Frontiers in Chemistry最新文献

Polyurethane (PU) pyrolysis characteristics were investigated using reactive force field molecular dynamics simulations to reveal the product distribution and thermal decomposition mechanisms. A PU molecular model was constructed and simulated its pyrolysis process at 1,500-3,000 K, analyzing potential energy changes, product species, carbon-containing component distribution, main gas products, main intermediate products and initial cleavage pathways. At 1,500 K, PU mainly decomposes into NHCOO and CH₂ fragments, with concurrent gas release. At 1,800-2,100 K, aromatic amines, olefins, and gases (including CO₂, CO, and NH₃) are formed through radical recombination. At higher temperatures (2,400-3,000 K), carbon rearrangement is promoted, yielding dense C₄₀ ⁺ species alongside persistent gases. The results show that PU pyrolysis initiates with the C-O-C bond cleavage of the NHCOOCH₂ group, generating NHCOO and CH₂ fragments, and this cleavage occurs via a homolytic pathway. The dynamic competition between main chain scission and radical recombination drives the complex pyrolysis network, with temperature governing product diversity. This work provides microscopic insights into PU thermal degradation, supporting applications in fire safety assessment and material recycling.

Salvia miltiorrhiza: is a widely used Chinese medicinal herb whose quality is significantly influenced by geographical origin. Establishing reliable methods for origin identification is therefore crucial for quality assurance. In this study, 67 batches of Salvia miltiorrhiza samples from Shandong, Shanxi, Henan, and Sichuan provinces were analyzed using near-infrared (NIR) and mid-infrared (MIR) spectroscopy combined with chemometric techniques. Six preprocessing methods were applied to optimize spectral data, and PLS-DA models were constructed based on the optimized results. To further improve model performance, uninformative variable elimination (UVE), competitive adaptive reweighted sampling (CARS), and random forest (RF) were employed for variable selection. Discriminant models were then established using NIR, MIR, and fused (NIR + MIR) data, with performance evaluated by accuracy. Results showed that in NIR, the 2nd-RF-PLS-DA model achieved the best performance with 96.72% accuracy, while in MIR, the SG-UVE-PLS-DA model reached 98.33% accuracy. After integrating NIR and MIR data, the 2nd-UVE-PLS-DA model achieved 100% accuracy, demonstrating the strongest discriminative capability. These findings demonstrate that combining NIR and MIR spectroscopy with appropriate preprocessing and variable selection strategies fully exploits complementary spectral information, enabling the construction of rapid, reliable, and efficient discriminant models. This approach provides an effective tool for origin tracing of Salvia miltiorrhiza and serves as a methodological reference for advancing quality evaluation of other Chinese herbal medicines.

[This retracts the article DOI: 10.3389/fchem.2021.710250.].

Tetrazoles are nitrogen-rich heterocycles that have attracted interest because of their numerous applications in pharmaceutical and medicinal chemistry. Four nitrogen atoms and one carbon atom make up these five-membered rings, which have special physicochemical and electrical characteristics, including acidity, resonance stabilization, and aromaticity. This article highlights the structure, spectroscopic characteristics, and physical and chemical characteristics of tetrazoles. It also describes how overlapping mechanisms, such as DNA replication inhibition, protein synthesis disruption, and oxidative stress induction, as well as similar therapeutic targets, enable inhibitors to serve as both antibacterial and anticancer agents. Tetrazole moieties have been fused with a range of pharmacophores, such as indoles, pyrazoles, quinolines, and pyrimidines, yielding fused derivatives that display substantial inhibitory activity against bacterial, fungal, and cancer cell lines, with certain compounds exhibiting efficacy comparable to or exceeding that of established therapeutic agents. The rational design of more efficacious tetrazole-based therapies is facilitated by structure-activity relationship analysis, which further highlights significant functional groups and scaffolds that contribute to increasing activity. We investigate the relationship between microbial inhibition and anticancer efficacy, opening up new avenues for the creation of multifunctional therapeutic agents. We hope that this study will offer significant guidance and serve as a valued resource for medicinal and organic researchers working on drug development and discovery in multifunctional therapeutics. The review involves a thorough investigation of tetrazole in recent years.

Introduction: A major challenge in nanomedicine is developing multifunctional nanoplatforms capable of achieving synergistic cancer therapy.

Methods: In the present study, we developed a CD44-targeted nanocomposite, named UiO-SNO@CuS/HA, for efficacy evaluation in combination therapy including photothermal therapy (PTT), nitric oxide (NO) gas therapy and chemodynamic therapy (CDT) The nanoplatform was produced through the preparation of UiO-66-SH metal-organic framework (MOF) followed by the post-synthetic nitrosation of S-thiols to give S-nitrosothiols (SNO) as the NO donor. Afterward, in situ growth of ultrasmall CuS nanoparticles on the MOF surface led to the eventual coating of the hybrids with hyaluronic acid (HA) for active tumor targeting.

Results: Under 1064 nm laser irradiation, the CuS component mediated effective PTT with a photothermal conversion efficiency of 41.4%. The generated photothermal heat also leads to the release of a considerable amount of the gas NO (135 μM, pH 4.6) and promotes the release the ions Cu² + in the acidic tumor microenvironment. The Cu²⁺ that was released was reduced to Cu⁺ by glutathione, achieving GSH depletion of around 80%. This not only triggered a Fenton-like reaction with H₂O₂ to produce reactive hydroxyl radicals (·OH) for CDT, but also stimulated further production of NO from SNO moieties, forming a self-propagating therapeutic cycle. The series of events led to an increase of 4.2 times generation of intracellular reactive oxygen species (ROS), severe mitochondrial dysfunction with a decrease of 85% in membrane potential, and finally 78.4% apoptosis was induced in HeLa cells.

Discussion: The triple-combination therapy generated by UiO-SNO@CuS/HA was demonstrated to have much higher cancer cell killing efficacy in vitro than either single or dual therapies, and very good biocompatibility with normal cells. This study reports a rationally designed feedback-amplified nanosystem that enables potent and specific triple-synergistic tumor therapy, representing a practical strategy for advanced combinatorial cancer therapy.

Creating accurate models to explain the reaction mechanisms in thermochemical processing of solid polyolefins and their derivatives using non-thermal plasma (NTP) technology is crucial for improving recycling and reuse efforts. This area has gained significant attention over the past few decades. The model for polyolefin breakdown involves a mix of complex free radical reactions, along with formal and molecular processes. NTP reactors provide an environment with enhanced reactivity and performance, making them highly efficient for treating solid polyolefins and ideal for producing clean energy and other valuable products from polyolefin waste. Therefore, developing adaptable and precise simulations to identify the best geometric configurations for NTP reactors is key to improving their performance. Utilising various computational techniques and integrating suitable algorithms to build models that meet design goals and predict results offers a cutting-edge approach for engineering applications. Mathematical modelling and cutting-edge computational simulations can enhance themselves by incorporating data and verifying results experimentally, with a focus on linking inputs to anticipated results. This method is crucial in interpreting the mathematical connections among various intricate procedures and actual response circumstances. In this study, a concise overview of new, promising research advances in the treatment of polyolefin waste using NTP has been presented. The subjects covered in this study include i) advancements in various class modelling techniques for analysing and understanding the reaction dynamics of NTP-treated polyolefin wastes, ii) simulation approaches for NTP reactors, and iii) existing challenges and future outlooks. The process can be commercialised due to the potentially high market value of its products, which include chemicals and fuels. Additionally, by creating appropriate models through solving sets of equations and assessing system performances under the complex conditions required for these products, the selectivity of this technology can be enhanced. An immediate requirement exists to summarise the current methods, pinpoint the technological limitations, and outline necessary research in this developing area.

Oral wounds, particularly those coupled with bone defects like osteoradionecrosis and periodontitis, present a profound clinical challenge. While conventional biomaterial dressings offer basic therapeutic benefits, their static nature hinders dynamic interaction with the complex wound microenvironment, where factors like fluctuating pH and enzymatic activity impair healing. This review focuses on the development of "smart" stimuli-responsive dressings that overcome this limitation. These advanced systems are engineered to sense specific intraoral signals, such as pH, reactive oxygen species, or enzymes, or external triggers like light, enabling on-demand drug release and active wound microenvironment reprogramming. We critically synthesize recent progress in their design, stimuli-responsive mechanisms and therapeutic application, with a dedicated emphasis on bone-related oral pathologies. Furthermore, the review addresses the critical translational challenges and future prospects for bridging material innovation with clinical needs, aiming to facilitate next-generation regenerative therapies for oral and craniofacial defects.

[This retracts the article DOI: 10.3389/fchem.2023.1079288.].

[This retracts the article DOI: 10.3389/fchem.2022.902719.].