Picomolar Detection of Lead Ions (Pb2+) by Functionally Modified Fluorescent Carbon Quantum Dots from Watermelon Juice and Their Imaging in Cancer Cells

Abstract

Water contamination due to the presence of lead is one of the leading causes of environmental and health hazards because of poor soil and groundwater waste management. Herein we report the synthesis of functionally modified luminescent carbon quantum dots (CQDs) obtained from watermelon juice as potential nanomaterials for the detection of toxic Pb2+ ions in polluted water and cancer cells. By introducing surface passivating ligands such as ethanolamine (EA) and ethylenediamine (ED) in watermelon juice, watermelon-ethanolamine (WMEA)-CQDs and watermelon-ethylenediamine (WMED)-CQDs exhibited a remarkable ~10-fold and ~6-fold increase in fluorescence intensity with respect to non-doped WM-CQDs. The relative fluorescence quantum yields of WMEA-CQDs and WMED-CQDs were found to be 8% and 7%, respectively, in an aqueous medium. Among various functionally-modified CQDs, only WMED-CQDs showed high selectivity towards Pb2+ ions with a remarkably good limit of detection (LoD) of 190 pM, which is less than that of the permissible limit (72 nM) in drinking water. The functionally altered WMED-CQDs detected Pb2+ metal ions in polluted water and in a human cervical cancer cell line (HeLa), thus advocating new vistas for eco-friendly nanomaterials for their use as diagnostic tools in the environment and biomedical research areas.

Green synthesis of gardenia seeds-based carbon dots for bacterial imaging and antioxidant activity in aqueous and oil samples

“…In another study, Goel's research group reported the synthesis of luminescent carbon quantum dots (CQDs) derived from watermelon juice. 19 These CQDs were functionalized and used as nanomaterials for the detection of toxic lead (Pb 2+ ) ions in contaminated water and cancer cells. By incorporating surface passivating ligands such as ethanolamine (EA) and ethylenediamine (ED) into watermelon juice, watermelon–ethanolamine (WMEA)-CQDs and watermelon–ethylenediamine (WMED)-CQDs were obtained.…”

Development of fluorescent carbon nanoparticles fromMadhuca longifoliaflower for the sensitive and selective detection of Cr6+: a collective experimental–computational approach

“…[15][16][17][18] Thus, CNPs are considered alternative uorescent materials to organic dyes and semiconductor quantum dots (QDs). The properties of CNPs have been extensively used in various applications such as biomedicine, 19,20 optoelectronics, 21,22 uorescence sensing, 23,24 photocatalysts, 25,26 water purication, 27,28 and visible ink. 29,30 Carbon-rich precursors are used for the synthesis of uorescent CNPs on a feasible scale using the top-down and bottom-up approaches.…”

Comprehensive advances in the synthesis, fluorescence mechanism and multifunctional applications of red-emitting carbon nanomaterials

“…Apart from biomedical applications, FCNMs are also widely used in various technologies such as light-induced catalytic water splitting, optoelectronics, photocatalysis, sensing, anti-counterfeiting, etc. [1][2][3][4][5][6][7][8] Numerous types of FCNMs have been developed so far. However, the majority of them only exhibit an intense blue-to-green uorescence short emissive spectrum when excited by ultraviolet light.…”