Fluorescence enhancement of CdTe quantum dots by HBcAb-HRP for sensitive detection of HO 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 HO have been constructed. In this assay, sulfurs in HBcAb-HRP, which possess a strong affinity towards Cd, can improve greatly the recombination fluorescence of CdTe QDs by creating more radiative centers at CdTe/Cd-SR complex. Then, HO 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 HO was 6.9×10mol L (3σ/slope), and the excellent linear range was 1.0×10~1.5×10molL. By using sodium diethyldithiocarbamate (DDTC) and NHOH as masking agents of Ag, Hg and Cu, HO can be selectively detected in coexistence with Ag, Hg and Cu, and the biosensor has been used to detect HO in human serum with satisfactory results. The superior properties of this biosensor showed great potential usage in more chemical and biological researches.