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Herein, for the first time, we present a one-pot ingenious preparative method for fluorescent carbon dots from 2-propanol (2P-CDs) without external treatments. Structure, morphology, chemical composition and fluorescence properties of the 2P-CDs were examined. These results confirm that the as-synthesized 2P-CDs are amorphous, monodispersed, spherical and the average particle size is 2.5 ± 0.7 nm. Most importantly, excitation-dependent emission properties were observed, which suggest that these 2P-CDs may be used in multicolor bioimaging applications. When incubated with HeLa cells, the 2P-CDs exhibit low cytotoxicity, and positive biocompatibility. Confocal microscopy image shows the uptake of 2P-CDs by HeLa cells and the application of probable biomarker is demonstrated.

We here report a simple fabrication of tin incorporated chitosan polymer matrix coated pencil graphite electrode Sn/Cs/PGE for the electrochemical detection of riboflavin (RF). The tin incorporated chitosan polymer was prepared by mixing tin chloride in an aqueous acidic chitosan solution and the fabrication of Sn/Cs/PGE was done by simple immersion method for the first time. The surface characterization of the electrode sensor was carried out by Fourier transform infrared (FTIR), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy and elemental mapping analysis. Electrochemical characterization was performed by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) using 0.1 M KCl containing K3[Fe(CN)6]. These results revealed that the Sn/Cs/PGE shows a sensitive and fast electrocatalytic response towards the sensing of RF in physiological pH with a wide linear range (10 to 1200 nM) and low limit of detection (5.56 nM) compared to other electrodes. Moreover, the Sn/Cs/PGE possesses better stability with the anti-inference ability and the practical feasibility of the fabricated electrode shows satisfactory results towards the medicinal and food analysis.

In the present study, we here report a simple, cost-effective and highly sensitive electrochemical sensor for the selective determination of hydroquinone (HQ) and catechol (CC) using electrochemically pretreated pencil graphite electrode (PPGE). The electrochemical pretreatment of pencil graphite electrode (PGE) was done in phosphate buffer solutions (PBS) and characterized by FT-IR, XRD, SEM and EDX. FT-IR and EDX analysis shows the introduction of oxygen functionalization on the PPGE surface. Further the electrodes were electrochemically characterized using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in 0.1 M KCl containing K4[Fe(CN)6] as redox probe. Interestingly, The PPGE shows a significant enhancement in the redox peak current of Fe2+/3+, owing to the effective increment in the electroactive surface area at PPGE (1.22 cm2) compared with the PGE (0.29 cm2). Then the PPGE was utilized for the electrochemical determination of HQ and CC in 0.1 M PBS (pH 7.0). A reversible electrochemical redox peak for HQ and CC were occurred at PPGE, while PGE doesn't efficiently catalyze the HQ and CC redox reaction under identical experimental conditions. The oxidation current response of HQ and CC at PPGE were increased three and four times respectively compared with the PGE. Further, the DPV analysis displays a wide range of linear responses from 2 to 200 μM with a limit of detection (LOD) of 1.17 μM for HQ and 1.32 μM for CC (S/N = 3), respectively. Consequently, the concentration of HQ and CC were successfully determined in the presence of major interferents (10 folds) such as, glucose, ascorbic acid and uric acid. The practical utilization of as-fabricated PPGE was tested in water samples; the obtained results demonstrated that PPGE can be used as a potential candidate for environmental sensor application.