Water-soluble Ag2S quantum dots for near-infrared fluorescence imaging in vivo

A one-step method for synthesizing water-soluble Ag2S quantum dots terminated with carboxylic acid group has been reported. The crystal structure and surface of the prepared Ag2S quantum dots were characterized. The prepared Ag2S quantum dots exhibited bright photoluminescence and excellent photostabilities. The photoluminescence emissions could be tuned from visible region to near-infrared (NIR) region (from 510 nm to 1221 nm). Ultra-small sized Ag2S nanoclusters were synthesized with high initial monomer concentration in the current system. The in vivo imaging experiments of nude mice showed that the NIR photoluminescence of the prepared Ag2S quantum dots could penetrate the body of mice. Compared to the conventional NIR quantum dots, the Ag2S quantum dots don't contain toxic elements to body (such as Cd and Pb), thus, the prepared Ag2S quantum dots could serve as excellent NIR optical imaging probes and would open the opportunity to study nanodiagnostics and imaging in vivo. (C) 2012 Elsevier Ltd. All rights reserved.