One-step fabrication of nitrogen-doped fluorescent nanoparticles from non-conjugated natural products and their temperature-sensing and bioimaging applications

A facile solvothermal method was used to prepare N-doped fluorescent nanoparticles (NFNPs) at gram scale from tartaric acid/citric acid/ethylenediamine using oleic acid as the reaction medium. The quantum yield of the obtained fluorescent nanoparticles could reach 48.7%. The NFNPs were characterized by multiple analytical techniques. By combining with the circular dichroism (CD) spectra, the structure and the origin of photoluminescence of the NFNPs were discussed. The fluorescent intensity of the obtained NFNPs had remarkable stability, and exhibited a reversible temperature-dependent enhancement/quenching. The products with low cytotoxicity could be introduced into the target cells for in vitro bioimaging.