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Abstract

Speaker Biography

Time : 2:35 – 2:55 p.m.Date : 13 Nov 2009 (Friday)Venue : Y301, Lee Shau Kei Building, The Hong Kong Polytechnic UniversityGuest : Professor Kwok-yin WONG, Chair Professor, Speaker Department of Applied Biology & Chemistry Technology (ABCT) and

Dean of Faculty of Applied Science & Textiles (FAST)

Lactam antibiotics such as penicillins and cephalosporins have been widely used in the treatment of acterial infections. These two classes of antibiotics kill bacteria by binding with the enzymes responsible for cell-wall synthesis, resulting in the inhibition of their action. Overuse of -lactam antibiotics, however, has led to bacterial resistance towards these drugs. The bacteria can protect themselves from the attack of -lactamantibiotics by producing -lactamases that can effectively hydrolyze the four-membered-lactam rings to inactive carboxylic acids.Our work on the use of fluorophore-labelled -lactamase mutants as biosensors for -lactam antibiotics and -lactamase inhibitors will be presented in the workshop. Thiol-containing -lactamase mutants were prepared by site-directed mutagenesis in which one of the amino acid residues on the omega loop was replaced with cysteine. The mutants were subsequently labeled with thiol-reactive and environment-sensitive fluorophores. The presence of environment-sensitive fluorophore close to the active site allows sensitive detection of microenvironmental changes due to the binding of -lactam antibiotics or -lactamase inhibitors. The biosensors can be used for the detection of trace of antibiotic residues and in the high-throughput screening of inhibitors.

Kwok-Yin Wong obtained his BSc(Hons) in Chemistry in 1981, and PhD in Inorganic Electrochemistry in 1986 from the University of Hong Kong. He was a postdoctoral research fellow at Caltech in 1986-87. He worked as a forensic chemist in the Hong Kong Government Laboratory from 1987 to 1990. In 1990, he joined the then Hong Kong Polytechnic as a lecturer. He was promoted to full professor in 1995, and to chair professor in 2005. He serves as the Head of the Department of Applied Biology and Chemical Technology from 2005 to 2009, and as Dean of the Faculty of Applied Science and Textiles since May 2008. Wong is the author and co-author of over 140 peer-reviewed journal papers and book chapters. His research interest includes electrochemistry, green chemistry and biosensors.

Over the past several decades, a great variety of biosensors have been successfully commercialized for the point-of-care (POC) diagnostics of a number of key metabolites (e.g., glucose for diabetes and lactate for hypoxia) and protein biomarkers (e.g., cardiac troponin I for myocardial infarction). In terms of the signal transduction of the biorecognition events (e.g., enzyme-substrate reaction and antibody-antigen binding) on the sensors’ surfaces, electrochemical detection is the most common one due to its high sensitivity, simple instrumentation, lost cost, and high portability. Since early 1990s, tremendous efforts have been made on electrochemical deoxyribonucleic acid (DNA) sensors. Typically, an electrode surface is immobilized with an oligonucleotide probe (i.e., short strand of DNA, about 15 to 25 bases long) complementary to a target sequence. When a sample containing the target is added to the electrode surface, hybridization reaction occurs and probe target hybrid is formed. The hybridization event can then be transduced to an electrical signal by either label-based (e.g., intercalator/groove binder, non-intercalating marker, and nanoparticle) or label-free approach (e.g., guanine oxidation and change in interfacial electrical property). Towards the goal of POC nucleic acid testing, real samples of unamplified long sequences or enzymatically amplified sequences (e.g., polymerase chain reaction, PCR, amplicons) would be the targets instead of synthetic short targets that were considered by many previous studies. In this presentation, various strategies for the label-based electrochemical detection of PCR amplicons will be discussed. Emphasis will be given to a new technique that allows real-time monitoring of the PCR amplification process. The integration of these electrochemical DNA sensors with microfluidic devices to achieve complete DNA analysis on a single biochip will be presented.

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Abstract

Dr. Thomas Ming-Hung Lee received his BEng, MPhil, and PhD degrees in Chemical Engineering from The Hong Kong University of Science and Technology. Then, he had his postdoctoral training at New Mexico State University and Arizona State University. In 2006, he joined the Department of Health Technology and Informatics at The Hong Kong Polytechnic University as Assistant Professor. His research interests include biosensors, biochips, point-of-care diagnostics, molecular diagnostics, and nanobiotechnology. He has been reviewer for a number of journals such as Analytical Chemistry, Electroanalysis, and Langmuir.

Guest Speaker Biography

Time : 2:55 – 3:15 p.m.Date : 13 Nov 2009 (Friday)Venue : Y301, Lee Shau Kei Building, The Hong Kong Polytechnic UniversityGuest : Dr Thomas LEE, Assistant Professor, Speaker Department of Health Technology and Informatics (HTI)

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Abstract

Speaker Biography

Time : 3:15 – 3:35 p.m.Date : 13 Nov 2009 (Friday)Venue : Y301, Lee Shau Kei Building, The Hong Kong Polytechnic UniversitySpeaker : Dr Thomas LEI, Lecturer,

Research Institute of Innovative Products and Technologies (RIIPT)

An electrical detection method of immunoassay has been developed using indium tin oxide (ITO) interdigitated electrodes on a biochip. The result of sandwich immunoassay can be measured by a multimeter. In this work, ITO interdigitatedelectrodes were fabricated on a glass substrate (biochip) as detection sites. Hence, an array of detection sites can be designed on one single biochip. The surface of the biochip was first functionalized by 3-aminopropyltriethoxysilane (APTES) and glutaraldehyde (GA). This surface modification can prepare an activated surface for protein immobilization. Sandwich immunoassay was performed on the detection sites. We designed the secondary antibody was conjugated to biotin; therefore, gold nanoparticles were applied and bound to the antibodies through biotin-streptavidinlinkage as an indicator of the immunoassay. Then, gold enhancement was performed for enlarging the gold nanoparticles. Hence, a conductive layer was formed across the electrode gaps. The resistance values across the electrodes can be measured by a multimeter directly. The concentrations of the antigen can be represented by the resistance values quantitatively. This detection method is simplicity and miniaturization ; therefore, it is possible to be integrated into the microfluidic system and potentially be developed a portable diagnostic device.

Thomas K.F. LEI obtained his B.Eng. in Mechanical Engineering from National TsingHua University in 1998, M.Phil. and Ph.D. in Mechanical and Automation Engineering from The Chinese University of Hong Kong in 2000 and 2005, respectively. In 2006, he was working in University of Western Ontario as a postdoctoral fellow. In 2007, he joined the Research Institute of Innovative Products and Technologies (RIIPT) of The Hong Kong Polytechnic University as a Lecturer and also an Associate Research Engineer. His research interests include microfluidic devices and systems, bio-sensing, bio-molecular manipulation, active DNA hybridization, immunoassay inmicrofluidic chip, and high aspect ratio microelectromechanical systems (MEMS) components.

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Abstract

Speaker Biography

Time : 3:35 – 3:55 p.m.Date : 13 Nov 2009 (Friday)Venue : Y301, Lee Shau Kei Building, The Hong Kong Polytechnic UniversitySpeaker : Dr Ching-Hsiang CHENG, Assistant Professor,

Research Institute of Innovative Products and Technologies (RIIPT)

For biomedical applications, more sensors and actuators were replaced with micro devices to provide better accuracy on measurement and control from the benefit on the advance of micro and nanotechnology. To improve the performance on the healthcare products, three sensors have been developed including large strain and tactile sensor to measure the biomechanical deformation and force, shear and normal force sensor for pressure mapping applications, bio and gas sensors for identifying the species and quantity of the biology and chemical samples, and different micropumpsfor drug delivery applications. When combining sensing and actuation, a Smart Therapy product has been realized to provide real-time monitoring and treatment to arthritis patients for pain management.

Ching-Hsiang Cheng obtained his B.S. degree in Mechanical Engineering from National Taiwan University in 1993, three Master’s degrees in both Electrical and Mechanical Engineering at Cornell University in 1998, and Ph.D. degree in Electrical Engineering at Stanford University in 2005. After completing his postdoctoral research, he joined Industrial Technology Research Institute (ITRI) in Taiwan as a researcher and became a project leader. In 2006, he has been appointed as an Assistant Professor and also a Research Engineer in the Research Institute of Innovative Products and Technologies (RIIPT) of The Hong Kong Polytechnic University. His research interests include large strain and tactile sensor, shear and normal force sensor, capacitive micromachined ultrasonic transducers (CMUT), microvalve and micropump, gas sensor, electrical through-wafer interconnects, nanotechnology, and microelectromechanical systems (MEMS) for healthcare applications.

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Abstract

Guest Speaker Biography

Time : 4:15 – 4:35 p.m.Date : 13 Nov 2009 (Friday)Venue : Y301, Lee Shau Kei Building, The Hong Kong Polytechnic UniversityGuest : Dr Feng YAN, Assistant Professor, Speaker Department of Applied Physics (AP)

Thin film transistor (TFT) has been proved to be a very sensitive device in the application of various types of sensors. TFT-based sensors are suitable for miniaturization, multiplexing and high-throughput sensing. In this talk, I will report several types of disposable biosensors based on low cost TFTs. (1) We have developed a pH sensor based on polycrystalline silicon TFTs fabricated on glass substrates. Nearly ideal pH sensitivity and stable operation has been achieved. A penicillin sensor has been fabricated based on the pH sensor by functionalizing the sensing area with penicillinase. (2) A novel DNA sensor based on organic TFTs has been fabricated by solution process. Single strand DNA and double strand DNA are differentiated successfully in the experiments indicating that this is a promising technique for sensing DNA hybridization without labeling. (3) Organic electrochemical transistor has been developed for various applications including ion sensors, cell-based biosensor and glucose sensor, et al. It has been found that the sensitivity of such transistor-based sensor is higher than normal electrochemical detection.

Dr Feng Yan has research interests on organic electronics, thin film transistors (TFT) for displays and biosensors, solar cells and smart materials. He received his PhD degree in physics from Nanjing University. In Nanjing University, he worked on ferroelectric materials and C60. Dr Yan joined Electrical Engineering Department of Cambridge University in 2001 as a Research Associate and then a senior Research Associate, being in close collaboration with Seiko Epson Corporation (Japanese company). In Cambridge, he studied poly-Si TFT, single-grain Si TFT, organic TFT and biosensors for five years. In April 2006, he became a Higher Research Scientist,in National Physical Laboratory in UK. Then he joined Applied Physics Department of the Hong Kong Polytechnic University as an assistant professor in September 2006. In polyU, he setup a laboratory for organic electronics, focusing on organic TFTs and organic solar cells.

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Abstract

Guest Speaker Biography

Time : 4:35 – 4:55 p.m.Date : 13 Nov 2009 (Friday)Venue : Y301, Lee Shau Kei Building, The Hong Kong Polytechnic UniversityGuest : Dr Mo YANG, Assistant Professor, Speaker Department of Health Technology and Informatics (HTI)

The measured signals of impedance spectroscopy provide the interfacial dielectric information of liquid/surface layer based on the charge transfer rate and surface electrochemical reaction. Due to the nanoscale dimension, the nanostructuredsubstrates have enhanced charge transfer rate and increased surface reaction/affinity area compared with flat substrates. With the capabilities of integrating electrochemical impedance spectroscopy with nanometrology, nanostructured substrates have been widely used for biosensing. High aspect ratio nano-ordered materials are particularly intriguing for the dramatic increasing of surface area, surface chemical reaction rate and intensification of the electron transfer (i.e. biosensor output signal) through the solid–liquid interface. In this talk, the nanoporous alumina membrane based biosensor via impedance spectroscopy for cell morphology sensing and fast bacteria detection will be discussed.

Dr. Mo Yang received the B.E. and M.S. degrees in mechanical engineering from Shanghai Jiaotong University of China, in 1998 and 2001, respectively. He received the Ph.D. degree in mechanical engineering from the University of California, Riverside, in 2004. Currently, he is an Assistant Professor in the Department of Health Technology and Informatics, the Hong Kong Polytechnic University. His research interests include cell based biosensing, microfluidics and instrumentation of biomedical micro-devices. He has published more than 40 journal papers and received 2 GRF as PI.

In this study, we discovered that we can use high frequency ultrasound imaging to monitor the real-time digestion process of trypsin in articular cartilage for depleting proteoglycan. The digestion front of trypsin can be continuously monitored using additional ultrasound echoes generated between the digested and undigested portions of articular cartilage. The depletion of proteoglycan in articular cartilage causes lose of negative electrical charges bounded with proteoglycan, thus reduces the swelling effects inside articular cartilage, subsequently reduces the modulus of the tissue. The reduction of modulus causes the decrease of the acoustic impedance and creates an interface with mismatched impedances between the digested and undigested cartilage. This interface generates an ultrasound echo when an ultrasound pulse is transmitted into the cartilage. We named this novel technique for monitoring the interaction of different molecules as electro-mechano-acoustic (EMA) sensing and imaging. With the EMA method, we cannot only sense the dynamic interaction and existence of proteoglycan and trypsin molecules, but also monitor the inhibition process of trypsin. We found that different inhibition methods have very different results in habiting the trypsin digestion process. We expect that the application of EMA method can be extended to the monitoring interaction of other molecules as long as the process involves the electro-mechano-acoustic changes.

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Abstract

Speaker Biography

Time : 4:55 – 5:15 p.m.Date : 13 Nov 2009 (Friday)Venue : Y301, Lee Shau Kei Building, The Hong Kong Polytechnic UniversitySpeaker : Professor Yong-Ping ZHENG, Associate Director,

Research Institute of Innovative Products and Technologies (RIIPT) &Professor, Department of Health Technology and Informatics (HTI)

Prof Yong-Ping Zheng received the BSc in Electronics and Information Engineering and MEngin Ultrasound Instrumentation from the University of Science and Technology of China, Hefei. He received the PhD degree in Biomedical Engineering from the Hong Kong Polytechnic University (PolyU), Hong Kong, in 1997. After a postdoctoral fellowship in acoustic microscope and nonlinear acoustics at the University of Windsor, Windsor, ON, Canada, he joined PolyUas an Assistant Professor in 2001 and was promoted to Associate Professor and Professor in 2005 and 2008, respectively, in the Department of Health Technology and Informatics. He also serves as the Associate Director of the Research Institute of Innovative Products in PolyU since Aug 2008. Dr. Zheng’s main research interests include ultrasound elasticity imaging and measurement, three-dimensional ultrasound imaging, tissue ultrasonic characterization, ultrasound molecular imaging, ultrasound instrumentation, and wearable vital sign sensors. He has received 6 GRF as PI and 11 as Co-I. He has 4 US and 4 Chinese patents issued and another 13 patents pending, in the field of biomedical ultrasound and wearable sensors. Out them, 4 patents have been successfully licensed to companies. He is in the editorial boards of number of journals and is a Senior Member of IEEE.