Avenue 8, Singapore569830, Singapore
| | - Zichen Zhao
- Department of Mathematics, National University of Singapore, 10 Lower Kent Ridge Road, Singapore119076, Singapore
| | - Yu Jun Tan
- Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore117575, Singapore
| | - Wei Yao
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore117575, Singapore
| | - Qianxiao Li
- Department of Mathematics, National University of Singapore, 10 Lower Kent Ridge Road, Singapore119076, Singapore
- Institute for Functional Intelligent Materials, National University of Singapore, 4 Science Drive 2, Singapore117544, Singapore
| | - Benjamin C K Tee
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore117575, Singapore
- Department of Electrical & Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore117583, Singapore
- Institute for Health Innovation & Technology (iHealthTech), National University of Singapore, 14 Medical Drive, Singapore117599, Singapore
- The N.1 Institute for Health, National University of Singapore, 28 Medical Drive, Singapore117456, Singapore
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Wang XY, Su BY, Chen ZY, Kuang HB, Guan P, Cao ZZ, Tan YJ. [Comparison of QuantiFERON-TB Gold Plus and QuantiFERON-TB Gold In Tube in the diagnosis of pulmonary tuberculosis]. Zhonghua Jie He He Hu Xi Za Zhi 2022; 45:445-452. [PMID: 35527459 DOI: 10.3760/cma.j.cn112147-20220206-00095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Objective: To compare the screening value of QuantiFERON-TB Gold Plus (QFT-Plus) and QuantiFERON®-TB Gold in tube (QFT-GIT) in the auxiliary diagnosis of pulmonary tuberculosis (TB). Methods: A screening test was performed. Patients who were hospitalized in Guangzhou Chest Hospital and underwent QFT-GIT testing from October to December 2020 were prospectively included as research subjects, QFT-Plus testing was added. And the basic information, clinical manifestations, laboratory test results, imaging examinations and other data of these patients were collected. A total of 207 patients were included and divided into tuberculosis group and non-tuberculosis group according to these data. There were 124 cases in the tuberculosis group (94 confirmed patients and 30 clinically diagnosed patients), including 90 males and 34 females, aged 18-93 years, with a median age of 57 (38, 67) years. The non-tuberculosis group included 83 patients (16 patients with non-tuberculous Mycobacteria and 67 patients with other lung diseases), including 49 males and 34 females, with a median age of 60 (51, 68) years. The confirmed patients were subdivided into three grades of low, medium and high Mycobacteriam tuberculosis (MTB) bacterial load, and three grades of mild, moderate and severe pulmonary tuberculosis. The results of QFT-Plus and QFT-GIT were compared, and the levels of IFN-γ in different antigen tubes were compared. Differences between different groups were compared using Mann-Whitney U test and Kruskal-Wallis H test. Results: The QFT-Plus showed a high degree of agreement with the QFT-GIT (κ=0.786, 95%CI: 0.740-0.832), while the main discordant result was QFT-GIT negative/QFT-Plus positive, accounting for 15/17. The sensitivity of QFT-GIT was 80.7%(95%CI: 0.706-0.880), the specificity was 76.3%(95%CI: 0.649-0.850), the positive predictive value was 79.8%(95%CI: 0.697-0.873), and the negative predictive value was 77.3%(95%CI: 0.659-0.859), repectively. QFT-Plus showed a sensitivity of 84.3%(95%CI: 0.743-0.910), a specificity of 78.8% (95%CI: 0.679-0.868), and a positive predictive value of 80.5%(95%CI: 0.703-0.879), the negative predictive value being 82.9%(95%CI: 0.721-0.902), slightly improved to that of the QFT-GIT. Also, this study found that there were significant differences in IFN-γ values between different MTB load or disease severity (P<0.05). Conclusions: There is a good consistency between the QFT-Plus test and the QFT-GIT test, both of which show good application value in the auxiliary diagnosis of pulmonary tuberculosis. Moreover, because of the addition of tuberculosis-specific CD8 cell antigen, the QFT-Plus test has higher sensitivity, lower uncertainty and more application value. This study also found that the bacterial load and disease severity of patients with pulmonary tuberculosis may have a certain correlation with the measured value of IFN-γ.
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Affiliation(s)
- X Y Wang
- Graduate School, Guangzhou Medical University, Guangzhou 511436, China
| | - B Y Su
- Department of Pathogenic Laboratory, Guangzhou Chest Hospital, Guangzhou 510095, China
| | - Z Y Chen
- Department of Pathogenic Laboratory, Guangzhou Chest Hospital, Guangzhou 510095, China
| | - H B Kuang
- Department of Clinical Tuberculosis, Guangzhou Chest Hospital, Guangzhou 510095, China
| | - P Guan
- Department of Pathogenic Laboratory, Guangzhou Chest Hospital, Guangzhou 510095, China
| | - Z Z Cao
- Department of Pathogenic Laboratory, Guangzhou Chest Hospital, Guangzhou 510095, China
| | - Y J Tan
- Department of Pathogenic Laboratory, Guangzhou Chest Hospital, Guangzhou 510095, China
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Abstract
Fully recyclable and degradable materials have been used for the development of soft devices for omnidirectional sensing and actuation.
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Affiliation(s)
- Yu Jun Tan
- Department of Mechanical Engineering, College of Design and Engineering, National University of Singapore, 117575, Singapore. Centre for Additive Manufacturing (AM.NUS), National University of Singapore, 117602, Singapore.
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Chao WQ, Azman MZ, Rosdi SA, Tuan-Mustafa T, Tan YJ, Abdullah S, Aizuddin AN. Epidemiology and Factors Affecting Functional Outcome of Distal Radial Fracture in an Urban Tertiary Medical Centre in Malaysia. Malays Orthop J 2021; 15:84-90. [PMID: 34966500 PMCID: PMC8667256 DOI: 10.5704/moj.2111.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 07/19/2021] [Indexed: 11/05/2022] Open
Abstract
Introduction Distal radial fracture is a commonly encountered fracture. This study aims to study the epidemiology of distal radial fracture and factors affecting the patients' functional outcome one to two years after the injury. Materials and methods This is a retrospective cohort study. The records of patients, fulfilling the radiographical diagnosis of distal radial fracture, and aged 18 and above, who presented to our Emergency Department from 1st January 2018 to 31st December 2018 were retrieved. According to AO classification, we grouped our patients into A (extra-articular), B (partial articular) and C (complete articular). Patients with congenital abnormalities were excluded. Epidemiological data and relevant medical history were obtained and tabulated. A Malaysian language translation of Disability of the Arm, Shoulder and Hand (DASH) questionnaire was used to assess the functional outcome. Results Out of 168 patients' data retrieved, only 110 patients' data were found complete for purposes of this study. The mean DASH score was 13.7 ± 7.87 approximately one to two years post-injury regardless of treatment method. Increasing age was associated with higher DASH score with r=0.407(p<0.001). Several variables had significantly better functional outcome: male gender (p=0.01), Type A fracture configuration (p=0.007) and non-operational treatment (p=0.03). There was no significant difference between treatment modalities in Type A fracture (p=0.094), but Type B (p=0.043) and Type C (p=0.007) had better outcome without surgery. There was no significant difference between different ethnic groups, open or closed fracture and mechanism of injury. Conclusion Better functional outcome after sustaining distal radial fracture was associated with young age, male gender, type A fracture and treated non-operatively. Interestingly, more complex fracture pattern had better functionality were observed without surgery.
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Affiliation(s)
- W Q Chao
- Department of Orthopaedics and Traumatology, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
| | - M Z Azman
- Department of Orthopaedics and Traumatology, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
| | - S A Rosdi
- Department of Orthopaedics and Traumatology, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
| | - Taw Tuan-Mustafa
- Department of Orthopaedics and Traumatology, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
| | - Y J Tan
- Department of Orthopaedics and Traumatology, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
| | - S Abdullah
- Department of Orthopaedics and Traumatology, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
| | - A N Aizuddin
- Department of Orthopaedics and Traumatology, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
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Tan XL, Thomas BR, Tan YJ, O'Toole EA. Effects of systemic therapies on pruritus in adults with atopic dermatitis: a systematic review and meta-analysis. Clin Exp Dermatol 2021; 47:658-666. [PMID: 34643956 DOI: 10.1111/ced.14976] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 09/20/2021] [Accepted: 10/11/2021] [Indexed: 11/29/2022]
Abstract
Pruritus is a hallmark of atopic dermatitis (AD), affecting disease severity and patients' quality of life. In AD uncontrolled with first-line topical therapies or in moderate-to-severe AD, systemic therapies are used, however, there are paucity of head-to-head trials comparing their effectiveness. The aim was to compare the effectiveness between the systemic therapies on relieving pruritus in moderate-to-severe AD in adults through meta-analysis. PubMed, EMBASE, Medline and CINAHL databases were searched from inception up to 31 May 2020 for placebo-controlled randomised controlled trials investigating the effectiveness of systemic therapies on pruritus with moderate-to-severe AD in adults aged ≥ 16. 26 studies were identified (n = 5,190 participants). There was a large reduction in pruritus compared to placebo (standard mean difference [95% confidence interval]) with dupilumab every 2 weeks (q2w) (-0.88 [-1.13, -0.63]), q2w + topical corticosteroids (-0.77 [-0.91, -0.62]); dupilumab once weekly (qw) (-0.99 [-1.29, -0.68]), qw + topical corticosteroids (-0.70 [-0.81, -0.59]); a large reduction with ciclosporin (-1.30 [-2.34, -0.26]); a small reduction with mepolizumab (-0.27 [-0.89, 0.35]), interferon gamma (-0.31 [-0.75, 0.12]); a large reduction with azathioprine (-0.85 [-2.07, 0.35]). Amongst investigational drugs, nemolizumab 2.0mg/kg was the most effective (-8.13 [-9.31, -6.94]). The majority of systemic therapies were superior to placebo in reducing pruritus. In particular, dupilumab studies consistently showed large improvements in pruritus and nemolizumab showed the strongest anti-pruritic effects, however future head-to-head trials are required for conclusive evidence.
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Affiliation(s)
- X L Tan
- Centre for Cell Biology and Cutaneous Research, The Blizard Institute, Barts and the London School of Medicine and Dentistry, 4 Newark Street, London, E1 2AT, UK
| | - B R Thomas
- Centre for Cell Biology and Cutaneous Research, The Blizard Institute, Barts and the London School of Medicine and Dentistry, 4 Newark Street, London, E1 2AT, UK.,Department of Dermatology, Royal London Hospital and ERN Skin, Barts Health NHS Trust, Whitechapel Road, London, E1 1BB, UK
| | - Y J Tan
- Centre for Cell Biology and Cutaneous Research, The Blizard Institute, Barts and the London School of Medicine and Dentistry, 4 Newark Street, London, E1 2AT, UK
| | - E A O'Toole
- Centre for Cell Biology and Cutaneous Research, The Blizard Institute, Barts and the London School of Medicine and Dentistry, 4 Newark Street, London, E1 2AT, UK.,Department of Dermatology, Royal London Hospital and ERN Skin, Barts Health NHS Trust, Whitechapel Road, London, E1 1BB, UK
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Zhao Y, Tan YJ, Yang W, Ling S, Yang Z, Teo JT, See HH, Lee DKH, Lu D, Li S, Zeng X, Liu Z, Tee BCK. Scaling Metal-Elastomer Composites toward Stretchable Multi-Helical Conductive Paths for Robust Responsive Wearable Health Devices. Adv Healthc Mater 2021; 10:e2100221. [PMID: 34272931 DOI: 10.1002/adhm.202100221] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 06/20/2021] [Indexed: 11/07/2022]
Abstract
Stretchable electronics have advanced rapidly and many applications require high repeatability and robustness under various mechanical deformations. It has been described here that how a highly stretchable and reliable conductor composite made from helical copper wires and a soft elastomer, named eHelix, can provide mechanically robust and strain-insensitive electronic conductivity for wearable devices. The reversibility of the mechanical behavior of the metal-elastomer system has been studied using finite element modeling methods. Optimal design parameters of such helical metal-elastomer structures are found. The scaling of multiple copper wires into such helical shapes to form a Multi-eHelix system is further shown. With the same elastomer volume, Multi-eHelix has more conductive paths and a higher current density than the single-eHelix. Integrations of these eHelix stretchable conductors with fabrics showed wearable displays that can survive machine-washes and hundreds of mechanical loading cycles. The integration of the eHelix developed by us with a wearable optical heart rate sensor enabled a wearable health monitoring system that can display measured heart rates on clothing. Furthermore, Multi-eHelix conductors are used to connect flexible printed circuit boards and piezoresistive sensors on a tactile sensing glove for the emerging sensorized prosthetics.
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Affiliation(s)
- Yue Zhao
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, 119077, Singapore
- Institute of Manufacturing Technology, Agency for Science, Technology and Research (A*STAR), Singapore, 138634, Singapore
| | - Yu Jun Tan
- Department of Material Science and Engineering, National University of Singapore, Singapore, 117583, Singapore
| | - Weidong Yang
- Department of Material Science and Engineering, National University of Singapore, Singapore, 117583, Singapore
| | - Shaohua Ling
- Department of Material Science and Engineering, National University of Singapore, Singapore, 117583, Singapore
| | - Zijie Yang
- Department of Material Science and Engineering, National University of Singapore, Singapore, 117583, Singapore
| | - Ju Teng Teo
- Department of Material Science and Engineering, National University of Singapore, Singapore, 117583, Singapore
| | - Hian Hian See
- Department of Material Science and Engineering, National University of Singapore, Singapore, 117583, Singapore
| | - David Kwok Hung Lee
- Department of Material Science and Engineering, National University of Singapore, Singapore, 117583, Singapore
| | - Dingjie Lu
- Institute of High Performance Computing, Agency for Science, Technology and Research (A*STAR), Singapore, 138632, Singapore
| | - Shihao Li
- Department of Material Science and Engineering, National University of Singapore, Singapore, 117583, Singapore
| | - Xianting Zeng
- Institute of Manufacturing Technology, Agency for Science, Technology and Research (A*STAR), Singapore, 138634, Singapore
| | - Zhuangjian Liu
- Institute of High Performance Computing, Agency for Science, Technology and Research (A*STAR), Singapore, 138632, Singapore
| | - Benjamin C K Tee
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, 119077, Singapore
- Department of Material Science and Engineering, National University of Singapore, Singapore, 117583, Singapore
- Institute for Health Innovation & Technology (iHealthtech), National University of Singapore, Singapore, 117599, Singapore
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Tan YJ, Susanto GJ, Anwar Ali HP, Tee BCK. Progress and Roadmap for Intelligent Self-Healing Materials in Autonomous Robotics. Adv Mater 2021; 33:e2002800. [PMID: 33346389 DOI: 10.1002/adma.202002800] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Revised: 08/05/2020] [Indexed: 06/12/2023]
Abstract
Robots are increasingly assisting humans in performing various tasks. Like special agents with elite skills, they can venture to distant locations and adverse environments, such as the deep sea and outer space. Micro/nanobots can also act as intrabody agents for healthcare applications. Self-healing materials that can autonomously perform repair functions are useful to address the unpredictability of the environment and the increasing drive toward the autonomous operation. Having self-healable robotic materials can potentially reduce costs, electronic wastes, and improve a robot endowed with such materials longevity. This review aims to serve as a roadmap driven by past advances and inspire future cross-disciplinary research in robotic materials and electronics. By first charting the history of self-healing materials, new avenues are provided to classify the various self-healing materials proposed over several decades. The materials and strategies for self-healing in robotics and stretchable electronics are also reviewed and discussed. It is believed that this article encourages further innovation in this exciting and emerging branch in robotics interfacing with material science and electronics.
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Affiliation(s)
- Yu Jun Tan
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
- Institute of Innovation in Health Technology (iHealthtech), National University of Singapore, Singapore, 117599, Singapore
| | - Glenys Jocelin Susanto
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Hashina Parveen Anwar Ali
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Benjamin C K Tee
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
- Institute of Innovation in Health Technology (iHealthtech), National University of Singapore, Singapore, 117599, Singapore
- Electrical and Computer Engineering, National University of Singapore, Singapore, 117583, Singapore
- N.1 Institute of Health, National University of Singapore, Singapore
- Institute of Materials Research and Engineering, Agency for Science Technology and Research, Singapore, 138634, Singapore
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Li H, Zheng H, Tan YJ, Tor SB, Zhou K. Development of an Ultrastretchable Double-Network Hydrogel for Flexible Strain Sensors. ACS Appl Mater Interfaces 2021; 13:12814-12823. [PMID: 33427444 DOI: 10.1021/acsami.0c19104] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The weak mechanical properties of hydrogels due to the inefficient dissipation of energy in the intrinsic structures limit their practical applications. Here, a double-network (DN) hydrogel has been developed by integrating an ionically cross-linked agar network, a covalently cross-linked acrylic acid (AAC) network, and the dynamic and reversible ionically cross-linked coordination between the AAC chains and Fe3+ ions. The proposed model reveals the mechanisms of the improved mechanical performances in the DN agar/AAC-Fe3+ hydrogel. The hydrogen-bond cross-linked double helices of agar and ionic-coordination interactions of AAC-Fe3+ can be temporarily sacrificed during large deformation to readily dissipate the energy, whereas the reversible AAC-Fe3+ interactions can be regenerated after stress relief, which greatly increases the material toughness. The developed DN hydrogel demonstrates a remarkable stretchability with a break strain up to 3174.3%, high strain sensitivity with the gauge factor being 0.83 under a strain of 1000%, and good 3D printability, making the material a desirable candidate for fabricating flexible strain sensors, electronic skin, and soft robots.
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Affiliation(s)
- Huijun Li
- Singapore Centre for 3D Printing, School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
| | - Han Zheng
- Environmental Process Modelling Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, Singapore 637141, Singapore
| | - Yu Jun Tan
- Institute for Health Innovation & Technology, National University of Singapore, Singapore 117599, Singapore
| | - Shu Beng Tor
- Singapore Centre for 3D Printing, School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
| | - Kun Zhou
- Singapore Centre for 3D Printing, School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
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Guo H, Tan YJ, Chen G, Wang Z, Susanto GJ, See HH, Yang Z, Lim ZW, Yang L, Tee BCK. Artificially innervated self-healing foams as synthetic piezo-impedance sensor skins. Nat Commun 2020; 11:5747. [PMID: 33184285 PMCID: PMC7665015 DOI: 10.1038/s41467-020-19531-0] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 10/12/2020] [Indexed: 11/09/2022] Open
Abstract
Human skin is a self-healing mechanosensory system that detects various mechanical contact forces efficiently through three-dimensional innervations. Here, we propose a biomimetic artificially innervated foam by embedding three-dimensional electrodes within a new low-modulus self-healing foam material. The foam material is synthesized from a one-step self-foaming process. By tuning the concentration of conductive metal particles in the foam at near-percolation, we demonstrate that it can operate as a piezo-impedance sensor in both piezoresistive and piezocapacitive sensing modes without the need for an encapsulation layer. The sensor is sensitive to an object's contact force directions as well as to human proximity. Moreover, the foam material self-heals autonomously with immediate function restoration despite mechanical damage. It further recovers from mechanical bifurcations with gentle heating (70 °C). We anticipate that this material will be useful as damage robust human-machine interfaces.
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Affiliation(s)
- Hongchen Guo
- NUS Graduate School for Integrative Sciences and Engineering (NGS), National University of Singapore, Singapore, Singapore
- Department of Materials Science and Engineering (MSE), National University of Singapore, Singapore, Singapore
| | - Yu Jun Tan
- Department of Materials Science and Engineering (MSE), National University of Singapore, Singapore, Singapore
- Institute of Innovation in Health Technology (iHealthtech), National University of Singapore, Singapore, Singapore
| | - Ge Chen
- Department of Materials Science and Engineering (MSE), National University of Singapore, Singapore, Singapore
| | - Zifeng Wang
- Department of Materials Science and Engineering (MSE), National University of Singapore, Singapore, Singapore
| | - Glenys Jocelin Susanto
- Department of Materials Science and Engineering (MSE), National University of Singapore, Singapore, Singapore
| | - Hian Hian See
- Department of Materials Science and Engineering (MSE), National University of Singapore, Singapore, Singapore
| | - Zijie Yang
- Department of Materials Science and Engineering (MSE), National University of Singapore, Singapore, Singapore
| | - Zi Wei Lim
- Department of Materials Science and Engineering (MSE), National University of Singapore, Singapore, Singapore
| | - Le Yang
- Institute of Materials Research and Engineering, Agency for Science Technology and Research, Singapore, Singapore
| | - Benjamin C K Tee
- NUS Graduate School for Integrative Sciences and Engineering (NGS), National University of Singapore, Singapore, Singapore.
- Department of Materials Science and Engineering (MSE), National University of Singapore, Singapore, Singapore.
- Institute of Innovation in Health Technology (iHealthtech), National University of Singapore, Singapore, Singapore.
- Institute of Materials Research and Engineering, Agency for Science Technology and Research, Singapore, Singapore.
- Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore.
- N.1 Institute of Health, National University of Singapore, Singapore, Singapore.
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12
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Yao H, Yang W, Cheng W, Tan YJ, See HH, Li S, Ali HPA, Lim BZH, Liu Z, Tee BCK. Near-hysteresis-free soft tactile electronic skins for wearables and reliable machine learning. Proc Natl Acad Sci U S A 2020; 117:25352-25359. [PMID: 32989151 PMCID: PMC7568242 DOI: 10.1073/pnas.2010989117] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Electronic skins are essential for real-time health monitoring and tactile perception in robots. Although the use of soft elastomers and microstructures have improved the sensitivity and pressure-sensing range of tactile sensors, the intrinsic viscoelasticity of soft polymeric materials remains a long-standing challenge resulting in cyclic hysteresis. This causes sensor data variations between contact events that negatively impact the accuracy and reliability. Here, we introduce the Tactile Resistive Annularly Cracked E-Skin (TRACE) sensor to address the inherent trade-off between sensitivity and hysteresis in tactile sensors when using soft materials. We discovered that piezoresistive sensors made using an array of three-dimensional (3D) metallic annular cracks on polymeric microstructures possess high sensitivities (> 107 Ω ⋅ kPa-1), low hysteresis (2.99 ± 1.37%) over a wide pressure range (0-20 kPa), and fast response (400 Hz). We demonstrate that TRACE sensors can accurately detect and measure the pulse wave velocity (PWV) when skin mounted. Moreover, we show that these tactile sensors when arrayed enabled fast reliable one-touch surface texture classification with neuromorphic encoding and deep learning algorithms.
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Affiliation(s)
- Haicheng Yao
- Materials Science and Engineering, National University of Singapore, 117575 Singapore, Singapore
| | - Weidong Yang
- Materials Science and Engineering, National University of Singapore, 117575 Singapore, Singapore
| | - Wen Cheng
- Materials Science and Engineering, National University of Singapore, 117575 Singapore, Singapore
| | - Yu Jun Tan
- Materials Science and Engineering, National University of Singapore, 117575 Singapore, Singapore
- Institute for Health Innovation & Technology iHealthtech, National University of Singapore, 117599 Singapore, Singapore
| | - Hian Hian See
- Materials Science and Engineering, National University of Singapore, 117575 Singapore, Singapore
| | - Si Li
- Materials Science and Engineering, National University of Singapore, 117575 Singapore, Singapore
- Institute for Health Innovation & Technology iHealthtech, National University of Singapore, 117599 Singapore, Singapore
| | | | - Brian Z H Lim
- Materials Science and Engineering, National University of Singapore, 117575 Singapore, Singapore
| | - Zhuangjian Liu
- Institute of High Performance Computing, A*STAR Research Entities, 138632 Singapore, Singapore
| | - Benjamin C K Tee
- Materials Science and Engineering, National University of Singapore, 117575 Singapore, Singapore;
- Institute for Health Innovation & Technology iHealthtech, National University of Singapore, 117599 Singapore, Singapore
- The N.1 Institute for Health, National University of Singapore, 117456 Singapore, Singapore
- Electrical and Computer Engineering, National University of Singapore, 117583 Singapore, Singapore
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13
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Huan H, Liu C, Yang Z, Bao JL, Liu C, Wang JT, Zhang L, Wang CH, Ci RSP, Tu QL, Ren T, Xu D, Zhang HJ, Li XG, Kang N, Li XP, Wu YH, Pu X, Tan YJ, Cao JJ, Luo SWQ, Luo SQP, Zhuo M, Qi XL. [Current situation of screening, prevention and treatment of bleeding esophageal varices in cirrhotic portal hypertension in Tibet region: a multicenter study]. Zhonghua Gan Zang Bing Za Zhi 2020; 28:737-741. [PMID: 33053972 DOI: 10.3760/cma.j.cn501113-20200615-00318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Objective: To investigate and analyze the current situation, screening, clinical characteristics, prevention and treatment of bleeding esophageal varices in cirrhotic patients with portal hypertension in Tibet region. Methods: Clinical data of cirrhotic patients with portal hypertension through March 2017 to February 2020 from Tibet region were collected and analyzed retrospectively. Results: 511 cases with liver cirrhosis were included in the study, of which 185 cases (36.20%) had compensated cirrhosis and 326 cases (63.80%) had decompensated cirrhosis. Further analysis of the etiological data of liver cirrhosis showed that 306 cases (59.88%) were of chronic hepatitis B, 113 cases (22.11%) of alcoholic liver disease, and 68 cases (13.31%) of chronic hepatitis B combined with alcoholic liver disease. Among patients with compensated liver cirrhosis, 48 cases (25.95%) underwent endoscopic examination of which 33 diagnosed as high-risk variceal bleeding. However, none of these 33 cases had received non-selective β-blocker therapy, and only four patients had received endoscopic variceal banding therapy. Among patients with decompensated liver cirrhosis, 83 cases (25.46%) had a history of upper gastrointestinal bleeding, 297 cases (91.10%) had ascites, 23 cases (7.05%) had hepatic encephalopathy, and 3 cases (0.92%) had hepatorenal syndrome. Among the patients with a history of upper gastrointestinal bleeding, 42 cases (50.60%) had received secondary preventive treatment for bleeding esophageal varices, including 39 cases of endoscopic treatment, 1 case of endoscopic combined drug treatment, 3 cases of interventional treatment, and 2 cases of surgical treatment. Conclusion: Chronic hepatitis B and alcoholic liver diseases are the main causes of liver cirrhosis in Tibet region. Moreover, this region lacks screening, prevention and treatment for bleeding esophageal varices in cirrhotic patients with portal hypertension. Therefore, it is necessary to increase the screening of high-risk groups to prevent and improve the first-time bleeding, and promote multidisciplinary team to prevent and treat re-bleeding.
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Affiliation(s)
- H Huan
- Department of Gastroenterology, Hospital of Chengdu Office of People's Government of Tibetan Autonomous Region, Chengdu 610041, China
| | - C Liu
- Department of Gastroenterology, Hospital of Chengdu Office of People's Government of Tibetan Autonomous Region, Chengdu 610041, China
| | - Z Yang
- Department of Hepatology, The Third People's Hospital of Tibet Autonomous Region, Lasa 850000, China
| | - J L Bao
- Department of Gastroenterology,Shannan People's Hospital, Shannan 856000, China
| | - C Liu
- CHESS Center, Institute of Portal Hypertension, The First Hospital of Lanzhou University, Lanzhou 730000, China
| | - J T Wang
- CHESS Center, Institute of Portal Hypertension, The First Hospital of Lanzhou University, Lanzhou 730000, China
| | - L Zhang
- Beijing Tsinghua Changgung Hospital, Tsinghua University, Beijing 102218, China
| | - C H Wang
- Department of Gastroenterology, The Second People's Hospital of Tibet Autonomous Region, Lasa 850000, China
| | - R S P Ci
- Department of Internal Medicine, Naqu Tibetan Hospital, Naqu 852000, China
| | - Q L Tu
- Department of Gastroenterology, Hospital of Chengdu Office of People's Government of Tibetan Autonomous Region, Chengdu 610041, China
| | - T Ren
- Department of Gastroenterology, Hospital of Chengdu Office of People's Government of Tibetan Autonomous Region, Chengdu 610041, China
| | - D Xu
- CHESS Center, Institute of Portal Hypertension, The First Hospital of Lanzhou University, Lanzhou 730000, China
| | - H J Zhang
- CHESS Center, Institute of Portal Hypertension, The First Hospital of Lanzhou University, Lanzhou 730000, China
| | - X G Li
- CHESS Center, Institute of Portal Hypertension, The First Hospital of Lanzhou University, Lanzhou 730000, China
| | - N Kang
- CHESS Center, Institute of Portal Hypertension, The First Hospital of Lanzhou University, Lanzhou 730000, China
| | - X P Li
- Department of Gastroenterology, Hospital of Chengdu Office of People's Government of Tibetan Autonomous Region, Chengdu 610041, China
| | - Y H Wu
- Department of Gastroenterology, Hospital of Chengdu Office of People's Government of Tibetan Autonomous Region, Chengdu 610041, China
| | - X Pu
- Department of Gastroenterology, Hospital of Chengdu Office of People's Government of Tibetan Autonomous Region, Chengdu 610041, China
| | - Y J Tan
- Department of Gastroenterology, Hospital of Chengdu Office of People's Government of Tibetan Autonomous Region, Chengdu 610041, China
| | - J J Cao
- Medical Administration, Ali District Health and Safety Commission, Ali 859000, China
| | - S W Q Luo
- Department of Internal Medicine, Naqu Tibetan Hospital, Naqu 852000, China
| | - S Q P Luo
- Department of Pediatrics, Ali District People's Hospital, Ali 859000, China
| | - M Zhuo
- Department of Gastroenterology, Lasa People's Hospital, Lasa 850000, China
| | - X L Qi
- CHESS Center, Institute of Portal Hypertension, The First Hospital of Lanzhou University, Lanzhou 730000, China
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14
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Tan YJ, Godaba H, Chen G, Tan STM, Wan G, Li G, Lee PM, Cai Y, Li S, Shepherd RF, Ho JS, Tee BCK. A transparent, self-healing and high-κ dielectric for low-field-emission stretchable optoelectronics. Nat Mater 2020; 19:182-188. [PMID: 31844282 DOI: 10.1038/s41563-019-0548-4] [Citation(s) in RCA: 81] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 10/30/2019] [Indexed: 06/10/2023]
Abstract
Stretchable optoelectronic materials are essential for applications in wearable electronics, human-machine interfaces and soft robots. However, intrinsically stretchable optoelectronic devices such as light-emitting capacitors usually require high driving alternating voltages and excitation frequencies to achieve sufficient luminance in ambient lighting conditions. Here, we present a healable, low-field illuminating optoelectronic stretchable (HELIOS) device by introducing a transparent, high permittivity polymeric dielectric material. The HELIOS device turns on at an alternating voltage of 23 V and a frequency below 1 kHz, safe operating conditions for human-machine interactions. We achieved a brightness of 1,460 cd m-2 at 2.5 V µm-1 with stable illumination demonstrated up to a maximum of 800% strain. The materials also self-healed mechanically and electronically from punctures or when severed. We further demonstrate various HELIOS light-emitting capacitor devices in environment sensing using optical feedback. Moreover, our devices can be powered wirelessly, potentially enabling applications for untethered damage-resilient soft robots.
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Affiliation(s)
- Yu Jun Tan
- Department of Materials Science and Engineering, National University of Singapore, Singapore, Singapore
- Institute of Innovation in Health Technology (iHealthtech), National University of Singapore, Singapore, Singapore
| | - Hareesh Godaba
- Department of Materials Science and Engineering, National University of Singapore, Singapore, Singapore
- Institute of Innovation in Health Technology (iHealthtech), National University of Singapore, Singapore, Singapore
| | - Ge Chen
- Department of Materials Science and Engineering, National University of Singapore, Singapore, Singapore
| | - Siew Ting Melissa Tan
- Institute of Innovation in Health Technology (iHealthtech), National University of Singapore, Singapore, Singapore
| | - Guanxiang Wan
- Department of Materials Science and Engineering, National University of Singapore, Singapore, Singapore
| | - Guojingxian Li
- Institute of Innovation in Health Technology (iHealthtech), National University of Singapore, Singapore, Singapore
| | - Pui Mun Lee
- Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Yongqing Cai
- Institute Of High Performance Computing, Agency for Science Technology and Research, Singapore, Singapore
- Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Avenida da Universidade, Taipa, Macau, China
| | - Si Li
- Department of Materials Science and Engineering, National University of Singapore, Singapore, Singapore
| | - Robert F Shepherd
- Mechanical & Aerospace Engineering, Cornell University, Ithaca, NY, USA
| | - John S Ho
- Institute of Innovation in Health Technology (iHealthtech), National University of Singapore, Singapore, Singapore
- Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
- N.1 Institute of Health, National University of Singapore, Singapore, Singapore
| | - Benjamin C K Tee
- Department of Materials Science and Engineering, National University of Singapore, Singapore, Singapore.
- Institute of Innovation in Health Technology (iHealthtech), National University of Singapore, Singapore, Singapore.
- Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore.
- N.1 Institute of Health, National University of Singapore, Singapore, Singapore.
- Institute of Materials Research and Engineering, Agency for Science Technology and Research, Singapore, Singapore.
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15
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Lee WW, Tan YJ, Yao H, Li S, See HH, Hon M, Ng KA, Xiong B, Ho JS, Tee BCK. A neuro-inspired artificial peripheral nervous system for scalable electronic skins. Sci Robot 2019; 4:4/32/eaax2198. [PMID: 33137772 DOI: 10.1126/scirobotics.aax2198] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 06/21/2019] [Indexed: 12/20/2022]
Abstract
The human sense of touch is essential for dexterous tool usage, spatial awareness, and social communication. Equipping intelligent human-like androids and prosthetics with electronic skins-a large array of sensors spatially distributed and capable of rapid somatosensory perception-will enable them to work collaboratively and naturally with humans to manipulate objects in unstructured living environments. Previously reported tactile-sensitive electronic skins largely transmit the tactile information from sensors serially, resulting in readout latency bottlenecks and complex wiring as the number of sensors increases. Here, we introduce the Asynchronously Coded Electronic Skin (ACES)-a neuromimetic architecture that enables simultaneous transmission of thermotactile information while maintaining exceptionally low readout latencies, even with array sizes beyond 10,000 sensors. We demonstrate prototype arrays of up to 240 artificial mechanoreceptors that transmitted events asynchronously at a constant latency of 1 ms while maintaining an ultra-high temporal precision of <60 ns, thus resolving fine spatiotemporal features necessary for rapid tactile perception. Our platform requires only a single electrical conductor for signal propagation, realizing sensor arrays that are dynamically reconfigurable and robust to damage. We anticipate that the ACES platform can be integrated with a wide range of skin-like sensors for artificial intelligence (AI)-enhanced autonomous robots, neuroprosthetics, and neuromorphic computing hardware for dexterous object manipulation and somatosensory perception.
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Affiliation(s)
- Wang Wei Lee
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore.,Institute for Health Innovation and Technology, National University of Singapore, Singapore 117599, Singapore
| | - Yu Jun Tan
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore.,Institute for Health Innovation and Technology, National University of Singapore, Singapore 117599, Singapore
| | - Haicheng Yao
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore
| | - Si Li
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore.,Institute for Health Innovation and Technology, National University of Singapore, Singapore 117599, Singapore
| | - Hian Hian See
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore
| | - Matthew Hon
- Graduate School of Integrative Sciences and Engineering, National University of Singapore, Singapore 117456, Singapore
| | - Kian Ann Ng
- N.1 Institute for Health, National University of Singapore, Singapore 117456, Singapore
| | - Betty Xiong
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore
| | - John S Ho
- Institute for Health Innovation and Technology, National University of Singapore, Singapore 117599, Singapore.,N.1 Institute for Health, National University of Singapore, Singapore 117456, Singapore.,Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore
| | - Benjamin C K Tee
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore. .,Institute for Health Innovation and Technology, National University of Singapore, Singapore 117599, Singapore.,Graduate School of Integrative Sciences and Engineering, National University of Singapore, Singapore 117456, Singapore.,N.1 Institute for Health, National University of Singapore, Singapore 117456, Singapore.,Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore
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16
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Wang T, Tan YJ, Wu SJ, Huang M, Yin BT, Huang J, Wei N, Wei W, Wang F. [The ratio of tuberculosis-specific antigen to phytohemagglutinin in T-SPOT assay in the diagnosis of active tuberculosis]. Zhonghua Jie He He Hu Xi Za Zhi 2019; 42:262-267. [PMID: 30955283 DOI: 10.3760/cma.j.issn.1001-0939.2019.04.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Objective: The aim of this study was to determine the performance of the ratio of tuberculosis-specific antigen (TBAg) to phytohemagglutinin (PHA) (TBAg/PHA ratio) in T-SPOT assay in the diagnosis of active tuberculosis (ATB). Methods: Between January 2014 and January 2017, 378 Mycobacterium tuberculosis (MTB) culture positive patients (268 cases of pulmonary tuberculosis, 110 extra-pulmonary tuberculosis) and 824 healthy individuals were recruited from Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology. T-SPOT assay was performed and TBAg/PHA ratio was calculated in all the participants. To validate the study, another group of 223 MTB culture positive TB patients with positive T-SPOT results were recruited from Guangzhou Chest Hospital between January 2017 and December 2017. This was a retrospective case-control study and differences between groups were analyzed using the Mann-Whitney U-test. Results: Of the 378 culture positive ATB patients, 344 patients had positive T-SPOT results. Of the 824 healthy individuals, 204 individuals had positive T-SPOT results. Using healthy individuals as the control group, the sensitivity and specificity of T-SPOT assay in the diagnosis of ATB were 91.0% (344/378) and 75.2% (620/824). Directly using T-SPOT results had a limited accuracy in distinguishing ATB from latent tuberculosis infection (LTBI). The area under the receiver operating characteristic (ROC) curve was between 0.7 and 0.8. However, a further calculation of the TBAg/PHA ratio showed a better performance than TBAg in distinguishing these two conditions, and the area under the ROC curve was 0.881 (95% CI: 0.853-0.909). If using the threshold value of 0.234, the sensitivity and specificity of the TBAg/PHA ratio in distinguishing ATB from LTBI were 69.5% (239/344) and 94.12% (192/204). The validation data showed that the performance of the TBAg/PHA ratio in distinguishing ATB from LTBI was also satisfactory, and the area under the ROC curve was 0.901 (95% CI: 0.872-0.931). Furthermore, the TBAg/PHA ratio had an important role in the diagnosis of extra-pulmonary tuberculosis. If using the threshold value of 0.234, the sensitivity and specificity of the TBAg/PHA ratio in the diagnosis of extra-pulmonary tuberculosis were 79.2% (76/96) and 94.1% (192/204). The area under the ROC curve was 0.932 (95% CI: 0.897-0.967). Conclusions: The TBAg/PHA ratio in T-SPOT assay was better than directly using T-SPOT results in distinguishing ATB from LTBI. This ratio also showed a potential use in the diagnosis of extra-pulmonary tuberculosis.
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Affiliation(s)
- T Wang
- Department of Laboratory Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Y J Tan
- Department of Clinical Laboratory, Guangzhou Chest Hospital, Guangzhou 510095, China
| | - S J Wu
- Department of Laboratory Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - M Huang
- Department of Laboratory Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - B T Yin
- Department of Laboratory Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - J Huang
- Department of Laboratory Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - N Wei
- Department of Laboratory Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - W Wei
- Department of Laboratory Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - F Wang
- Department of Laboratory Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
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17
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Zhou M, Lee BH, Tan YJ, Tan LP. Microbial transglutaminase induced controlled crosslinking of gelatin methacryloyl to tailor rheological properties for 3D printing. Biofabrication 2019; 11:025011. [DOI: 10.1088/1758-5090/ab063f] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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18
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Tan YJ, Wendy T, Chieng JY. Detection rate of colonic polyp among patients who had undergone colonoscopy at gastroenterology unit of Serdang Hospital, Malaysia. Med J Malaysia 2019; 74:20-24. [PMID: 30846657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
OBJECTIVE The aim of this study was to evaluate the demography, and to determine the detection rate of polyps, and detection rate of adenoma at a Malaysian tertiary hospital. METHODS This is a retrospective study of all the patients who had undergone colonoscopy at Gastroenterology endoscopy unit, Serdang Hospital from 1st January 2010 to 31st December 2016. Patients who had a history of colorectal cancer, polyp or inflammatory bowel disease were excluded. Data collected which included patients' demography, indication for colonoscopy, colonoscopy finding, and histopathology results. Data was analysed with SPSS version 16. RESULTS Among the 559 patients who had fulfilled the inclusion criteria (68 males, 44 females), 112 patients were found to have at least one polyp giving the polyp detection rate (PDR) of 20% and 168 polypectomies were performed. The PDR among male patients was higher than that of females (22.5% vs 17.1%, p<0.05). The detection rate of polyp was nearly equal in Malays, Chinese, Indians, and Others. The polyps were more common in those of age 40 years old and above (p<0.05), with the mean age of 63.0±1.5 years. The commonest morphology of polyp in our patients was sessile (58%) and majority was medium size (5-9mm). Otherwise, the polyps were commonly found in the distal colon those that in proximal colon (55.3% vs 38.7%, p<0.05). The adenoma detection rate (ADR) was 19.1% (107/559). CONCLUSION The detection rate of colonic polyp from colonoscopy is 20% in our centre.
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Affiliation(s)
- Y J Tan
- Hospital Serdang, Medical Department, Selangor, Malaysia.
| | - T Wendy
- Hospital Serdang, Medical Department, Selangor, Malaysia
| | - J Y Chieng
- Putra University of Malaysia, Faculty of Medicine and Health Sciences, Medical Department, Selangor, Malaysia
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19
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Abstract
The survivability of living organisms relies critically on their ability to self-heal from damage in unpredictable situations and environmental variability. Such abilities are most important in external facing organs such as the mammalian skin. However, the properties of bulk elemental materials are typically unable to perform self-repair. Consequently, most conventional smart electronic devices today are not designed to repair themselves when damaged. Thus, inspired by the remarkable capability of self-healing in natural systems, smart self-healing materials are being intensively researched to mimic natural systems to have the ability to partially or completely self-repair damages inflicted on them. This exciting area of research could potentially power a sustainable and smart future.
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Affiliation(s)
- Yu Jun Tan
- Biomedical Institute for Global Health and Research (BIGHEART) , National University of Singapore , 119077 Singapore
| | - Jiake Wu
- Department of Polymer Science and Engineering , Zhejiang University , Hangzhou 310027 , P. R. China
| | - Hanying Li
- Department of Polymer Science and Engineering , Zhejiang University , Hangzhou 310027 , P. R. China
| | - Benjamin C K Tee
- Biomedical Institute for Global Health and Research (BIGHEART) , National University of Singapore , 119077 Singapore
- Materials Science and Engineering Department , National University of Singapore , 117575 Singapore
- Institute of Materials Research and Engineering , Agency for Science Technology and Research , 138632 Singapore
- Department of Electrical & Computer Engineering , National University of Singapore , 117583 Singapore
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20
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Curtin C, Nolan JC, Conlon R, Deneweth L, Gallagher C, Tan YJ, Cavanagh BL, Asraf AZ, Harvey H, Miller-Delaney S, Shohet J, Bray I, O'Brien FJ, Stallings RL, Piskareva O. A physiologically relevant 3D collagen-based scaffold-neuroblastoma cell system exhibits chemosensitivity similar to orthotopic xenograft models. Acta Biomater 2018; 70:84-97. [PMID: 29447961 DOI: 10.1016/j.actbio.2018.02.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Revised: 02/02/2018] [Accepted: 02/05/2018] [Indexed: 12/18/2022]
Abstract
3D scaffold-based in vitro cell culturing is a recent technological advancement in cancer research bridging the gap between conventional 2D culture and in vivo tumours. The main challenge in treating neuroblastoma, a paediatric cancer of the sympathetic nervous system, is to combat tumour metastasis and resistance to multiple chemotherapeutic drugs. The aim of this study was to establish a physiologically relevant 3D neuroblastoma tissue-engineered system and explore its therapeutic relevance. Two neuroblastoma cell lines, chemotherapeutic sensitive Kelly and chemotherapeutic resistant KellyCis83 were cultured in a 3D in vitro model on two collagen-based scaffolds containing either glycosaminoglycan (Coll-GAG) or nanohydroxyapatite (Coll-nHA) and compared to 2D cell culture and an orthotopic murine model. Both neuroblastoma cell lines actively infiltrated the scaffolds and proliferated displaying >100-fold increased resistance to cisplatin treatment when compared to 2D cultures, exhibiting chemosensitivity similar to orthotopic xenograft in vivo models. This model demonstrated its applicability to validate miRNA-based gene delivery. The efficacy of liposomes bearing miRNA mimics uptake and gene knockdown was similar in both 2D and 3D in vitro culturing models highlighting the proof-of-principle for the applicability of 3D collagen-based scaffolds cell system for validation of miRNA function. Collectively, this data shows the successful development and characterisation of a physiologically relevant, scaffold-based 3D tissue-engineered neuroblastoma cell model, strongly supporting its value in the evaluation of chemotherapeutics, targeted therapies and investigation of neuroblastoma pathogenesis. While neuroblastoma is the specific disease being focused upon, the platform may have multi-functionality beyond this tumour type. STATEMENT OF SIGNIFICANCE Traditional 2D cell cultures do not completely capture the 3D architecture of cells and extracellular matrix contributing to a gap in our understanding of mammalian biology at the tissue level and may explain some of the discrepancies between in vitro and in vivo results. Here, we demonstrated the successful development and characterisation of a physiologically relevant, scaffold-based 3D tissue-engineered neuroblastoma cell model, strongly supporting its value in the evaluation of chemotherapeutics, targeted therapies and investigation of neuroblastoma pathogenesis. The ability to test drugs in this reproducible and controllable tissue-engineered model system will help reduce the attrition rate of the drug development process and lead to more effective and tailored therapies. Importantly, such 3D cell models help to reduce and replace animals for pre-clinical research addressing the principles of the 3Rs.
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Affiliation(s)
- C Curtin
- Tissue Engineering Research Group, Dept. of Anatomy, Royal College of Surgeons in Ireland, Dublin, Ireland; Trinity Centre for Bioengineering, Trinity College Dublin, Dublin, Ireland; Advanced Materials and Bioengineering Research Centre (AMBER), RCSI and TCD, Dublin, Ireland
| | - J C Nolan
- Molecular & Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin, Ireland; National Children's Research Centre, Our Lady's Children's Hospital, Crumlin, Dublin, Ireland
| | - R Conlon
- Molecular & Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - L Deneweth
- Molecular & Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - C Gallagher
- Molecular & Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Y J Tan
- Molecular & Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - B L Cavanagh
- Cellular and Molecular Imaging Core, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - A Z Asraf
- Molecular & Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - H Harvey
- Molecular & Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - S Miller-Delaney
- Molecular & Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - J Shohet
- Department of Pediatrics, Section of Hematology-Oncology, Baylor College of Medicine, TX, United States
| | - I Bray
- Molecular & Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - F J O'Brien
- Tissue Engineering Research Group, Dept. of Anatomy, Royal College of Surgeons in Ireland, Dublin, Ireland; Trinity Centre for Bioengineering, Trinity College Dublin, Dublin, Ireland; Advanced Materials and Bioengineering Research Centre (AMBER), RCSI and TCD, Dublin, Ireland
| | - R L Stallings
- Molecular & Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin, Ireland; National Children's Research Centre, Our Lady's Children's Hospital, Crumlin, Dublin, Ireland
| | - O Piskareva
- Molecular & Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin, Ireland; National Children's Research Centre, Our Lady's Children's Hospital, Crumlin, Dublin, Ireland.
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Li H, Tan YJ, Leong KF, Li L. 3D Bioprinting of Highly Thixotropic Alginate/Methylcellulose Hydrogel with Strong Interface Bonding. ACS Appl Mater Interfaces 2017; 9:20086-20097. [PMID: 28530091 DOI: 10.1021/acsami.7b04216] [Citation(s) in RCA: 122] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
A robust alginate/methylcellulose (Alg/MC) blend hydrogel, with a strategy to improve adhesion between printed layers, has been fabricated for the first time for three-dimensional (3D) bioprinting. The optimized Alg/MC blend hydrogel exhibits a highly thixotropic property, great extrudability, and stackability. With treatment by a trisodium citrate (TSC) solution, the interfacial bonding between the printed layers is significantly improved. The TSC solution acts as a chelating agent to remove the superficial calcium ions at each layer. Post-cross-linking in a CaCl2 bath after 3D printing further enhances the adhesion strength between the layers. The key parameters affecting the interfacial strength of the Alg/MC hydrogel are found to be the concentration of TSC, the volume of TSC, and the concentration of CaCl2 in the bath. The Alg/MC hydrogel with the aid of TSC demonstrates superior printability, high stackability (150 layers can be printed), and high shape fidelity. A good cell viability of >95% is obtained for a freshly 3D-bioprinted Alg/MC construct. The novel Alg/MC hydrogel with the aid of TSC has been shown to have a great potential as an advanced 3D bioprinting material.
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Affiliation(s)
- Huijun Li
- Singapore Center for 3D Printing and ‡School of Mechanical and Aerospace Engineering, Nanyang Technological University , 50 Nanyang Avenue, 639798 Singapore
| | - Yu Jun Tan
- Singapore Center for 3D Printing and ‡School of Mechanical and Aerospace Engineering, Nanyang Technological University , 50 Nanyang Avenue, 639798 Singapore
| | - Kah Fai Leong
- Singapore Center for 3D Printing and ‡School of Mechanical and Aerospace Engineering, Nanyang Technological University , 50 Nanyang Avenue, 639798 Singapore
| | - Lin Li
- Singapore Center for 3D Printing and ‡School of Mechanical and Aerospace Engineering, Nanyang Technological University , 50 Nanyang Avenue, 639798 Singapore
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Tan XP, Tan YJ, Chow CSL, Tor SB, Yeong WY. Metallic powder-bed based 3D printing of cellular scaffolds for orthopaedic implants: A state-of-the-art review on manufacturing, topological design, mechanical properties and biocompatibility. Mater Sci Eng C Mater Biol Appl 2017; 76:1328-1343. [PMID: 28482501 DOI: 10.1016/j.msec.2017.02.094] [Citation(s) in RCA: 157] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 02/21/2017] [Indexed: 01/15/2023]
Abstract
Metallic cellular scaffold is one of the best choices for orthopaedic implants as a replacement of human body parts, which could improve life quality and increase longevity for the people needed. Unlike conventional methods of making cellular scaffolds, three-dimensional (3D) printing or additive manufacturing opens up new possibilities to fabricate those customisable intricate designs with highly interconnected pores. In the past decade, metallic powder-bed based 3D printing methods emerged and the techniques are becoming increasingly mature recently, where selective laser melting (SLM) and selective electron beam melting (SEBM) are the two representatives. Due to the advantages of good dimensional accuracy, high build resolution, clean build environment, saving materials, high customisability, etc., SLM and SEBM show huge potential in direct customisable manufacturing of metallic cellular scaffolds for orthopaedic implants. Ti-6Al-4V to date is still considered to be the optimal materials for producing orthopaedic implants due to its best combination of biocompatibility, corrosion resistance and mechanical properties. This paper presents a state-of-the-art overview mainly on manufacturing, topological design, mechanical properties and biocompatibility of cellular Ti-6Al-4V scaffolds via SLM and SEBM methods. Current manufacturing limitations, topological shortcomings, uncertainty of biocompatible test were sufficiently discussed herein. Future perspectives and recommendations were given at the end.
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Affiliation(s)
- X P Tan
- Singapore Centre for 3D Printing, School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore.
| | - Y J Tan
- Singapore Centre for 3D Printing, School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore
| | - C S L Chow
- Singapore Centre for 3D Printing, School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore
| | - S B Tor
- Singapore Centre for 3D Printing, School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore
| | - W Y Yeong
- Singapore Centre for 3D Printing, School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore
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Tan YJ, Tan X, Yeong WY, Tor SB. Hybrid microscaffold-based 3D bioprinting of multi-cellular constructs with high compressive strength: A new biofabrication strategy. Sci Rep 2016; 6:39140. [PMID: 27966623 PMCID: PMC5155425 DOI: 10.1038/srep39140] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 11/17/2016] [Indexed: 12/27/2022] Open
Abstract
A hybrid 3D bioprinting approach using porous microscaffolds and extrusion-based printing method is presented. Bioink constitutes of cell-laden poly(D,L-lactic-co-glycolic acid) (PLGA) porous microspheres with thin encapsulation of agarose-collagen composite hydrogel (AC hydrogel). Highly porous microspheres enable cells to adhere and proliferate before printing. Meanwhile, AC hydrogel allows a smooth delivery of cell-laden microspheres (CLMs), with immediate gelation of construct upon printing on cold build platform. Collagen fibrils were formed in the AC hydrogel during culture at body temperature, improving the cell affinity and spreading compared to pure agarose hydrogel. Cells were proven to proliferate in the bioink and the bioprinted construct. High cell viability up to 14 days was observed. The compressive strength of the bioink is more than 100 times superior to those of pure AC hydrogel. A potential alternative in tissue engineering of tissue replacements and biological models is made possible by combining the advantages of the conventional solid scaffolds with the new 3D bioprinting technology.
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Affiliation(s)
- Yu Jun Tan
- Singapore Centre for 3D Printing, School of Mechanical &Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore
| | - Xipeng Tan
- Singapore Centre for 3D Printing, School of Mechanical &Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore
| | - Wai Yee Yeong
- Singapore Centre for 3D Printing, School of Mechanical &Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore
| | - Shu Beng Tor
- Singapore Centre for 3D Printing, School of Mechanical &Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore
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Tan YJ, Tan X, Yeong WY, Tor SB. Additive Manufacturing of Patient-Customizable Scaffolds for Tubular Tissues Using the Melt-Drawing Method. Materials (Basel) 2016; 9:E893. [PMID: 28774013 PMCID: PMC5457202 DOI: 10.3390/ma9110893] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Revised: 10/12/2016] [Accepted: 10/31/2016] [Indexed: 11/26/2022]
Abstract
Polymeric fibrous scaffolds for guiding cell growth are designed to be potentially used for the tissue engineering (TE) of tubular organs including esophagi, blood vessels, tracheas, etc. Tubular scaffolds were fabricated via melt-drawing of highly elastic poly(l-lactide-co-ε-caprolactone) (PLC) fibers layer-by-layer on a cylindrical mandrel. The diameter and length of the scaffolds are customizable via 3D printing of the mandrel. Thickness of the scaffolds was varied by changing the number of layers of the melt-drawing process. The morphology and tensile properties of the PLC fibers were investigated. The fibers were highly aligned with a uniform diameter. Their diameters and tensile properties were tunable by varying the melt-drawing speeds. These tailorable topographies and tensile properties show that the additive-based scaffold fabrication technique is customizable at the micro- and macro-scale for different tubular tissues. The merits of these scaffolds in TE were further shown by the finding that myoblast and fibroblast cells seeded onto the scaffolds in vitro showed appropriate cell proliferation and distribution. Human mesenchymal stem cells (hMSCs) differentiated to smooth muscle lineage on the microfibrous scaffolds in the absence of soluble induction factors, showing cellular shape modulation and scaffold elasticity may encourage the myogenic differentiation of stem cells.
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Affiliation(s)
- Yu Jun Tan
- Singapore Centre for 3D Printing, School of Mechanical & Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
| | - Xipeng Tan
- Singapore Centre for 3D Printing, School of Mechanical & Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
| | - Wai Yee Yeong
- Singapore Centre for 3D Printing, School of Mechanical & Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
| | - Shu Beng Tor
- Singapore Centre for 3D Printing, School of Mechanical & Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
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25
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Tan YJ, Yeong WY, Tan X, An J, Chian KS, Leong KF. Characterization, mechanical behavior and in vitro evaluation of a melt-drawn scaffold for esophageal tissue engineering. J Mech Behav Biomed Mater 2016; 57:246-59. [DOI: 10.1016/j.jmbbm.2015.12.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2015] [Revised: 12/10/2015] [Accepted: 12/14/2015] [Indexed: 12/28/2022]
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Yu YL, Wu XM, Li SN, Fang H, Tan YJ, Yu JQ. Bioavailability of butachlor and myclobutanil residues in soil to earthworms. Chemosphere 2005; 59:961-967. [PMID: 15823329 DOI: 10.1016/j.chemosphere.2004.11.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2004] [Revised: 10/23/2004] [Accepted: 11/03/2004] [Indexed: 05/24/2023]
Abstract
To establish chemical extraction procedures for predicting bioavailability of butachlor and myclobutanil in soil, several solvent systems, including methanol, methanol-water (9:1), methanol-water (1:1), acetone-water (5:3), petroleum ether and water, were assessed for their feasibility in determining extractability of the target compounds from soil samples. Experimental data showed that the extractability of butachlor and myclobutanil by the solvents was well linearly correlated with their bioavailability to Eisenia foetida and Allolobophora caliginosa, indicating that these extraction procedures may be efficient for predicting bioavailability of the two pesticides. The concentrations of the pesticides accumulated in E. foetida and A. caliginosa varied with species, suggesting that the availability of the soil-sequestered pesticide is a species-dependent process.
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Affiliation(s)
- Y L Yu
- Department of Plant Protection, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310029, People's Republic of China.
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27
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Wu YC, Zhao YB, Lu CZ, Qiao J, Tan YJ. Correlation between serum level of neuron-specific enolase and long-term functional outcome after acute cerebral infarction: prospective study. Hong Kong Med J 2004; 10:251-4. [PMID: 15299170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/30/2023] Open
Abstract
OBJECTIVE To determine the value of measuring serum levels of neuron-specific enolase in predicting extent of disease and short- and long-term functional outcome after acute cerebral infarction. DESIGN Prospective study. SETTING Neurology departments at two university teaching hospitals, Shanghai. PATIENTS Thirty-eight patients who presented for acute cerebral infarction between October 1998 and October 2000 were divided into two groups: those whose infarction extended to the cerebral cortex in the carotid artery region (cortical group) and those with an infarction in the subcortical carotid artery region (subcortical group). MAIN OUTCOME MEASURES Using a solid-phase enzyme immunoassay, we measured serum levels of neuron-specific enolase on admission and on days 2, 3, and 15. Infarct volume was measured by computed tomography on day 5. The Activities of Daily Living scale was used to assess the clinical outcome at 1-, 3-, and 6-month follow-up after onset. RESULTS Mean (standard deviation) serum neuron-specific enolase levels were significantly higher among patients with acute cerebral infarction than among controls (18.48 [16.61] ng/mL versus 9.00 [2.70] ng/mL; P<0.001). The neuron-specific enolase level was also higher in the cortical group than in the subcortical group (33.54 [29.71] ng/mL versus 15.97 [5.91] ng/mL; P<0.01). Levels peaked after 2.11 (0.86) days and correlated positively with the infarct volume (r=0.81; P<0.01) and negatively with clinical outcome at 1 month (r= -0.37; P<0.05), 3 months (r= -0.45; P<0.01), and 6 months (r= -0.65; P<0.001), as assessed on the Activities of Daily Living scale. CONCLUSION Serum neuron-specific enolase levels after cerebral infarction may be a useful marker to predict infarct volume and short- or long-term functional outcome.
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Affiliation(s)
- Y C Wu
- Department of Neurology, First People's Hospital of Shanghai Jiao Tong University, 85 Wu Jin Road, Shanghai 200080, PRC.
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Goh PY, Tan YJ, Lim SP, Lim SG, Tan YH, Hong WJ. The hepatitis C virus core protein interacts with NS5A and activates its caspase-mediated proteolytic cleavage. Virology 2001; 290:224-36. [PMID: 11883187 DOI: 10.1006/viro.2001.1195] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Viral proteins interact with one another during viral replication, assembly, and maturation. Systematic interaction assays of the hepatitis C virus (HCV) proteins using the yeast two-hybrid method have uncovered a novel interaction between core and NS5A. This interaction was confirmed by in vitro binding assays, and coimmunoprecipitation in mammalian cells. Core and NS5A are also colocalized in COS-7 cells. Interestingly, NS5A is cleaved to give specific-size fragments, when core is coexpressed in mammalian cells. Overexpression of core produced many dying and rounded cells and effects such as DNA laddering and the truncation of poly(ADP-ribose) polymerase 1 (PARP1), both indicators of apoptosis. These observations led us to investigate the link between the induction of apoptosis by core and the cleavage of NS5A. The proteolysis of NS5A and these apoptotic events can be inhibited by caspase inhibitor, Z-VAD, indicating that core induces apoptosis and the cleavage of NS5A by caspases. In cells infected by the HCV, core may provide the intrinsic apoptotic signal, which produces truncated forms of NS5A. The biological function of core-NS5A interaction and the downstream effect of NS5A cleavage are discussed.
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Affiliation(s)
- P Y Goh
- Collaborative Anti-viral Research Group, Institute of Molecular and Cell Biology, 30 Medical Drive, Singapore 117609.
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Kazmirski SL, Wong KB, Freund SM, Tan YJ, Fersht AR, Daggett V. Protein folding from a highly disordered denatured state: the folding pathway of chymotrypsin inhibitor 2 at atomic resolution. Proc Natl Acad Sci U S A 2001; 98:4349-54. [PMID: 11274353 PMCID: PMC31838 DOI: 10.1073/pnas.071054398] [Citation(s) in RCA: 141] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Previous experimental and theoretical studies have produced high-resolution descriptions of the native and folding transition states of chymotrypsin inhibitor 2 (CI2). In similar fashion, here we use a combination of NMR experiments and molecular dynamics simulations to examine the conformations populated by CI2 in the denatured state. The denatured state is highly unfolded, but there is some residual native helical structure along with hydrophobic clustering in the center of the chain. The lack of persistent nonnative structure in the denatured state reduces barriers that must be overcome, leading to fast folding through a nucleation-condensation mechanism. With the characterization of the denatured state, we have now completed our description of the folding/unfolding pathway of CI2 at atomic resolution.
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Affiliation(s)
- S L Kazmirski
- Department of Medicinal Chemistry, University of Washington, Seattle, WA 98195-7610, USA
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Abstract
We found that a mutant, Bcl-X(L)(F131V), which was previously reported to have impaired binding capacity, can bind to Bax almost as strongly as wild-type Bcl-X(L). In the absence of detergent, the Bcl-X(L)(F131V) mutant adopts the same conformation as wild-type Bcl-X(L), as determined by circular dichroism spectroscopy and size-exclusion chromatography. However, non-ionic detergent induces a conformational change in the Bcl-X(L)(F131V) mutant and causes it to lose Bax-binding capacity. Wild-type Bcl-X(L), on the other hand, is more resistant to detergent-induced effects and retains its ability to bind Bax in the presence of detergent. Since it has been shown that the Bcl-X(L)(F131V) mutant has nearly the same anti-apoptotic activity as wild-type Bcl-X(L), it would be likely that the Bcl-X(L)(F131V) mutant can adopt the wild-type conformation, rather than the detergent-induced conformational state and can bind to Bax in vivo. Therefore, our data demonstrated that non-ionic detergent can have unpredicted effects on protein conformation, differential effects on wild-type and mutant Bcl-X(L) proteins in this case and may cause complications in the interpretation of in vitro binding studies.
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Affiliation(s)
- Y J Tan
- Institute of Molecular and Cell Biology, 30 Medical Drive, Singapore 117609, Republic of Singapore.
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Abstract
We are investigating compounds that could be useful in the treatment of neoplastic lesions of the cervix by acting on the oncoprotein E6 of human papillomavirus-16. The E6 protein contains two potential zinc-binding domains that are required for most of its functions. We have published tests that measure (i) the release of zinc ions after chemical alteration of the cysteine groups of these zinc-binding domains (TSQ assay), (ii) the interaction of E6 with the cellular proteins E6AP and E6BP (BIACORE assay), and (iii) the viability of tumor cell lines that require the continuous expression of HPV oncoproteins (WST1 assay). Based on these tests, we identified 4.4'-dithiodimorpholine as a potential lead compound. In this study we examined whether the dithiobisamine moiety of 4,4'-dithiodimorpholine may be an important molecular prerequisite for further drug development in this system. We have evaluated 59 new substances including organic disulfides and those containing the dithiobisamine moiety, as well as structural analogues. The compounds with significant reactivity in all three assays were observed only for dithiobisamine derivatives with saturated cyclic amines and aryl substituted piperazines. The identity of these substances suggests that the N-S-S-N moiety is necessary but not sufficient for reactivity in our assays, and that dithiobisamine based substances are useful as lead compounds that target the cysteine groups of HPV-16 E6 zinc fingers.
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Affiliation(s)
- W Beerheide
- Drug Screen Development Laboratory, Institute of Molecular and Cell Biology, Singapore.
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Beerheide W, Tan YJ, Teng E, Ting AE, Jedpiyawongse A, Srivatanakul P. Downregulation of proapoptotic proteins Bax and Bcl-X(S) in p53 overexpressing hepatocellular carcinomas. Biochem Biophys Res Commun 2000; 273:54-61. [PMID: 10873563 DOI: 10.1006/bbrc.2000.2891] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
As the occurrence of structural p53 mutations in hepatocellular carcinoma (HCC) in Thailand was previously reported to be much lower than that found in other high-incidence HCC areas, we analyzed 16 HCC samples from Thailand to determine the expression and functionality of p53 protein. We observed the overexpression of p53 protein in 69% of HCC, despite the prevalence of the wild-type p53 gene. However, the overexpressed p53 protein was nonfunctional as suggested by its inability to modulate the expressions of several p53 effector proteins (p21 and Bcl-2 family proteins). In addition, we observed significant underexpression of two proapoptotic proteins, Bax and Bcl-X(S), in 81% (P = 0.02) and 64% (P = 0.03) of HCC, respectively. Consequently, the ratios of proapoptotic to antiapoptotic BCL-2 family proteins were reduced in 88% of the HCC tumor tissues when compared to normal tissues, such that the rheostat between BCL-2 family proteins is strongly skewed toward enhanced cell survival in the tumor cells.
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Affiliation(s)
- W Beerheide
- Institute of Molecular and Cell Biology, 30 Medical Drive, Singapore, 117609, Republic of Singapore
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Abstract
Recent results on the 102 residue protein U1A show that protein aggregation is not always slow and irreversible but may take place transiently in refolding studies on a millisecond time scale. In this study we observe a similar aggregation behavior with the classical two-state protein CI2. Since both U1A and CI2 appear to fold directly from the coil at low protein concentrations, it is likely that the aggregates also form directly from the coil. This is in contrast to the behavior of larger multistate proteins where aggregation occurs in connection to "sticky" intermediates.
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Affiliation(s)
- M Silow
- Department of Biochemistry, Chemical Centre, Lund University, Sweden
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Beerheide W, Bernard HU, Tan YJ, Ganesan A, Rice WG, Ting AE. Potential drugs against cervical cancer: zinc-ejecting inhibitors of the human papillomavirus type 16 E6 oncoprotein. J Natl Cancer Inst 1999; 91:1211-20. [PMID: 10413422 DOI: 10.1093/jnci/91.14.1211] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND The principal agent in the etiology of cervical cancer, i.e., human papillomavirus (HPV) type 16, encodes three oncoproteins, E5, E6, and E7. Structural and mutational studies have identified two potential zinc-finger domains as critical for E6 protein function. We investigated several assays to identify and characterize compounds that interfere with the binding of zinc to E6. METHODS Thirty-six compounds were selected on the basis of their structure, which would facilitate their participation in sulfhydryl residue-specific redox reactions, and were tested for their ability to release zinc from E6 protein. The zinc-ejecting compounds were then tested for their ability to inhibit E6 binding to E6-associated protein (E6AP) and E6-binding protein (E6BP), two coactivators of E6-mediated cellular transformation. The binding of E6 to E6BP and E6AP was measured by use of surface plasmon resonance (a technique that monitors molecular interactions by measuring changes in refractive index) and by use of in vitro translation assays. The compounds were also tested for their effects on the viability of HPV-containing cell lines. RESULTS Nine of the 36 tested compounds ejected zinc from E6. Two of the nine compounds inhibited the interaction of E6 with E6AP and E6BP, and one of these two, 4, 4'-dithiodimorpholine, selectively inhibited cell viability and induced higher levels of p53 protein (associated with the induction of apoptosis [programmed cell death]) in tumorigenic HPV-containing cells. CONCLUSION We have described assay systems to identify compounds, such as 4,4'-dithiodimorpholine, that can potentially interfere with the biology and pathology of HPV. These assay systems may be useful in the development of drugs against cervical cancer, genital warts, and asymptomatic infections by genital HPVs.
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Affiliation(s)
- W Beerheide
- Screening for Novel Inhibitors Laboratory, Institute of Molecular and Cell Biology, Singapore, Republic of Singapore
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Abstract
The overexpression of Bax, a member of the Bcl-2 family, promotes cell death and the dimerization (or oligomerization) of Bax has been shown to be important for its function. Using size-exclusion chromatography and in vitro cross-linking experiments, we demonstrated that Bax exists mainly as a large oligomer of approximately 30 monomeric units. Furthermore, several binding assays demonstrated that Bcl-XL, an anti-apoptotic member of the Bcl-2 family, can bind to the oligomeric form of Bax without requiring Bax to dissociate to monomers.
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Affiliation(s)
- Y J Tan
- Institute of Molecular and Cell Biology, Singapore
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Oliveberg M, Tan YJ, Silow M, Fersht AR. The changing nature of the protein folding transition state: implications for the shape of the free-energy profile for folding. J Mol Biol 1998; 277:933-43. [PMID: 9545382 DOI: 10.1006/jmbi.1997.1612] [Citation(s) in RCA: 119] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
According to landscape theory proteins do not fold by localised pathways, but find their native conformation by a progressive organisation of an ensemble of partly folded structures down a folding funnel. Here, we use kinetics and protein engineering to investigate the shape of the free-energy profile for two-state folding, which is the macroscopic view of the funnel process for small and rapidly folding proteins. Our experiments are based mainly on structural changes of the transition state of chymotrypsin inhibitor 2 (CI2) upon destabilisation with temperature and GdnHCl. The transition state ensemble of CI2 is a localised feature in the free-energy profile that is sharply higher than the other parts of the activation barrier. The relatively fixed position of the CI2 transition state on the reaction coordinate makes it easy to characterise but contributes also to overshadow the rest of the free-energy profile, the shape of which is inaccessible for analysis. Results from mutants of CI2 and comparison with other two-state proteins, however, point at the possibility that the barrier for folding is generally broad and that localised transition states result from minor ripples in the free-energy profile. Accordingly, variabilities in the folding kinetics may not indicate different folding mechanisms, but could be accounted for by various degrees of ruggedness on top of very broad activation barriers for folding. The concept is attractive since it summarises a wide range of folding data which have previously seemed unrelated. It is also supported by theory. Consistent with experiment, broad barriers predict that new transition state ensembles are exposed upon extreme destabilisation or radical mutations.
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Affiliation(s)
- M Oliveberg
- Biochemistry, Chemical Centre, S-221 00 Lund, Sweden
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Tan YJ, Oliveberg M, Otzen DE, Fersht AR. The rate of isomerisation of peptidyl-proline bonds as a probe for interactions in the physiological denatured state of chymotrypsin inhibitor 2. J Mol Biol 1997; 269:611-22. [PMID: 9217264 DOI: 10.1006/jmbi.1997.1043] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
There are four peptidyl-proline bonds in the 64-residue protein chymotrypsin inhibitor 2 (CI2), all of which are in the trans conformation in the native structure. The isomerisation of one or more of these peptidyl-proline bonds to the cis conformation in the denatured state gives rise to heterogeneity, leading to both fast and slow-folding species. The refolding of the fast-folding species, which has all trans peptidyl-proline bonds, is much faster than that of the slow-folding species, which have one or more cis peptidyl-proline bonds. In CI2, the slow-folding species can be classified into two groups by their rates of refolding, temperature-dependence, pH-dependence and [GdmCl]-dependence of the rate constants and the effect of peptidyl-prolyl isomerase on the rate constants. The replacement of Pro6 by Ala removes one of the slow refolding phases, suggesting that the cis peptidyl-Pro6 conformation is solely responsible for one of the slow-folding species. Pro6 is located in a region of the protein where non-random interactions have been found in a series of N-terminal fragments of CI2 (residues 1 to 13, 1 to 25, 1 to 28 and 1 to 40). In addition, NMR studies on a mutant fragment, (1-40)T3A, have confirmed that this non-native interaction is associated with the bulky side-chain of Trp5. The atypical rate of cis to trans isomerisation of the peptidyl-Pro bond is indicative of the presence of a similar hydrophobic cluster in the physiological denatured state of intact CI2.
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Affiliation(s)
- Y J Tan
- Cambridge Centre for Protein Engineering, UK
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Tan YJ, Oliveberg M, Fersht AR. Titration properties and thermodynamics of the transition state for folding: comparison of two-state and multi-state folding pathways. J Mol Biol 1996; 264:377-89. [PMID: 8951383 DOI: 10.1006/jmbi.1996.0647] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
CI2 folds and unfolds as a single cooperative unit by simple two-state kinetics, which enables the properties of the transition state to be measured from both the forward and backward rate constants. We have examined how the free energy of the transition state for the folding of chymotrypsin inhibitor 2 (CI2) changes with pH and temperature. In addition to the standard thermodynamic quantities, we have measured the overall acid-titration properties of the transition state and its heat capacity relative to both the denatured and native states. We were able to determine the latter by a method analogous to a well-established procedure for measuring the change in heat capacity for equilibrium unfolding: the enthalpy of activation of unfolding at different values of acid pH were plotted against the average temperature of each determination. Our results show that the transition state of CI2 has lost most of the electrostatic and van der Waals' interactions that are found in the native state, but it remains compact and this prevents water molecules from entering some parts of the hydrophobic core. The properties of the transition state of CI2 are then compared with the major folding transition state of the larger protein barnase, which folds by a multi-state mechanism, with the accumulation of a partly structured intermediate (Dphys or I). CI2 folds from a largely unstructured denatured state under physiological conditions via a transition state which is compact but relatively uniformly unstructured, with tertiary and secondary structure being formed in parallel. We term this an expanded pathway. Conversely, barnase folds from a largely structured denatured state in which elements of structure are well formed through a transition state that has islands of folded elements of structure. We term this a compact pathway. These two pathways may correspond to the two extreme ends of a continuous spectrum of protein folding mechanisms. Although the properties of the two transition states are very different, the activation barrier for folding (Dphys-->++) is very similar for both proteins.
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Affiliation(s)
- Y J Tan
- Cambridge Centre for Protein Engineering, UK
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Abstract
We show in this study that the ionisation equilibria of denatured proteins in pure water are inconsistent with the "fully-unfolded" conformation being an extended coil where the residues are isolated from one another by the intervening solvent. The effects of acid and salt on the stability of the barley chymotrypsin inhibitor 2 (CI2) were investigated and the pKA-values of all carboxylate residues in the native protein were determined by NMR. A comparison of the experimentally determined pH-dependence of the protein stability and that calculated using observed pKA-values in the native state, reveals that the pKA-values in the denatured state are, on average, 0.3 pH units lower than those of model compounds. An increase in ionic strength eliminates these pKA shifts in the denatured state. This shows that there are electrostatic interactions in the denatured state of CI2. Since previous studies on barnase and the Ovomucoid Third Domain also report anomalous titration behaviours of the denatured states, it appears that perturbed pKA-values in the denatured state is a general phenomenon, indicating that the unfolded conformation in pure water is a fairly compact species. In addition, we used a mutational approach to determine the pKA-values of a carboxylate group in both the native and denatured states. The pKA-value in the native state obtained by this method is in precise agreement with that obtained by NMR.
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Affiliation(s)
- Y J Tan
- Cambridge Centre for Protein Engineering, England, U.K
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Abstract
Although the rates of chemical reactions become faster with increasing temperature, the converse may be observed with protein-folding reactions. The rate constant for folding initially increases with temperature, goes through a maximum, and then decreases. The activation enthalpy is thus highly temperature dependent because of a large change in specific heat (delta Cp). Such a delta Cp term is usually presumed to be a consequence of a large decrease in exposure of hydrophobic surfaces to water as the reaction proceeds from the denatured state to the transition state for folding: the hydrophobic side chains are surrounded by "icebergs" of water that melt with increasing temperature, thus making a large contribution to the Cp of the denatured state and a smaller one to the more compact transition state. The rate could also be affected by temperature-induced changes in the conformational population of the ground state: the heat required for the progressive melting of residual structure in the denatured state will contribute to delta Cp. By examining two proteins with different refolding mechanisms, we are able to find both of these two processes; barley chymotrypsin inhibitor 2, which refolds from a highly unfolded state, fits well to a hydrophobic interaction model with a constant delta Cp of activation, whereas barnase, which refolds from a more structured denatured state, deviates from this ideal behavior.
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Affiliation(s)
- M Oliveberg
- Cambridge Center for Protein Engineering, United Kingdom
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Qu Y, Tan YJ, Qian CZ. [Preliminary report of observation on therapeutic effect in chronic active hepatitis treated with short wave infrared information radiotherapy]. Zhong Xi Yi Jie He Za Zhi 1986; 6:90-2, 68. [PMID: 2425992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Wang GX, Tan YJ, Xia QG. Brain base abnormal vascular network. Clinical and radiologic analysis of 27 cases. Chin Med J (Engl) 1983; 96:583-90. [PMID: 6416755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
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