Terbium(III)-coated carbon quantum dots for the detection of clomipramine through aggregation-induced emission from the analyte

Abstract

Environmental contamination due to increase in drug levels is reaching an alarming stage. An array of drugs, such as antibiotics, antidepressants, analgesics, and chemotherapy drugs, have been found to be polluting agriculture soils and rivers. Here we developed optical sensors based on terbium(III)-coated carbon quantum dots (Tb-CQDs) synthesized by carrying out a single-step one-pot hydrothermal process in an aqueous medium and characterized by using UV-visible, fluorescence, DLS, HRTEM and XRD measurements. Photophysical studies showed the ability of CQD-Tb to act as a chemosensor of the antidepressant drug clomipramine in aqueous medium. A competitive binding assay using CQD-Tb and clomipramine was carried out in the presence of other drugs. No interference resulted from the presence of the other drugs; and hence, the developed chemosensor can be used for selective detection of clomipramine. A functional group analysis was done using FTIR spectroscopy and a mechanism for drug binding with the chemosensor was derived. To target the interfacial behavior with different drugs, vibrational sum-frequency generation (VSFG) spectroscopy was carried out and further confirmed the ability of the synthesized CQD-Tb to act as a chemosensor for the selective detection of clomipramine in the presence of other drugs.