Cannabis sativa-derived carbon dots co-doped with N–S: highly efficient nanosensors for temperature and vitamin B12

Abstract

With the enhancement in biomimetic and bioinspired synthesis approaches, plant-derived nanostructures provide the most suitable synthesis alternatives in terms of being non-toxic, economical and eco-friendly. The present work focused on Cannabis sativa-derived carbon dots co-doped with nitrogen and sulphur (N–S@CsCD) as a nanosensor. N–S@CsCD exhibited size distribution in the range of 4–6 nm and showed an excitation-independent emission behaviour with an emission wavelength around 414 nm. The XPS spectra confirmed the presence of heteroatom doping by nitrogen and sulphur with the concentrations of 10.71% and 1.94%, respectively. N–S@CsCD showed excellent stability to pH, time and salt concentration. Interestingly, N–S@CsCD exhibited a reversible temperature-responsive fluorescence “turn-off” behaviour. Furthermore, N–S@CsCD showed a selective fluorescence “turn-off” behaviour in the presence of vitamin B₁₂ (VB₁₂), with a limit of detection of 7.87 μg mL⁻¹. The fluorescence lifetimes of N–S@CsCD with and without VB₁₂ were similar, which implied that the sensing behaviour was purely static in nature. Moreover, N–S@CsCD showed biocompatible and non-toxic behaviours with very high cell viability. The fluorescence nature of N–S@CsCD was further evaluated for intracellular imaging.