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Attri K, Chudasama B, Mahajan RL, Choudhury D. Therapeutic potential of lactoferrin-coated iron oxide nanospheres for targeted hyperthermia in gastric cancer. Sci Rep 2023; 13:17875. [PMID: 37857677 PMCID: PMC10587155 DOI: 10.1038/s41598-023-43725-3] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 09/27/2023] [Indexed: 10/21/2023] Open
Abstract
Lactoferrin (LF) is a non-heme iron-binding glycoprotein involved in the transport of iron in blood plasma. In addition, it has many biological functions, including antibacterial, antiviral, antimicrobial, antiparasitic, and, importantly, antitumor properties. In this study, we have investigated the potential of employing lactoferrin-iron oxide nanoparticles (LF-IONPs) as a treatment modality for gastric cancer. The study confirms the formation of LF-IONPs with a spherical shape and an average size of 5 ± 2 nm, embedded within the protein matrix. FTIR and Raman analysis revealed that the Fe-O bond stabilized the protein particle interactions. Further, we conducted hyperthermia studies to ascertain whether the proposed composite can generate a sufficient rise in temperature at a low frequency. The results confirmed that we can achieve a temperature rise of about 7 °C at 242.4 kHz, which can be further harnessed for gastric cancer treatment. The particles were further tested for their anti-cancer activity on AGS cells, with and without hyperthermia. Results indicate that LF-IONPs (10 µg/ml) significantly enhance cytotoxicity, resulting in the demise of 67.75 ± 5.2% of cells post hyperthermia, while also exhibiting an inhibitory effect on cell migration compared to control cells, with the most inhibition observed after 36 h of treatment. These findings suggest the potential of LF-IONPs in targeted hyperthermia treatment of gastric cancer.
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Affiliation(s)
- Komal Attri
- School of Chemistry and Biochemistry, Thapar Institute of Engineering and Technology, Patiala, Punjab, 147004, India
- TIET-VT Centre of Excellence for Emerging Materials, Thapar Institute of Engineering and Technology, Patiala, Punjab, 147004, India
| | - Bhupendra Chudasama
- School of Physics and Material Sciences, Thapar Institute of Engineering and Technology, Patiala, Punjab, 147004, India.
- TIET-VT Centre of Excellence for Emerging Materials, Thapar Institute of Engineering and Technology, Patiala, Punjab, 147004, India.
| | - Roop L Mahajan
- Department of Mechanical Engineering, Department of Materials Science and Engineering, Virginia Tech, Blacksburg, VA, 24061, USA.
- TIET-VT Centre of Excellence for Emerging Materials, Thapar Institute of Engineering and Technology, Patiala, Punjab, 147004, India.
| | - Diptiman Choudhury
- School of Chemistry and Biochemistry, Thapar Institute of Engineering and Technology, Patiala, Punjab, 147004, India.
- TIET-VT Centre of Excellence for Emerging Materials, Thapar Institute of Engineering and Technology, Patiala, Punjab, 147004, India.
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Lee SY, Kim YH, Mahajan RL, Park SJ. Determination of Hydrophobic Dispersive Surface Free Energy of Activated Carbon Fibers Measured by Inverse Gas Chromatographic Technique. Nanomaterials (Basel) 2023; 13:1113. [PMID: 36986007 PMCID: PMC10055709 DOI: 10.3390/nano13061113] [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] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 03/15/2023] [Accepted: 03/16/2023] [Indexed: 06/18/2023]
Abstract
Activated carbon fibers (ACFs) as one of the most important porous carbon materials are widely used in many applications that involve rapid adsorption and low-pressure loss, including air purification, water treatment, and electrochemical applications. For designing such fibers for the adsorption bed in gas and aqueous phases, in-depth comprehension of the surface components is crucial. However, achieving reliable values remains a major challenge due to the high adsorption affinity of ACFs. To overcome this problem, we propose a novel approach to determine London dispersive components (γSL) of the surface free energy of ACFs by inverse gas chromatography (IGC) technique at an infinite dilution. Our data reveal the γSL values at 298 K for bare carbon fibers (CFs) and the ACFs to be 97 and 260-285 mJ·m-2, respectively, which lie in the regime of secondary bonding of physical adsorption. Our analysis indicates that these are impacted by micropores and defects on the carbon surfaces. Comparing the γSL obtained by the traditional Gray's method, our method is concluded as the most accurate and reliable value for the hydrophobic dispersive surface component of porous carbonaceous materials. As such, it could serve as a valuable tool in designing interface engineering in adsorption-related applications.
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Affiliation(s)
- Seul-Yi Lee
- Department of Chemistry, Inha University, 100 Inharo, Incheon 22212, Republic of Korea
| | - Yeong-Hun Kim
- Department of Chemistry, Inha University, 100 Inharo, Incheon 22212, Republic of Korea
| | - Roop L. Mahajan
- Department of Mechanical Engineering and Institute for Critical Technology and Applied Science, Virginia Tech, Blacksburg, VA 24061, USA
| | - Soo-Jin Park
- Department of Chemistry, Inha University, 100 Inharo, Incheon 22212, Republic of Korea
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Lee SY, Lee JH, Kim YH, Mahajan RL, Park SJ. Surface energetics of graphene oxide and reduced graphene oxide determined by inverse gas chromatographic technique at infinite dilution at room temperature. J Colloid Interface Sci 2022; 628:758-768. [DOI: 10.1016/j.jcis.2022.07.183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 07/24/2022] [Accepted: 07/29/2022] [Indexed: 10/16/2022]
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Kaur P, Ghosh S, Bhowmick A, Gadhave K, Datta S, Ghosh A, Garg N, Mahajan RL, Basu B, Choudhury D. Bacterioboat-A novel tool to increase the half-life period of the orally administered drug. Sci Adv 2022; 8:eabh1419. [PMID: 35275724 PMCID: PMC8916724 DOI: 10.1126/sciadv.abh1419] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 01/22/2022] [Indexed: 06/14/2023]
Abstract
The short half-life in the GI tract necessitates an excess of drugs causing side effects of oral formulations. Here, we report the development and deployment of Bacterioboat, which consists of surface-encapsulated mesoporous nanoparticles on metabolically active Lactobacillus reuteri as a drug carrier suitable for oral administration. Bacterioboat showed up to 16% drug loading of its dry weight, intestinal anchorage around alveoli regions, sustained release, and stability in physiological conditions up to 24 hours. In vivo studies showed that oral delivery of 5-fluorouracil leads to increased potency, resulting in improved shrinkage of solid tumors, enhanced life expectancy, and reduced side effects. This novel design and development make this system ideal for orally administrable drugs with low solubility or permeability or both and even making them effective at a lower dose.
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Affiliation(s)
- Parmandeep Kaur
- School of Chemistry and Biochemistry, Thapar Institute of Engineering and Technology, Patiala, Punjab, India
| | - Sandip Ghosh
- Department of Neuroendocrinology and Experimental Hematology, Chittaranjan National Cancer Institute, Kolkata, West Bengal, India
| | - Arghya Bhowmick
- Department of Biochemistry, Bose Institute, EN Block, Sector V, Bidhannagar, Kolkata, West Bengal 700091, India
| | - Kundlik Gadhave
- Indian Institute of Technology (IIT) Mandi, Mandi, Himachal Pradesh, India
| | - Satabdi Datta
- School of Chemistry and Biochemistry, Thapar Institute of Engineering and Technology, Patiala, Punjab, India
| | - Abhrajyoti Ghosh
- Department of Biochemistry, Bose Institute, EN Block, Sector V, Bidhannagar, Kolkata, West Bengal 700091, India
| | - Neha Garg
- Indian Institute of Technology (IIT) Mandi, Mandi, Himachal Pradesh, India
- Department of Medicinal Chemistry, Faculty of Ayurveda, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India
| | - Roop L. Mahajan
- Thapar Institute of Engineering and Technology–Virginia Tech (USA) Centre for Excellence in Material Sciences; Thapar Institute of Engineering and Technology, Patiala, Punjab, India
| | - Biswarup Basu
- Department of Neuroendocrinology and Experimental Hematology, Chittaranjan National Cancer Institute, Kolkata, West Bengal, India
| | - Diptiman Choudhury
- School of Chemistry and Biochemistry, Thapar Institute of Engineering and Technology, Patiala, Punjab, India
- Thapar Institute of Engineering and Technology–Virginia Tech (USA) Centre for Excellence in Material Sciences; Thapar Institute of Engineering and Technology, Patiala, Punjab, India
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Kim Y, Kim JS, Lee SY, Mahajan RL, Kim YT. Exploration of hybrid nanocarbon composite with polylactic acid for packaging applications. Int J Biol Macromol 2019; 144:135-142. [PMID: 31805326 DOI: 10.1016/j.ijbiomac.2019.11.239] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 11/25/2019] [Accepted: 11/30/2019] [Indexed: 02/06/2023]
Abstract
Polylactic acid (PLA) nanocomposite films were fabricated with graphene oxide (GO) and single-walled carbon nanotubes (CNT) as a hybrid-co-filler with GOCNT fraction varying from 0.05 to 0.4% by weight. The effect of the GOCNT on the physical, thermal, morphological, gas permeation, and optical properties was investigated. The X-ray diffraction test reveals no restacking and coagulation of GOCNT in the composite films. Differential Scanning Calorimetry analysis shows an insignificant shift of glass transition and melting temperature but enhanced crystallization resulting from the existence of GOCNT as a nucleating agent. Scanning Electron Microscope scans indicate GOCNT embedded homogeneously without considerable aggregates in the PLA. Transmission of ultraviolet-visible radiation decreases to 30% with increasing fraction of GOCNT while Oxygen Transmission Rate diminishes to 67% in the film. These are attributed to the tortuous pathways provided by the well-dispersed hybrid GOCNT in the PLA. Compared to the pristine PLA film, the composite film shows an increase of 75% and 130% in the tensile strength and Young's modulus, respectively. Taken together, all of these improvements observed in the hybrid GOCNT-PLA composites should provide useful guidelines in customizing designs for applications across a range of fields including packaging, life sciences, cosmetics, and conventional synthetic plastics.
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Affiliation(s)
- Yoojin Kim
- Department of Sustainable Biomaterials, Virginia Tech, Blacksburg, VA 24061, United States
| | - Jun Seok Kim
- Department of Sustainable Biomaterials, Virginia Tech, Blacksburg, VA 24061, United States
| | - Seul-Yi Lee
- Department of Mechanical Engineering, Virginia Tech, Blacksburg, VA 24061, United States; Institute for Critical Technology and Applied Science, Virginia Tech, Blacksburg, VA 24061, United States
| | - Roop L Mahajan
- Department of Mechanical Engineering, Virginia Tech, Blacksburg, VA 24061, United States; Institute for Critical Technology and Applied Science, Virginia Tech, Blacksburg, VA 24061, United States
| | - Young-Teck Kim
- Department of Sustainable Biomaterials, Virginia Tech, Blacksburg, VA 24061, United States.
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Abstract
Public “upstream engagement” and other approaches to the social control of technology are currently receiving international attention in policy discourses around emerging technologies such as nanotechnology. To the extent that such approaches hold implications for research and development (R&D) activities, the distinct participation of scientists and engineers is required. The capacity of technoscientists to broaden the influences on R&D activities, however, implies that they conduct R&D differently. This article discusses the possibility for more reflexive participation by scientists and engineers in the internal governance of technology development. It reviews various historical attempts to govern technoscience and introduces the concept of midstream modulation, through which scientists and engineers, ideally in concert with others, bring societal considerations to bear on their work.
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7
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Bonakdar M, Latouche EL, Mahajan RL, Davalos RV. The Feasibility of a Smart Surgical Probe for Verification of IRE Treatments Using Electrical Impedance Spectroscopy. IEEE Trans Biomed Eng 2015; 62:2674-84. [PMID: 26057529 DOI: 10.1109/tbme.2015.2441636] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
SIGNIFICANCE Irreversible electroporation (IRE) is gaining popularity as a focal ablation modality for the treatment of unresectable tumors. One clinical limitation of IRE is the absence of methods for real-time treatment evaluation, namely actively monitoring the dimensions of the induced lesion. This information is critical to ensure a complete treatment and minimize collateral damage to the surrounding healthy tissue. GOAL In this study, we are taking advantage of the biophysical properties of living tissues to address this critical demand. METHODS Using advanced microfabrication techniques, we have developed an electrical impedance microsensor to collect impedance data along the length of a bipolar IRE probe for treatment verification. For probe characterization and interpretation of the readings, we used potato tuber, which is a suitable platform for IRE experiments without having the complexities of in vivo or ex vivo models. We used the impedance spectra, along with an electrical model of the tissue, to obtain critical parameters such as the conductivity of the tissue before, during, and after completion of treatment. To validate our results, we used a finite element model to simulate the electric field distribution during treatments in each potato. RESULTS It is shown that electrical impedance spectroscopy could be used as a technique for treatment verification, and when combined with appropriate FEM modeling can determine the lesion dimensions. CONCLUSIONS This technique has the potential to be readily translated for use with other ablation modalities already being used in clinical settings for the treatment of malignancies.
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Hassounah IA, Rowland WC, Sparks SA, Orler EB, Joseph EG, Camelio JA, Mahajan RL. Processing of multilayered filament composites by melt blown spinning. J Appl Polym Sci 2014. [DOI: 10.1002/app.40786] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Ibrahim A. Hassounah
- Institute for Critical Technology and Applied Sciences (ICTAS), Virginia Polytechnic Institute and State University; Blacksburg Virginia 24061
| | - William C. Rowland
- Institute for Critical Technology and Applied Sciences (ICTAS), Virginia Polytechnic Institute and State University; Blacksburg Virginia 24061
| | - Stephanie A. Sparks
- Institute for Critical Technology and Applied Sciences (ICTAS), Virginia Polytechnic Institute and State University; Blacksburg Virginia 24061
| | - Edward B. Orler
- Institute for Critical Technology and Applied Sciences (ICTAS), Virginia Polytechnic Institute and State University; Blacksburg Virginia 24061
- Department of Chemistry; Virginia Polytechnic Institute and State University; Blacksburg Virginia 24061
| | - Eugene G. Joseph
- Institute for Critical Technology and Applied Sciences (ICTAS), Virginia Polytechnic Institute and State University; Blacksburg Virginia 24061
- Nanoscale Characterization and Fabrication Laboratory; Virginia Polytechnic Institute and State University; Blacksburg Virginia 24061
| | - Jaime A Camelio
- Institute for Critical Technology and Applied Sciences (ICTAS), Virginia Polytechnic Institute and State University; Blacksburg Virginia 24061
- Nanoscale Characterization and Fabrication Laboratory; Virginia Polytechnic Institute and State University; Blacksburg Virginia 24061
- Institute for Industrial and Systems Engineering, Virginia Polytechnic Institute and State University; Blacksburg Virginia 24061
| | - Roop L. Mahajan
- Institute for Critical Technology and Applied Sciences (ICTAS), Virginia Polytechnic Institute and State University; Blacksburg Virginia 24061
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Hassounah IA, Shehata NA, Kimsawatde GC, Hudson AG, Sriranganathan N, Joseph EG, Mahajan RL. Studying the activity of antitubercluosis drugs inside electrospun polyvinyl alcohol, polyethylene oxide, and polycaprolacton nanofibers. J Biomed Mater Res A 2014; 102:4009-16. [DOI: 10.1002/jbm.a.35070] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 12/04/2013] [Accepted: 12/18/2013] [Indexed: 11/10/2022]
Affiliation(s)
- Ibrahim Anwar Hassounah
- Institute for Critical Technology and Applied Sciences (ICTAS); Virginia Polytechnic Institute and State University; Blacksburg Virginia 24061
| | - Nader Abdelmonem Shehata
- The Bradley Department of Electrical and Computer Engineering (ECE); Virginia Polytechnic Institute and State University; Blacksburg Virginia 24061
- Department of Engineering Mathematics and Physics, Faculty of Engineering; Alexandria University; Alexandria 21526 Egypt
| | - Gade Carolyn Kimsawatde
- Department of Biomed Sciences and Pathobiology (DBSP); Virginia Polytechnic Institute and State University; Blacksburg Virginia 24061
| | - Amanda Gayle Hudson
- Department of Chemistry; Virginia Polytechnic Institute and State University; Blacksburg Virginia 24061
| | - Nammalwar Sriranganathan
- Department of Biomed Sciences and Pathobiology (DBSP); Virginia Polytechnic Institute and State University; Blacksburg Virginia 24061
- Center for Molecular Medicine and Infectious Diseases (CMMID); Virginia Polytechnic Institute and State University; Blacksburg Virginia 24061
| | - Eugene Gregory Joseph
- Institute for Critical Technology and Applied Sciences (ICTAS); Virginia Polytechnic Institute and State University; Blacksburg Virginia 24061
- Nanoscale Characterization and Fabrication Laboratory (NCFL); Virginia Polytechnic Institute and State University; Blacksburg Virginia 24061
| | - Roop L. Mahajan
- Institute for Critical Technology and Applied Sciences (ICTAS); Virginia Polytechnic Institute and State University; Blacksburg Virginia 24061
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Arena CB, Mahajan RL, Nichole Rylander M, Davalos RV. An Experimental and Numerical Investigation of Phase Change Electrodes for Therapeutic Irreversible Electroporation. J Biomech Eng 2013; 135:111009. [DOI: 10.1115/1.4025334] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Accepted: 09/06/2013] [Indexed: 12/18/2022]
Abstract
Irreversible electroporation (IRE) is a new technology for ablating aberrant tissue that utilizes pulsed electric fields (PEFs) to kill cells by destabilizing their plasma membrane. When treatments are planned correctly, the pulse parameters and location of the electrodes for delivering the pulses are selected to permit destruction of the target tissue without causing thermal damage to the surrounding structures. This allows for the treatment of surgically inoperable masses that are located near major blood vessels and nerves. In select cases of high-dose IRE, where a large ablation volume is desired without increasing the number of electrode insertions, it can become challenging to design a pulse protocol that is inherently nonthermal. To solve this problem we have developed a new electrosurgical device that requires no external equipment or protocol modifications. The design incorporates a phase change material (PCM) into the electrode core that melts during treatment and absorbs heat out of the surrounding tissue. Here, this idea is reduced to practice by testing hollow electrodes filled with gallium on tissue phantoms and monitoring temperature in real time. Additionally, the experimental data generated are used to validate a numerical model of the heat transfer problem, which is then applied to investigate the cooling performance of other classes of PCMs. The results indicate that metallic PCMs, such as gallium, are better suited than organics or salt hydrates for thermal management, because their comparatively higher thermal conductivity aids in heat dissipation. However, the melting point of the metallic PCM must be properly adjusted to ensure that the phase transition is not completed before the end of treatment. When translated clinically, phase change electrodes have the potential to continue to allow IRE to be performed safely near critical structures, even in high-dose cases.
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Affiliation(s)
- Christopher B. Arena
- Bioelectromechanical Systems Lab, Virginia Tech-Wake Forest School of Biomedical Engineering and Sciences, Virginia Tech, 330 Kelly Hall (MC0298), Stanger Street, Blacksburg, VA 24061 e-mail:
| | - Roop L. Mahajan
- Institute for Critical Technology and
Applied Science (ICTAS), Virginia Tech Department of Mechanical Engineering, Virginia Tech Department of Engineering Science and Mechanics, Virginia Tech, 410 H Kelly Hall (MC0298), Stanger Street, Blacksburg, VA 24061
| | - Marissa Nichole Rylander
- Tissue Engineering Nanotechnology and
Cancer Research Lab, Virginia Tech-Wake Forest School of Biomedical Engineering and Sciences, Virginia Tech Department of Mechanical Engineering, Virginia Tech, 335 Kelly Hall (MC0298), Stanger Street, Blacksburg, VA 24061
| | - Rafael V. Davalos
- Bioelectromechanical Systems Lab, Virginia Tech-Wake Forest School of Biomedical Engineering and Sciences, Virginia Tech, 329 Kelly Hall (MC0298), Stanger Street, Blacksburg, VA 24061
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Affiliation(s)
- Ming Yi
- Institute for Critical Technology and Applied Science, Virginia Tech, Blacksburg, VA 24061, USA.
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Abstract
We demonstrate the fabrication and testing of a prototype microtome knife based on a multiwalled carbon nanotube (MWCNT) for cutting approximately 100 nm thick slices of frozen-hydrated biological samples. A piezoelectric-based 3D manipulator was used inside a scanning electron microscope (SEM) to select and position individual MWCNTs, which were subsequently welded in place using electron beam-induced deposition. The knife is built on a pair of tungsten needles with provision to adjust the distance between the needle tips, accommodating various lengths of MWCNTs. We performed experiments to test the mechanical strength of a MWCNT in the completed device using an atomic force microscope tip. An increasing force was applied at the mid-point of the nanotube until failure occurred, which was observed in situ in the SEM. The maximum breaking force was approximately (8 x 10(-7)) N which corresponds well with the typical microtome cutting forces reported in the literature. In situ cutting experiments were performed on a cell biological embedding plastic (epoxy) by pushing it against the nanotube. Initial experiments show indentation marks on the epoxy surface. Quantitative analysis is currently limited by the surface asperities, which have the same dimensions as the nanotube.
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Affiliation(s)
- G Singh
- Department of Mechanical Engineering, University of Colorado at Boulder, CO 80309, USA.
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13
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Podhajsky RJ, Yi M, Mahajan RL. Differential and directional effects of perfusion on electrical and thermal conductivities in liver. Annu Int Conf IEEE Eng Med Biol Soc 2009; 2009:4295-4298. [PMID: 19964824 DOI: 10.1109/iembs.2009.5334299] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Two different measurement probes--an electrical probe and a thermal conductivity probe--were designed, fabricated, calibrated, and used in experimental studies on a pig liver model that was designed to control perfusion rates. These probes were fabricated by photolithography and mounted in 1.5-mm diameter catheters. We measured the local impedance and thermal conductivity, respectively, of the artificially perfused liver at different flow rates and, by rotating the probes, in different directions. The results show that both the local electrical conductivity and the thermal conductivity varied location to location, that thermal conductivity increased with decreased distance to large blood vessels, and that significant directional differences exist in both electrical and thermal conductivities. Measurements at different perfusion rates demonstrated that both the local electrical and local thermal conductivities increased linearly with the square root of perfusion rate. These correlations may be of great value to many energy-based biomedical applications.
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Finch DS, Oreskovic T, Ramadurai K, Herrmann CF, George SM, Mahajan RL. Biocompatibility of atomic layer-deposited alumina thin films. J Biomed Mater Res A 2008; 87:100-6. [PMID: 18085647 DOI: 10.1002/jbm.a.31732] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Presented in this paper is a study of the biocompatibility of an atomic layer-deposited (ALD) alumina (Al2O3) thin film and an ALD hydrophobic coating on standard glass cover slips. The pure ALD alumina coating exhibited a water contact angle of 55 degrees +/- 5 degrees attributed, in part, to a high concentration of -OH groups on the surface. In contrast, the hydrophobic coating (tridecafluoro-1,1,2,2-tetrahydro-octyl-methyl-bis(dimethylamino)silane) had a water contact angle of 108 degrees +/- 2 degrees. Observations using differential interference contrast microscopy on human coronary artery smooth muscle cells showed normal cell proliferation on both the ALD alumina and hydrophobic coatings when compared to cells grown on control substrates. These observations suggested good biocompatibility over a period of 7 days in vitro. Using a colorimetric assay technique to assess cell viability, the cellular response between the three substrates can be differentiated to show that the ALD alumina coating is more biocompatible and that the hydrophobic coating is less biocompatible when compared to the control. These results suggest that patterning a substrate with hydrophilic and hydrophobic groups can control cell growth. This patterning can further enhance the known advantages of ALD alumina, such as conformality and excellent dielectric properties for bio-micro electro mechanical systems (Bio-MEMS) in sensors, actuators, and microfluidics devices.
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Affiliation(s)
- Dudley S Finch
- National Institute of Standards and Technology, Materials Reliability Division (853), 325 Broadway, Boulder, Colorado 80305-3328, USA.
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Shellman YG, Howe WR, Miller LA, Goldstein NB, Pacheco TR, Mahajan RL, LaRue SM, Norris DA. Hyperthermia Induces Endoplasmic Reticulum-Mediated Apoptosis in Melanoma and Non-Melanoma Skin Cancer Cells. J Invest Dermatol 2008; 128:949-56. [DOI: 10.1038/sj.jid.5701114] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Abstract
We report damage threshold measurements of novel absorbers comprised of either liquid-cooled silicon carbide or vitreous carbon foams. The measurements demonstrate damage thresholds up to 1.6x10(4) W/cm(2) at an incident circular spot size of 2 mm with an absorbance of 96% at 1.064 microm. We present a summary of the damage threshold as a function of the water flow velocity and the absorbance measurements. We also present a qualitative description of a damage mechanism based on a two-phase heat transfer between the foam and the flowing water.
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Affiliation(s)
- Krishna Ramadurai
- Department of Mechanical Engineering, 427 UCB, University of Colorado, 1111 Engineering Drive, Boulder, CO 80309, USA.
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17
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Abstract
There is a need for experimental techniques that allow the simultaneous imaging of cellular cystoskeletal components with quantitative force measurements on single cells. A bioMEMS device has been developed for the application of strain to a single cell while simultaneously quantifying its force response. The prototype device presented here allows the mechanical study of a single, adherent cell in vitro. The device works in a fashion similar to a displacement-controlled uniaxial tensile machine. The device is calibrated using an AFM cantilever and shows excellent agreement with the calculated spring constant. The device is demonstrated on a single fibroblast. The force response of the cell is seen to be linear until the onset of de-adhesion with the de-adhesion from the cell platform occurring at a force of approximately 1500 nN.
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Affiliation(s)
- David B Serrell
- National Institute of Standards and Technology, Boulder, CO, USA.
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18
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Sharp AA, Panchawagh HV, Ortega A, Artale R, Richardson-Burns S, Finch DS, Gall K, Mahajan RL, Restrepo D. Toward a self-deploying shape memory polymer neuronal electrode. J Neural Eng 2006; 3:L23-30. [PMID: 17124327 DOI: 10.1088/1741-2560/3/4/l02] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The widespread application of neuronal probes for chronic recording of brain activity and functional stimulation has been slow to develop partially due to long-term biocompatibility problems with existing metallic and ceramic probes and the tissue damage caused during probe insertion. Stiff probes are easily inserted into soft brain tissue but cause astrocytic scars that become insulating sheaths between electrodes and neurons. In this communication, we explore the feasibility of a new approach to the composition and implantation of chronic electrode arrays. We demonstrate that softer polymer-based probes can be inserted into the olfactory bulb of a mouse and that slow insertion of the probes reduces astrocytic scarring. We further present the development of a micromachined shape memory polymer probe, which provides a vehicle to self-deploy an electrode at suitably slow rates and which can provide sufficient force to penetrate the brain. The deployment rate and composition of shape memory polymer probes can be tailored by polymer chemistry and actuator design. We conclude that it is feasible to fabricate shape memory polymer-based electrodes that would slowly self-implant compliant conductors into the brain, and both decrease initial trauma resulting from implantation and enhance long-term biocompatibility for long-term neuronal measurement and stimulation.
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Affiliation(s)
- Andrew A Sharp
- Rocky Mountain Taste and Smell Center, Neuroscience Program and Department of Cell and Developmental Biology, University of Colorado at Denver and Health Sciences Center, Aurora, CO 80045, USA.
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Scuor N, Gallina P, Panchawagh HV, Mahajan RL, Sbaizero O, Sergo V. Design of a novel MEMS platform for the biaxial stimulation of living cells. Biomed Microdevices 2006; 8:239-46. [PMID: 16718403 DOI: 10.1007/s10544-006-8268-3] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [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: 11/24/2022]
Abstract
Micromechanical systems are increasingly being used as tools in biological applications, since their characteristic dimensions permit to operate at the same length scale of the structures under investigation. Here, we present a methodology for the design, fabrication and operation of a tool for the assessment of mechanical properties of single cells. In particular, we describe a microsystems platform to study bio-mechanical response of single living cells to in-plane biaxial stretching. The proposed device employs a new linkage design in order to obtain the displacement of the quadrants of a sliced circular plate in mutually-orthogonal directions using just one linear actuator. With this linkage geometry, the whole device has only one degree of freedom. This results in a very predictable and reliable mechanical behaviour, thereby allowing use a simple and easily available control electronics. Results of this study have relevance for the design of a powerful yet simple BioMEMS platform for the characterization of living cells as in-plane bi-axial loading simulated the conditions experienced by cells in vivo more realistically than a uniaxial stretching.
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Affiliation(s)
- N Scuor
- CENMAT-Center of Excellence for Nanostructured Materials, University of Trieste, Via Valerio 2, 34127 Trieste, Italy.
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Liu Z, Ahmed M, Weinstein Y, Yi M, Mahajan RL, Goldberg SN. Characterization of the RF ablation-induced 'oven effect': the importance of background tissue thermal conductivity on tissue heating. Int J Hyperthermia 2006; 22:327-42. [PMID: 16754353 DOI: 10.1080/02656730600609122] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
PURPOSE To determine the effect of background tissue thermal conductivity on RF ablation heating using ex vivo agar phantoms and computer modelling. METHOD Two-compartment cylindrical agar phantom models (5% agar, 5% NaCl, 3% sucrose) were constructed. These included a standardized inner compartment (2 cm diameter, 4 cm length, 0.25% agar) representing a tumour, surrounded by an outer compartment representing background tissue. The thermal conductivity of the outer compartment was varied from 0.48 W m-1 degrees Celsius (normal liver) to 0.23 W m-1 degrees Celsius (fat) by adding a fat-saturated oil-based solute (10-90%) to the agar. RF ablation was applied at 2000 mA current for 2 min. Temperatures were recorded up to 4 cm from the electrode tip at 1 cm intervals. Subsequently, a 2-D finite element computer model was used to simulate RF ablation of 2-24 min duration for tumours measuring 2-4 cm in diameter surrounded by tissues of different thermal conductivity with the presence or absence of perfusion (0-5 kg m-3 s-1) (n = 44). A comparison of results was performed. RESULTS In agar phantoms, the amount of fat in the background tissue correlated with thermal conductivity as a negative exponential function (r2 = 0.98). Significantly increased temperatures were observed at the edge of the inner compartment (1 cm from the electrode tip) as the fat content of the outer compartment increased (p < 0.01). Thus, temperatures at 2 min measured 31.5 +/- 2.2 degrees Celsius vs 45.1 +/- 3.1 degrees Celsius for thermal conductivities of 0.46 W m-1 degrees Celsius (10% fat) and 0.23 W m-1 degrees Celsius (90% fat), respectively. On the other hand, higher levels of fat led to lower temperature increases in the background compartment (0.2 +/- 0.3 degrees Celsius for 90% fat vs. 1.1 +/- 0.05 degrees Celsius for 10% fat, p < 0.05). Phantom thermal heating patterns correlated extremely well with computer modelling (r2 = 0.93), demonstrating that background tissues with low thermal conductivity increase heating within the central tumour, particularly for longer durations of RF ablation and in smaller tumours. Furthermore, computer modelling demonstrated that increases in temperature at the tumour margin for background tissues of lower thermal conductivity persisted in the presence of perfusion, with a clinically relevant 4.5 degrees Celsius difference between background thermal conductivities of fat and soft tissue for a 3 cm tumour with perfusion of 2 kg m-3 s-1, treated for 12 min. CONCLUSION Lower thermal conductivity of background tissues significantly increases temperatures within a defined ablation target. These findings provide insight into the 'oven effect' (i.e. increased heating efficacy for tumours surrounded by cirrhotic liver or fat) and highlight the importance of both the tumour and the surrounding tissue characteristics when contemplating RF ablation efficacy.
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Affiliation(s)
- Zhengjun Liu
- Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
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Scuor N, Gallina P, Sbaizero O, Mahajan RL. Modeling of a microfluidic channel in the presence of an electrostatic induced cross-flow. Biomed Microdevices 2005; 7:231-42. [PMID: 16133811 DOI: 10.1007/s10544-005-3030-9] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Amongst the processes that have been implemented in microfluidic devices, electrophoretic transport of charged molecules, along microfluidic channels, is one of the most commonly found. However, less work has been done about continuous, pressure gradient driven flow systems where an electric field is applied orthogonally with respect to the microchannel walls. The perspective applications of this technique, include continuous flow separation and concentration of analyte molecules, and the kinetic control of surface reactions. In order to dimensioning and optimizing such a device, a mathematical model has been formulated and analyzed both with numeric and analytic methods. The given solutions let the designer of microfluidic devices able to estimate the concentration profiles along the microchannel length, as a function of the main system parameters. As a practical example of application which could be of great interest in biotechnology applications, the results relative to the simulation of the electrostatic induced cross flow of single strand DNA oligonucleotides of about 20 bases has been reported.
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Affiliation(s)
- N Scuor
- CENMAT-Center of Excellence for Nanostructured Materials, University of Trieste, 34127 Trieste, Italy.
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Bhatikar SR, DeGroff C, Mahajan RL. A classifier based on the artificial neural network approach for cardiologic auscultation in pediatrics. Artif Intell Med 2005; 33:251-60. [PMID: 15811789 DOI: 10.1016/j.artmed.2004.07.008] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2003] [Revised: 07/15/2004] [Accepted: 07/24/2004] [Indexed: 12/20/2022]
Abstract
OBJECTIVE This research work was aimed at developing a reliable screening device for diagnosis of heart murmurs in pediatrics. This is a significant problem in pediatric cardiology because of the high rate of incidence of heart murmurs in this population (reportedly 77-95%), of which only a small fraction arises from congenital heart disease. The screening devices currently available (e.g. chest X-ray, electrocardiogram, etc.) suffer from poor sensitivity and specificity in detecting congenital heart disease. Thus, patients with heart murmurs today are frequently assessed by consultation as well with advanced imaging techniques. The most prominent among these is echocardiography. However, echocardiography is expensive and is usually only available in healthcare centers in major cities. Thus, for patients being evaluated with a heart murmur, developing a more accurate screening device is vital to efforts in reducing health care costs. METHODS AND MATERIAL The data set was collected from incoming pediatrics at the cardiology clinic of The Children's Hospital (Denver, Colorado), on whom echocardiography had been performed to identify congenital heart disease. Recordings of approximately 10-15s duration were made at 44,100Hz and the average record length was approximately 60,000 points. The best three cycles with respect to signal quality sounds were extracted from the original recording. The resulting data comprised 241 examples, of which 88 were examples of innocent murmurs and 153 were examples of pathological murmurs. The selected phonocardiograms were subject to the digital signal processing (DSP) technique of fast Fourier transform (FFT) to extract the energy spectrum in frequency domain. The spectral range was 0-300Hz at a resolution of 1Hz. The processed signals were used to develop statistical classifiers and a classifier based on our in-house artificial neural network (ANN) software. For the latter, we also tried enhancements to the basic ANN scheme. These included a method for setting the decision-threshold and a scheme for consensus-based decision by a committee of experts. RESULTS Of the different classifiers tested, the ANN-based classifier performed the best. With this classifier, we were able to achieve classification accuracy of 83% sensitivity and 90% specificity in discriminating between innocent and pathological heart murmurs. For the problem of discrimination between innocent murmurs and murmurs of the ventricular septal defect (VSD), the accuracy was higher, with sensitivity of 90% and specificity of 93%. CONCLUSIONS An ANN-based approach for detection and identification of congenital heart disease in pediatrics from heart murmurs can result in an accurate screening device. Considering that only a simple feature set was used for classification, the results are very encouraging and point out the need for further development using improved feature set with more potent diagnostic variables.
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Affiliation(s)
- Sanjay R Bhatikar
- Department of Mechanical Engineering, University of Colorado, CB #427, Boulder, CO 80309, USA.
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Shellman YG, Ribble D, Yi M, Pacheco T, Hensley M, Finch D, Kreith F, Mahajan RL, Norris DA. Fast response temperature measurement and highly reproducible heating methods for 96-well plates. Biotechniques 2004; 36:968-72, 974-6. [PMID: 15211747 DOI: 10.2144/04366st01] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Hyperthermia, the procedure of exposing cells to a temperature between 42° and 49°C, has been shown to be a promising approach for cancer treatment. To understand the underlying mechanisms of hyperthermic killing of cancer cells, it is critical to have an accurate temperature measurement technique and a heating method with high reproducibility. To this end, we have developed a method using fine thermocouples with fast response time to measure the temperatures in multiple wells of a 96-well plate. The accuracy of temperature measurement was ±0.2°C. Such a capability allows a complete record of the time and temperature of the treatment procedure and helps define an accurate thermal dose. We have also compared several methods for heating 96-well plates and found that use of copper blocks in contact with the lower surface of the 96-well plate in an incubator provides a highly reproducible heating method. The common method of using water bath to heat cells in vitro resulted in a decrease of cell viability even at the control temperature of 37°C and a decrease in the reproducibility of certain biological assays. In summary, using these improved techniques, proposed thermal dose can be defined more precisely, and highly reproducible heating in vitro can be achieved.
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Slifka AJ, Panchawagh H, Mahajan RL, Finch D, Rorrer RA. Static and quasi-static calibration of a bio-MEMS device. Biomed Sci Instrum 2004; 40:429-34. [PMID: 15133996] [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: 04/29/2023]
Abstract
A bio-MEMS device that has been designed to stimulate cells by oscillatory actuation in the vertical direction has been calibrated. The displacement of this device was determined experimentally by a laser interferometer when actuated by a static voltage, and by an atomic force microsope when actuated quasi-statically at 0.1 Hz. Both experimental calibrations were compared to a simple model.
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Abstract
In this paper, we present our experimental results on the determination of the thermal conductivity of biological tissues using a transient technique based on the principles of the cylindrical hot-wire method. A novel, 1.45 mm diameter, 50 mm long hot-wire probe was deployed. Initial measurements were made on sponge, gelatin and Styrofoam insulation to test the accuracy of the probe. Subsequent experiments conducted on sheep collagen in the range of 25 degrees C < T < 55 degrees C showed the thermal conductivity to be a linear function of temperature. Further, these changes in the thermal conductivity were found to be reversible. However, when the tissue was heated beyond 55 degrees C, irreversible changes in thermal conductivity were observed. Similar experiments were also conducted for determining the thermal conductivity of cow liver. In this case, the irreversible effects were found to set in much later at around 90 degrees C. Below this temperature, in the range of 25 degrees C < T < 90 degrees C, the thermal conductivity, as for sheep collagen, varied linearly with temperature. In the second part of our study, in vivo measurements were taken on the different organs of a living pig. Comparison with reported values for dead tissues shows the thermal conductivities of living organs to be higher, indicating thereby the dominant role played by blood perfusion in enhancing the net heat transfer in living tissues. The degree of enhancement is different in different organs and shows a direct dependence on the blood flow rate.
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Affiliation(s)
- A Bhattacharya
- Mechanical Engineering Department, University of Colorado at Boulder, Boulder, CO 80309-0427, USA
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Bhatikar SR, Mahajan RL, DeGroff C. A novel paradigm for telemedicine using the personal bio-monitor. Biomed Sci Instrum 2002; 38:59-70. [PMID: 12085659] [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: 02/25/2023]
Abstract
The foray of solid-state technology in the medical field has yielded an arsenal of sophisticated healthcare tools. Personal, portable computing power coupled with the information superhighway open up the possibility of sophisticated healthcare management that will impact the medical field just as much. The full synergistic potential of three interwoven technologies: (1) compact electronics, (2) World Wide Web, and (3) Artificial Intelligence is yet to be realized. The system presented in this paper integrates these technologies synergistically, providing a new paradigm for healthcare. Our idea is to deploy internet-enabled, intelligent, handheld personal computers for medical diagnosis. The salient features of the 'Personal Bio-Monitor' we envisage are: (1) Utilization of the peripheral signals of the body which may be acquired non-invasively and with ease, for diagnosis of medical conditions; (2) An Artificial Neural Network (ANN) based approach for diagnosis; (3) Configuration of the diagnostic device as a handheld for personal use; (4) Internet connectivity, following the emerging bluetooth protocol, for prompt conveyance of information to a patient's health care provider via the World Wide Web. The proposal is substantiated with an intelligent handheld device developed by the investigators for pediatric cardiac auscultation. This device performed accurate diagnoses of cardiac abnormalities in pediatrics using an artificial neural network to process heart sounds acquired by a low-frequency microphone and transmitted its diagnosis to a desktop PC via infrared. The idea of the personal biomonitor presented here has the potential to streamline healthcare by optimizing two valuable resources: physicians' time and sophisticated equipment time. We show that the elements of such a system are in place, with our prototype. Our novel contribution is the synergistic integration of compact electronics' technology, artificial neural network methodology and the wireless web resulting in a revolutionary new paradigm for healthcare management.
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Affiliation(s)
- Sanjay R Bhatikar
- Department of Mechanical Engineering, University of Colorado, CO 80309, USA
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Abstract
BACKGROUND Early recognition of heart disease is an important goal in pediatrics. Efforts in developing an inexpensive screening device that can assist in the differentiation between innocent and pathological heart murmurs have met with limited success. Artificial neural networks (ANNs) are valuable tools used in complex pattern recognition and classification tasks. The aim of the present study was to train an ANN to distinguish between innocent and pathological murmurs effectively. METHODS AND RESULTS Using an electronic stethoscope, heart sounds were recorded from 69 patients (37 pathological and 32 innocent murmurs). Sound samples were processed using digital signal analysis and fed into a custom ANN. With optimal settings, sensitivities and specificities of 100% were obtained on the data collected with the ANN classification system developed. For future unknowns, our results suggest the generalization would improve with better representation of all classes in the training data. CONCLUSION We demonstrated that ANNs show significant potential in their use as an accurate diagnostic tool for the classification of heart sound data into innocent and pathological classes. This technology offers great promise for the development of a device for high-volume screening of children for heart disease.
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Affiliation(s)
- C G DeGroff
- University of Colorado Health Sciences Center, the Children's Hospital, Denver, CO 80218, USA.
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