AUTHOR=Chang Qiang , Huang Jie , He Liming , Xi Fengna TITLE=Simple immunosensor for ultrasensitive electrochemical determination of biomarker of the bone metabolism in human serum JOURNAL=Frontiers in Chemistry VOLUME=10 YEAR=2022 URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2022.940795 DOI=10.3389/fchem.2022.940795 ISSN=2296-2646 ABSTRACT=

Ultrasensitive and selective determination of biomarkers of the bone metabolism in serum is crucial for early screening, timely treatment, and monitoring of the curative effect of osteoporosis, which is a silent disease with serious health threats. Immunoassay with a simple sensing interface and ultrahigh sensitivity is highly desirable. Herein, a simple electrochemical immunosensor is demonstrated based on gold nanoparticles (AuNPs) electrodeposited on chitosan-reduced graphene oxide (CS-G) composite modified electrode, which can achieve sensitive determination of the important biomarker of bone metabolism, bone gamma-carboxyglutamate protein (BGP). To overcome the agglomeration of graphene and introduce a biocompatible matrix with functional amino groups, CS-G is prepared and modified on the supporting glassy carbon electrode (GCE). Then, AuNPs are electrodeposited on CS-G through their interaction between amine groups of CS. The immobilized AuNPs provide numerous binding sites to immobilize anti-BGP antibodies (AbBGP). The specific recognition between BGP and AbBGP results in a reduction in the mass transfer of the electrochemical probe (Fe(CN)63-/4-) in solution, leading to a reduced electrochemical signal. Based on this mechanism, fast and ultrasensitive electrochemical detection of BGP is achieved when the concentration of BGP ranges from 100 ag ml−1 to 10 μg mL−1 with a limit of detection (LOD) of 20 ag ml−1 (S/N = 3). The determination of BGP in human serum is also realized with high reliability.