Novel amperometric aptasensor based on analyte-induced suppression of enzyme catalysis in polymeric bionanocomposites

We report on a novel label-free biosensing interface based on multifunctional polymeric bionanocomposites (PBNCs) and its application for sensitive detection of protein based on the analyte-induced suppression of enzymatic catalysis in PBNCs. Thrombin and its aptamer are adopted as a model system to construct an amperometric aptasensor. First, polydopamine-based PBNCs with glucose oxidase (GOx) entrapped at high load/activity and Au nanoparticles (AuNPs) dispersed in high abundance on the surface were prepared through a chemical/biochemical synthesis method, as proven by UV-vis spectrophotometry, digital imaging, and transmission electron microscopy. Then, the PBNCs were cast-coated onto an Au electrode. The PBNC-modified Au electrode presented a high chronoamperometric sensitivity of 113 ± 2 μA cm(-2) mM(-1) to glucose, as well as a high capability of immobilizing the aptamer through the surficial AuNPs to fabricate a label-free aptasensing interface. The binding of thrombin to the aptasensor surface significantly hindered the mass-transfer of the enzymatic substrates/products and thus suppressed the enzymatic catalysis efficiency, which produced obvious signal change through measuring the electrooxidation of enzymatically generated H(2)O(2). The thus-prepared aptasensor could detect thrombin with a broad detection range (1-100 nM), a detection limit down to 0.1 nM, and satisfactory specificity. The developed aptasensing method may find broad applications in the fields of clinical diagnosis, environmental protection, and food safety.