Search

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. [ABSTRACT FROM AUTHOR]

The design and synthesis of organic molecules having aggregation induced emission (AIE) property has been a prime area of research in recent years. In this regard, we have synthesized new pyranone based AIEgens with interesting photophysical properties. The synthesized donor-acceptor based pyranones 3 and 4a-d show multicolour emission in the range of 476-585 nm in solid state. The compound 3 also showed blue emission (485 nm) in DMSO solution and surprisingly exhibits orange emission (572 nm) with remarkable bathochromic shift in 99% water in DMSO due to AIE characteristics. The detailed study of AIE behaviour of 3 was carried out in increasing fraction of water (0-99%) in THF, the intensity of emission at 485 nm gradually increased upto 80% of water and then decreased at 90% water. Interestingly, the THF solution of 3 in 99% water showed remarkable bathochromic shift (~100 nm) of emission maximum from blue (λmax 485 nm) to orange region (λmax 585 nm) due to formation of nano-aggregates leading to restriction in intramolecular rotation (RIR). The time-correlated single photon counting (TCSPC) analysis of 3 in the water−THF (99:1) mixture showed an average lifetime of 4.8 ns for these nano-aggregates. The pyrrolyl-pyranone 3 having Solution-Solid Dual Emissive (SSDE) characteristics may be utilized in exploring its application in both biomedical and material research fields. [ABSTRACT FROM AUTHOR]