Peptide aptamer-based biosensor for the detection of human chorionic gonadotropin by converting silver nanoparticles-based colorimetric assay into sensitive electrochemical analysis

We presented an antibody -free electrochemical technique for the determination of human chorionic gonadotropin (hCG) using silver nanoparticles (AgNPs) as the redox reporters and a hCG-specific binding peptide as the receptor. Peptide -induced AgNPs assembly was achieved on the electrode surface that was modified with the same sequence of peptide (recognition element) used in the AgNPs aggregation. As a result, a well-defined linear -sweep voltammetry (ISV) peak was observed. The attachment of hCG on the electrode surface made the peptide probe lose its ability to trigger the in situ formation of the AgNPsbased network architecture on the electrode surface, thus leading to a much attenuated ISV current. The current decreased with the increase of hCG concentration ranging from 1 mIU/mL to 0.2 IU/mL. Consequently, a detection limit of 0.mIU/mL was achieved. To demonstrate the amenability of our method, the contents of hCG in human serum/urine samples were determined. The results were consistent with those obtained by the enzyme linked immunosorbent assay (ELISA). Based on the well-defined and amplified electrochemical signal of the AgNPs-based network architecture, our work would also be valuable for the design of novel electrochemical sensors by marrying specific receptors. (C) 2016 Elsevier B.V. All rights reserved.