Fluorescence enhancement of CdTe quantum dots by HBcAb-HRP for sensitive detection of H 2 O 2 in human serum

A simple, high selective, ultra-sensitive and stable biosensor based on hepatitis B core antibody labeled with horseradish peroxidase (HBcAb-HRP) induced fluorescent enhancement of CdTe QDs for recognition of H2O2 have been constructed. In this assay, sulfurs in HBcAb-HRP, which possess a strong affinity towards Cd2+, can improve greatly the recombination fluorescence of CdTe QDs by creating more radiative centers at CdTe/Cd-SR complex. Then, H2O2 oxidizes Cd-S bonds in CdTe QDs to organic disulfide product (RS-SR), causing thioglycolic acid (TGA) and HBcAb-HRP detach from surface of CdTe QDs and thus leading to fluorescence quenching. Just with the addition of HBcAb-HRP, sensitivity of the new biosensor has been improved by near one order of magnitude as compared with CdTe QDs probe. Detection limit of HBcAb-HRP-CdTe QDs biosensor for determination of H2O2 was 6.9×10-8mol L-1 (3σ/slope), and the excellent linear range was 1.0×10-7~1.5×10-4molL-1. By using sodium diethyldithiocarbamate (DDTC) and NH4OH as masking agents of Ag+, Hg2+ and Cu2+, H2O2 can be selectively detected in coexistence with Ag+, Hg2+ and Cu2+, and the biosensor has been used to detect H2O2 in human serum with satisfactory results. The superior properties of this biosensor showed great potential usage in more chemical and biological researches.