A one-step electrochemical method for synthesis of ultrathin g-C3N4 nanosheets is reported. This method does not need dangerous reagents and largely reduces the reaction time.
Hydro-rich C-dots were used as both the reducing and stabilizing agent in the preparation of noble metal nanoparticles (AuNPs, AgNPs and Au@AgNPs) for the detection of glucose.
Abstract Carbon nanodots (C‐dots) show great potential as an important material for biochemical sensing, energy conversion, photocatalysis, and optoelectronics because of their water solubility, chemical inertness, low toxicity, and photo‐ and electronic properties. Numerous methods have been proposed for the preparation of C‐dots. However, complex procedures and strong acid treatments are often required, and the as‐prepared C‐dots tend to be of low quality, and in particular, have a low efficiency for photoluminescence. Herein, a facile and general strategy involving the electrochemical carbonization of low‐molecular‐weight alcohols is proposed. As precursors, the alcohols transited into carbon‐containing particles after electrochemical carbonization under basic conditions. The resultant C‐dots exhibit excellent excitation‐ and size‐dependent fluorescence without the need for complicated purification and passivation procedures. The sizes of the as‐prepared C‐dots can be adjusted by varying the applied potential. High‐quality C‐dots are prepared successfully from different small molecular alcohols, suggesting that this research provides a new, highly universal method for the preparation of fluorescent C‐dots. In addition, luminescence microscopy of the C‐dots is demonstrated in human cancer cells. The results indicate that the as‐prepared C‐dots have low toxicity and can be used in imaging applications.
High quality carbon dots (C-dots) with down- and up-conversion fluorescence have been synthesized through low-temperature carbonization using sweet pepper as the carbon source. The C-dots with a quantum yield (QY) of 19.3% exhibit superior photophysical properties, for example, narrow and symmetric emission spectra, large stock shifts, resistance to photobleaching, and excitation-dependent fluorescence behavior. The excellent C-dots serve as useful fluorescent probes for hypochlorite (ClO−) detection by both down- and up-conversion fluorescence. Two consecutive linear ranges allow a wide determination of ClO− concentrations with a low detection limit of 0.05 μmol L−1 and 0.06 μmol L−1 (S/N = 3) for down- and up-conversion fluorescence measurements, respectively. The proposed detection method is advantageous because it is simple, sensitive, dual-signalling model and low-cost and has potential extensive applications in environmental and biological assays.
Au nanoparticles (AuNPs) have good absorption properties in the visible region, while upconversion nanoparticles (UCNPs) have an emission at 547 nm upon excitation with a 980 nm laser, which could avoid most interfering signals of biomolecules in serum. In this paper, we developed an aptasensor for platelet-derived growth factor (PDGF–BB) detection in 30% blood serum based on fluorescence resonance energy transfer between AuNPs and UCNPs. With the proposed aptasensor, PDGF–BB in 30% blood serum was detected. Two consecutive linear ranges allow a wide determination of PDGF–BB concentrations with a low detection limit of 10 nM (S/N = 3). Importantly, the fluorescence biosensor can directly detect PDGF–BB in blood serum of lymphoma patient. This detection approach can also exhibit good stability and selectivity.
Si quantum dots have been demonstrated to be environmentally friendly photoluminescence probes and their fluorescence was quenched by H2O2 that was produced from the glucose oxidase-catalyzed oxidation of glucose. This strategy could be used to detect glucose with high sensitivity and selectivity.
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