Colorimetric detection of silver ions in different pH conditions using Pongamia pinnata leaf extract derived carbon dots

Abstract

In this study, carbon dots (PPCDs) with OH and COOH functional groups were synthesized using Pongamia pinnata leaf extract as a carbon source by oxidation and a hydrothermal process. The colorimetric sensing results reveal the intensity of PPCDs enhancement upon the addition of the different concentrations of the silver ions, with LODs of 7.8, 0.758, and 0.340 μM in 5.1, 7.2, and 10 pH conditions, respectively. On the other hand, point-of-care kit (POC) data exhibits an intensive band that appeared after the addition of the silver ions at three pH conditions. The formation of the OH and COOH functionalities on the surface of the PPCDs might be responsible for the highly selective and sensitive detection of the Ag+ ions through metal–ligand charge transfer complex formation.