Binding studies of L-tryptophan to human serum albumin with nanogold-structured sensor by piezoelectric quartz crystal impedance analysis

Piezoelectric quartz crystal impedance (PQCI) analysis was applied to study the binding of _L-tryptophan to human serum albumin (HSA), which was immobilized on the matrix of bare gold elelctrode/chitosan/glutaraldehyde/cysteamine/nanogold particles to maintain biocompatibility, increase capacity and allow renewing the electrode. The real-time course of the resonant frequency and equivalent circuit parameters of the sensor during the protein-amino acid binding and the competition between _L-tryptophan and serum solutes extracted from uremic patients undergoing hemodialysis by ultrafiltration before dialysis treatment were investigated for the first time by the piezoelectric quartz crystal impedance. Additionally, the kinetics of the binding process was also investigated.