Green synthesis of carbon quantum dots using quince fruit (Cydonia oblonga) powder as carbon precursor: Application in cell imaging and As3+ determination

High stable and luminescent multicolor carbon quantum dots (CQDs) were prepared using quince fruit (Cydonia oblonga) powder as carbon precursors in one pot via microwave irradiation. The Taguchi orthogonal array using four factors at three levels was applied to obtain CQDs with high photoluminescent intensity. Taguchi ranking results revealed that temperature and microwave power has the most and the least effect on the CQDs photoluminescence intensities, respectively. Prepared CQDs were characterized using different microscopic and spectroscopic techniques. The results reveal that average size of the prepared particles was 4.85 +/- 0.07 nm. The CQDs have maximum emission intensity at 450 nm if excited at 350 nm with a quantum yield of 8.55%. CQDs prepared via microwave in 30 min were compared with those synthesized hydrothermally in a Teflon-linen stainless steel body autoclave at 200 degrees C. High performance liquid chromatographic / photodiode array detector evaluation of the CQDs reveals different surface functionality for the carbon dots. Fe3+ among cations and MnO4- among the anions, strongly extinguish the photoluminescence at 450 nm. Oxidation of As3+ by MnO4- became the basis for arsenic assay in aqueous solutions. Addition of As3+ to MnO4- before mixing with CQDs, compare to permanganate alone, increases the photoluminescence. This increase has a linear relation with As3+ concentration, in the range of 0.1-2 mu gm(-1). Finally, it revealed that the CQDs are not cytotoxic for HT-29 cell line and it is possible to use them in cell imaging and drug delivery.