Preparation of Nitrogen-Doped Biomass-Based Carbon Quantum Dots and their Application to Fe Detection and Bioimaging.

Carbon quantum dots are a new type of fluorescent material with promising application prospects in bioimaging, photocatalysis, and metal ions detection. Biomass is a plentiful and renewable natural resource containing a large amount of carbon, hydrogen and oxygen, and is an ideal precursor for the preparation of carbon quantum dots. Although biomass-based carbon dots possess numerous advantages, there are still several challenges. Specifically, the luminescence mechanism remains unidentified. Additionally, how to control the surface functionalization of biomass-based carbon dots is also a challenge. In this work, nitrogen-doped carbon quantum dots were synthesized sheep manure with glycine under optimized hydrothermal conditions to enhance nitrogen-containing functional groups. The results showed that the nitrogen-doped carbon quantum dots were synthesized when sheep manure mixed with glycine in a mass ratio of 4:1 and reacted at 240 ℃ for 12 h exhibited a quantum yield of 10.63%, a fluorescence lifetime of 7.82 ns, and exceptional stability-retaining fluorescence intensity above 630,855 a.u. after 30 days of storage. Furthermore, the nitrogen-doped carbon quantum dots exhibit high selectivity and sensitivity to Fe (detection limit:4.7 μM, linear range: 0-200 μM) along with excellent bioimaging performance in L929 cells, demonstrating their dual-functional applications in both environmental sensing and bioimaging.