Latest ArticlesIn this paper, supra-amphiphilic compounds containing disaccharides and azobenzene ends have been constructed via dynamic covalent bond. It was found that the slight structural difference of the disaccharides made significant difference in the self-assembled morphologies. Namely, three kinds of azo-disaccharide supra-amphiphiles were found to assemble into different morphologies, with the only difference in chemical structure from the disaccharides. More importantly, the structural difference between the disaccharides, including lactoside, maltoside and cellobioside was trivial. Molecular simulation revealed the packing of molecules was due to the different contribution from hydrogen bonds. The above results clearly indicated the contribution of saccharide packing, especially the related hydrogen bonding, to the final morphology of the assembled structures.
Oral and maxillofacial diseases are a group of high-incidence disorders that affect people's life quality to a great extent, while the wet and highly movable environment of the related regions brings challenges to traditional therapies. Faced with the obstacles of insufficient adhesive strength and ensuing short drug retention time, conventional oral therapeutic agents often have difficulty in achieving their desired efficacy. Oral and maxillofacial wet-adhesive materials have the advantages of excellent wet environment retention, internal stability, plasticity, and clinical potential, thus have become a significant research direction in the field of oral related disorders healing. In the past decade, the development of oral adhesive materials with good wet adhesion has accelerated based on the chemical molecular interaction, physical interlocking, and biological adhesion mechanisms, including biomimetic-inspired materials, naturally derived polymer–based materials and adhesive electrospun fiber films. These fancy wet-adhesive materials can be used for oral mucosal drug delivery, oral vaccination, wound healing, and bone defects treatments. Despite their numerous novel applications, wet-adhesive materials in stomatology still face unresolved challenges from material and biological aspects. Here, advances in designs of oral and maxillofacial wet-adhesive materials are reviewed in terms of design backgrounds, attachment mechanisms, and common classifications. Recent demonstrations of wet-adhesive materials for oral and maxillofacial region medical applications from drug delivery to multifunctional tissue treatments are presented. To conclude, current challenges and prospects on potential applications of oral and maxillofacial wet-adhesive materials are also briefly discussed.
Pulmonary delivery is an effective drug delivery strategy for the treatment of local respiratory diseases. However, the rapid systemic absorption through the lung due to the thin barrier and persistent lung clearances influence the drug retention in the lung. In this study, we designed a lipid-coated genistein nanocrystals (Lipo-NCs) formulation to achieve enhanced efficiency of local pulmonary delivery. The Lipo-NCs were fabricated by modifying genistein nanocrystals (NCs) with phospholipid membrane through thin film hydration following the homogenization method. The prepared Lipo-NCs exhibited a decreased drug release rate compared with the naked NCs. Our results demonstrated that intracellular uptake and transcellular transport of NCs by the Calu-3 epithelial layer were reduced after lipid coating. Furthermore, the macrophages clearance was also impeded by this Lipo-NCs formulation. In vivo lung retention and distribution revealed that more genistein was retained in the lung after intratracheal administration of Lipo-NCs. The pharmacokinetic study displayed that the AUC(0-t) values of Lipo-NCs were 1.59-fold lesser than those of the NCs group, indicating a reduced systemic absorption. In conclusion, this research indicated that Lipo-NCs could be a suitable formulation for reducing systemic absorption and macrophages clearance, and thus enhancing drug concentration in lung by pulmonary delivery.
The magnetism of nanographene is dominated by the structure of its carbon skeleton. However, the magnetism engineering of nanographene is hindered due to finite precursors. Here, we demonstrate an ingenious synthetic strategy to engineer the magnetism of nanographene through hetero-coupling two precursors on Au(111) surface. Bond-resolved scanning tunneling microscopy and spectroscopy results show that two homo-coupled products host a closed-shell structure, while the products with five membered ring defects perform as an open-shell one with the total spin number of 1/2, confirmed by spin-polarized density functional theory calculations. While two hetero precursors on Au(111) substrate, the hetero-coupled products both perform as the magnetic structure with total spin quantum numbers of 1/2 and 1, resulting from carbon skeleton transformations. Our work provides an effective way to engineer the magnetism of nanographene by enriching the magnetic products simultaneous, which could be extended into other controllable magnetic nanographene instruction.
Repeated waves of influenza virus H7N9 epidemics after 2013 have caused severe influenza in humans, with mortality reaching approximately 40%–50%. To prevent possible pandemics, the development of highly effective vaccines against influenza virus H7N9 is highly desired. In the present study, by taking advantage of the d-tetra-peptide adjuvant (GDFDFDY), we reported a simple method to prepare H7N9 vaccines. Naproxen (Npx), with good anti inflammatory and broad anti-viral effects, was employed as an N-terminal capping group to construct a hydrogel precursor, Npx-GDFDFDY. The hydrogel adjuvant was prepared using a routine heating cooling protocol and the final vaccine was ready after mixing with the split A/Zhejiang/DTID-ZJU01/2013 (H7N9) antigen by vortexing. Compared with the traditional Al(OH)3 adjuvant vaccine and the split vaccine, our hydrogel adjuvant vaccine showed the best preventive effects against H7N9 infection. A mechanistic study illustrated that higher antibody responses and variations in cytokine expression might account for its increased protective effects. Our strategy demonstrated the advantages of a peptide hydrogel adjuvant in the application of vaccines against H7N9 and demonstrated its potential application in vaccines against emerging threats from other viruses.
Stability of liposomes plays a crucial role in drug delivery, especially in oral aspect. The structural modification of liposomes has been the orientation of efforts to improve their stability and enable the controllability of payload release. This study reported a selenylation strategy to optimize the liposomal structure in an attempt to enhance the nanocarrier's stability, hence the bioavailability of emodin (EM), an active compound with poor water-solubility. EM-loaded selenized liposomes (EM-Se@LPs) were prepared by thin film dispersion followed by in situ reduction technique. The results showed that EM-Se@LPs were provided with enhancive gastrointestinal stability and exhibited sustained release of drug compared with EM-loaded liposomes (EM-LPs). However, the modified liposomes with Se depositing onto the interior and exterior bilayers did not substantially facilitate absorption of EM. The reinforced structure of liposomes irrelevant to absorption was affirmed to be due to good stability and absorbability of EM itself. Nevertheless, the present work provides an alternative option for stabilization of liposomes instead of conventional methods, which may be promising for oral delivery of physiologically unstable and/or poorly absorbed drugs and systemic drug delivery.
2D MBenes have been theoretically predicted to possess unique electronic structures and physicochemical properties, and thus shown great promise in various applications. However, the synthesis of individual single-layer MBene remains a grand challenge due to its orthorhombic structure of MAB phases. Recently, scientists from Linköping University have fabricated 2D monolayer Mo4/3B2-xTz with ordered metal vacancies. Their results demonstrated the feasibility of top-down approach by chemical exfoliation of laminated compounds and provided the principle for further preparation of a wealth of MBenes.
Fabricating an efficient charge transfer pathway at the compact interface between two kinds of semiconductors is an important strategy for designing hydrogen production heterojunction photocatalysts. In this work, we prepared a compact, stable and oxygen vacancy-rich photocatalyst (SnO2/TiO2 heterostructure) via a simple and reasonable in-situ synthesis method. Briefly, SnCl2–2H2O is hydrolyzed on the TiO2 precursor. After the pyrolysis process, SnO2 nanoparticles (5 nm) were dispersed on the surface of ultrathin TiO2 nanosheets uniformly. Herein, the heterojunction system can offer abundant oxygen vacancies, which can act as active sites for catalytic reactions. Meanwhile, the interfacial contact of SnO2/TiO2 grading semiconductor oxide is uniform and tight, which can promote the separation and migration of photogenerated carriers. As shown in the experimental results, the hydrogen production rate of SnO2/TiO2 is 16.7 mmol h−1 g−1 (4.4 times higher than that of TiO2), which is owing to its good dynamical properties. This work demonstrates an efficient strategy of tight combining SnO2/TiO2 with abundant oxygen vacancies to improve catalytic efficiency.
This study explored the catalytic mechanism and performance impacted by the materials ratio of Fe3O4-GOx composites in three typical advanced oxidation processes (AOPs) of O3, peroxodisulfate (PDS) and photo-Fenton processes for tetracycline hydrochloride (TCH) degradation. The ratio of GO in the Fe3O4-GOx composites exhibited different trends of degradation capacity in each AOPs based on different mechanisms. Fe3O4-rGO20wt% exhibited the optimum catalytic performance which enhanced the ozone decomposition efficiency from 33.48% (ozone alone) to 51.83% with the major reactive oxygen species (ROS) of O2•−. In PDS and photo-Fenton processes, Fe3O4-rGO5wt% had the highest catalytic performance in PDS and H2O2 decomposition for SO4•‒, and •OH generation, respectively. Compared with using PDS alone, PDS decomposition rate and TCH degradation rate could be increased by 5.97 and 1.73 times under Fe3O4-rGO5wt% catalysis. In the photo-Fenton system, Fe3O4-rGO5wt% with the best catalyst performance in H2O2 decomposition, and TCH degradation rate increased by 2.02 times compared with blank group. Meantime, the catalytic mechanisms in those systems of that the ROS produced by conversion between Fe2+/Fe3+ were also analyzed.
A new biobased flame retardant (MHPA) with remarkable compatibility was synthesized via a facile and low-cost neutralization reaction of magnesium hydroxide (MH) and phytic acid (PA). By blending the prepared MHPA into ethylene vinyl acetate (EVA), the fire retardancy, smoke suppression and mechanical properties of the composites were significantly improved. When 50 wt% of MH was added into EVA matrix, the value of limiting oxygen index (LOI) reached 26.1%. Whereas, when 10 wt% MH in the EVA composites (with initial 50 wt% MH) was replaced by MHPA, the resulted EVA composites had a LOI value of 30.8%, indicating high efficiency of addition of MHPA to improve flame retardancy. Moreover, the heat release rate (HRR) and total smoke production (TSP) of the EVA composites reduced by 54.4% and 27.6%, respectively, suggesting that incorporation of MHPA could effectively hinder rapid degradation of EVA composites during burning process. The fire-retardant mechanism may reside in that the MHPA combined with MH can present the excellent carbonization and expansion effects. This study illustrates that the biobased MHPA has a broad application prospect to develop flame-retardant EVA composites.
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