Protein-Directed Synthesis of Lead(II) and Temperature Dual-Responsive Red Fluorescent Gold Nanoclusters and Their Applications in Cellular and Bacterial Imaging

摘要

Low toxicity and fluorescent nanomaterials have many advantages in biological imaging. Herein, we report a simple protein-directed synthesis of water-soluble and fluorescent gold nanoclusters (NCs) using bovine serum albumin (BSA) as the stabilizing agent. The as-prepared Au NCs show red fluorescence with a maximum peak at about 630 nm (quantum yield 7.6%) and are characterized in terms of photoluminescence spectrum, photoluminescence excitation spectrum, transmission electron microscopy, Fourier transform infrared spectroscopy (FT-IR), circular dichroism spectra (CD) and Xray photoelectron spectroscopy. The resultant Au NCs are shown to be viable fluorescent probes for the determination of lead(II) ion and temperature due to aggregation-induced quenching of fluorescence. Furthermore, the nanosensor exhibits high sensitivity to Pb~(2+) ion with a detection limit of 7.9 nmol L~(–1) and has been demonstrated for determination of Pb~(2+) ion in real water samples including tap water and mineral water. In addition, with the advantages including red fluorescence and good biocompatibility, the resultant BSA-Au NCs could be used as nanosensors for Pb~(2+) ion and temperature in biological imaging.