Near-infrared MnCuInS/ZnS@BSA and urchin-like Au nanoparticle as a novel donor-acceptor pair for enhanced FRET biosensing.

An enhanced near-infrared (NIR) FRET biosensing system based on the novel donor-acceptor pair (MnCuInS/ZnS@BSA and urchin-like Au NPs) was developed for the sensitive detection of HER2 protein. In this strategy, MnCuInS/ZnS quantum dots (QDs) were chosen due to their NIR emission, high quantum efficiency, and low toxicity. Amounts of MnCuInS/ZnS QDs were encapsulated in BSA to form MnCuInS/ZnS@BSA nanoparticles, which can easily transfer MnCuInS/ZnS QDs from organic phase into aqueous solution, and the formed nanoparticles were applied as the energy donor which significantly enhanced the fluorescence intensity. As for the energy acceptor, urchin-like Au nanoparticles (Au NPs) with novel structure, good stability and excellent quenching ability towards NIR fluorescence were selected. Thus, the NIR MnCuInS/ZnS@BSA and urchin-like Au NPs were designed as a novel donor-acceptor pair for FRET assay. By combining the optical advantages of NIR QDs encapsulated BSA nanoparticles with the excellent fluorescence quenching ability of urchin-like Au NPs, the proposed FRET-based biosensor realized enhanced FRET effect for highly sensitive detection of HER2 in human serum samples. A wide detection range (2-100 ng mL-1) and a low detection limit (1 ng mL-1) were obtained. This sensing system can decrease the interference of other biomolecules in NIR region, can be applied to other biomarker determination in vitro, and also shows great potential for in vivo diagnosis.