Amperometric hydrogen peroxide biosensor based on the immobilization of horseradish peroxidase (HRP) on the layer-by-layer assembly films of gold colloidal nanoparticles and toluidine blue

The precursor film was first formed on the An electrode surface based on the self-assembly Of L-cysteine and the adsorption of gold colloidal nanoparticles (nano-Au). Layer-by-layer (LBL) assembly films of toluidine blue (TB) and nano-Au were fabricated by alternately immersing the electrode with precursor film into the solution of toluidine blue and gold colloid. Cyclic voltammetry (CV) and quartz crystal microbalance (QCM) were adopted to monitor the regular growth of {TB/Au} bilayer films. The successful assembly of {TB/Au}(n) films brings a new strategy for electrochemical devices to construct layer-by-layer assembly films of nanomaterials and low molecular weight materials. In this article, {TB/Au}(n) films were used as model films to fabricate a mediated H2O2 biosensor based on horseradish peroxidase, which responded rapidly to H2O2 in the linear range from 1.5 X 10(-7) mol/L to 8.6 x 10(-3) mol/L with a detection limit of 7.0 x 10(-8) mol/L. Morphologies of the final assembly films were characterized with scanning probe microscopy (SPM).