Synthesis of corn-derived carbon quantum dots and their application in intracellular pH sensing and multicolor cellular imaging

Biomass corn was utilized as both carbon and nitrogen precursors to synthesize nitrogen self-doped carbon quantum dots (N-CQDs) via a hydrothermal method. The N-CQDs were further used as a nano-fluorescent probe for multicolor cellular imaging and real-time intracellular pH sensing. Experimental results showed that the N-CQDs exhibited a quantum yield of 18.13%, along with excellent biocompatibility, outstanding photoelectrochemical properties, and pH-responsive fluorescence sensing capabilities. The fluorescence intensity of the N-CQDs nanoprobes showed a strong linear correlation with pH values in the range of 4.2-8.4. In live HeLa cells, the N-CQDs nanoprobes displayed high-performance multicolor imaging, and their blue fluorescence intensity also maintained a good linear relationship with pH (4.2-8.4). These findings indicate that the synthesized N-CQDs nanoprobes can be used for the semi-quantitative measurement of intracellular pH, holding great potential for biomedical applications such as cellular imaging and intracellular pH sensing.