Preparation of carbon dot‐based ratiometric fluorescent probes for cellular imaging from Curcuma longa

This work derived biocompatible and stable probes based on fluorescent nanoparticles (FNPs) from a natural source, Curcuma longa. The multi‐color fluorescence emissions from carbonized Curcuma longa (C‐FNPs) obtained through defined dehydration conditions are soluble in water and have a small particle size (~17 nm). The surface passivation with polyethylene glycol (PEG) capped with amine groups in FNPs (P‐FNPs) generated a probe with a higher quantum yield and longer fluorescence lifetime than obtained with C‐FNPs. The X‐ray photoelectron spectroscopy and X‐ray diffraction spectra confirmed the associated chemical moieties of C‐FNPs and P‐FNPs. Furthermore, the prepared material showed non‐toxic effects with almost 100% cell viability, even at high concentrations. In conclusion, fluorescence sensors from natural sources may be useful for numerous biomedical research applications.