Combined voltammetric and spectroscopic investigation of binding interaction between nifedipine and human serum albumin on polyelectrolyte modified ITO electrode

The binding interaction between the drug molecule, nifedipine (Nf), and the human serum albumin (HSA)on polyelectrolyte modified indium tin oxide (ITO) electrode has been investigated by the combinationof electrochemical and fluorescence spectroscopy techniques. Surface modification has also been characterized by scanning electron microscopy (SEM) and Contact Angle (CA) measurements in each step. The cyclic voltammetry, electrochemical impedance parameters (peak potential difference (ΔEp)), peak cur-rent difference (ΔIp) and charge-transfer resistance (R ct) indicate that nifedipine strongly interacted with human serum albumin molecule on the polyelectrolyte modified ITO electrode surface. Stern-Volmerquenching constant Ka is inversely correlated with the temperature, which indicates that the probable quenching mechanism of the nifedipine-human serum albumin binding reaction is initiated by complexformation. The results obtained from these techniques showed that Nf could bind to HSA. The bindingconstant (Kb) and the number of binding sites (n) of the drug with HSA at different temperatures were determined. At 298 K, Kb was found as 4.04 × 10-3and n was 1.08 for Nf-HSA. According to the van't Hoffequation, the thermodynamic parameters, ΔG, ΔH and ΔS, were obtained, showing the involvement ofhydrophobic and electrostatic force in this interaction. © 2013 Elsevier Ltd. All rights reserved.