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Gold nanoparticles (GNPs) were allowed to self-assemble onto a glassy carbon electrode (GCE) that was prior modified by L-cysteine. The modified electrode was then used as a voltammetric sensor in detecting the neurotransmitter serotonin. The electrode exhibited a linear voltammetric response for serotonin within a concentration range of 6.0 x 10(-8) M to 6 x 10(-6) M, with a detection limit of 2 x 10(-8) M. The detection of serotonin was found to be unaffected by the presence of epinephrine, dopamine, ascorbic acid and folic acid. The electrode was applied to detect serotonin added to human blood serum, with an average recovery value of 104.67%.

Aiming to prepare photovoltaic materials with light and thermal stability, ruthenium complexes with broad absorption in the visible region were introduced to a polyimide, bpy-PI, which contains a bipyridine ligand in each repeating unit. The chemical structures of the monomers and polymers were confirmed by 1 H NMR, IR, and elemental analysis. The prepared polyimide containing ruthenium complexes (bpy-PI-Ru) showed good solubility in common organic solvents such as DMF, NMP, DMSO and DMAc. UV-vis measurements revealed that bpy-PI-Ru exhibits very broad absorptions in the range 350-750 nm due to the introduction of ruthenium complexes. Such absorption enhancement would enable the polymer to harvest solar light in the visible region. The onset oxidation potential of bpy-PI-Ru was measured as 0.68 V (vs. SCE), which is about 0.06 V lower than that of bpy-PI. The band gap of bpy-PI-Ru is 1.35 eV as measured by cyclic voltammetry. Solar cell devices were fabricated based on bpy-PI-Ru or the blend of bpy-PI-Ru and PCBM. Current density-voltage (J-V) measurement of the devices showed a typical rectifying behavior under a 55 mW cm À2 compact white arc lamp. The open-circuit voltages and short-circuit densities were measured to be in the ranges 0.19-0.52 V and 0.0015-0.38 mA cm À2 , respectively. The short-circuit density could be further improved by anode modification through deposition of PEDOT:PSS on ITO surface.