Novel polymeric bionanocomposites with catalytic Pt nanoparticles label immobilized for high performance amperometric immunoassay

We report on the aqueous preparation of novel polymeric bionanocomposites (PBNCs) with poly-dopamine (PDA) as an efficient matrix to support antibody and uniformly dispersed abundant Pt nanoparticles (PtNPs) for high performance sandwich-type amperometric immunoassay. We prepare three kinds of PBNCs (PBNCs 1, 2, and 3) via chemical polymerization synthesis (1) and further adsorption (2) or glutaldehyde (CA) covalent crosslinking (3) of antibody. Transmission electron microscopy, atomic force microscopy, and quartz crystal microbalance are used to characterize the PBNCs. The results show that PDA is an excellent matrix to support antibody and PtNPs due to its high biocompatibility, adsorbability, and processibility, and the thus-prepared PBNCs are of high immuno-recognition efficiency and high catalytic activity toward H2O2 reduction. Then, we examine the applicability of the prepared PBNCs for sandwich-type amperometric immunosensing using a model immuno-pair of human immunoglobulin G (hIgG) and anti-hIgG, and obtain the signal by detecting the electro-reduction of H2O2 catalyzed by the PtNPs label. The constructed immunosensors using PBNCs 1, 2 and 3 exhibit detection limits of 0.068, 0.037, and 0.018 ng mL(-1), respectively, being competitive with or better than the reported analogues. Our immunosensors also present good reproducibility, stability, regeneration ability, specificity, and satisfactory feasibility for target assay in clinical human serum samples. The suggested protocol for the preparation of PBNCs with high signal-transduction ability is expected to find wide bioassay applications. (C) 2009 Elsevier B.V. All rights reserved.