Ultrasmall Au-Ag Alloy Nanoparticles: Protein-directed Synthesis, Biocompatibility and X-ray Computed Tomography Imaging ?

摘要： The ultrasmall sizes of nanoparticles have attracted significant attention for potential application in the fields of catalysis and nanomedicine. Herein, we reported on the green preparation and X-ray computed tomography (CT) imaging of ultrasmall bimetallic bovine serum albumin-directed gold-silver (Au-Ag@BSA) nanoparticles (2–4 nm) using BSA as a stabilizing and template-directed agent. Further, the effects of synthesis condition were systematically explored to prepare products by adjusting the different molar ratios of Au/Ag. The resulting Au-Ag@BSA nanoparticles exhibited the spherical shape, well-dispersed ability, as well as long-term room-temperature stability. The cytotoxicity effects of Au-Ag@BSA nanoparticles on A549 and MCF-7 cells were compared with those of individual Ag nanoparticles, and the results indicated lower cytotoxicity effect by Au-Ag@BSA nanoparticles. Furthermore, the in vivo toxicity of Au-Ag@BSA nanoparticles was investigated in the early-stage zebrafish embryos. The results indicate that there are not any obvious changes of survival and hatching percentages at multiple growth stages (4-120 hpf) even a high level of Au-Ag@BSA nanoparticles (up to 80 mM), revealing the good biocompatibility. Interestingly, a rational design of Au/Ag molar ratio (3:2) surprisingly possessed the enhanced CT performances compared to the Au nanoparticles and iohexol. Accordingly, this study highlights a new prospect in the green preparation of ultrasmall alloy nanomaterials with good biocompatibility and will be of great interest in developing CT contrast agent, catalyst as well as drug delivery carrier.