Browsing Materials Science Research Seminar Series by Title
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Bionanofabrication: engineering biomaterials for in situ remodeling and drug deliveryThe bionanofabrication of smart materials presents opportunities in fields as far ranging as food science and medicine. The tools of molecular biology allow for the in vivo and in vitro production of unique biomolecules enabling not only the direct(ed) creation of novel proteins but also catalysts that can then produce other non-protein polymers. An example is the biodegradable polymer, polyhydroxyalkanoate (PHA), which is normally produced by a number of different bacteria. It is synthesized through a series of three enzymes but only one, polyhydroxalkanoate synthetase (PHAC) is required for the conversion of a soluble CoA-substrate into an insoluble hydrophobic polymer. Our laboratory has pioneered the in situ formation of PHA by engineering PHAC and targeting it toward fabricated and native substrates. Once on-site polymer formation can be initiated by introducing the substrate. Alternatively polymers can be formed in vitro and then delivered to the target site. Beyond the localized impact by the introduction of significant quantities of a highly hydrophobic polymer, PHA can also be used as a vehicle for the delivery of therapeutic drugs and once there release their cargo through its normal degradation process. Applications to cancer therapy and in situ engineering of microvasculature will be presented.
DESIGN AND SYNTHESIS OF HYBRID CONJUGATES AS POTENTIAL ANTI-INFECTIVE AGENTSInfectious diseases caused by pathogenic microorganisms are major challenges despite all the steps taken to control or cure. New drug development with high efficacy/selectivity for infectious diseases is a point of interest for many researchers. It has reported that tuberculosis is one of the ten major causes of death in the world. Multi-drug resistance (MDR) is another major concern in bacterial and fungal infections. The present study deals with the development of new conjugates of pyrazinoic acid and isoniazid linked via an amino acid. The synthesized conjugates show promising and interesting results against a variety of microbial strains, tuberculous and non-tuberculous mycobacteria. Molecular modeling studies were used for understanding and validation of the experimental data.
The FluoroDichroSpectroPhotometer: Multi-function Instrumentation for Biophysical Spectroscopy in the Ultraviolet, Visible and Near InfrareThe decade-wide region of the electromagnetic spectrum from wavelengths of roughly 150 nm in the far ultraviolet (UV) to 1.5 μ in the near infrared (NIR) is particularly important for biophysical spectroscopy because water is relatively transparent, while most other molecules important in bio-molecular systems absorb in some part of this "water window". In addition to spectrophotometers, which measure the absorption spectrum of a sample, the most widely used instruments are fluorometers, which measure the light emitted after absorption of a photon, and dichrometers, which measure the difference between the absorption or emission of two polarizations, either circular or linear. I will describe the rationales for, and the design and construction of a laboratory instrument capable of measuring fluorescence as well as circular dichroism (CD) and magnetic CD (MCD). A second instrument of the same general type was optimized for CD in the far and vacuum UV by the use of UV radiation from a synchrotron light source. Other developments have included the simultaneous measurement of CD and the absorption spectrum of the sample, fluorescence detected CD/MCD, and the measurement of fluorescence polarization anisotropy using the components normally associated with a dichrometer. Since its introduction in 1969, essentially all dichrometers have used photoelastic modulators (PEM) to periodically modulate the polarization of a monochromatic photon beam, which makes possible the detection of very small differences in the absorption of different polarization components of the same wavelength – to about one part in a million. I will also discuss the programming of PEMs as a function of wavelength to achieve their proper operation for the measurement of CD/MCD, linear dichroism (LD), and fluorescence polarization anisotropy, and the limits of certain approximations made in the derivation of the mathematical descriptions of the operations of dichrometers.
Sodium Titanates for Separations, Catalysis and Biomedical ApplicationsSodium titanates are a class of inorganic materials having chemical and surface properties that can be exploited for numerous applications. For example, sodium titanates have proved very effective in removing certain radioactive contaminants from high-level nuclear waste solutions at the Savannah River Site and contaminated waters at the Fukushima site in Japan. This presentation will follow the development of the titanate materials for radiochemical separations as well as our more recent studies into the synthesis of materials for use as photocatalysts and in biomedical applications.