Theoretical Insights into the Effect of Different Numbers of Thiophene Groups on Hydrogen Bond Interaction and Excited-State Intramolecular Proton-Transfer Process for Flavonoid Derivatives.

In this study, we systematically explored the impact of varying the number of thiophene groups on the hydrogen bond interaction and excited-state intramolecular proton-transfer (ESIPT) processes in flavonoid derivatives (STF, DTF, and TTF) using the density functional theory and time-dependent density functional theory methods. Initially, a thorough analysis of the optimized geometric structures revealed that the intramolecular hydrogen bond in the S1 state is enhanced and gradually weakened as the number of thiophene groups increases. To gain a deeper understanding of the hydrogen bond interaction, topological analysis, interaction region indicator scatter plots, and isosurface plots were employed. These images provide further insights that align with the structural analysis. Additionally, we observed a red-shift in the electronic spectra (absorption and fluorescence spectra), which is primarily attributed to the narrowing of the energy gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital, as elucidated by the frontier molecular orbitals. Furthermore, a combined analysis between the hole-electron distribution and the transition density matrix heat map shows that electron excitation involves the unidirectional charge-transfer mechanism. In the end, by conducting relaxed potential energy curve scans, we found that an increase in the number of thiophene groups elevates the energy barrier for ESIPT, making it more challenging for the reaction. In summary, our study underscores the vital effect of thiophene-substituted numbers in modulating the ESIPT process, which is able to provide valuable insights for the design and synthesis of desired organic fluorescent probes in the future.

Design, Synthesis, and Structure-Activity relationships of Evodiamine-Based topoisomerase (Top)/Histone deacetylase (HDAC) dual inhibitors.

On the basis of synergistic effect between topoisomerase (Top) and histone deacetylase (HDAC) inhibitors, a series of novel evodiamine-based Top/HDAC dual inhibitors were designed and synthesized. Systematic structure-activity relationship (SAR) studies led to the discovery of compounds 29b and 45b, which simultaneously inhibited Top and HDAC and exhibited potent antitumor activities against the HCT116 cell line. Compounds 29b and 45b efficiently induced apoptosis with G2 cell cycle arrest and significantly inhibited cellular HDACs in HCT116 cells with good in vitro metabolic stabilities. Collectively, this work provides valuable SAR information and lead compounds for evodiamine-based Top/HDAC dual inhibitors.

Density-matrix formalism for modal coupling and dispersion in mode-division multiplexing communications systems.

Borrowing methodology from quantum mechanics, we propose and develop a density-matrix formalism for modal coupling and dispersion in mode-division multiplexing communications systems. The central concept in our formalism is the density matrix, from which all observable information of an optical field can be handily accessed. In the formalism, we derive fundamental evolution equations and concatenation rules for the key elements that characterize essential modal properties, and construct a statistical model ready for the numerical analysis of stochastic light propagation in randomly perturbed fibers. Unlike the Stokes-vector formalism that requires J2 - 1 auxiliary Gell-Mann matrices, the density-matrix formalism can be directly formulated for arbitrary modal-space dimension J. Based on the density-matrix formalism, the statistical modal properties of a 4-mode fiber under random perturbation are numerically investigated, which raises an interesting possibility of optimizing the modal dispersion by manipulation of the random perturbation.

Efficient synthesis of an antiviral drug intermediate using an enhanced short-chain dehydrogenase in an aqueous-organic solvent system.

(2R,3S)-N-tert-Butoxycarbonyl-3-amino-1-chloro-2-hydroxy-4-phenylbutane (1b) is key for the synthesis of the antiviral drug atazanavir. It can be obtained via the stereoselective bioreduction of (3S)-3-(N-Boc-amino)-1-chloro-4-phenyl-butanone (1a) with short-chain dehydrogenase/reductase (SDR). However, the stereoselective bioreduction of this hydrophobic and bulky substrate still remained a challenge because of the steric hindrance effect and low mass transfer rate. In this study, SDR isolated from Novosphingobium aromaticivorans (NaSDR) having low activity to 1a, which was engineered to enhance catalytic efficiency through active pocket iterative saturation mutagenesis (ISM). The obtained mutant (muSDR) (G141V/I195L) had 3.57 times higher kcat than the wild type (WT) towards 1a. Molecular docking analysis revealed considerable differences in the distance between the substrate and catalytic residues in WT and mutant SDR. Moreover, muSDR reduced 15 ketones with excellent enantioselectivity, indicating broad substrate acceptance. After optimization of expression and reaction conditions, the conversion was completed in a scale-up reaction (500 mL) using 50% toluene with 500 mM substrate without additional NADH. These results show that muSDR may be a valuable biocatalyst for future industrial applications.

Tailor-made ion-imprinted polymer based on functionalized graphene oxide for the preconcentration and determination of trace copper in food samples.

A tailor-made Cu(II) ion-imprinted polymer based on large-surface-area graphene oxide sheets has been synthesized for the preconcentration and determination of trace copper from food samples by solid-phase extraction. Attributed to the ultrahigh surface area and hydrophilicity of graphene oxide, the Cu(II) ion-imprinted polymer prepared by the surface ion-imprinting technique exhibited a high binding capacity and a fast adsorption rate under the optimized experimental conditions. In the static adsorption experiments, the maximum adsorption capacity of Cu(II) ion-imprinted polymer is 109.38 mg/g at 25°C, which is much higher than that of the nonimprinted polymer (32.12 mg/g). Meanwhile, the adsorption is very rapid and equilibrium is reached after approximately 30 min. The adsorption mechanism is found to follow Langmuir adsorption model and the pseudo-second-order adsorption process. The Cu(II) ion-imprinted polymer was used for extracting and detecting Cu(II) in food samples combined with graphite flame atomic adsorption spectrometry with high recoveries in the range of 97.6-103.3%. The relative standard deviation and limit of detection of the method were evaluated as 1.2% and 0.37 µg/L, respectively. The results showed that the novel absorbent can be utilized as an effective material for the selective enrichment and determination of Cu(II) from food samples.

Preparation of a Two-Dimensional Ion-Imprinted Polymer Based on a Graphene Oxide/SiO2 Composite for the Selective Adsorption of Nickel Ions.

In the present work, a novel two-dimensional (2D) nickel ion-imprinted polymer (RAFT-IIP) has been successfully synthesized based on the graphene oxide/SiO2 composite by reversible addition-fragmentation chain-transfer (RAFT) polymerization. The imprinted materials obtained are characterized by Fourier transmission infrared spectrometry (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The results show that the thermal stability of the graphene oxide/SiO2 composite is obviously higher than that of graphene oxide. RAFT-IIP possesses an excellent 2D homogeneous imprinted polymer layer, which is a well-preserved unique structure of graphene oxide/SiO2. Owing to the intrinsic advantages of RAFT polymerization and 2D imprinted material, RAFT-IIP demonstrate a superior specific adsorption capacity (81.73 mg/g) and faster adsorption kinetics (30 min) for Ni(II) in comparison to the ion-imprinted polymer prepared by traditional radical polymerization and based on the common carbon material. Furthermore, the adsorption isotherm and selectivity toward Ni(II) onto RAFT-IIP and nonimprinted polymer (NIP) are investigated, indicating that RAFT-IIP has splendid recognizing ability and a nearly 3 times larger adsorption capacity than that of NIP (30.94 mg/g). Moreover, a three-level Box-Behnken experimental design with three factors combining the response surface method is utilized to optimize the desorption process. The optimal conditions for the desorption of Ni(II) from RAFT-IIP are as follows: an HCl-type eluent, an eluent concentration of 2.0 mol/L, and an eluent volume of 10 mL.

Influence of atomic electronegativity on ESIPT behaviour for the BTDI and its derivatives: Theoretical exploration.

In this work, we theoretically explored the influence of atomic electronegativity on excited-state intramolecular proton transfer (ESIPT) behavior among novel fluorescent probes BTDI and its derivatives (BODI and BSeDI). A thorough examination of the optimized structural parameters and infrared vibrational spectra reveals an enhancement in intramolecular hydrogen bonding within BTDI and its derivatives upon light excitation. This finding is further reinforced by topological analysis and interaction region indicator scatter plots, which underscores the sensitivity of atomic electronegativity to variations in hydrogen bonding strength. With regards to absorption and fluorescence spectra, the decrease in atomic electronegativity leads to a pronounced redshift, primarily attributed to the narrowing of the energy gap. Additionally, an analysis of potential energy curves and the exploration of intrinsic reaction coordinate paths based on transition state structures afford a deeper understanding of the mechanism underlying ESIPT and being modulated through the manipulation of atomic electronegativity. We anticipate that this work on atomic electronegativity regulating ESIPT behavior will serve as a catalyst for novel fluorescent probes in the future, offering fresh perspectives and insights.

Speciation, adsorption and determination of chromium(III) and chromium(VI) on a mesoporous surface imprinted polymer adsorbent by combining inductively coupled plasma atomic emission spectrometry and UV spectrophotometry.

In the present study, a Cr(III)-imprinted polymer (Cr(III)-IIP) was prepared by an easy one-step sol-gel reaction with a surface imprinting technique on the support of silica mesoporous material. A new SPE method for the speciation, separation, preconcentration, and determination of Cr(III) and Cr(VI) by inductively coupled plasma atomic emission spectrometry and UV on the mesoporous-imprinted polymer adsorbent was developed. The structure of the imprinted polymer was characterized by Fourier transform infrared spectroscopy, X-ray powder diffraction, transmission electron microscopy, and nitrogen adsorption-desorption isotherms. The adsorption kinetics, thermodynamics behavior, and recognition ability toward Cr(III) on Cr(III)-IIP and nonimprinted polymer were compared. The results showed that Cr(III)-IIP had higher selectivity and nearly a two times larger Langmuir adsorption capacity (38.50 mg/g) than that of NIP. The proposed method has been successfully applied in the determination and speciation of chromium in natural water samples with satisfactory results.

Ginsenoside Rg1 Inhibits STAT3 Expression by miR-15b-5p to Attenuate Lung Injury in Mice with Type 2 Diabetes Mellitus-Associated Pulmonary Tuberculosis.

Type 2 diabetes mellitus (T2DM) has been regarded as a critical risk factor for pulmonary tuberculosis (PTB). Ginsenoside Rg1 has been identified as a potential therapeutic agent for T2DM by suppressing the inflammatory response. However, the effect of Rg1 on T2DM-associated PTB has not been reported. In this study, we aimed to explore the function of Rg1 in the regulation of T2DM-associated PTB. We established a T2DM-associated PTB mouse model and found that the fibrosis of lung tissues was inhibited by Rg1 in T2DM-associated PTB mice. The lung injury of T2DM-associated PTB mice was repressed by Rg1. Moreover, the levels of IL-6, TNF-α, and IL-1ß in the lung tissues and serum were decreased by Rg1 in T2DM-associated PTB mice. The treatment with Rg1 inhibited the levels of free fatty acid and enhanced the expression of miR-15b-5p in lung tissues of T2DM-associated PTB mice. MiR-15b-5p targeted and inhibited the STAT3 expression. The expression of STAT3 was downregulated by Rg1, while the inhibition of miR-15b-5p reversed the downregulation. The expression of miR-15b-5p was reduced, but the expression of STAT3 was upregulated in the lung tissues of T2DM-associated PTB mice. We validated that miR-15b-5p attenuated inflammation and lung injury in the T2DM-associated PTB mouse model. The overexpression of STAT3 or the suppression of miR-15b-5p restored lung fibrosis and injury inhibited by Rg1 in T2DM-associated PTB mice. Meanwhile, the Rg1-repressed levels of IL-6, TNF-α, and IL-1ß were enhanced by the overexpression of STAT3 or the suppression of miR-15b-5p. In addition, the levels of free fatty acid repressed by Rg1 were reversed by STAT3 overexpression and miR-15b-5p inhibition. Thus, we conclude that ginsenoside Rg1 inhibits the STAT3 expression by miR-15b-5p to attenuate lung injury in mice with type 2 diabetes mellitus-associated pulmonary tuberculosis.

Length-controllable catalyzing-synthesis and length-corresponding properties of FeCo/Pt nanorods.

Newly designed magnetic-alloy/noble-metal FeCo/Pt nanorods have been first reported and fabricated through a length-controllable catalyzing-synthesis process in which the growth of FeCo nanorods was induced on Pt nanotips. The length of FeCo/Pt nanorods depends on the number of platinum nanotips. The proposed synthesis mechanism was corroborated by scanning electron microscopy, transition electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. With the decrease of Fe content in Fe(x)Co(96-x)/Pt(4) nanoalloys from 77 to 15, the morphology changes from nanorods with different lengths to nanoparticles. The analysis of the magnetic hysteresis loops indicated that the magnetic saturation and coercivity were strongly dependent on the length of the nanorods in which maximum saturation magnetization and minimum coercivity were obtained for Fe(77)Co(19)/Pt(4) nanorods with the length of ∼2.5 µm. In particular, FeCo/Pt exhibited length-dependent reactivity towards 1,1,2,2-tetrachloroethane, and Fe(77)Co(19)/Pt(4) nanorods with the length of ∼2.5 µm yielded the greatest dechlorination rate. Moreover, Pt can enhance the dechlorination of 1,1,2,2-tetrachloroethane.