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With the characteristics of low toxicity and biodegradability, recombinant collagen-like proteins have been chemically and genetically engineered as a scaffold for cell adhesion and proliferation. However, most of the existing hydrogels crosslinked with peptides or polymers are not pure collagen, limiting their utility as biomaterials. A major roadblock in the development of biomaterials is the need for high purity collagen that can self-assemble into hydrogels under mild conditions. In this work, we designed a recombinant protein, S-VCL-S, by introducing cysteine residues into the Streptococcus pyogenes collagen-like protein at both the N-and C-termini of the collagen with a trimerization domain (V) and a collagen domain (CL). The S-VCL-S protein was properly folded in complete triple helices and formed self-supporting hydrogels without polymer modifications. In addition, the introduction of cysteines was found to play a key role in the properties of the hydrogels, including their microstructure, pore size, mechanical properties, and drug release capability. Moreover, two/three-dimensional cell-culture assays showed that the hydrogels are noncytotoxic and can promote long-term cell viability. This study explored a crosslinking collagen hydrogel based on disulfide bonds and provides a design strategy for collagen-based biomaterials.

Metal oxide semiconductor (MOS) thin films are promising sensing layer for integration in gas sensor devices for detecting toxic and harmful molecules. Herein, tungsten oxide (WO3) thin films are deposited on interdigital electrodes by vacuum thermal evaporation to realize batch fabrication of high-performance gas sensors. Subsequent annealing at different temperatures allows for regulation of the concentration of oxygen vacancies in the WO3 films, which has been found to exert a great influence on the sensor properties. In addition, the surface structure of WO3 films is also highly dependent on the annealing temperature. Gas sensing investigations show that the WO3 sensor annealed at 500 °C possesses the best sensing properties for detecting triethylamine (TEA) including very high response, good selectivity, fast response, and low limit of detection (63 ppb). The excellent sensor performances are attributed to the enhanced adsorption of oxidative oxygen species due to the presence of abundant oxygen vacancies. The scalable fabrication of WO3 thin film gas sensors and the oxygen vacancy engineering strategy proposed herein may shed some light to developing high performance environmental sensors.

Methanol has long been used as a hole scavenger in photocatalysis to improve charge separation. Although the prototypical methanol/TiO2(110) system shows salient adsorption-state-dependent photoact...

The activation of hepatic stellate cells (HSCs) has proved to be pivotal in hepatic fibrosis. Therefore, the suppression of HSC activation is an effective anti-fibrotic strategy. Although studies have indicated that eupatilin, a bioactive flavone found in Artemisia argyi, has anti-fibrotic properties, the effect of eupatilin on hepatic fibrosis is currently unclear. In this study, we used the human hepatic stellate cell line LX-2 and the classical CCl4-induced hepatic fibrosis mouse model for in vitro and vivo experiments. We found that eupatilin significantly repressed the levels of the fibrotic markers COL1α1 and α-SMA, as well as other collagens in LX-2 cells. Meanwhile, eupatilin markedly inhibited LX-2 cell proliferation, as verified by the reduced cell viability and down-regulation of c-Myc, cyclinB1, cyclinD1, and CDK6. Additionally, eupatilin decreased the level of PAI-1 in a dose-dependent manner, and knockdown of PAI-1 using PAI-1-specific shRNA significantly suppressed the levels of COL1α1, α-SMA, and the epithelial–mesenchymal transition (EMT) marker N-cadherin in LX-2 cells. Western blotting indicated that eupatilin reduced the protein level of β-catenin and its nuclear translocation, while the transcript level of β-catenin was not affected in LX-2 cells. Furthermore, analysis of histopathological changes in the liver and markers of liver function and fibrosis revealed that hepatic fibrosis in CCl4-treated mice was markedly alleviated by eupatilin. In conclusion, eupatilin ameliorates hepatic fibrosis and hepatic stellate cell activation by suppressing the β-catenin/PAI-1 pathway.

Microplastics (MPs) are ubiquitous in the environment, of which 94 % undergo the aging process. Accelerated aging induced by advanced oxidation processes (AOPs) is significant in explaining the formation pathway of secondary MPs and enables possible mineralization. In this study, ozonation coupled with hydrogen peroxide (O

Background. The composition and metabolic activities of gut microbiota are strongly interconnected with cardiac fibrosis (CF) and heart failure (HF). Qige Huxin formula (QHF), a traditional Chinese medicine (TCM) formulation originating from a classical Fangji Huangqi decoction, has been widely used to clinically treat HF for decades. However, it is still unclear whether QHF alleviates CF by modulating gut microbiota and intestinal integrity. Purpose. This study aimed to investigate the cardioprotective effects of QHF in isoprenaline-induced CF through modulating gut microbiota and intestinal integrity. Methods. Fifty mice were randomly divided into five groups after one week of acclimatization feeding: control group, model group, 2.56 g/kg/d group (low-dose QHF), 5.12 g/kg/d group (high-dose QHF), and meto group (15 mg/kg/d). The CF model was established by subcutaneously injecting the mice with isoprenaline (10 mg/kg/d for 14 days), followed by QHF treatment. The heart volume, cardiac weight index (CWI), serum myocardial enzymes, serum inflammatory cytokines, serum lipopolysaccharide, histopathology of the heart and colon tissues, ZO-1, and occludin of colon tissues were then measured. Fecal samples from mice were analyzed using 16S rRNA sequencing. Results. QHF treatment significantly reduced heart volume, CWI, and serum CK and CK-MB levels, attenuated cardiac histopathological alterations, and alleviated CF. QHF treatment also downregulated TNF-α, IL-1β, and IL-6 in serum. Moreover, QHF treatment decreased the serum level of lipopolysaccharide and maintained intestinal integrity by upregulating ZO-1 and occludin. The 16S rRNA microbiota analysis revealed that QHF treatment increased the relative abundance of Marvinbryantia and Phascolarctobacterium. Conclusions. QHF treatment exerts cardioprotective effects through modulating gut microbiota, protecting intestinal integrity, and alleviating inflammation. This study shows that gut microbiota may enhance heart-gut interaction.

Herein, an environmentally friendly CoP/Zn2In2S5 catalyst is reported as a visible-light photocatalyst for the selective activation of the α-C-H bond of methanol to generate ethylene glycol with a selectivity of as high as 90%. The catalytic system also illustrates the first example of visible-light-driven dehydrogenative coupling of ethanol to 2,3-butanediol.

Atenolol (ATL), a kind of largely used beta-blockers, has been widely detected in the aquatic environment, which could cause adverse impact on human beings. In this study, bismuth oxychloride (BiOCl) photocatalyst was synthesized and applied to remove ATL in the aqueous system under simulated natural light. Emphasis was laid on the reaction kinetics and the impact of natural organic matter (NOM) (0–20 mg/L). Possible transformation pathways were systematically investigated based on identification of reaction products via liquid chromatography-mass spectrometry (LC-MS). As a consequence, BiOCl presents highly photocatalytic efficiency yielding up to nearly 100% ATL conversion after 60 min of interaction, together with fairly high photostability evidenced by considerably efficient removal of ATL after 10 catalytic cycles. Four kinds of possible products are detected using LC-MS in the process of reaction, indicating possible transformation ways of ATL photocatalysis. NOM has an inhibiting impact on the removal of ATL and influences the products distribution. This study provides an emerging nanocatalyst for ATL photodegradation and could eventually lead to development of novel methods to control pharmaceutical contamination in water.

As an important component of biomaterials, collagen provides three-dimensional scaffolds and biological cues for cell adhesion and proliferation in tissue engineering. Recombinant collagen-like proteins, which were initially discovered in Streptococcus pyogenes and produced in heterologous hosts, have been chemically and genetically engineered for biomaterial applications. However, existing collagen-like proteins do not form gels, limiting their utility as biomaterials. Here, we present a series of rationally designed collagen-like proteins composed of a trimerization domain, triple-helical domains with various lengths, and a pair of heterotrimeric coiled-coil sequences attached to the N- and C-termini as adhesive ends. These designed proteins fold into triple helices and form self-supporting gels. As the triple-helical domains are lengthened, the gels become less stiff, pore sizes increase, and structural anisotropy decreases. Moreover, cell-culture assay confirms that the designed proteins are noncytotoxic. This study provides a design strategy for collagen-based biomaterials. The sequence variations reveal a relationship between the protein primary structure and material properties, where variations in the cross-linking density and association energies define the gelation of the protein network.

As one of non-covalent forces to stabilize protein, cation-π interactions in collagen have been received much attention. Three chains of collagen form its characteristic secondary structure, triple helices. Based on a collagen heterotrimer, abc, a library containing 15 mutant peptides was built to characterize the stabilizing effects of 24 pairwise cation-π interactions. The six stabilizing pairs, axial FK, YK, WK, RF, and RW, and lateral RF, have been identified, among which only axial RF frequently occurs in natural collagen sequences. This suggests that cation-π interactions might not be optimized in natural collagen.

Collagen is composed of three chains, which wind into triple helices. As there are high percentages of acidic and basic residues in natural collagen, mechanisms of how salt bridges could modulate the trimerization have been received much attention. Sixteen pairwise salt bridges were constructed in a collagen heterotrimer abc, making an energetic-contribution library for collagen stability. The local stability of type I collagen was predicted from the library. Separation between the stabilizing and ligand-binding regions of type I collagen suggests that there be a balance between overall stability to maintain triple helices and local instability relevant to biological functions.

In this study, we systematically investigated the effect of multiwall carbon nanotubes (MWCNTs) on the removal of tetrabromobisphenol A (TBBPA) mediated by horseradish peroxidase (HRP) at varying important conditions. The results suggested that the presence of MWCNTs significantly enhanced the removal of TBBPA mediated by HRP and the reaction rate constant was linear with the MWCNTs dosage. The enhancement of MWCNTs on the HRP-mediated reaction was attributed to two facts, one is that MWCNTs protected HRP from inactivation, the other is that the presence of MWCNTs made the homogeneous reaction of TBBPA be heterogeneous reaction by adsorbing TBBPA on its surface. Moreover, the influence of MWCNTs on TBBPA products distribution was further elucidated. We found that the species of reaction product had no difference between the HRP-mediated systems with and without the presence of MWCNTs. However, the presence of MWCNTs significantly decreased the yields of each product. These results give insight into the role of MWCNTs in HRP-mediated TBBPA reactions and provide theoretical foundation for potential development of novel enzymatic methods to control TBBPA contamination. MWCNTs enhanced the removal of TBBPA mediated by HRP/H2O2, because it protected HRP from inactivation and adsorbed TBBPA on its surface to form a heterogeneous reaction process.

Lithium-sulfur batteries have suffered from shuttle effects and active materials loss for decades, leading to the unsatisfying rate performance and cyclability. Here, inspired by red blood cells, commonly known as an important medium for oxygen transportation, we build a biomimetic micro cell by implement of Aspergillus niger-derived carbon decorated with TiO2-x nanoparticles as an efficient medium for energy storage. Red blood cell-mimetic micro cell can confine active materials inside the large space, with abundant and shortened electron/ion channels endowed by the biconcave structure. Meanwhile, the structure also shows excellent durability, so that once active materials have been loaded, the sufficient reaction sites would facilitate the stable adsorption and conversion of polysulfides for a long-term cycling, enabling to operate like the cell membranes with selective permeability and conversion ability. The as-prepared micro cell cathode demonstrates great application potential, delivering the discharge capacities of 995 and 720 mAh g−1 after 500 and 700 cycles at 0.5 and 2 C, with the capacity retention around 80%. Density functional theory calculations further show that the oxygen defects can enhance the chemisorption ability of polysulfides, as well as expedite redox reactions of polysulfides by facilitating surface ion transportation.

Laccase is a multicopper oxidase containing four coppers as reaction sites, including one type 1, one type 2, and two type 3. We here provide the first experimental data showing that As (III) can be effectively removed from water and transformed to As (V) through reactions mediated by laccase with the presence of oxygen. To this end, the As (III) removal, As (V) yields, total protein, active laccase, and copper concentrations in the aqueous phase were determined, respectively. Additionally, electron paramagnetic resonance spectra and UV-vis spectra were applied to probe possible structural changes of the laccase during the reaction. The data offer the first evidence that laccase can be inactivated by As (III) attack thus leading to the release of type 2 copper. The released copper has no reactivity with the As (III). These findings provide new ideas into a significant pathway likely to master the environmental transformation of arsenite, and advance the understanding of laccase inactivation mechanisms, thus providing a foundation for optimization of enzyme-based processes and potential development for removal and remediation of arsenite contamination in the environment.