Synthesis of highly fluorescent carbon dots from lemon and onion juices for determination of riboflavin in multivitamin/mineral supplements

Abstract

In this work, lemon and onion biomasses commonly found in street markets are for the first time used to develop a facile, fast and low-cost one-step microwave-assisted carbonization method for synthesis of highly fluorescent carbon dots (CDs). The structure and optical properties of CDs were investigated by TEM, XRD, XRF, UV–Vis, FTIR, and fluorescence spectroscopy. CDs displayed satisfactory optical proprieties, a high quantum yield of 23.6%, and excellent water solubility, and the particle size was 4.23–8.22 nm with an average diameter of 6.15 nm. An efficient fluorescent resonance energy transfer (FRET) between the CDs and riboflavin was achieved with CDs acting as donor and riboflavin as acceptor. A linear relationship between FRET and the riboflavin concentration from 0.10 to 3.0 μg/mL was observed, allowing the development of an accurate and fast analytical method to determine this vitamin in multivitamin/mineral supplements. Despite the potential interferences in these supplements, CDs were selective for riboflavin under optimized conditions. A paired t -test at a 95% confidence level indicated no statistically significant difference between the proposed and the reference methods. Recovery test presented values ranged from 96.0% to 101.4%. The limit of detection and relative standard deviation were estimated at 1.0 ng/mL and <2.6% ( n = 3), respectively. CDs were successfully synthesized in a domestic microwave oven (1450 W, 6 min), presenting satisfactory parameters when compared with results of other studies reported in the literature, suggesting that the proposed method is a potentially useful method for the synthesis of CDs and determination of riboflavin.

Endogenous Fluorescence Carbon Dots Derived from Food Items

“…Wang et al 61 reported the formation of fluorescent CDs from milk by microwave cooking. Monte-Filho et al 62 revealed the production of CDs derived from lemon and onion after microwave treatment, which added further evidence to support the conclusion that microwave heating leads to the formation of CDs from food items.…”

“…35 Generally, food-borne CDs were amorphous, and X-ray diffraction patterns displayed a broad peak centered at about 20 . 62,[70][71][72] Notably, high-resolution transmission electron microscopy observations suggested the presence of lattice spacing in CDs in some cases. 69 These results reveal that CDs may have both amorphous and crystalline zones.…”

Carbon dots for cancer nanomedicine: a bright future

“…Moreover, CDs exhibited a good linear relationship between the fluorescent resonance energy transfer and the riboflavin concentration, suggesting the develop of an analytical method for the determination of riboflavin in multivitamin and mineral supplements. 288 Ahmadian-Fard-Fini et al were able to detect E. coli by a fluorescence sensor of CDs derived from grapefruit extracts and lemon. Fluorescence signals from various concentrations of E. coli-labeled CDs were observed.…”

Carbon Dots-Mediated Fluorescent Scaffolds: Recent Trends in Image-Guided Tissue Engineering Applications

“…These fluorescent CDs demonstrated a 2–7 nm particle size with a 12% of quantum yield [ 91 ]. Another report by Filho et al reported fluorescent carbon dots with 23.6% quantum yield synthesized from lemon biomass and onion juices via a microwave method [ 92 ]. The synthesized CDs had a spherical morphology with higher monodispersity and a particle size of about 6.15 nm.…”