In situ Growth of Gold Nanoparticles Based on Simultaneous Green Reduction by Methylene Blue for Non-Enzymatic Glucose Sensing

We presents a novel approach for in situ growth of highly-dispersed gold nanoparticles (AuNPs) on the electropolymerized methylene blue (PMB)/ITO electrode (Au/PMB/ITO) without using additional binding molecules and toxic reductants. Methylene blue (MB) monomers remaining in the PMB films on ITO served as both the reductant to form AuNPs by reducing AuCl4-, and as anchoring sites for in situ growth of AuNPs via the electrostatic interaction between AuCl4- and positively charged MB that avoids the aggregation of AuNPs, thereby improving their dispersity. Cyclic voltammetry (CV), differential pulse voltammetry (DPV), scanning electron microscope (SEM), UV-Vis spectroscopy (UV-Vis) and Fourier transformation infrared spectroscopy (FTIR) were used to characterize the resulting polymer and nanoparticles. The as-prepared Au/PMB/ITO exhibited an excellent electrocatalytic activity towards glucose oxidation with a high sensitivity of 312 mu A mM(-1) cm(-2) at a low operating potential of 0.04 V.