Chemical/Biochemical Preparation of New Polymeric Bionanocomposites with Enzyme Labels Immobilized at High Load and Activity for High-Performance Electrochemical Immunoassay

We report on the chemical/biochemical preparation of novel polymeric bionanocomposites (PBNCs) material consisting of polydopamine (PDA), Pt nanoparticles (PtNPs), glucose oxidase (GOx), Au nanoparticles (AuNPs), and antibody for high-performance sandwich-type electrochemical immunoassay. The preparation includes chemical synthesis of PDA-PtNPs-GOx bionanocomposites with abundant GOx and PtNPs immobilized in/on the PDA matrix and biochemical synthesis of AuNPs/PDA-PtNPs-GOx bionanocomposites with highly dispersed AuNPs on the PDA-PtNPs-GOx for successive efficient adsorption of antibody and GOx finally yielding GOx(ads)/antibody/AuNPs/PDA-PtNPs-GOx bionanocomposites (PBNCs 1). The thus prepared PBNCs 1 exhibit high load and activity of the enzyme label immobilized both in the interior and on the surface for ultrasensitive signal readout, as well as high load of antibody on the surface for significant immuno-recognition efficiency. Transmission electron microscopy, atomic force microscopy, UV-vis spectroscopy, and electrochemical quartz crystal microbalance are used to characterize the prepared bionanocomposites. We use PBNCs 1 to construct sandwich-type electrochemical immunosensors, which can detect the target antigen of human immunoglobulin G down to a concentration of 2 pg mL(-1). We believe that the chemical/biochemical preparation of new immuno-active PBNCs here may open a new avenue to develop other multifunctionalized PBNCs materials for wide applications in biosensing, bioseparation, and immuno-oriented drug delivery.