Search

Tetrazole compounds are a category of energetic materials with great potential. Their stability is inherently related to their aromatics. On the basis of research in DFT at b31yp/6-311** level on three compounds interested, viz. 5-amino-1 H-tetrazole, 5-carboxyl-1 H-tetrazole, and 2-mefhyl-5-carboxyl-tetrazole, their aromatic characters are extensively analyzed by virtue of different estimation method. Analyses show that these methods, Nucleus-independent Chemical Shift, iso-chemical shielding surface, adaptive natural density partitioning, [pi]-electrons density, and localized orbital locator of [pi]-electron density are efficient for substituted-tetrazole ring aromaticity estimation. Conclusion denotes that both substituent and substituted position can significantly affect the aromaticity of tetrazole ring of tetrazole compound. Among these given substituents, electro-withdrawing group -COOH significantly increases the aromaticity of the tetrazole rings due to the withdrawing to jr-electrons thereof but electro-donating group -[NH.sub.2] weakens the one of the tetrazole rings due to the donating to jr-electrons thereof. But for 2-methyl-5-carboxyl-tetrazole, the aromaticity increasing of -COOH imposed on jr-electrons of tetrazole ring thereof is partially balanced by the existence of the electron-donating group -[CH.sub.3] at asymmetric meta-position of tetrazole ring. Consequently the aromaticity order is 5-Carboxyl-1 H-tetrazole > 2-methyl-5-Carboxyl-tetrazole > 5-amino-1 H-tetrazole. Key words: theoretical study, aromaticity, substituents, tetrazole ring, 1. Introduction With the employ of the term 'aromaticity' by August Wilhelm Hofmann in 1855, (1) followed by the found of 'benzene' by Friedrich August Kekule in 1865, the particular [...]

Immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment, demonstrating unprecedented efficacy against advanced cancers. However, their clinical applications are significantly hampered by low overall response rates. Dual blockade of two immune checkpoints represents a promising strategy to enhance immunotherapeutic efficacy. In this study, we developed hybrid cell membrane nanovesicles adorned with PD-1 and SIRPα receptors for combination immunotherapy in melanoma. Our hybrid nanovesicles (PD-1/SIRPα NVs) demonstrated high specificity to PD-L1 and CD47 ligands, facilitating the phagocytosis of melanoma cells by macrophages. In a melanoma mouse model, PD-1/SIRPα NVs significantly suppressed 77% of tumor growth and elicited a robust antitumor immune response for immunotherapy. In conclusion, our findings highlight the promising potential of PD-1/SIRPα NVs as novel and effective ICIs for cancer immunotherapy. [ABSTRACT FROM AUTHOR]

The chemical tolerance of ketoenamine covalent organic frameworks (COFs) is excellent; however, the tight crystal structure and low surface area limit their applications in the field of catalysis. In this work, a porous single-atom iron catalyst (FeSAC) with a core–shell structure and high surface area was synthesized by using Schiff base COF nanospheres as the core and ketoenamine COF nanosheets growth on the surfaces. Surface defects were created using sodium cyanoborohydride etching treatment to increase specific surface area. The dye degradation experiments by peroxymonosulfate (PMS) catalyzed by the FeSAC proved that methylene blue can be degraded with a degradation rate constant of 0.125 min−1 under the conditions of 0.1 g L−1 catalyst dosage and 0.05 g L−1 peroxymonosulfate. The FeSAC/PMS system effectively degrades various pollutants in the pH range of 4–10 with over 80% efficiency for four cycles and can be recovered by soaking in iron salt solution. Free radical quenching experiments confirmed that singlet oxygen and superoxide radicals are the main active species for catalysis. [ABSTRACT FROM AUTHOR]

The development of fluorescent molecular imprinting sensors for direct, rapid, and sensitive detection of small organic molecules in aqueous systems has always presented a significant challenge in the field of detection. In this study, we successfully prepared a hydrophilic colloidal molecular imprinted polymer (MIP) with 2,4-dichlorophenoxyacetic acid (2,4-D) using a one-pot approach that incorporated polyglycerol methacrylate (PGMMA-TTC), a hydrophilic macromolecular chain transfer agent, to mediate reversible addition-fragmentation chain transfer precipitation polymerization (RAFTPP). To simplify the polymerization process while achieving ratiometric fluorescence detection, red fluorescent CdTe quantum dots (QDs) and green fluorescent nitrobenzodiazole (NBD) were introduced as fluorophores (with NBD serving as an enhancer to the template and QDs being inert). This strategy effectively eliminated background noise and significantly improved detection accuracy. Uniform-sized MIP microspheres with high surface hydrophilicity and incorporated ratiometric fluorescent labels were successfully synthesized. In aqueous systems, the hydrophilic ratio fluorescent MIP exhibited a linear response range from 0 to 25 μM for the template molecule 2,4-D with a detection limit of 0.13 μM. These results demonstrate that the ratiometric fluorescent MIP possesses excellent recognition characteristics and selectivity towards 2,4-D, thus, making it suitable for selective detection of trace amounts of pesticide 2,4-D in aqueous systems. [ABSTRACT FROM AUTHOR]

Endogenous stimuli-responsive injectable hydrogels hold significant promise for practical applications due to their spatio-temporal controllable drug delivery. Herein, we report a facile strategy to construct a series of in situ formation polypeptide hydrogels with thermal responsiveness and enzyme-triggered dynamic self-assembly. The thermo-responsive hydrogels are from the diblock random copolymer mPEG-b-P(Glu-co-Tyr). The L-glutamic acid (Glu) segments with different γ-alkyl groups, including methyl, ethyl, and n-butyl, offer specific secondary structure, facilitating the formation of hydrogel. The L-tyrosine (Tyr) residues not only provide hydrogen-bond interactions and thus adjust the sol–gel transition temperatures, but also endow polypeptide enzyme-responsive properties. The PTyr segments could be phosphorylated, and the phosphotyrosine copolymers were amphiphilies, which could readily self-assemble into spherical aggregates and transform into sheet-like structures upon dephosphorylation by alkaline phosphatase (ALP). P(MGlu-co-Tyr/P) and P(MGlu-co-Tyr) copolymers showed good compatibility with both MC3T3-E1 and Hela cells, with cell viability above 80% at concentrations up to 1000 μg/mL. The prepared injectable polypeptide hydrogel and its enzyme-triggered self-assemblies show particular potential for biomedical applications. [ABSTRACT FROM AUTHOR]

In the treatment of various cancers, photodynamic therapy (PDT) has been extensively studied as an effective therapeutic modality. As a potential alternative to conventional chemotherapy, PDT has been limited due to the low Reactive Oxygen Species (ROS) yield of photosensitisers. Herein, a nanoplatform containing mesoporous Fe3O4@TiO2 microspheres was developed for near-infrared (NIR)-light-enhanced chemodynamical therapy (CDT) and PDT. Titanium dioxide (TiO2) has been shown to be a very effective PDT agent; however, the hypoxic tumour microenvironment partly affects its in vivo PDT efficacy. A peroxidase-like enzyme, Fe3O4, catalyses the decomposition of H2O2 in the cytoplasm to produce O2, helping overcome tumour hypoxia and increase ROS production in response to PDT. Moreover, Fe2+ in Fe3O4 could catalyse H2O2 decomposition to produce cytotoxic hydroxyl radicals within tumour cells, which would result in tumour CDT. The photonic hyperthermia of Fe3O4@TiO2 could not only directly damage the tumour but also improve the efficiency of CDT from Fe3O4. Cancer-killing effectiveness has been maximised by successfully loading the chemotherapeutic drug DOX, which can be released efficiently using NIR excitation and slight acidification. Moreover, the nanoplatform has high saturation magnetisation (20 emu/g), making it suitable for magnetic targeting. The in vitro results show that the Fe3O4@TiO2/DOX nanoplatforms exhibited good biocompatibility as well as synergetic effects against tumours in combination with CDT/PDT/PTT/chemotherapy. [ABSTRACT FROM AUTHOR]

To further comprehensively study the intramolecular weak interaction of the gaseous TKX‐50 molecule, the two conformations of the TKX‐50 molecule were analyzed via the Independent Gradient Model based on the Hirshfeld Partition (IGMH) method based on the B3LYP/6‐311 g (d,p) level for geometry optimization and for single point energy. The conclusions manifest that the weak interactions between these fragments are mainly composed of hydrogen bonds and van der Waals interactions. From the strength of inter‐fragment interactions formed by contributing atomic pairs and their percentage contributions, these H bonds, together with dispersion‐dominated weak interactions provided by non‐direct facing atomic pairs near these H bonds, dominate the inter‐fragment interaction resulting in the stability of the molecular structure. Meanwhile, the weak interactions enclosed by end‐atoms of two fragments not only include the contributions provided by inter‐fragment atomic pairs of two fragments but also include the contributions provided by intra‐fragment atomic pairs of fragment 1. For conformation II, due to the H transfer between fragments, a pair of symmetric H bonds at the corresponding regions are extremely strong to reach the level of covalent bond while the two groups −OH at the other end become looser, resulting in conformation II own lower energy. Differences in inter‐fragment interactions between two conformations were essentially brought by the stronger electron‐withdrawing ability of atom O than that of atom N. [ABSTRACT FROM AUTHOR]