Na+ induced improved fluorescence of carbon nanoparticles from human hair: an exclusive sensing platform for Ag.

Fluorescent carbon particles, originating from biological waste, are a recent trend in research. We synthesized novel emissive carbon nanoparticles (15 nm) from human hair via a modified hydrothermal method. The emissive behaviour was further intensified with the interaction of Na+ with the heteroatom-doped carbon nanoparticles. Thus, turn-on fluorescence was made possible for Na+ (linear in the range from 10− 2 M to 10− 5 M and limit of quantification (LOQ) was 0.0018 M). The Na+ modified the electrostatic behaviour and exhibited natural crystallization confinement effect, resulting in fluorescence enhancement. Ag+ quenched the fluorescence selectively with the formation of Ag2O in the reaction mixture, and an Ag+ sensor was designed (linear detection range to be 5 × 10− 7 M to 10− 3, while LOQ was 0.0003 M). Non-radiative energy transfer from fluorophore to Ag2O was pivotal for Ag+ sensing. A non-expensive, green, and circular economic approach was reported here for environmental monitoring.