Preparation of carbon dots from succinic acid and glycerol as ferrous ion and hydrogen peroxide dual-mode sensors and for cell imaging

Fluorescent carbon dots are optically unique materials that have many applications, including photocatalysis, drug delivery, and biosensing. In this work, carbon dots were synthesized in high yields from succinic acid and glycerol using a green, one-step hydrothermal method, and without the addition of acid or base catalysts. Blue-and green-fluorescence could be selected for simply by varying the reaction time, at quantum efficiencies of 11% and 7%, respectively. The blue-fluorescent carbon dots were tested as dual-mode sensors for the detection of ferrous ion (Fe2+) and hydrogen peroxide (H2O2). They were shown to be selective to Fe2+ and H2O2 in solutions, with limits of detection of 21.9 and 0.7 mu M, respectively. The carbon dots were used to prepare paper-based sensors that can be used to determine Fe2+ and H2O2 concentrations as low as 30 mu M and 400 nM, respectively. Fe2+ and H2O2 in several real water samples were determined with excellent recovery and repeatability. They were also demonstrated to be luminescent in the polymeric materials, giving them a wide range of potential solid-state applications. In the tests of cell imaging, they were shown to have excellent biocompatibility, with cell viability of 90% at carbon dot concentrations of up to 1 g L-1. Our carbon dots are thus suitable for use as chemical and intracellular probes.