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An efficient nicotinamide adenine dinucleotide (NADH) regeneration system is of great significance for the application of oxidoreductase-catalyzed reactions. Photochemical regeneration has been a research hotspot in recent years. Graphite carbon nitride (g-C3N4) has important application prospects. However, bulk g-C3N4 (BCN) has some disadvantages that lead to a low catalytic efficiency. Herein, nanoporous g-C3N4 (PCN) was prepared using silica nanoparticles as templates, and the effects of the mass ratio of cyanamide to silica and the particle size of the templates on the structure, optical, and catalytic properties of PCN were investigated. Then, cyanamide was separately co-polymerized with two types of thiophene compounds and imidazole-, benzene-, and quinolone-based compounds, and the effects of the structure and number of aromatic rings introduced into PCN on the properties of catalysts were studied. The results show that PCN had much better catalytic performance than BCN, the initial reaction rate of NADH regeneration could be upgraded from 18.01 to 37.14 mmol/(g·min) after PCN was modified with thiophene compound, and the yield of NADH after 20 min increased from 56.8 to 82.7%. When other aromatic compounds were added in the PCN preparation process, a catalytic performance similar to that of thiophene-modified PCN was acquired. [ABSTRACT FROM AUTHOR]

The solubility of racemic potassium2-(1-hydroxypentyl)-benzoate(dl-PHPB) in methanol, ethanol, n-propanol, isopropyl alcohol, ethyl acetate, and acetone from 298.15to 333.15 K was measured by an equilibrium method. The solubilitydata of dl-PHPB in six different solvents was correlatedby the modified Apelblat equation. The correlation coefficients wereobserved in the range of 0.993 to 0.998, indicating a good fit. Theresults showed that the mole fraction solubility of dl-PHPB in methanol (6.22 × 10–2), ethanol (2.58× 10–2), n-propanol (2.39× 10–2), and isopropyl alcohol (6.72 ×10–3) was significantly higher than in acetone (2.58× 10–4) and ethyl acetate (8.02 × 10–5) at 298.15 K. The experiment data would be usefulfor optimizing purification and recrystallization processes of dl-PHPB in industry. [ABSTRACT FROM AUTHOR]

In response to growing concerns about public safety and environmental conservation, it is essential to develop a precise identification method for trace explosives. To improve the stability and detection sensitivity of perovskite quantum dots (PQDs) and address the issue of low porosity in traditional polymer-based photonic crystals (PhCs), this study proposed a PQD photoluminescence (PL) enhancement strategy based on the slow light effect of ZIF-8 PhCs for highly sensitive, selective, and convenient detection of 2,4,6-trinitrophenol (TNP). The slow light effect at the photonic band gap edge is the basis of amplifying the PL signal. PhCs were fabricated by the evaporation-induced self-assembly method. The diffraction wavelength overlapping the whole visible region was designed to match the emission wavelength of PQDs. Results showed that PhCs matching the PBG edge with PQDs' emission peak amplified the PL signal 11.3 times, significantly improving sensitivity for trace TNP detection with a limit as low as 2.52 nM. Moreover, there was a 13.3-fold enhancement of PQDs' fluorescence lifetime when the emission wavelength fell in the PBG range. The hydrophobic surface of ZIF-8 PhCs enhanced the PQDs' stability and moisture resistance. Furthermore, the selective quenching mechanism of TNP by the sensor was photoinduced electron transfer (PET) verified by DFT calculations and time-resolved PL decay dynamics measurements. This study demonstrated great potential for manipulating light emission enhancement by PhCs in developing efficient fluorescent sensors for trace environmental pollutant detection.

Real-time sensing and monitoring of temperature are of great significance for assessing human health. The sensitivity and stability are inevitable issues for thermometers. In this study, a thermometer with the cylindrical thermochromic hydrogel was prepared for real-time visual monitoring of temperature, which had excellent temperature sensitivity, angle-independence axially, and environmental stability. The customization of their initial optical properties depended on the PMMA concentrations and the content of the hydrogel monomer. The glycerol introduced with solvent displacement formed hydrogen bonds with the hydrogel network, which stabilized their mechanical properties, and the reflection peak blue-shifted from 653 to 499 nm when tensile strain was 57.85%. At the same time, the environmental stability originated from the moisturizing properties of the glycerol, which enabled the hydrogel to reliably transmit the information on temperature into the air without losing moisture. The reflection peak of the cylindrical thermochromic hydrogel shifted from 657 to 455 nm when the temperature increased from 22 to 45 °C, which realized temperature visual monitoring in the full-color range. The temperature sensitivity of the glycerol─nonclose-packed photonic crystals remained stable for 1 month, which provided an optimal option for continuous visual temperature monitoring.

We present a microplate assay for the detection of HIV and SARS-CoV-2 which involves the preadsorption of carboxy-modified polystyrene microspheres to the microplate wells and their self-assembly leading to the formation of a photonic crystal colloidal array (PCCA). PCCA is then cross-linked with amino-modified aptamers selected for viral cell surface glycoproteins, i.e., S1-protein of SARS-CoV-2 and gp120 of the human immunodeficiency virus (HIV), to develop an aptamer-linked photonic crystal assay (ALPA). ALPA is then utilized as a proof-of-concept method for the detection of S1-protein, gp120, and two whole viruses, i.e., SARS-CoV-2 and HIV, as well. The aptamers are stable at room temperature and can bind with the viruses' proteins via hydrogen bonding. This binding leads to color generation from PCCA, and the signal can easily be measured and quantified by a UV/vis spectrometer. The assay carries the advantage of a two-step detection process by the addition of the virus sample directly to a 96-well microplate and incubation of 5 min followed by convenient detection through a UV/vis-spectrometer. The assay does not require any additional reagents and can be customized for similar viruses utilizing specific aptamers targeting their cell surface receptors.

The components in polymer-bonded explosive X, including cyclotetramethylene-tetranitramine, paraffin, and polytetrafluoroethylene, were determined using near-infrared (NIR) spectroscopy. Using partial least squares as the multivariate calibration method, quantitative calibration models for components in X were verified internally and externally. The possible combinations of eight general spectral pretreatment methods and different bands of the scanning spectral region (12,500-4000 cm -1 ) were established. The models were analyzed, evaluated, and optimized via the fitting effect. The data were combined with the mathematical meaning of the model spectral pretreatment methods and the chemical significance of the modeling spectral bands. Prediction performance offered optimal quantitative calibration models. Paired bilateral Student's t tests show that there is no significant difference between the values obtained by NIR and chemical analysis methods, and the NIR method has good accuracy. Moreover, the precision of the NIR method is better than that of the chemical method, and the analysis time is reduced from 2 days to a few minutes., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

Due to its double bond, istradefylline rapidly isomerizes to Z -istradefylline when exposed to normal daylight in dilute solution. To solve the poor photostability of the istradefylline solution, a series of istradefylline derivatives (in total 17 compounds, including II-1 and II-2 series) were designed and synthesized, and their biological activity in inhibiting cAMP was evaluated. The IC 50 values of compounds II-1-3, II-2-1, II-2-2, II-2-3, II-2-4, and II-2-6 were 7.71, 6.52, 6.16, 7.23, 7.96, and 9.68 μg/mL, respectively, which had the same order of activity as that of istradefylline (IC 50 value was 1.94 μg/mL). The preliminary structure-activity relationship suggested that the 6-amino in adenine played an important role in binding an A 2A receptor. The results of photostability experiments showed that the photostability of the target compounds of II-1 and II-2 series was improved when compared with that of istradefylline., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

A precise determination method of azilsartan solubility between 293.15 and 333.15 K in several ordinary solvents and some of their aqueous mixtures was established by high-performance liquid chromatography. In all tested solvents, its solubility shows exponential growth with the increase in temperature. This trend is especially pronounced in methanol and ethanol. The order of solubility of azilsartan can be expressed as ethanol > tetrahydrofuran > ethanol/water (8/2, v/v) > methanol > methanol/water (8/2, v/v) > n -propanol > isopropanol > ethanol/Water (5/5, v/v) > acetonitrile. The solubility data of azilsartan were well correlated by the λ h model. Moreover, the thermodynamic data including the dissolving enthalpy, entropy, and Gibbs free energy of azilsartan in each solvent were calculated which is crucial to its preparation technology study., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

Polyvinyl pyrrolidone polymer (PVP) has been widely applied in biological and medical fields. A few in vitro studies indicated that PVP might cause toxicity. However, the underlying mechanism is poorly understood. In this work, we found that PVP directly induced strand breakages of various DNA molecules, implicating a cleavage activity. Moreover, reactive oxygen species (ROS) scavenging analysis shows that DNA cleavage activity of PVP is not related to ROS-induced oxidation. As revealed by gel electrophoresis and liquid chromatography/mass spectrometry analysis, the major cleavage products of DNA were identified as two purine bases, guanine and adenine, suggesting that PVPs have a novel depurination activity. The selective depurination and DNA cleavage activity of PVPs were further confirmed by studying the interaction of PVP with four nucleosides and four well-designed oligodeoxynucleotides probes containing specific nucleotides. This study may provide insights into PVP-DNA interactions and resultant genotoxicity and may also open a new way for DNA study.

The toxicity of NPs is not well characterized in terms of their size. In particular, the size-based toxicity of fullerene (C(60)) remains an issue because of a lack of C(60) NPs with a well-controlled size. In this work, six fractions of the nano-C(60) aggregates (nC(60)) with different size distribution were prepared by a simple differential centrifugation. By using these nC(60) fractions, we demonstrate the size-dependent inhibition of DNA polymerase and reduced-size enhanced cytotoxicity. Above all, we found that nC(60) NPs with smaller size may have higher toxicity potency. These size-dependent effects were observed at the high exposure doses (4-6 mg/L). Interestingly, at 20-times lower and noncytotoxic doses, the size-dependent effect can be indicated by apoptosis-related fluorescent protein fused Bax translocation. Considering the toxicity of NPs is often ignored in the traditional end-point analysis for cytotoxicity when the exposure dose is low, the findings presented here will assist in the evaluation of the size-dependent cytotoxicity and dose-response relationships of toxicity mediated by nC(60) NPs at low doses.

A synthetic molecularly imprinted polymer (MIP) sorbent for estrogenic compounds was prepared using a noncovalent imprinting technique. MIP microspheres sized from 1 to 2 microm were synthesized in acetonitrile by using alpha-estradiol as the template, acrylamide as the functional monomer, and trimethylpropanol trimethacrylate as the cross-linker. When compared with the nonimprinted polymer (NIP), the MIP showed outstanding affinity toward alpha-estradiol in aqueous solution with a binding site capacity (B(max)) of 380 nmol mg(-1) MIP, imprinting effect of 35, and a dissociation constant (Kd) of 38 microM. The MIP exhibited significant binding affinity toward other related estrogenic compounds such as beta-estradiol, diethylstilbestrol, estriol, and estrone, suggesting that this material may be appropriate for treating a complex mixture of estrogenic pollutants. The feasibility of removing estrogenic compounds from environmental water by the MIP was demonstrated using lake water spiked with alpha-estradiol. In addition, the MIP reusability without any deterioration in performance was demonstrated for at least five repeated cycles.