Silver Nanoparticle-Enzyme Composite Films for Hydrogen Peroxide Detection

For high-performance biosensor development, two key issues to be significantly considered are the effective integration of biological enzymes with electrode transducer and the rapid communication across the biosensing interface. To combat these issues, the present work reported a robust enzymatic biosensor platform based on binary nanoparticles film composed of enzyme-loaded polymeric nanoparticles and conductive silver nanoparticles (Ag NPs) by a facile electrophoretic deposition method. First, horseradish peroxidase (HRP) as a model enzyme was coassembled with an amphiphilic and photo-cross-linkable polypeptide of 7-amino-4-methylcoumarin chemically modified poly(γ-glutamic acid) (γ-PGA–AMC, PGA-C), generating enzyme-loaded colloidal nanoparticles (HRP@PGA-C NPs) in aqueous solution. Thanks to the presence of abundant carboxyl groups in HRP@PGA-C NPs, they were electrodeposited simultaneously with water-dispersed silver colloidal nanoparticles (Ag NPs) onto the electrode surface, generating a robust biocomposite HRP@PGA-C/Ag film after subsequent photo-cross-linking. As a result, an enzymatic biosensor for hydrogen peroxide (H2O2) determination was successfully developed based on the above binary composite sensing film. The enzymatic biosensor exhibited high sensitivity, low detection limit, wide detection range, and high stability for H2O2 detection, which were attributed to the synergetic functionalities from the robust sensing materials and the special nanostructure of the NPs film. The enzymatic biosensor was also practically applied in liquid milk and human urine sample with satisfactory results, illustrating a promising feature for its applications in real samples. This facile one-step fabrication strategy of enzymatic biosensor based on binary NPs film would provide inspiring insights for the development of new biosensing systems and other bioelectronic devices.