In the present study, an ecofriendly and zero-cost approach has been demonstrated for the preparation of carbon quantum dots by one-pot hydrothermal treatment of leaf extracts of neem (Azadirachta indica). The as-synthesized neem carbon quantum dots (N-CQDs) exhibited high fluorescent quantum yields (QYs) up to 27.2%. Moreover, N-CQDs also act with a peroxidase-like-mimetic activity toward the oxidation of peroxidase substrate 3,3′,5,5′-tetramethyl­benzidine (TMB) in association with hydrogen peroxide (H2O2). Further, the kinetics of peroxidase-like catalytic activity follows the Michaelis–Menten and ping-pong pathway. In addition, the H2O2 sensitive TMB oxidation motivated the colorimetric detection of H2O2 which showed linearity from 0.1 to 0.5 mmol/L with a detection limit (LOD) of 0.035 mmol/L. Furthermore, the blue colors of oxidized TMB (ox-TMB) were selectively reduced in native TMB with ascorbic acid (AA) without any interference of other reducing agents. The linear range of AA detection was lying between 5 and 40 μM with a LOD up to 1.773 μM. The practicability assay of the proposed sensing system toward the detection of AA was also investigated in real sample analysis such as common fruits which showed good sensitivity to the presence of AA. Therefore, this convenient, ecofriendly, and cost-effective peroxidase-based sensing system opens a new platform for analysis of AA in real samples and in complex biological systems.

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Synthesis of nitrogen–sulphur dual-doped carbon quantum dots and their peroxidase like mimetic activity for the colorimetric detection of H2O2 and glutathione in human blood serum.

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Herein a green synthetic route has been developed for the synthesis of water-soluble CQDs by facile single-step hydrothermal treatment of latexes of E. milii plant for the first time. This methodology is zero-cost; uses ultrapure water as a green solvent; does not use strong concentrated acid; and avoids the use of post surface passivating agents. The as-prepared CQDs exhibited excellent optical properties, including high QY up to 39.2%, resistance to high salt strength, and long time photostability. Furthermore, the as-prepared CQDs served as an intrinsic peroxidase-mimic activity to catalyze the chromogenic substrate 3,3′,5,5′-tetramethylbenzidine (TMB) associated with H2O2, which resulted into a blue-colored reaction with a characteristic absorbance peak at 652 nm. Afterward, the proposed TMB-based oxidation system act as a probe for the detection of GSH and offers the high selectivity relative to the different amino acids and various other interfering agents which can be easily seen with naked eye. The limit of detection (LOD) was found to be 5.3 nM in a linear range 0.02 to 0.1 μM of GSH concentration which showed to be superior under the optimal condition as compared with another probe. To demonstrate the practical feasibility for the GSH detection, the present system was successfully applied on human blood serums with good recovery.

Introduction: Diseases of upper gastrointestinal tract are responsible for a great deal of morbidity and mortality. The histopathological study of endoscopic biopsies permits exact diagnosis for further management.The aim of this study is to find out the histopathological pattern of endoscopic biopsy.Methods: A descriptive study was conducted in consecutive endoscopic gastric biopsies in a Hospital over a period of one year. The patient of all ages and both sexes who underwent gastric biopsy during the study period was included.Results: Endoscopic biopsies were studied on patients of age ranging from 20 years female to 84 years male. The histopathology revealed non-neoplastic lesions 54 (67.5%) and neoplastic lesions 26 (32.5%). Most common non-neoplastic lesion noted was mild chronic gastritis 22(27.5%) followed by chronic active gastritis 15 (18.75%) while H. pylori was present in 13 (16.25%) and absent in 2 (2.5%).Conclusions: Mild chronic gastritis was the commonest lesion noted in non-neoplastic lesions and adenocarcinoma was the commonest neoplastic lesion in the endoscopic gastric biopsies.______________________________________________________________________________________Keywords: biopsy; endoscopy; gastritis; histopathological.

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