Green and cost-effective fluorescent carbon nanoparticles for the selective and sensitive detection of iron (III) ions in aqueous solution: Mechanistic insights and cell line imaging studies

Abstract

In this work, a simple, green and cost-effective fluorescence based analytical procedure using water soluble carbon nanoparticles (CNPs) is described for selective and sensitive detection of Iron (III) (i.e. ferric (Fe3+)) ions in water. The CNPs were synthesized by acid treatment of naturally occurring d-glucose followed by heating at 80°C. The fluorescence intensity of the CNPs (excited at 360nm) was found to decrease with the increase in concentration of Fe3+ ions. The fluorescence lifetime of CNPs remained unchanged with increasing Fe3+ concentration, suggesting the quenching to be static. The zeta potential which was negative for CNPs became positive on addition of Fe3+, thus indicating the adsorption of Fe3+ on CNPs surface. The sensing of Fe3+ by CNPs was also observed in-vivo using DLD cells. The limit of quantification and limit of detection of Fe3+ ions were found to be 18ppm and as 56.0ppb, respectively. Validation of the proposed fluorescence quenching based technique was achieved by comparing with Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES).