An ultrasensitive competitive chemiluminescence immunosensor coupled flow injection cell modified by oxidized graphene-chitosan for the detection of Hg2+

In this work, an ultra-sensitive and simple chemiluminescence (CL) immunosensor has been constructed to detect Hg2+ in real water samples. It is based on the excellent properties of oxidized graphene and chitosan modified a novel flow cell to achieve satisfactory results. Oxidized graphene has good biocompatibility, can effectively immobilize antigens and construct an efficient biosensor interface. Chitosan has excellent biodegradability, excellent film-forming and biocompatibility. Hereby, oxidized graphene-chitosan composites provide a favorable microenvironrnent for immobilizing coating-antigen and introducing HRP-labeled secondary antibodies into the CL reaction of luminol-PIP-H2O2. With a competitive-type assay mode, the Hg2+ in solution competed with the immobilized coating antigen for the limited binding sites of monoclonal antibody, which resulted in the CL of this system decreases because of less HRP. At the optimal conditions, the CL signal displayed a good linear relation toward Hg2+ in the range of 0.001-300 ng mL(-1) with a detection limit (3 sigma) of 0.33 pg mL(-1). The immunosensor possessed acceptable accuracy, high specificity and reproducibility, and was applied to examine Hg2+ in real water samples and cream with favorable results. The successful development of this method also provides reliable prospects and technical support for the follow-up detection of similar environmental pollutants.