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Fibronectin immobilized by covalent conjugation or physical adsorption shows different bioactivity on aminated-PET

Materials Science and Engineering C 2007年第2期27卷 213-219页

作者： Zhang, Yue Chai, Chou Jiang, Xue Song Teoh, Swee Hin Leong, Kam W. Graduate Programme in Bioengineering National University of Singapore Singapore Tissue and Therapeutics Engineering Laboratory Division of Johns Hopkins Singapore Deparment of Mechanical Engineering National University of Singapore Singapore Department of Biomedical Engineering School of Medicine Johns Hopkins University Baltimore United States

To manipulate the cellular response to synthetic surfaces, extracellular matrix (ECM) proteins such as fibronectin (FN) and collagen are often immobilized on the surface to promote interaction between these ligands and the cell receptors. In this study we compared the biological properties of FN-decorated polyethylene terephthalate (PET) produced by two widely used immobilization techniques: adsorption and conjugation. As revealed by the micro-bicinchoninic acid (micro-BCA) assay and AFM, the modified surface topography was dependent on the immobilization methods. Adsorption method preserved the compact conformation of FN, reaching saturation when a monolayer of FN was formed. Covalent conjugation induced FN unfolding and fibrillogenesis, forming multiple layers of FN. Biological characterization by adhesion of baby hamster kidney 21 (BHK21) cells and enzyme-linked immunosorbent assay (ELISA) for active Arg-Gly-Asp (RGD) domains suggested that the difference in conformation of FN led to different bioactivities. Adsorption maintained a more active RGD domain, thereby promoting cell adhesion, whereas conjugation induced fibrillogenesis and blocked the access of RGD, consequently suppressing cell adhesion as the surface density of FN increased. This study suggests that in addition to choosing the nature of the adhesion molecule, the mode of immobilization may also significantly influence the bioactivity of the surface. © 2006 Elsevier B.V. All rights reserved.

关键词： Proteins

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Focus optimization with binary wave-front coding

Focus optimization with binary wave-front coding

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Conference on and Quantum Electronics and Laser Science Conference Lasers and Electro-Optics, QELS 2008

作者： Liu, Linbo Diaz, Frédéric Loiseaux, Brigitte Huignard, Jean-Pierre Chen, Nanguang Sheppard, C.J.R. Graduate Programme in Bioengineering National University of Singapore 117576 Singapore Singapore Thales Research and Technology RD 128 91767 Palaiseau Cedex France Division of Bioengineering National University of Singapore 117576 Singapore Singapore Department of Electrical and Computer Engineering National University of Singapore 117576 Singapore Singapore

Novel schemes to optimize the focusing condition of Gaussian beam are proposed. Super-resolution is achieved along a DOF 4 times larger than the confocal parameter. The experimental results are presented by use of an ... 详细信息

ISBN: (纸本)1557528594

关键词： Gaussian beams

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In vitro degradation of novel bioactive polycaprolactone-20% tricalcium phosphate composite scaffolds for bone engineering

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Materials Science and Engineering C 2007年第2期27卷 293-298页

作者： Lei, Y. Rai, B. Ho, K.H. Teoh, S.H. Graduate Programme in Bioengineering National University of Singapore MD 11 #03-02 117597 Singapore Faculty of Dentistry National University of Singapore National University Hospital 5 Lower Kent Ridge Road 119074 Singapore Department of Mechanical Engineering Faculty of Engineering National University of Singapore 9 Engineering Drive 1 117576 Singapore

Our group recently fabricated novel 3D polycaprolactone-20% tricalcium phosphate (PCL-TCP) composite scaffolds for applications in bone engineering. The bioactivity of such synthetic biomaterials can be evaluated by examining its ability to initiate the formation of apatite on its surface when immersed in simulated body fluids (SBF). In this study, the in vitro degradation behaviors of these scaffolds were systematically monitored for varying time periods of 1, 7, 14, 21 and 28 days post-immersion in SBF at 37 °C. Weight loss and water absorption of the samples indicated that PCL-TCP scaffolds were only slowly degraded. Biochemical assays and pH measurements revealed that hydroxyapatite, the main inorganic constituent of bone, commenced to form on the surface of the scaffolds after 17 days of immersion in SBF. Von Kossa assays demonstrated that calcium deposits increased progressively on the surface of the scaffolds after soaking in SBF for 2 weeks. Scanning electron microscopy verified the surface crystallization of the apatite layer formed over the entire period of time. In conclusion, the synergy of PCL with TCP in a composite scaffold confers both bioresorbability as well as bioactivity that offer an exciting approach for bone regeneration purposes. © 2006.

关键词： Biomaterials

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Catalytic surface modification of roll-milled poly(Ε-caprolactone) biaxially stretched to ultra-thin dimension

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Materials Science and Engineering C 2007年第2期27卷 299-303页

作者： Foo, H.L. Taniguchi, A. Yu, H. Okano, T. Teoh, S.H. Graduate Programme in Bioengineering National University of Singapore Singapore Bionic Materials Technology Group Biomaterials Center National Institute for Materials Science Japan Department of Physiology National University of Singapore Singapore Institute of Biomedical Engineering Tokyo Women's Medical University Japan Department of Mechanical Engineering National University of Singapore Singapore

A novel roll-milling polymer processing technique along with biaxial stretching was used to fabricate 10 μm thick poly(Ε-caprolactone) films. A less invasive collagen surface modification was used, involving a reaction between corona-preactivated membranes and ferrous-containing acrylic acid solution at the low temperature of 42 °C. Successful modified films were characterized by Toluidine Blue O assay and X-ray photoelectron spectroscopy. Human umbilical vein endothelial cells also showed both higher proliferation rate and differentiated cobblestone morphology on these collagen-immobilized substrates. © 2006 Elsevier B.V. All rights reserved.

关键词： Collagen

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Real-time High Resolution Optical Coherence Microscopy with a Phase Shifting Apodizer

Real-time High Resolution Optical Coherence Microscopy with ...

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2007 IEEE/ICME International Conference on Complex Medical Engineering-CME2007(CME2007 第二届国际复合医学工程学术大会)

作者： C.J.R. Sheppard Linbo Liu Cheng Liu Wong Chee Howe Nanguang Chen 1Division. of Bioengineering National University of Singapore Singapore 117576 Graduate Programme 1Division. of Bioengineering National University of Singapore Singapore 117576 Department of Electrical and Computing Engineering National University of Singapore Singapore 117 1Division. of Bioengineering National University of Singapore Singapore 117576 Graduate Programme

In conventional optical coherence microscopy (OCM) systems, there is an inherent tradeoff between the depth of focus (DOF) and lateral resolution. A new method to overcome this limitation for real-time optical coherence microscopy is proposed. By simply incorporating a three-zone, pure phase, phase shifting apodizer in a conventional OCM setup, we improve DOF by a factor of 3. A nearly constant lateral resolution of 5.0 μm or better over a depth range of 500 μm is experimentally verified. Since pure phase masks can be easily fabricated and miniaturized, the merits of the proposed method are especially desired in real-time, high-resolution endoscopic OCM systems.

关键词： Optical microscopy Biomedical optical imaging Lenses Optical refraction Optical variables control Spatial resolution Image resolution Apertures Focusing Optical imaging

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Systems analysis of bone mechanotransduction at cellular level

Systems analysis of bone mechanotransduction at cellular lev...

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IEEE Symposium on Bioinformatics and bioengineering (BIBE)

作者： Kalyan C. Mynampati Peter Lee Vee Sin Graduate Programme Bioengineering National University of Singapore Singapore Department of Mechanical Engineering Melbourne School ofEngineering University of Melbourne Australia

A dasiasystems-levelpsila computational modeling approach is implemented to study the mechano-regulation of bone at cellular level. Issues addressed using this approach include - determining the intra-cellular response of bone cells to mechanical stimulus, bone response to different mechanical loading conditions, the role of intra-cellular feedback regulation in bone remodeling, and the link between reduced mechanical loading and decreased bone mass. An inter-connected network of signal transduction pathways in osteoblasts and osteoclasts is considered for modeling. The salient features of this modeling technique are systems biology based network modeling to simulate the temporal dynamics of the signaling proteins, parameter estimation based on evolutionary computing, and control systems theory to model feedback in the signaling network. The results indicate that signaling networks respond uniquely to different mechanical stimuli, the stimulus signal is gradually attenuated in the signaling cascade, and the disruption of intra-cellular feedback regulation leads to decreased bone formation in osteoblasts and increased bone resorption in osteoclasts. This results in low bone mass, a phenomenon generally observed in reduced loading conditions. It is deduced that reduced mechanical loading leads to disruption in the feedback to result in low bone mass. The results of these simulation studies are expected to serve as useful guidelines for planning relevant experimental work to study the effect of mechanical loading on bone at cellular level.

关键词： Bones Biological system modeling Feedback Computational modeling Systems biology Proteins Parameter estimation Biology computing Computer networks Control system synthesis

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Alteration in Foot Strike Pattern While Running with Elastic Insoles: Case Study on the Effects of Long-term Training

Alteration in Foot Strike Pattern While Running with Elastic...

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IEEE/RAS-EMBS International Conference on Biomedical Robotics and Biomechatronics (BioRob)

作者： Ryo Fujihara Kohei Kozasa Hiroaki Hirai Hermano Igo Krebs Graduate School of Engineering Science Osaka University Toyonaka Japan Programme Bioengineering & Biosciences University Campus Bio-Medico of Rome Rome Italy

ISBN: (纸本)9781538681848

Motor adaptation is a form of motor learning that involves changes in the control of movements that occur as a consequence of optimization in repeated task exposure or practice. A good example of this can be found in human running. It is thought that humans run in accordance with the presence or absence and shape of shoes. Three foot strike patterns exist in running, classified according to which portion of the sole first connects with the ground: RFS (rear-foot-strike; heel connection), MFS (mid-foot-strike, simultaneous heel and toe connections), and FFS (fore-foot-strike; toe, or ball connection). RFS is often seen in runners wearing shoes, whereas FFS is commonly seen during routine barefoot running. This study examined how humans adapt to assistive footwear (environmental exposure)s throughout approximately one month of running training. We found that the shape and stiffness of a modified insole affected the foot, functioning as a spring during running. As training continued, the subject adapted to the structure of the footwear by altering his foot strike pattern while reducing his heart rate. The foot strike pattern changed from heel contact to contact from the side of the toe or arch, and the pattern of the ground reaction force changed from that of RFS to that of FFS or MFS. These results indicate that the change in foot compliance while landing and during grounding affects the foot strike pattern to improve the efficiency and capability of running through long-term training.

关键词： Foot Training Footwear Radio frequency Heart rate Force Kinematics

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Standardized quantification for liver fibrosis assessment using second harmonic generation microscopy

Standardized quantification for liver fibrosis assessment us...

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Frontiers in Optics, FiO 2008

作者： Tai, D.C.S. Xu, S.Y. Kang, C.H. Tan, N. Chia, S.M. Cheng, C.L. Yu, H. Institute of Bioengineering and Nanotechnology A-STAR The Nanos #04-01 31 Biopolis Way Singapore 138669 Singapore Singapore-MIT Alliance E4-04-10 4 Engineering Drive 3 Singapore 117576 Singapore Department of Pediatrics KK Women's and Children's Hospital 100 Bukit Timah Road Singapore 229899 Singapore Department of Physiology Yong Loo Lin School of Medicine #03-03 2 Medical Drive Singapore 117597 Singapore NUS Graduate Programme in Bioengineering NUS Graduate School for Integrative Science and Engineering National University of Singapore Singapore 117597 Singapore NUS Tissue-Engineering Programme DSO Labs National University of Singapore Singapore 117597 Singapore Department of Haematology-Oncology National University Hospital Singapore 119074 Singapore

We have developed a standardized quantification technique for assessing the progression of liver fibrosis by combining second harmonic generation microscopy and automated quantification algorithms. We have also valida... 详细信息

ISBN: (纸本)9781557528612

关键词： Harmonic generation

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Clinical utility of Epstein-Barr virus DNA and other liquid biopsy markers in nasopharyngeal carcinoma

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Cancer Communications 2020年第11期40卷 564-585页

作者： Rong Tan Sean Kean Ann Phua Yoke Lim Soong Lynette Lin Ean Oon Kian Sing Chan Sasidharan Swarnalatha Lucky Jamie Mong Min Han Tan Chwee Ming Lim Yong Loo Lin School of Medicine National University of SingaporeSingapore 117599Singapore Department of Radiation Oncology National Cancer CenterSingapore 169608Singapore Department of Molecular Pathology Singapore General HospitalSingapore 169608Singapore Institute of Bioengineering and Nanotechnology Singapore 138669Singapore Department of Otorhinolaryngology-Head and Neck Surgery Singapore General HospitalSingapore 169608Singapore Lucence Diagnostics Singapore 159552Singapore Surgery Academic Clinical Programme Duke-NUS Graduate Medical SchoolSingapore 169857Singapore

Nasopharyngeal carcinoma(NPC)is a malignant epithelial tumor ubiquitously associated with the Epstein-Barr virus(EBV),which is highly prevalent in South China,Southeast Asia,and North *** being a highly radio-sensitive and treatable cancer,a majority of NPC patients are diagnosed in their advanced stage,and locoregional and distant relapses following definitive treatment contribute largely to cancer-specific mortality among these *** that EBV-driven NPC is the predominant variant seen in endemic regions,various EBV detection methods have been developed and are utilized in screening,prognostication,and post-treatment surveillance of NPC *** the Immunoglobulin A(IgA)serology assay is the most extensively studied EBV detection method,the detection of plasma EBV DNA released during replication or cellular apoptosis has shown superior outcomes in endemic population screening,prognostication,and detection of distant ***,there is emerging evidence on the use of circulating tumor cells,microRNAs,DNA hypermethylation,and combination assays in various clinical ***,this paper provides a comprehensive overview of the relevant studies using various EBV detection techniques in the management of ***,the recent advances,clinical evidence,and challenges associated with the clinical application of EBV liquid biopsies in population screening,prognostication,and surveillance of NPC are presented.

关键词： circulating tumor cells EBV DNA Epstein-Barr virus microRNA nasopharyngeal carcinoma prognosis screening serology surveillance

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Alteration in Foot Strike Pattern while Running with Elastic Insoles: Case Study on the Effects of Long-term Training 7

Alteration in Foot Strike Pattern while Running with Elastic...

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7th IEEE RAS/EMBS International Conference on Biomedical Robotics and Biomechatronics, BIOROB 2018

作者： Fujihara, Ryo Kozasa, Kohei Hirai, Hiroaki Krebs, Hermano Igo Osaka University Graduate School of Engineering Science Toyonaka Japan Department of Mechanical Engineering Massachusetts Institute of Technology Cambridge United States Department of Neurology University of Maryland School of Medicine Baltimore United States Department of Physical Medicine and Rehabilitation Fujita Health University Nagoya Japan Institute of Neuroscience Newcastle University Newcastle-upon-Tyne United Kingdom Wolfson School of Engineering Loughborough University Loughborough United Kingdom Programme Bioengineering and Biosciences University Campus Bio-Medico of Rome Rome Italy Department of Mechanical Science and Bioengineering Osaka University Osaka Japan

ISBN: (纸本)9781538681831

Motor adaptation is a form of motor learning that involves changes in the control of movements that occur as a consequence of optimization in repeated task exposure or practice. A good example of this can be found in human running. It is thought that humans run in accordance with the presence or absence and shape of shoes. Three foot strike patterns exist in running, classified according to which portion of the sole first connects with the ground: RFS (rear-foot-strike;heel connection), MFS (mid-foot-strike, simultaneous heel and toe connections), and FFS (fore-foot-strike;toe, or ball connection). RFS is often seen in runners wearing shoes, whereas FFS is commonly seen during routine barefoot running. This study examined how humans adapt to assistive footwear (environmental exposure)s throughout approximately one month of running training. We found that the shape and stiffness of a modified insole affected the foot, functioning as a spring during running. As training continued, the subject adapted to the structure of the footwear by altering his foot strike pattern while reducing his heart rate. The foot strike pattern changed from heel contact to contact from the side of the toe or arch, and the pattern of the ground reaction force changed from that of RFS to that of FFS or MFS. These results indicate that the change in foot compliance while landing and during grounding affects the foot strike pattern to improve the efficiency and capability of running through long-term training. © 2018 IEEE.

关键词： Biophysics

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