Self-aligned microchip device for automated measurement of quantal exocytosis

The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file.Title from PDF of title page (University of Missouri--Columbia, viewed on February 28, 2011).Dissertation advisors: Dr. Shubhra Gangopadhyay and Dr. Kevin Gillis.Vita.Ph. D. University of Missouri--Columbia 2010.Here we describe a method to fabricate a multi-channel high-throughput microchip device for measurement of quantal transmitter release from individual cells. Instead of bringing carbon-fiber electrodes to cells, the device uses a self-aligning surface chemistry approach to bring cells to an array of electrochemical microelectrodes. The microelectrodes are small and "" in order to promote adhesion of a single cell whereas all other areas of the chip are covered with a thin "cytophobic" film to block cell attachement and facilitate movement of cells to electrodes. This film also insulates unused areas of the conductive film, thus the device is "self aligned." Amperometric spikes resulting from single-granule fusion events were recorded on the device and had amplitudes and kinetics similar to those measured using carbon-fiber microelectrodes. Use of this device will increase the pace of basic neuroscience research and may also find applications in drug discovery or validation.Includes bibliographical reference

Mesoporous iron oxide energetic composites with slow burn rate, sustained pressure and reduced ESD sensitivity for propellant applications

The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file.Title from title screen of research.pdf file (viewed on May 7, 2009)Includes bibliographical references.Thesis (M.S.) University of Missouri-Columbia 2006.Dissertations, Academic -- University of Missouri--Columbia -- Electrical engineering.The objective of this thesis is to synthesize a slow burning nanoenergetic formulation of mesoporous iron oxide with sustainable pressure characteristics and reduced electrostatic discharge ignition sensitivity. The choice of iron oxide is made because of its redox reaction with Al-particles. We have attempted to reduce the combustion wave velocity by infiltrating polymers inside porous Fe₂O₃ and combining it with Al-nanoparticles. Furthermore, modifications with the polymers can reduce the electrostatic discharge (ESD) ignition sensitivity of nanoenergetic composites. The composites reported in this thesis will be useful for propellant applications because these propellants in general burn at a slow rate and provide sustained pressure in MPa range for few milliseconds. Propellant formulations that are currently being investigated contain metal oxide oxidizer and fuel nanoparticles that does not show sustained pressure characteristics. This thesis presents the results obtained with the nanoenergetic composites prepared using polymers, which exhibit the desired propellant characteristics

Self-Aligned Microchip Device for Automated Measurement of Quantal Exocytosis [abstract]

Biomedical Tissue Engineering, Biomaterials, & Medical Devices Poster SessionNeurons and endocrine cells secrete neurotransmitters and hormones as a method for cell-to-cell communication through the process of exocytosis. Disruption of exocytosis underlie neurological disorders such as Parkinson's disease and the accounts for the toxicity of clostridial neurotoxins. In order to study the regulation of exocytosis it is important to carry out studies at the level of single-cells and resolve single-vesicle release events. Carbon-fiber microelectrodes are commonly used to perform single-cell measurements but are slow and labor-intensive to use. Therefore we are developing microchip devices with arrays of electrochemical electrodes for high-throughput measurement of single-vesicle release events. One challenge in the development of these devices is automatically targeting individual cells to each recording electrode. Here we describe a microchip device that uses a self-aligning surface chemistry approach to target individual cells to each electrochemical microelectrode in an array. The microelectrodes are small and “cytophilic” in order to promote adhesion of a single cell whereas all other areas of the chip are covered with a thin “cytophobic” film to block cell attachement and facilitate movement of cells to electrodes. This cytophobic film also insulates unused areas of the conductive film. Amperometric spikes resulting from single-granule fusion events were recorded on the device and had amplitudes and kinetics similar to those measured using carbon-fiber microelectrodes. Use of this device will increase the pace of basic neuroscience research and may also find applications in assaying neurotoxins and development of pharmaceuticals