Nanosilver and protonated carbon nitride co-coated carbon cloth fibers based non-enzymatic electrochemical sensor for determination of carcinogenic nitrite.

A novel electrochemical nitrite (NaNO2) sensor was fabricated by combining nanosilver with protonated carbon nitride (H-C3N4) supported on carbon cloth (CC). H-C3N4 was distributed uniformly on the CC surface, providing more active sites for the electrocatalytic active center (nanosilver). CC as a substrate improved the H-C3N4 conductivity and provided the sensor with a flexible feature. The strong synergistic effect between CC, H-C3N4, and nanosilver can exert a significant electrocatalytic performance on the flexible sensor. The Ag/H-C3N4/CC flexible sensor electrode did not consume much more time to polish the surface of traditional electrodes, and possessed a high sensitivity of 0.85537 µA/mg, a wide linear response range that spanned 5 to 1000 µM, a low detection limit of 0.216 µM (S/N = 3), and high selectivity for nitrite in the presence of common organic and inorganic interfering species (such as CaCl2, NaCl, MgCl2, NaNO3, glucose, urea, and p-nitrophenol). The Ag/H-C3N4/CC flexible sensor can be used for sample detection of nitrite as it has a strong anti-interference ability, good reproducibility, repeatability, and long-term stability. The Ag/H-C3N4/CC sensor is a promising alternative electrode to traditional ones such as ITO, gold or glassy carbon electrodes.

Nature of the Synergistic Effect of N and S Co-Doped Graphene for the Enhanced Simultaneous Determination of Toxic Pollutants.

N-doped graphene (NG), S-doped graphene (SG), and N and S co-doped graphene nanocatalysts with different doping sequences (N-SG and S-NG) are successfully synthesized by a facile low-temperature hydrothermal method. By changing the synthetic sequence, S-NG significantly increases the electron transport rate of the sensor and the electrocatalytic ability compared to NG, SG, and N-SG due to the optimal proportion of doping element content and suitable N- and S-bonding configurations. The origin of the synergistic effect of N and S co-doped graphene is confirmed. Traces of S doping greatly enhance the electrochemical performance. The large volume of S-Ox groups may prevent the analytes from approaching the catalytic sites of the sensing materials due to a steric hindrance effect. S-NG, which possesses less S-Ox groups, exhibits better performance than N-SG. Pyridinic N plays an important role in enhancing the electrochemical activity and conductivity. The simultaneous determination of aniline (AN), p-phenylenediamine (PPD), and nitrobenzene (NB) as typical toxic pollutants is performed by employing the S-NG nanoarchitecture. The detection limits (S/N = 3) for AN, PPD, and NB are 0.023, 0.051, and 0.216 µM, respectively. In addition, the S-NG sensors also have excellent anti-interference, stability, and reproducibility. The precise control and synthesis of multiheteroatoms into graphene represent a promising strategy to enhance the electrocatalytic performance in energy and environmental fields.

Combination Therapy With Hyperbaric Oxygen and Erythropoietin Inhibits Neuronal Apoptosis and Improves Recovery in Rats With Spinal Cord Injury.

BACKGROUND: Apoptosis plays an important role in various diseases, including spinal cord injury (SCI). Hyperbaric oxygen (HBO) and erythropoietin (EPO) promote the recovery from SCI, but the relationship between apoptosis and the combination therapeutic effect is not completely clear. OBJECTIVE: The purpose of this study was to investigate the effects of HBO and EPO on SCI and the mechanisms that underlie their therapeutic benefits. DESIGN: The study was designed to explore the effects of HBO and EPO on SCI through a randomized controlled trial. METHODS: Sixty young developing female Sprague-Dawley rats were randomly divided into groups of 12 rats receiving sham, SCI, HBO, EPO, or HBO plus EPO. The SCI model was modified with the Allen method to better control consistency. HBO was performed for 1 hour per day for a total of 21 days, and EPO was given once per week for a total of 3 weeks. Both methods were performed 2 hours after SCI. Locomotor function was evaluated with the 21-point Basso-Beattie-Bresnahan Locomotor Rating Scale, an inclined-plane test, and a footprint analysis. All genes were detected by Western blotting and immunohistochemistry. The level of cell apoptosis was determined by Hoechst staining. RESULTS: The results showed that HBO and EPO promoted the recovery of locomotor function in the hind limbs of rats by inhibiting the apoptosis of neurons. During this period, the expression of B-cell lymphoma/leukemia 2 protein (Bcl-2) increased significantly, whereas the expression of Bcl-2-associated X protein (Bax) and cleaved caspase 3 decreased significantly, indicating the inhibition of apoptosis. Meanwhile, the expression of G protein-coupled receptor 17 decreased, and that of myelin basic protein increased, suggesting that there may be a potential connection between demyelination and neuronal apoptosis. LIMITATIONS: The limitations of the study include deviations in the preparation of SCI models; lack of reverse validation of molecular mechanisms; absence of in vitro cell experiments; and only one time point after SCI was studied. CONCLUSIONS: HBO and EPO treatments are beneficial for SCI, especially when the 2 therapies are combined.

Hierarchical Self-Assembly of Cyclodextrin and Dimethylamino-Substituted Arylene-Ethynylene on N-doped Graphene for Synergistically Enhanced Electrochemical Sensing of Dihydroxybenzene Isomers.

An electrochemically active sensing nanomaterial (denoted as CD-MPEA-NG) has been successfully constructed by an hierarchical self-assembly of cyclodextrin (CD) and N,N-dimethyl-4-(phenylethynyl)aniline (MPEA) on N-doped graphene (NG) in a low-temperature hydrothermal process. The unique nanostructure of the high-performance CD-MPEA-NG was confirmed by utilizing Fourier transform infrared spectra, an X-ray diffractometer, and differential pulse voltammetry (DPV), etc. In particular, the method of density functional theory with dispersion energy (DFT-D) of wB97XD/LanL2DZ was employed to optimize and describe the face-to-face packing structure of heterodimers of NG and MPEA. The CD-MPEA-NG sensor exhibits highly sensitive performance toward dihydroxybenzene isomers, without relying on expensive noble metal or a complicated preparation process. The experimental results demonstrate that given the synergistic effect of NG and MPEA as a coupled sensing platform, CD as a supramolecular cavity can significantly enhance the electrochemical response. The detection limits (S/N = 3) for catechol (CT), resorcinol (RS), and hydroquinone (HQ) are 0.008, 0.018, and 0.011 µM by DPV, respectively. Besides, the CD-MPEA-NG sensor shows a superb anti-interference, reproducibility, and stability, and satisfactory recovery aimed at detecting isomers in Nanjing River water. The encouraging performance as well as simplified preparation approach strongly support the CD-MPEA-NG sensor is a fascinating electrode to develop as a seamless and sensitive electroanalytical technique.