Search

A hydrothermal synthetic approach is developed for the preparation of graphitic carbon nitride quantum dots (g-C 3 N 4 QDs) from human urine. The reported synthetic method is green, simple, low-cost, less time-consuming, and can be used for the large-scale production of the g-C 3 N 4 QDs. The as-prepared g-C 3 N 4 QDs possess a high quantum yield of 15.7% by using quinine sulfate as a reference, and display excitation-wavelength dependent fluorescent emission. In addition, the g-C 3 N 4 QDs exhibit high photostability, low cytotoxicity. and are successfully used as fluorescent probes for cell multicolor imaging. It is believed that the valuable nanomaterials, g-C 3 N 4 QDs, which are transformed from the human bodily wastes, are promising in diverse chemical applications. [ABSTRACT FROM AUTHOR]

We report a simple one-pot synthesis of highly fluorescent carbon dots (CDs) via modified hydrothermal (MHT) treatment of alkaline solution of dopamine and cysteine. These CDs ( λ ex =320 nm, λ em =390 nm, and quantum yield ∼5.1%) are of ∼2–3 nm in diameter. Further attempt of synthesizing CDs in some common water-miscible solvents ends up the fact that the MHT product from acetone medium is nonfluorescent. However, CDs, produced in aqueous medium, are so stable that they can be dried as a deliverable solid (WCD) without any alteration of fluorescing property if reversibly dispersed in water. Fluorescence of WCD is quenched selectively in acetone. Quenching occurs presumably due to the disruption of radiative recombination along with the hindrance in quantum confinement of the emissive energy traps to the particle surface. Successive quenching of fluorescence of WCD in different acetone concentration admixed in water paves the way to selective acetone sensing (LOD=8.75×10 −7 M). The synthesized CDs (in aqueous medium) are cytocompatible and are efficient fluorescent probe for cell imaging. Only living cells are recognized exclusively from fluorescence imaging leaving aside dead cells, while cells are treated with CDs. [ABSTRACT FROM AUTHOR]