Ultra-radiant photoluminescence of glutathione rigidified reduced carbon quantum dots (r-CQDs) derived from ice-biryani for in vitro and in vivo bioimaging applications

Abstract

Fabrication of beneficial materials from food waste is an extremely challenging task in the current research scenario. In this study, we report the facile synthesis of fluorescent carbon quantum dots (CQDs) using ice-biryani (processed white rice waste) as a precursor and its application in bioimaging was evaluated using in vitro and in vivo models. CQDs was synthesized from carbonized ice-biryani by means of nitric acid treatment. To improve the quantum yield (QY) of as synthesized CQDs, we adopted two-step surface modification processes i.e., (i) preparation of reduced-state CQDs (r-CQDs) via borohydride reduction method followed by (ii) rigidifying with a tripeptide i.e., glutathione (r-CQDs-GS).The effective interactions of oxygen rich r-CQDs and GS stabilization has enhanced the QY from (bare CQDs) 5.46 % to (r-CQDs-GS) 41 %. The resultant r-CQDs-GS was found to be an average particle size of ∼2−5 nm with pH tuned emission between pH 1–10. The biocompatibility of r-CQDs-GS was tested using A549 cells and it was observed that almost 90 % cell viability and normal morphology was retained even after treated with concentrations up to 100 μg/ml. The synergetic effect of r-CQDs rigidified with glutathione have resulted in an efficient in vitro/in vivo bioimaging applications.