ascorbic-acid and picric-acid

In this work, nitrogen-doped carbon dots (N-CDs) were successfully utilized as a photoluminescent platform for multi-mode sensing of chromium(VI) [Cr(VI)], 2,4,6-trinitrophenol (TNP) and ascorbic acid (AA). The N-CDs with green fluorescent emission were synthesized via one-pot method using p-phenylenediamine and ammonia as precursors. The structure and optical properties were characterized by Fourier transform infrared spectroscopy, ultraviolet visible spectroscopy and fluorescence spectroscopy, respectively. Cr(VI) and TNP were able to absorb the excitation band and emission band of N-CDs and decreased the photoluminescence of N-CDs from internal filtration effect (IFE). Besides, the construction of N-CDs/Cr(VI) mixture can implement as a fluorescence platform for further detection of AA on the basis of the oxidation-reduction reactions between Cr(VI) and AA. Meanwhile, as-prepared N-CDs exhibit strong photostability, low toxicity and great biocompatibility. Moreover, the as-fabricated N-CDs have been smoothly achieved bioimaging in SMMC7721 cells owing to its low toxicity. It is prospective that N-CDs can be applied as a rapid multi-function sensing platform to biosensing and biomedical optical imaging.

Topics: Ascorbic Acid; Carbon; Chromium; Drinking Water; Fluorescence; Fruit and Vegetable Juices; Healthy Volunteers; Humans; Nitrogen; Optical Imaging; Particle Size; Picrates; Quantum Dots; Surface Properties

Copper nanoclusters (CuNCs) exhibit susceptibility to oxidation in the subnanometer size range. In this work, a facile and green protocol is reported for the successful synthesis of water soluble CuNCs, with poly(vinylpyrrolidone) as a template and ascorbic acid as a mild reducing agent. The as-prepared CuNCs exhibit a green fluorescence and high quantum yield (QY = 44.67%) in water, which is the highest among the reported water soluble CuNCs. The origin of their highly luminescent nature was also investigated. In addition, the obtained CuNCs show good tolerability to high ionic strength, superior antioxidation properties, good photostability, time-stability, a large Stokes shift and ultralow cytotoxicity, laying the foundation for living cell imaging in THP-1 macrophages. A bright green fluorescence can be observed from the cells, indicating the potential practicality of CuNCs as a fluorescence marker in bioapplications. Interestingly, the as-prepared CuNCs exhibit a good selective fluorescence quenching response towards trinitrophenol over other nitro compounds. Furthermore, CuNCs were employed for sensing trinitrophenol based on the inner filter effect. A good linear relationship was obtained in the low concentration range of trinitrophenol, with a limit of detection of 3.91 × 10-7 M in aqueous medium. This result suggests the potential application of CuNCs as a probe in sensing and monitoring toxic trinitrophenol in the field of environmental security.

Topics: Ascorbic Acid; Cell Line; Cell Survival; Copper; Humans; Macrophages; Metal Nanoparticles; Microscopy, Fluorescence; Picrates; Povidone; Spectrometry, Fluorescence