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Langmuir and layer-by-layer films from molecules of biological interest


This proposal is aimed at providing continuity in the research on nanostructured organic films at the Polymer Group Bernhard Gross, from Instituto de Física de São Carlos. Emphasis will be placed on two scientific problems, namely i): i) novel film architectures with biomolecules to produce biosensors, whose performance will be optimized using information visualization methods; ii) use of Langmuir films as cell membrane models to investigate interaction with molecules of biological interest. In the first topic, layer-by-layer (LbL) films will be fabricated which contain enzymes such as cholesterol oxidase, monoamine oxidase and lipase, and may be incorporated into phospholipid liposomes, in order to seek synergy among the distinct materials in detecting various analytes. The principles of detection include impedance spectroscopy and electrochemical methods, with the data being treated using information visualization methods. The optimization of film fabrication conditions and the film characterization will be performed with several experimental techniques, including fluorescence spectroscopy, circular dichroism, UV-vis spectroscopy and atomic force microscopy (AFM). For the second topic, Langmuir and Langmuir-Blodgett (LB) films will be made with phospholipids to mimic the cell membrane. An investigation will be made of their interaction with chitosans and proteins, such as mucin and lipase. The main scientific problem to be addressed is to probe how molecular-level interactions are correlated with the physiological action of chitosan. For example, one hypothesis to be tested is whether the mucoadhesion of chitosan is affected by mucin, which would explain the possible chitosan activity of reducing weight in living beings. Furthermore, we shall also investigate whether chitosan affects the lipase activity. The molecular-level interactions will be studied with surface pressure and surface potential measurements, Brewster angle microscopy, polarization-modulated infrared reflection-absorption spectroscopy (PM-IRRAS) and AFM. (AU)

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