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Preparation and cell imaging of nitrogen-doped graphene quantum dot conjugated indomethacin
摘要： The nitrogen-doped graphene quantum dot conjugated indomethacin (N-GQD-IDM) was synthesized by an amide reaction. The results of FTIR indicated that the synthesis of N-GQD-IDM was successful. It was then co-cultured with MCF-7 cells, and obvious fluorescence was observed under a laser confocal scanning microscope. With the increase of incubation time, the material accumulated significantly in the cells and the fluorescence intensity of the cells was slightly improved. This compound could be suggested as a promising fluorescent probe in cancer cell labeling.
关键词： indomethacin,fluorescent probe,cancer cell labeling,nitrogen-doped graphene quantum dots
更新于2025-09-16 10:30:52
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Highly porous self-assembly of nitrogen-doped graphene quantum dots over reduced graphene sheets for photo-electrocatalytic electrode
摘要： Nitrogen-doped graphene quantum dots (NGQDs) are a diverse organic catalyst, competitive with other metallic catalysts due to their low cost, high stability, biocompatibility, and eco-friendliness. Highly functional multi-edge surfaces of NGQDs play a key role in imparting superb photocatalytic and electrocatalytic activity. However, when coating NGQDs by conventional techniques, such surfaces are not exposed for catalysis, due to the unwanted overlap of NGQDs sheets. To avoid this issue, here we propose a facile technique to orient NGQDs in a three-dimensional (3D) self-assembled foam-like structure, over reduced graphene oxide coated woven carbon fabric. This 3D assembled structure provides highly exposed active surfaces, which are readily available for catalytic reactions: however, in the conventional uniformly coated NGQDs layer, catalytic activity was limited by complex diffusion. The superb catalytic activity of the assembled NGQDs was utilized for the degradation of organic pollutant (methylene blue dye) from water. Additionally, the proposed electrode revealed much higher electrocatalytic activity than the rare Pt catalyst, owing to the easy diffusion of electrolyte and fast quenching of charges through the porous structure. The assembled NGQDs showed 50% higher photocatalytic degradation compared to uniformly coated NGQDs, which was further accelerated (50%) by application of the biased potential of 2 V; i.e. photo-electrocatalysis. The novel photo-electrocatalytic electrode offers high conductivity, stability, and flexibility, which make this complete carbon electrode highly attractive for other catalytic applications such as fuel cells, supercapacitors, and water splitting.
关键词： Reduced graphene oxide,Photo-electrocatalysis,Stable electrode,Three-dimensional self-assembly,Nitrogen-doped graphene quantum dots
更新于2025-09-12 10:27:22
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Folic Acid-conjugated nitrogen-doped graphene quantum dots as fluorescent diagnostic material for MCF-7 cells
摘要： This paper reports the preparation and application of folic acid-conjugated nitrogen-doped graphene quantum dot as a fluorescent diagnostic material for MCF-7 cells of breast cancer. Nitrogen-doped graphene quantum dots (N-GQD) were prepared by hydrothermal method using citric acid as carbon source and diethylamine as nitrogen source. The doping of different nitrogen contents was effectively controlled by diethylamine. As the amount of nitrogen increased, more binding sites on the nitrogen-doped graphene quantum dots were supplied to the folic acid. Laser confocal scanning microscopy showed that the more folic acid binding facilitated the recognition and swallowing by cancer cells, which made the labeled cells emit stronger fluorescence and thus cancer cells could be better detected. Cytotoxicity tests showed that the material was low cytotoxic, making it a promising prospect for fluorescent probes.
关键词： fluorescent diagnostic material,nitrogen-doped graphene quantum dots,folic acid
更新于2025-09-12 10:27:22
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Insights into the formation of N doped 3D-Graphene Quantum Dots. Spectroscopic and Computational Approach
摘要： In this work, we utilize a top-down approach to synthesize nitrogen doped graphene quantum dots from a 3D-graphene precursor via an eco-friendly hydrothermal method. The nanoparticles obtained showed a 2-3 nm diameter and well dispersion behavior in aqueous media. The reaction mechanism of insertion of nitrogen from polyvinylpolypyrrolidone onto the 3D-graphene structure, via an esterification reaction, was studied by the density functional theory, in addition, the kinetic and thermodynamic magnitudes of the reaction was analyzed with the help of Eyring's transition state theory and statistical thermodynamics. After analysis by ss-NMR and XPS spectroscopies, the functional groups involved in this process were characterized, and N was found mainly as amide / amine groups. Fluorescence emission, which exhibited a red shift (552 nm) and an emission maximum at 512 nm when excited at 480 nm, demonstrated a low stoke shift (Δλ =32 nm), explained by the proposed structural model.
关键词： XPS,solid-state NMR,Nitrogen doped graphene quantum dots,DFT calculations
更新于2025-09-12 10:27:22
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Variation of Optical Properties of Nitrogen-doped Graphene Quantum Dots with Short/Mid/Long-wave Ultraviolet for the Development of the UV Photodetector
摘要： Nitrogen-doped graphene quantum dots (NGQDs) synthesized from a single glucosamine precursor are utilized to develop a novel UV-photodetector. Optical properties of NGQDs can be altered with short (254 nm), mid (302 nm) and longwave (365 nm) UV (ultra-violet) exposure leading to the reduction of absorption from deep to mid UV (200 to 320 nm) and enhancement above 320 nm. Significant quenching of blue and near-IR fluorescence accompanied by the dramatic increase of green/yellow emission of UV-treated NGQDs can be used as a potential UV-sensing mechanism. These emission changes are attributed to the reduction of functional groups detected by Fourier transformed infrared spectroscopy, and free radical-driven polymerization of the NGQDs increasing their average size from 4.70 to 11.20 nm at 60 min treatment. Due to strong UV absorption and sensitivity to UV irradiation, NGQDs developed in this work are utilized to fabricate UV photodetectors. Tested under long/mid/short-wave UV, these devices show high photo-responsivity (up to 0.59 A/W) and excellent photo-detectivity (up to 1.03X1011 Jones) with highly characteristic wavelength-dependent reproducible response. This study suggests that the optical/structural properties of NGQDs can be controllably altered via different wavelength UV-treatment leading us to fabricate NGQD-based novel UV photodetectors providing high responsivity and detectivity.
关键词： UV photodetector,Optical Properties Modification,Short/mid/long-wave UV treatment,UV sensor,Nitrogen-doped graphene quantum dots
更新于2025-09-12 10:27:22