Electrochemical Aptasensor Based on Proximity-Dependent Surface Hybridization Assay for Protein Detection

Sensitive and selective detection of proteins is of great importance in biomedical research and clinical diagnosis. Proximity-dependent surface hybridization assay affords a promising platform for specific and ultrasensitive electrochemical detection of proteins. An improved design of proximity-dependent surface hybridization assay is developed. A pair of aptamer probes that recognize different sites of target platelet-derived growth factor protein (PDGF) are designed with a short complementary sequences. Simultaneous recognition of a single PDGF molecule by the aptamer pair enables the hybridization between the complementary sequences of both aptamer probes, which keeps two tail sequences of both aptamer probes in close proximity and promotes cooperative annealing of the aptamer-protein-aptamer sandwiched complex on capture probes immobilized oil the electrode. Thus. ferrocene tag at the terminus of one aptamer probe is drawn in close contact with the electrode with strong redox signal readily obtained in voltammetric reading. The aptasensor is shown to have high sensitivity with a detection limit as low as 0.1 pg mL(-1) and excellent specificity with resistance to interference from coexisting proteins.