Karmeshu, Ph.D.
Dean & Professor, School of Computer & Systems Sciences & School of Computational & Integrative Sciences, Jawaharlal Nehru University, India.
Interspike Interval Distribution of Neuronal Model with distributed delay: Emergence of unimodal, bimodal and Power law
The study of interspike interval distribution of spiking neurons is a key issue in the field of computational neuroscience. A wide range of spiking patterns display unimodal, bimodal ISI patterns including power law behavior. A challenging problem is to understand the biophysical mechanism which can generate the empirically observed patterns. A neuronal model with distributed delay (NMDD) is proposed and is formulated as an integro-stochastic differential equation which corresponds to a non-markovian process. The widely studied IF and LIF models become special cases of this model. The NMDD brings out some interesting features when excitatory rates are close to inhibitory rates rendering the drift close to zero. It is interesting that NMDD model with gamma type memory kernel can also account for bimodal ISI pattern. The mean delay of the memory kernels plays a significant role in bringing out the transition from unimodal to bimodal ISI distribution. It is interesting to note that when a collection of neurons group together and fire together, the ISI distribution exhibits power law.
Seeram Ramakrishna, Ph.D.
Director, Center for Nanofibers & Nanotechnology, National University of Singapore
Biomaterials: Future Perspectives
From the perspective of thousands of years of history, the role of biomaterials in healthcare and wellbeing of humans is at best accidental. However, since 1970s with the introduction of national regulatory frameworks for medical devices, the biomaterials field evolved and reinforced with strong science and engineering understandings. The biomaterials field also flourished on the backdrop of growing need for better medical devices and medical treatments, and sustained investments in research and development. It is estimated that the world market size for medical devices is ~300 billion dollars and for biomaterials it is ~30 billion dollars. Healthcare is now one of the fastest growing sectors worldwide. Legions of scientists, engineers, and clinicians worldwide are attempting to design and develop newer medical treatments involving tissue engineering, regenerative medicine, nanotech enabled drug delivery, and stem cells. They are also engineering ex-vivo tissues and disease models to evaluate therapeutic drugs, biomolecules, and medical treatments. Engineered nanoparticles and nanofiber scaffolds have emerged as important class of biomaterials as many see them as necessary in creating suitable biomimetic micro-environment for engineering and regeneration of various tissues, expansion & differentiation of stem cells, site specific controlled delivery of biomolecules & drugs, and faster & accurate diagnostics. This lecture will capture the progress made thus far in pre-clinical and clinical studies. Further this lecture will discuss the way forward for translation of bench side research into the bed side practice. This lecture also seeks to identify newer opportunities for biomaterials beyond the medical devices.
Pandiaraj Manickam, Niroj Kumar Sethy, Kalpana Bhargava, Vepa Kameswararao and Karunakaran Chandran
Designing electrochemical label free immunosensors for cytochrome c using nanocomposites functionalized screen printed electrodes
Release of cytochrome c (cyt c) from mitochondria into cytosol is a hallmark of apoptosis, used as a biomarker of mitochondrial dependent pathway of cell death (Kluck et al. 1997; Green et al. 1998). We have previously reported cytochrome c reductase (CcR) based biosensors for the measurement of mitochondrial cyt c release (Pandiaraj et al. 2013). Here, we describe the development of novel label-free, immunosensor for cyt c utilizing its specific monoclonal antibody. Two types of nanocomposite modified immunosensing platforms were used for the immobilization of anti-cyt c; (i) Self-assembled monolayer (SAM) functionalized gold nanoparticles (GNP) in conducting polypyrrole (PPy) modified screen printed electrodes (SPE) (ii) Carbon nanotubes (CNT) incorporated PPy on SPE. The nanotopologies of the modified electrodes were confirmed by scanning electron microscopy (SEM). Cyclic voltammetry, electrochemical impedance spectroscopy (EIS) were used for probing the electrochemical properties of the nanocomposite modified electrodes. Method for cyt c quantification is based on the direct electron transfer between Fe3+/Fe2+-heme of cyt c selectively bound to anti-cyt c modified electrode. The Faradaic current response of these nanoimmunosensor increases with increase in cyt c concentration. The procedure for cyt c detection was also optimized (pH, incubation times, and characteristics of electrodes) to improve the analytical characteristics of immunosensors. The analytical performance of anti-cyt c biofunctionalized GNP-PPy nanocomposite platform (detection limit 0.5 nM; linear range: 0.5 nM–2 μM) was better than the CNT-PPy (detection limit 2 nM; linear range: 2 nM-500nM). The detection limits were well below the normal physiological concentration range (Karunakaran et al. 2008). The proposed method does not require any signal amplification or labeled secondary antibodies contrast to widespread ELISA and Western blot. The immunosensors results in simple and rapid measurement of cyt c and has great potential to become an inexpensive and portable device for conventional clinical immunoassays.