Department of Physics

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Subject: search.filters.subject.Carbon quantum dots (CQDs)

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    Biocompatible carbon dots derived from κ-carrageenan and phenyl boronic acid for dual modality sensing platform of sugar and its anti-diabetic drug release behavior
    (Elsevier, 2019-07) Gangopadhyay, Subhashis
    Detection of sugar by enzymatic assay has been suffering from costly, time-taking, instable and denaturation of glucose oxidase. Recently, chemosensors that have affinity towards boronate became the hot topic in the domain of monosaccharide detection. In this work, a novel strategy was addressed to fabricate carbon dots (C-dots) from linear sulfated polysaccharides κ- carrageenan and phenyl boronic acid for nonenzymatic monosaccharide (glucose) detection. The boronic acid group anchored C-dots surface can form assembly by covalently bonded with the cis-diol moiety of the glucose which caused fluorescence quenching of the C-dots. The inert surface nature of the luminescent C-dots enables them to sense as low as 1.7 μM glucose without the interference of other biomolecules. The proposed sensing system was successfully applied for assay of glucose in blood serum. Interestingly, these C-dots were used as a nano vehicle for delivery of anti-diabetic drug Metformin. Good biocompatibility results were found with MTT and hemolysis assay. Owing to its simplicity and effectiveness, the as-prepared C-dots offered great promise for blood sugar diagnosis and treatment.
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    Zinc and nitrogen ornamented bluish white luminescent carbon dots for engrossing bacteriostatic activity and Fenton based bio-sensor
    (Elsevier, 2018-07) Gangopadhyay, Subhashis
    Carbon dots with heteroatom co-doping associated with consummate luminescence features are of acute interest in diverse applications such as biomolecule markers, chemical sensing, photovoltaic, and trace element detection. Herein, we demonstrate a straightforward, highly efficient hydrothermal dehydration technique to synthesize zinc and nitrogen co-doped multifunctional carbon dots (N, Zn-CDs) with superior quantum yield (50.8%). The luminescence property of the carbon dots can be tuned by regulating precursor ratio and surface oxidation states in the carbon dots. A unique attribution of the as-prepared carbon dots is the high monodispersity and robust excitation-independent emission behavior that is stable in enormously reactive environment and over a wide range of pH. These N, Zn-CDs unveils captivating bacteriostatic activity against gram-negative bacteria Escherichia coli. Furthermore, the excellent luminescence properties of these carbon dots were applied as a platform of sensitive biosensor for the detection of hydrogen peroxide. Under optimized conditions, these N, Zn-CDs reveals high sensitivity over a broad range of concentrations with an ultra-low limit of detection (LOD) indicating their pronounced prospective as a fluorescent probe for chemical sensing. Overall, the experimental outcomes propose that these zero-dimensional nano-dots could be developed as bacteriostatic agents to control and prevent the persistence and spreading of bacterial infections and as a fluorescent probe for hydrogen peroxide detection.
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    Heteroatom doped blue luminescent carbon dots as a nano-probe for targeted cell labeling and anticancer drug delivery vehicle
    (Elsevier, 2019-11) Gangopadhyay, Subhashis
    Herein, a simple and efficient method to fabricate nitrogen and sulphur doped photoluminescent carbon dots (C-dots) has been judiciously developed for targeting cancer cells. Advancement in newfangled imaging tool for cancer cells is a vital and highly trustworthy strategy for cancer therapy. The fluorescent C-dots prepared from κ-carrageenan and folic acid can serve as an efficient cargo for cancer cell labeling expressing the folate receptor on their surface. The prepared C-dots unveiled good water solubility, excellent photostability, and biocompatibility. The C-dots played the role of nano-vehicle for anticancer drug capecitabine under different pH environments. Also, C-dots were applied as invisible marker and finger print recovery applications. The folate receptor in C-dots led to amazing targetability of cancer cells and which embraces a great promise in biomedical studies.