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Abstract
For diabetics, taking regular blood glucose measurements is crucial. However, traditional blood glucose monitoring methods are invasive and unfriendly to diabetics. Recent studies have proposed a biofluid-based glucose sensing technique that creatively combines wearable devices with noninvasive glucose monitoring technology to enhance diabetes management. This is a revolutionary advance in the diagnosis and management of diabetes, reflects the thoughtful modernization of medicine, and promotes the development of digital medicine. This paper reviews the research progress of noninvasive continuous blood glucose monitoring (CGM), with a focus on the biological liquids that replace blood in monitoring systems, the technical principles of continuous noninvasive glucose detection, and the output and calibration of sensor signals. In addition, the existing limits of noninvasive CGM systems and prospects for the future are discussed. This work serves as a resource for further promoting the development of noninvasive CGM systems.
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Affiliation(s)
- Yilin Li
- Department of Toxicology and Sanitary Chemistry, School of Public Health, Capital Medical University, Beijing, 100069, PR China
- Beijing Key Laboratory of Environmental Toxicology, Capital Medical University, Beijing, 100069, PR China
| | - Yueyue Chen
- Department of Toxicology and Sanitary Chemistry, School of Public Health, Capital Medical University, Beijing, 100069, PR China
- Beijing Key Laboratory of Environmental Toxicology, Capital Medical University, Beijing, 100069, PR China
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Effect of mucin on β-lactoglobulin and lactose interaction. J DAIRY RES 2023. [DOI: 10.1017/s0022029923000092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Abstract
Abstract
Functions of mucin, as the major macromolecular component in saliva or gastric fluids, are drawing increasing attention in the context of understanding the oral processing or digestion of dairy foods at the molecular level. This study was designed to investigate the interactions between β-lactoglobulin (BLG)-lactose, mucin-lactose and BLG-lactose-mucin at the molecular level under different temperature and pH conditions using fluorescence spectroscopy in combination with scanning electron microscopes (sem). It is the first study of its kind. There was no lactose-dependent quenching on BLG fluorophore in the range of 0–10 mM lactose concentration. On the contrary, there was a continuous increase in the fluorescence intensity of the BLG protein when the lactose concentration increased, especially at 25°C. BLG-lactose complex became thermally unstable at 37 and 45°C. Moreover, BLG exhibited a pH dependent conformational change and had higher fluorescence intensity at pH 3 than pH 6.8. The fluorescence result was in correspondence with sem images where we observed lactose crystals gathering around and on the BLG molecule, but lactose molecules could not be seen in the presence of mucin. It was anticipated that mucin molecules interacted with BLG-lactose complex via electrostatic attraction and formed an extra protective layer around the BLG molecules to avoid solvent exposure.
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Fiedorova K, Augustynek M, Kubicek J, Kudrna P, Bibbo D. Review of present method of glucose from human blood and body fluids assessment. Biosens Bioelectron 2022; 211:114348. [DOI: 10.1016/j.bios.2022.114348] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 03/22/2022] [Accepted: 05/05/2022] [Indexed: 12/15/2022]
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Valero M, Pola P, Falaiye O, Ingram KH, Zhao L, Shahriar H, Ahamed SI. Development of a Noninvasive Blood Glucose Monitoring System Prototype: Pilot Study. JMIR Form Res 2022; 6:e38664. [PMID: 36018623 PMCID: PMC9463623 DOI: 10.2196/38664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 07/06/2022] [Accepted: 07/09/2022] [Indexed: 11/26/2022] Open
Abstract
Background Diabetes mellitus is a severe disease characterized by high blood glucose levels resulting from dysregulation of the hormone insulin. Diabetes is managed through physical activity and dietary modification and requires careful monitoring of blood glucose concentration. Blood glucose concentration is typically monitored throughout the day by analyzing a sample of blood drawn from a finger prick using a commercially available glucometer. However, this process is invasive and painful, and leads to a risk of infection. Therefore, there is an urgent need for noninvasive, inexpensive, novel platforms for continuous blood sugar monitoring. Objective Our study aimed to describe a pilot test to test the accuracy of a noninvasive glucose monitoring prototype that uses laser technology based on near-infrared spectroscopy. Methods Our system is based on Raspberry Pi, a portable camera (Raspberry Pi camera), and a visible light laser. The Raspberry Pi camera captures a set of images when a visible light laser passes through skin tissue. The glucose concentration is estimated by an artificial neural network model using the absorption and scattering of light in the skin tissue. This prototype was developed using TensorFlow, Keras, and Python code. A pilot study was run with 8 volunteers that used the prototype on their fingers and ears. Blood glucose values obtained by the prototype were compared with commercially available glucometers to estimate accuracy. Results When using images from the finger, the accuracy of the prototype is 79%. Taken from the ear, the accuracy is attenuated to 62%. Though the current data set is limited, these results are encouraging. However, three main limitations need to be addressed in future studies of the prototype: (1) increase the size of the database to improve the robustness of the artificial neural network model; (2) analyze the impact of external factors such as skin color, skin thickness, and ambient temperature in the current prototype; and (3) improve the prototype enclosure to make it suitable for easy finger and ear placement. Conclusions Our pilot study demonstrates that blood glucose concentration can be estimated using a small hardware prototype that uses infrared images of human tissue. Although more studies need to be conducted to overcome limitations, this pilot study shows that an affordable device can be used to avoid the use of blood and multiple finger pricks for blood glucose monitoring in the diabetic population.
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Affiliation(s)
- Maria Valero
- Department of Information Technology, Kennesaw State University, Marietta, GA, United States
| | - Priyanka Pola
- Department of Information Technology, Kennesaw State University, Marietta, GA, United States
| | - Oluwaseyi Falaiye
- Department of Software Engineering and Game Development, Kennesaw State University, Marietta, GA, United States
| | - Katherine H Ingram
- Department of Exercise Science and Sport Management, Kennesaw State University, Kennesaw, GA, United States
| | - Liang Zhao
- Department of Information Technology, Kennesaw State University, Marietta, GA, United States
| | - Hossain Shahriar
- Department of Information Technology, Kennesaw State University, Marietta, GA, United States
| | - Sheikh Iqbal Ahamed
- Department of Computer Science, Marquette University, Milwaukee, WI, United States
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Photophysical Properties of BADAN Revealed in the Study of GGBP Structural Transitions. Int J Mol Sci 2021; 22:ijms222011113. [PMID: 34681772 PMCID: PMC8540541 DOI: 10.3390/ijms222011113] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 10/06/2021] [Accepted: 10/09/2021] [Indexed: 01/14/2023] Open
Abstract
The fluorescent dye BADAN (6-bromoacetyl-2-dimetylaminonaphtalene) is widely used in various fields of life sciences, however, the photophysical properties of BADAN are not fully understood. The study of the spectral properties of BADAN attached to a number of mutant forms of GGBP, as well as changes in its spectral characteristics during structural changes in proteins, allowed to shed light on the photophysical properties of BADAN. It was shown that spectral properties of BADAN are determined by at least one non-fluorescent and two fluorescent isomers with overlapping absorbing bands. It was found that BADAN fluorescence is determined by the unsolvated "PICT" (planar intramolecular charge transfer state) and solvated "TICT" (twisted intramolecular charge transfer state) excited states. While "TICT" state can be formed both as a result of the "PICT" state solvation and as a result of light absorption by the solvated ground state of the dye. BADAN fluorescence linked to GGBP/H152C apoform is quenched by Trp 183, but this effect is inhibited by glucose intercalation. New details of the changes in the spectral characteristics of BADAN during the unfolding of the protein apo and holoforms have been obtained.
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Periplasmic-binding protein-based biosensors and bioanalytical assay platforms: Advances, considerations, and strategies for optimal utility. TALANTA OPEN 2021. [DOI: 10.1016/j.talo.2021.100038] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Mai L, Tran T, Bui Q, Nhac-Vu HT. A novel nanohybrid of gold nanoparticles anchored copper sulfide nanosheets as sensitive sensor for nonenzymatic glucose detection. Colloids Surf A Physicochem Eng Asp 2019. [DOI: 10.1016/j.colsurfa.2019.123936] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Hassan HU, Bang O, Janting J. Polymer Optical Fiber Tip Mass Production Etch Mechanism to Achieve CPC Shape for Improved Biosensor Performance. SENSORS 2019; 19:s19020285. [PMID: 30642022 PMCID: PMC6359282 DOI: 10.3390/s19020285] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 01/04/2019] [Accepted: 01/08/2019] [Indexed: 12/03/2022]
Abstract
We report on a simple chemical etching method that enables nonlinear tapering of Polymer Optical Fiber (POF) tips to manufacture Compound Parabolic Concentrator (CPC) fiber tips. We show that, counter-intuitively, nonlinear tapering can be achieved by first etching the core and not the cladding. The etching mechanism is modelled and etched tips are characterized both geometrically and optically in a fluorescence glucose sensor chemistry. A Zemax model of the CPC tipped sensor predicts an optimal improvement in light capturing efficiency of a factor of 3.96 compared to the conventional sensor with a plane-cut fiber tip. A batch of eight CPC fiber tips has been manufactured by the chemical etching method. The batch average showed an increase of a factor of 3.16, which is only 20% less than the predicted value. The method is reproducible and can be up-scaled for mass production.
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Affiliation(s)
- Hafeez Ul Hassan
- DTU Fotonik, Department of Photonics Engineering, Technical University of Denmark, Frederiksborgvej 399, 4000 Roskilde, Denmark.
| | - Ole Bang
- DTU Fotonik, Department of Photonics Engineering, Technical University of Denmark, Ørsteds Plads, 2800 Kgs. Lyngby, Denmark.
| | - Jakob Janting
- DTU Fotonik, Department of Photonics Engineering, Technical University of Denmark, Ørsteds Plads, 2800 Kgs. Lyngby, Denmark.
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Kolanowski JL, Liu F, New EJ. Fluorescent probes for the simultaneous detection of multiple analytes in biology. Chem Soc Rev 2018; 47:195-208. [DOI: 10.1039/c7cs00528h] [Citation(s) in RCA: 215] [Impact Index Per Article: 35.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
This review identifies and discusses fluorescent sensors that are capable of simultaneously reporting on the presence of two analytes for biological application.
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Affiliation(s)
- Jacek L. Kolanowski
- School of Chemistry
- The University of Sydney
- Australia
- Institute of Bio-organic Chemistry
- Polish Academy of Sciences
| | - Fei Liu
- State Key Laboratory of Applied Microbiology Southern China
- Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application
- Guangdong Institute of Microbiology
- Guangdong
- People's Republic of China
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Tiangco C, Andar A, Quarterman J, Ge X, Sevilla F, Rao G, Stinchcomb A, Bunge A, Tolosa L. Measuring transdermal glucose levels in neonates by passive diffusion: an in vitro porcine skin model. Anal Bioanal Chem 2017; 409:3475-3482. [PMID: 28283718 DOI: 10.1007/s00216-017-0289-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 02/01/2017] [Accepted: 02/28/2017] [Indexed: 11/30/2022]
Abstract
Current glucose monitoring techniques for neonates rely heavily on blood glucose monitors which require intermittent blood collection through skin-penetrating pricks on the heel or fingers. This procedure is painful and often not clinically conducive, which presents a need for a noninvasive method for monitoring glucose in neonates. Our motivation for this study was to develop an in vitro method for measuring passive diffusion of glucose in premature neonatal skin using a porcine skin model. Such a model will allow us to initially test new devices for noninvasive glucose monitoring without having to do in vivo testing of newborns. The in vitro model is demonstrated by comparing uncompromised and tape-stripped skin in an in-line flow-through diffusion apparatus with glucose concentrations that mimic the hypo-, normo-, and hyper-glycemic conditions in the neonate (2.0, 5.0, and 20 mM, respectively). Transepidermal water loss (TEWL) of the tape-stripped skin was approximately 20 g m-2 h-1, which closely mimics TEWL for neonatal skin at about 190 days post-conceptional age. The tape-stripped skin showed a >15-fold increase in glucose diffusion compared to the uncompromised skin. The very small concentrations of collected glucose were measured with a highly selective and highly sensitive fluorescent glucose biosensor based on the glucose binding protein (GBP). The demonstrated method of glucose determination is noninvasive and painless, which makes it especially desirable for glucose testing in neonates and children. This study is an important step towards an in vitro model for noninvasive real-time glucose monitoring that may be easily transferred to the clinic for glucose monitoring in neonates. Graphical Abstract Glucose diffusion through model skin was measured using an in-line flow-through diffusion apparatus with glucose solutions mimicking hypo-, normo- and hyperglycemia in the neonate. Phosphate buffered saline was added to the top chamber and the glucose that diffused through the model skin into the buffer was measured using a fluorescent glucose binding protein biosensor.
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Affiliation(s)
- Cristina Tiangco
- Center for Advanced Sensor Technologycsm, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD, 21250, USA.,The Graduate School, University of Santo Tomas, España Boulevard, 1015, Manila, Philippines
| | - Abhay Andar
- Center for Advanced Sensor Technologycsm, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD, 21250, USA.,Department of Pharmaceutical Sciences, University of Maryland, 20 North Pine Street, Baltimore, MD, 21201, USA
| | - Juliana Quarterman
- Department of Pharmaceutical Sciences, University of Maryland, 20 North Pine Street, Baltimore, MD, 21201, USA
| | - Xudong Ge
- Center for Advanced Sensor Technologycsm, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD, 21250, USA
| | - Fortunato Sevilla
- The Graduate School, University of Santo Tomas, España Boulevard, 1015, Manila, Philippines
| | - Govind Rao
- Center for Advanced Sensor Technologycsm, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD, 21250, USA
| | - Audra Stinchcomb
- Department of Pharmaceutical Sciences, University of Maryland, 20 North Pine Street, Baltimore, MD, 21201, USA
| | - Annette Bunge
- Chemical and Biological Engineering Department, Colorado School of Mines, 1500 Illinois Street, Golden, CO, 80401, USA
| | - Leah Tolosa
- Center for Advanced Sensor Technologycsm, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD, 21250, USA.
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Hassan HU, Lacraz A, Kalli K, Bang O. Femtosecond laser micromachining of compound parabolic concentrator fiber tipped glucose sensors. JOURNAL OF BIOMEDICAL OPTICS 2017; 22:37003. [PMID: 28290597 DOI: 10.1117/1.jbo.22.3.037003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 02/21/2017] [Indexed: 06/06/2023]
Abstract
We report on highly accurate femtosecond (fs) laser micromachining of a compound parabolic concentrator (CPC) fiber tip on a polymer optical fiber (POF). The accuracy is reflected in an unprecedented correspondence between the numerically predicted and experimentally found improvement in fluorescence pickup efficiency of a Förster resonance energy transfer-based POF glucose sensor. A Zemax model of the CPC-tipped sensor predicts an optimal improvement of a factor of 3.96 compared to the sensor with a plane-cut fiber tip. The fs laser micromachined CPC tip showed an increase of a factor of 3.5, which is only 11.6% from the predicted value. Earlier state-of-the-art fabrication of the CPC-shaped tip by fiber tapering was of so poor quality that the actual improvement was 43% lower than the predicted improvement of the ideal CPC shape.
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Affiliation(s)
- Hafeez Ul Hassan
- Technical University of Denmark, Denmark Technical University Fotonik, Department of Photonics Engineering, Lyngby, Denmark
| | - Amédée Lacraz
- Cyprus University of Technology, Nanophotonics Research Group, Department of Electrical Engineering, Computer Engineering and Informatics, Limassol, Cyprus
| | - Kyriacos Kalli
- Cyprus University of Technology, Nanophotonics Research Group, Department of Electrical Engineering, Computer Engineering and Informatics, Limassol, Cyprus
| | - Ole Bang
- Technical University of Denmark, Denmark Technical University Fotonik, Department of Photonics Engineering, Lyngby, Denmark
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del Barrio M, Cases R, Cebolla V, Hirsch T, de Marcos S, Wilhelm S, Galbán J. A reagentless enzymatic fluorescent biosensor for glucose based on upconverting glasses, as excitation source, and chemically modified glucose oxidase. Talanta 2016; 160:586-591. [DOI: 10.1016/j.talanta.2016.07.062] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Revised: 07/22/2016] [Accepted: 07/25/2016] [Indexed: 11/27/2022]
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Sakadžić S, Lee J, Boas DA, Ayata C. High-resolution in vivo optical imaging of stroke injury and repair. Brain Res 2015; 1623:174-92. [PMID: 25960347 PMCID: PMC4569527 DOI: 10.1016/j.brainres.2015.04.044] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 04/21/2015] [Accepted: 04/22/2015] [Indexed: 12/15/2022]
Abstract
Central nervous system (CNS) function and dysfunction are best understood within a framework of interactions between neuronal, glial and vascular compartments comprising the neurovascular unit (NVU), all of which contribute to stroke-induced CNS injury, plasticity, repair, and recovery. Recent advances in in vivo optical microscopy have enabled us to observe and interrogate cells and their processes with high spatial resolution in real time and in their natural environment deep in the brain tissue. Here, we review some of these state-of-the-art imaging techniques with an emphasis on imaging the interactions among the constituents of the NVU during ischemic injury and repair in small animal models. This article is part of a Special Issue entitled SI: Cell Interactions In Stroke.
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Affiliation(s)
- Sava Sakadžić
- Optics Division, MHG/MIT/HMS Athinoula A Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA.
| | - Jonghwan Lee
- Optics Division, MHG/MIT/HMS Athinoula A Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA
| | - David A Boas
- Optics Division, MHG/MIT/HMS Athinoula A Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA
| | - Cenk Ayata
- Neurovascular Research Laboratory, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA; Stroke Service and Neuroscience Intensive Care Unit, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
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Kameya M, Sakaguchi-Mikami A, Ferri S, Tsugawa W, Sode K. Advancing the development of glycated protein biosensing technology: next-generation sensing molecules. J Diabetes Sci Technol 2015; 9:183-91. [PMID: 25627465 PMCID: PMC4604589 DOI: 10.1177/1932296814565784] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Research advances in biochemical molecules have led to the development of convenient and reproducible biosensing molecules for glycated proteins, such as those based on the enzymes fructosyl amino acid oxidase (FAOX) or fructosyl peptide oxidase (FPOX). Recently, more attractive biosensing molecules with potential applications in next-generation biosensing of glycated proteins have been aggressively reported. We review 2 such molecules, fructosamine 6-kinase (FN6K) and fructosyl amino acid-binding protein, as well as their recent applications in the development of glycated protein biosensing systems. Research on FN6K and fructosyl amino acid-binding protein has been opening up new possibilities for the development of highly sensitive and proteolytic-digestion-free biosensing systems for glycated proteins.
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Affiliation(s)
- Miho Kameya
- Department of Biotechnology & Life Science, Graduate School of Engineering, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Akane Sakaguchi-Mikami
- Department of Medical Technology, School of Health Sciences, Graduate School of Bionics, Computer and Media Sciences, Tokyo University of Technology, Tokyo, Japan
| | - Stefano Ferri
- Department of Biotechnology & Life Science, Graduate School of Engineering, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Wakako Tsugawa
- Department of Biotechnology & Life Science, Graduate School of Engineering, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Koji Sode
- Department of Biotechnology & Life Science, Graduate School of Engineering, Tokyo University of Agriculture and Technology, Tokyo, Japan Ultizyme International Ltd, Tokyo, Japan
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15
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Pickup JC. Banting Memorial Lecture 2014* Technology and diabetes care: appropriate and personalized. Diabet Med 2015; 32:3-13. [PMID: 25345658 DOI: 10.1111/dme.12613] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/20/2014] [Indexed: 12/11/2022]
Abstract
Continuous subcutaneous insulin infusion was initially developed as a research procedure in the 1970s but quickly became a routine treatment for selected people with Type 1 diabetes. Continuous subcutaneous insulin infusion and other diabetes technologies, such as continuous glucose monitoring, are now an established and evidence-based part of diabetes care, but there has been some confusion about effectiveness and best use, particularly because of conflicting results from meta-analyses. This is because literature summary meta-analyses (including all trials) are inappropriate for therapeutic and economic decision-making; such meta-analyses should only include trials representative of groups likely to benefit. For example, for continuous subcutaneous insulin infusion, this would be those with continued disabling hypoglycaemia or elevated HbA1c levels. Alternatively, individual patient data meta-analysis allows modelling of covariates that determine effect size, e.g. in the case of continuous glucose monitoring, baseline HbA1c and frequency of sensor usage. Diabetes technology is therefore an example of personalized medicine, where evaluation and use should be both appropriate and targeted. This will also apply to future technologies such as new 'patch' pumps for Type 2 diabetes, closed-loop insulin delivery systems and nanomedicine applications in diabetes that we are currently researching. These include fluorescence lifetime-based non-invasive glucose monitoring and nanoencapsulation of islets for improved post-transplant survival.
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Affiliation(s)
- J C Pickup
- Diabetes Research Group, King's College London School of Medicine, Guy's Hospital, London, UK
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Helassa N, Garnett JP, Farrant M, Khan F, Pickup JC, Hahn KM, MacNevin CJ, Tarran R, Baines DL. A novel fluorescent sensor protein for detecting changes in airway surface liquid glucose concentration. Biochem J 2014; 464:213-20. [PMID: 25220254 PMCID: PMC4357280 DOI: 10.1042/bj20141041] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Both lung disease and elevation of blood glucose are associated with increased glucose concentration (from 0.4 to ~4.0 mM) in the airway surface liquid (ASL). This perturbation of ASL glucose makes the airway more susceptible to infection by respiratory pathogens. ASL is minute (~1 μl/cm(2)) and the measurement of glucose concentration in the small volume ASL is extremely difficult. Therefore, we sought to develop a fluorescent biosensor with sufficient sensitivity to determine glucose concentrations in ASL in situ. We coupled a range of environmentally sensitive fluorophores to mutated forms of a glucose/galactose-binding protein (GBP) including H152C and H152C/A213R and determined their equilibrium binding properties. Of these, GBP H152C/A213R-BADAN (Kd 0.86 ± 0.01 mM, Fmax/F0 3.6) was optimal for glucose sensing and in ASL increased fluorescence when basolateral glucose concentration was raised from 1 to 20 mM. Moreover, interpolation of the data showed that the glucose concentration in ASL was increased, with results similar to that using glucose oxidase analysis. The fluorescence of GBP H152C/A213R-BADAN in native ASL from human airway epithelial cultures in situ was significantly increased over time when basolateral glucose was increased from 5 to 20 mM. Overall our data indicate that this GBP is a useful tool to monitor glucose homoeostasis in the lung.
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Affiliation(s)
- Nordine Helassa
- Institute of Cardiovascular and Cell Science, St George’s, University of London, London SW17 0RE, U.K
| | - James P. Garnett
- Institute for Infection and Immunity, St George’s, University of London, London SW17 0RE, U.K
| | - Matthew Farrant
- Institute for Infection and Immunity, St George’s, University of London, London SW17 0RE, U.K
| | - Faaizah Khan
- Diabetes Research Group, King’s College London, Guy’s Hospital Campus, London SE1 1UL, U.K
| | - John C. Pickup
- Diabetes Research Group, King’s College London, Guy’s Hospital Campus, London SE1 1UL, U.K
| | - Klaus M. Hahn
- Department of Pharmacology/Cell Biology & Physiology, University of North Carolina, Chapel Hill, NC, 27599 U.S.A
| | - Christopher J. MacNevin
- Department of Pharmacology/Cell Biology & Physiology, University of North Carolina, Chapel Hill, NC, 27599 U.S.A
| | - Robert Tarran
- Department of Pharmacology/Cell Biology & Physiology, University of North Carolina, Chapel Hill, NC, 27599 U.S.A
| | - Deborah L. Baines
- Institute for Infection and Immunity, St George’s, University of London, London SW17 0RE, U.K
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Near-infrared fluorescence glucose sensing based on glucose/galactose-binding protein coupled to 651-Blue Oxazine. Biochem Biophys Res Commun 2013; 438:488-92. [PMID: 23928160 DOI: 10.1016/j.bbrc.2013.07.111] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Accepted: 07/28/2013] [Indexed: 01/14/2023]
Abstract
Near-infrared (NIR) fluorescent dyes that are environmentally sensitive or solvatochromic are useful tools for protein labelling in in vivo biosensor applications such as glucose monitoring in diabetes since their spectral properties are mostly independent of tissue autofluorescence and light scattering, and they offer potential for non-invasive analyte sensing. We showed that the fluorophore 651-Blue Oxazine is polarity-sensitive, with a marked reduction in NIR fluorescence on increasing solvent polarity. Mutants of glucose/galactose-binding protein (GBP) used as the glucose receptor were site-specifically and covalently labelled with Blue Oxazine using click chemistry. Mutants H152C/A213R and H152C/A213R/L238S showed fluorescence increases of 15% and 21% on addition of saturating glucose concentrations and binding constants of 6 and 25mM respectively. Fluorescence responses to glucose were preserved when GBP-Blue Oxazine was immobilised to agarose beads, and the beads were excited by NIR light through a mouse skin preparation studied in vitro. We conclude GBP-Blue Oxazine shows proof-of-concept as a non-invasive continuous glucose sensing system.
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