Chitosan-Based Emissive Carbon Nanosheets and Their Solid-State Temperature-Dependent Photoluminescent Study

Biomass-derived luminescent nitrogen-doped carbon nanosheets have many advantages over other emissive nanobiomaterials for various sensing and bioimaging applications. In this study, emissive nitrogen-doped carbon nanosheets (N-CNS) are prepared from biomass chitosan (CS) at different temperatures in a furnace at atmospheric air, and their photoluminescent (PL) properties have been evaluated. The luminescent N-CNS are prepared by a unique ecofriendly, cost-effective green approach without any harsh chemical treatments. The as-prepared N-CNS demonstrated intense visible PL emissions in the solid state with an excitation-dependent behavior: with 355 nm excitation, a bluish emission appears, and for 532 nm excitation, an orange-red emission was observed. N-CNS shows temperature-dependent PL emissions without change in the peak positions, depicting the possible application in optical thermometry. The sensitivity value of 1.22% K-1 is obtained from the variation of PL intensity with temperature, which is better than the reported carbon nanomaterial-based sensors. The luminescence properties of N-CNS in the water-dispersed state were also analyzed, where an excitation-dependent emission is apparent, which is suitable for various biomedical applications. The obtained results demonstrated that environment-friendly N-CNS could be employed for nanoscale temperature-sensing, bioimaging, and other therapeutic applications.

Automated summary

Biomass-derived luminescent nitrogen-doped carbon nanosheets were prepared using an eco-friendly and cost-effective green method. The nitrogen-doped carbon nanosheets exhibited intense visible light emission with excitation-dependent behavior, as well as temperature-dependent photoluminescent properties. The nanosheets also showed excitation-dependent emissions in the dispersed state, making them suitable for various biomedical applications. Overall, this study demonstrates the potential of environmentally friendly nitrogen-doped carbon nanosheets for nanoscale temperature sensing, bioimaging, and therapeutic applications.