Prepared carbon dots from wheat straw for detection of Cu in cells and zebrafish and room temperature phosphorescent anti-counterfeiting.

The green synthesis of fluorescent carbon dots from biomass is critical for their sustainable application. Herein, using wheat straw as a single precursor, carbon dots (CDs) were prepared through a one-step carbonization process, and the obtained CDs have intense blue luminescence and excitation-independent photoluminescent behavior. The solution of CDs shows good biocompatibility, and low cytotoxicity successfully used as hopeful bioimaging and biosensing probe for Cu in HepG2 cells and zebrafish. Based on CDs, boron-doped carbon dots with IPA shells (CDs@IPA) can be obtained by doping boron element and isophthalic acid (IPA) coating. CDs@IPA irradiated with different wavelength ultraviolet lamps shows different solid fluorescence, while turning off the ultraviolet lamp can produce green visible room temperature phosphorescence (RTP) to the naked eyes for 5 s. The two kinds of wheat straw-based carbon dots have bifunctional luminescence properties and can be used to detect Cu and serve as RTP anti-counterfeiting signs to ensure information security.