A simple one-step hydrothermal route towards water solubilization of carbon quantum dots from soya-nuggets for imaging applications

A simple and low-cost pyrolytic carbonization method has been performed for the easy synthesis of carbon quantum dots from soya-nuggets under an insufficient amount of oxygen. Furthermore, hydrothermal functionalization of the carbonized black material after Soxhlet purification with nitric acid leads to the formation of its quantum sized water soluble version. The hydrothermally functionalized, water soluble carbon quantum dots (wsCQDs) are highly fluorescent and self-passivated, having a quantum yield value of similar to 3%, with a small range of size distribution. High photostability with high solubility makes these potential candidates for imaging purposes, and we used these for the fluorescent labeling of Escherichia coli cells.