Sulfur doped carbon nitride quantum dots with efficient fluorescent property and their application for bioimaging

Heteroatom doping can drastically alter electronic characteristics of carbon nitride quantum dots, thus resulting in unusual properties and related applications. Herein, we used sulfur as the doping element and investigated the influence of doping on the electronic distribution of carbon nitride and the corresponding fluorescent property. A simple synthetic strategy was applied to prepare sulfur-doped carbon nitride (S-g-C₃N₄) quantum dots through ultrasonic treatment of bulk S-g-C₃N₄. Characterization results demonstrated that the prepared S-g-C₃N₄ quantum dots with an average size of 2.0 nm were successfully prepared. Fluorescent properties indicated that S-g-C₃N₄ quantum dots have an emission peak at 460 nm and cover the emission spectra region up to 550 nm. Furthermore, the fluorescent intensity is greatly increased due to the sonication of bulk S-g-C₃N₄ into quantum dots. As a result, S-g-C₃N₄ quantum dots not only show a blue cell imaging, but have a bright green color. Therefore, S-g-C₃N₄ quantum dot is a promising candidate for bioimaging benefiting from the efficient fluorescent property, good biocompatibility, and low toxicity.