In the project described in this thesis we studied a simple bio-electronic device for solar energy conversion by surface-assembly of photosynthetic pigment-protein complexes on a bare gold... Show moreIn the project described in this thesis we studied a simple bio-electronic device for solar energy conversion by surface-assembly of photosynthetic pigment-protein complexes on a bare gold-electrode. Optical excitation of the photosynthetic pigments gives rise to charge separation in the so-called reaction center complex. Energy conversion is completed by subsequent electron transfer to the electrode, generating a light-induced electric current. The efficiency of the initial steps of charge separation is very high, the challenge lies in interfacing the protein complexes with conducting surfaces in an efficient manner to exploit the larger part of the harvesting energy. We have interfaced photosynthetic proteins with the Gold electrode by different techniques namely, simple incubation from solution, 2D crystallization and Langmuir-Blodgett deposition and measured photocurrent and current-voltage characteristics of these complexes. We conclude that Langmuir-Blodgett deposition gives a uniformly oriented mono-layer of protein complexes, which enhance the electron transfer efficiency between the electrode and proteins, resulting in highest ever photo-current density and internal quantum efficiency of a mono-layer of protein complexes. 2D crystals of photosynthetic proteins provide native like environment which is desirable for any application of the proteins.2D crystal packing of proteins seem to compete the excitation quenching by the gold electrode Show less
Carbon nanotubes have specific properties that make them potentially useful in biomedicine and biotechnology. However, carbon nanotubes may themselves be toxic, making it imperative to understand... Show moreCarbon nanotubes have specific properties that make them potentially useful in biomedicine and biotechnology. However, carbon nanotubes may themselves be toxic, making it imperative to understand how carbon nanotubes interact with biomolecules such as proteins. Here, we used NMR, CD, and ThT/fluorescence spectroscopy together with AFM imaging to study pH-dependent molecular interactions between single walled carbon nanotubes (SWNTs) and the amyloid-beta (A beta) peptide. The aggregation of the A beta peptide, first into oligomers and later into amyloid fibrils, is considered to be the toxic mechanism behind Alzheimer's disease. We found that SWNTs direct the A beta peptides to form a new class of beta-sheet-rich yet non-amyloid fibrils. Show less
