Carbon quantum dots from natural resource: A review

Carbon quantum dots (CQDs) are a new class of fluorescence small carbon nanoparticles with a particle size of less than 10 nm and have vast applications in the field of bioimaging, biosensing and disease-detection. These are promising materials for nano-biotechnology since it has smaller particle size, excellent biocompatibility and excitation wavelength dependent photoluminescence (PL) behavior, photo induced electron transfer, chemical inertness and low toxicity. These materials have excellent fluorescent properties such as broad excitation spectra, narrow and tunable emission spectra, and high photostability against photo bleaching and blinking than other fluorescent semiconductor quantum dots. This review article demonstrate the recent progress in the synthesis, functionalization and technical applications of carbon quantum dots using electrochemical oxidation, combustion/thermal, chemical change, microwave heating, arc-discharge, and laser ablation methods from various natural resources. Natural carbon sources are used for the preparation of CQDs due to its low cost, environmental friendly and widely available.