Inhibitory Effect of Depolymerized Sulfated Galactans from Marine Red Algae on the Growth and Adhesion of Diarrheagenic Escherichia coli.

Active polysaccharides as safe and natural polymers against bacterial diarrhea have been reconsidered as an alternative to antibiotics. This work investigated the inhibiting effect of depolymerized sulfated galactans from Eucheuma serra and Gracilaria verrucosa on the growth and adhesion of diarrheagenic enterotoxigenic Escherichia coli (ETEC) K88. Results showed that the sulfated polysaccharides with molecular weight distribution ≤20.0 kDa exhibited antibacterial activity against ETEC K88. A structure-activity study revealed that the anti-ETEC K88 activity of sulfated polysaccharides is strictly determined by their molecular weight distribution, sulfate group content, and monosaccharide composition. In addition, the promoted nucleic acid release and the fluorescence quenching of membrane proteins were observed after the treatment with selected polysaccharides. Scanning electron microscopy further confirmed that the depolymerized sulfated galactans can effectively inhibit ETEC K88 adhesion. In conclusion, depolymerized sulfated galactans exhibited an inhibitory effect on the growth and adhesion of ETEC K88.

Fast detection of tryptamine in meat products with azide-functionalized covalent organic frameworks confined in molecularly imprinted polymers.

Tryptamine is a biogenic amine that affects organoleptic quality through the generation of off-odours in foods. Herein, imine-based covalent organic frameworks (COFs) were synthesized via Schiff base reactions and postmodified with click chemistry to generate azide-functionalized COFs with tunable azide units on the walls. The combination of molecular imprinting with COFs enabled the specific recognition of the targets. The resulting optosensing system (azide-functionalized COFs@MIPs) was used as a sample-to-answer analyser for detecting tryptamine (detection time within 10 min). A linear relationship was observed for the fluorescence response to tryptamine concentrations in the range of 3-120 µg L-1, with a limit of detection of 1.74 µg L-1. The recoveries for spiked samples were satisfactory, with relative standard deviations <9.90%. The optosensing system is a potential tool for the quantitative detection of tryptamine in meat products because of its lower cost, shorter processing time, and simpler processing steps compared to conventional chromatographic techniques.

The impact of microbial inoculants on large-scale composting of straw and manure under natural low-temperature conditions.

Understanding large-scale composting under natural conditions is essential for improving waste management and promoting sustainable agriculture. In this study, corn straw (400 tons) and pig manure (200 tons) were composted with microbial inoculants. The thermophilic phase of composting lasted for fourteen weeks, resulting in an alkaline final product. Microbial systems with low-temperature initiation and high-temperature fermentation played a crucial role in enhancing lignocellulose degradation and humic substances (HS) formation. Adding microbes, including Rhodanobacter, Pseudomonas, and Planococcus, showed a positive correlation with degradation rates of cellulose, hemicellulose, and lignin. Bacillus, Planococcus, and Acinetobacter were positively correlated with HS formation. Microorganisms facilitated efficient hydrolysis of lignocelluloses, providing humic precursors to accelerate composting humification through phenolic protein and Maillard pathways. This study provides significant insights into large-scale composting under natural conditions, contributing to the advancement of waste management strategies and the promotion of sustainable agriculture.

From sea to sea: Edible, hydrostable, and degradable straws based on seaweed-derived insoluble cellulose fibers and soluble polysaccharides.

The widespread use of disposable plastic straws has caused a long-lasting environmental problem. Potential alternatives for plastic straws are far from satisfactory due to the low utility, poor water stability, and non-ideal natural degradability. In this work, an edible, hydrostable, and degradable straw was developed from the economically significant seaweed. Seaweed-derived insoluble cellulose fibers were used as the building block of the straw, and the soluble polysaccharide extracts were explored as the natural glue through the chelation with Ca2+. Repeated freeze-thawing was introduced to strengthen the molecular interactions, which further improved its mechanical stability and hydrostability. The straw exhibited remarkable natural degradability in open environments, particularly in marine-mimicking conditions. By incorporating pH-sensitive food pigments, the straws could indicate acid-base property of a beverage or even discriminate the freshness of milk. The versatile seaweed-derived straw adhered to the biocycle concept of "from sea to sea" to alleviate the burden of white pollution on oceans.

Insights into the transcriptomic mechanism and characterization of endoglucanases from Aspergillus terreus in cellulose degradation.

Filamentous fungi are the main industrial source of cellulases which are important in the process of converting cellulose to fermentable sugars. In this study, transcriptome analysis was conducted on Aspergillus terreus NEAU-7 cultivated using corn stover and glucose as carbon sources. Four putative endoglucanases (EG5A, EG7A, EG12A, and EG12C) from A. terreus NEAU-7 were efficiently expressed in Pichia pastoris. Among them, EG7A exhibited the highest enzyme activity (75.17 U/mg) with an optimal temperature of 40 °C and pH 5.0. EG5A and EG12A displayed specific activities of 19.92 U/mg and 14.62 U/mg, respectively, at 50 °C. EG12C showed acidophilic characteristics with an optimal pH of 3.0 and a specific activity of 12.21 U/mg at 40 °C. With CMC-Na as the substrate, the Km value of EG5A, EG7A, EG12A or, EG12C was, 11.08 ± 0.87 mg/mL, 6.82 ± 0.74 mg/mL, 7.26 ± 0.64 mg/mL, and 9.88 ± 0.86 mg/mL, with Vmax values of 1258.23 ± 51.62 µmol∙min-1∙mg-1, 842.65 ± 41.53 µmol∙min-1∙mg-1, 499.38 ± 20.42 µmol∙min-1∙mg-1, and 681.41 ± 30.08 µmol∙min-1∙mg-1, respectively. The co-treatment of EG7A with the commercial cellulase increased the yield of reducing sugar by 155.77 % (filter paper) and 130.49 % (corn stover). Molecular docking assay showed the interaction energy of EG7A with cellotetraose at -10.50 kcal/mol, surpassing EG12A (-10.43 kcal/mol), EG12C (-10.28 kcal/mol), and EG5A (-9.00 kcal/mol). Root Mean Square Deviation (RMSD) and Solvent Accessible Surface Area (SASA) values revealed that the presence of cellotetraose stabilized the molecular dynamics simulation of the cellotetraose-protein complex over a 100 ns time scale. This study provides valuable insights for developing recombinant enzymes and biomass degradation technologies.

Development of seaweed-derived polysaccharide/cellulose nanocrystal-based antifogging labels loaded with alizarin for monitoring aquatic products' freshness.

Intelligent freshness indicator labels have attracted great interest for their massive potential in monitoring the freshness of aquatic products over the years. However, there is still a challenge where fogging on the labels during dramatic temperature changes affects the reading of freshness. At the same time, the freshness indicator labels need high mechanical strength to resist collision damage during transportation and storage. Herein, an antifogging freshness indicator label was developed based on seaweed extracts and alizarin. Firstly, soluble polysaccharides and insoluble components were extracted from Gelidium amansii, and cellulose nanocrystal (CNC) was further prepared from the insoluble components by sulfuric acid hydrolysis. Subsequently, a polysaccharide-based film was fabricated using soluble polysaccharides as the matrix materials and CNC as the reinforcement agent. Antifogging experiments showed that the hydrophilic composite films presented good antifogging performance. After loading with alizarin, the composite indicator label exhibited both antifogging and freshness-indicating properties for the salmon sample. The work provided a new idea for developing freshness indicator labels suitable for low-temperature transportation and storage.

Design and characterization of an antibacterial film composited by hydroxyethyl cellulose (HEC), carboxymethyl chitosan (CMCS), and nano ZnO for food packaging.

For food packaging, a novel composite film was prepared by solution casting method using hydroxyethyl cellulose (HEC), carboxymethyl chitosan (CMCS), and zinc oxide nanoparticles as raw materials. The composite film successfully compounded the nanoparticles, as deduced by spectroscopy, crystallography and morphology observation. The addition of CMCS and ZnO enhanced the solvent resistance (the water solubility of the composite film was reduced by 94.3 %) and UV shielding ability (the UV shielding capacity of the composite film was increased by 45.73 %) of the composite film, thus improving the application prospects of the composite film in water-rich foods. In addition, the synergistic effect of CMCS and ZnO helped the composite film to efficiently inhibit the pathogenic bacteria Listeria monocytogenes and Pseudomonas aeruginosa (rate of inhibition>99.99 %) in food. The addition of CMCS and ZnO also significantly improved the elasticity (improve 494.34 %) and maximum load capacity (improve 142.24 %) of the composite film.

Lean-water hydrogel electrolyte for zinc ion batteries.

Solid polymer electrolytes (SPEs) and hydrogel electrolytes were developed as electrolytes for zinc ion batteries (ZIBs). Hydrogels can retain water molecules and provide high ionic conductivities; however, they contain many free water molecules, inevitably causing side reactions on the zinc anode. SPEs can enhance the stability of anodes, but they typically possess low ionic conductivities and result in high impedance. Here, we develop a lean water hydrogel electrolyte, aiming to balance ion transfer, anode stability, electrochemical stability window and resistance. This hydrogel is equipped with a molecular lubrication mechanism to ensure fast ion transportation. Additionally, this design leads to a widened electrochemical stability window and highly reversible zinc plating/ stripping. The full cell shows excellent cycling stability and capacity retentions at high and low current rates, respectively. Moreover, superior adhesion ability can be achieved, meeting the needs of flexible devices.

Translocation of a heterogeneous polymer.

We present results on the sequence dependence of translocation kinetics for a partially charged heteropolymer moving through a very thin pore using theoretical tools and Langevin dynamics simulational techniques. The chain is composed of two types of monomers of differing frictional interaction with the pore and charge. We present exact analytical expressions for passage probability, mean first passage time, and mean successful passage times for both reflecting/absorbing and absorbing/absorbing boundary conditions, showing rich and unexpected dependence of translocation behavior on charge fraction, distribution along the chain, and electric field configuration. We find excellent qualitative and good quantitative agreement between theoretical and simulation results. Surprisingly, there emerges a threshold charge fraction of a diblock copolymer beyond which the success rate of translocation is independent of charge fraction. Also, the mean successful translocation time of a diblock copolymer displays non-monotonic behavior with increasing length of the charged block; there is an optimum length of the charged block where the mean translocation rate is the slowest; and there can be a substantial range of higher charge fractions which make the translocation slower than even a minimally charged chain. Additionally, we find for a fixed total charge on the chain, finer distribution along the backbone significantly decreases mean translocation time.

Preparation, characterization and antibacterial activity of new ionized chitosan.

In order to improve the solubility and antibacterial activity of chitosan and expand its application range, ionized chitosan (ICS) was successfully synthesized from chitosan through methylation and sulfonation reactions in this study. The chemical structures of the polymers were verified by Fourier transform infrared spectroscopy (FTIR) and 1H NMR, and a series of characterizations of the polymer were carried out by analytical methods such as element analysis (EA), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The results showed that the water solubility of the modified ICS was significantly improved. The introduction of propyl sulfonic acid groups with particle size decreasing and potential increasing greatly improved the antibacterial activity of chitosan, indicating that the ICS had the potential as a water-soluble antibacterial agent.

Inhibition of cell proliferation through an ATP-responsive co-delivery system of doxorubicin and Bcl-2 siRNA.

Herein, DNA duplex was constructed through the hybridization of adenosine triphosphate (ATP)-responsive aptamer and its cDNA in which GC-rich motif could be used to load doxorubicin (DOX), and then, cationic polymer PEI25K was used as a carrier to simultaneously condense DOX-Duplex and Bcl-2 siRNA to prepare the ternary nanocomplex polyethylenimine (PEI)/DOX-Duplex/siRNA. The ATP concentration gradient between the cytosol and extracellular environment could achieve the stable loading of DOX in duplex and the rapid drug release in an ATP-responsive manner. Using human prostate tumor cell line PC-3 as a model, an obvious induction of cell proliferation could be detected with a cell viability of 53.3%, which was stronger than single cargo delivery, indicating the synergistic effect between these two components. The enhanced anti-proliferative effect of ternary nanocomplex could be attributed to the improved induction of cell apoptosis in a mitochondria-mediated pathway and cell-cycle arrest at the G2 phase. Overall, the ATP-responsive nanocarrier for co-delivering DOX and Bcl-2 siRNA has been demonstrated to be a smart delivery system with favorable anti-proliferative effect, especially for solving the multidrug resistance of tumors.

Disulfiram-loaded porous PLGA microparticle for inhibiting the proliferation and migration of non-small-cell lung cancer.

In this study, poly(lactic-co-glycolic acid) (PLGA) was used as a carrier to construct disulfiram-loaded porous microparticle through the emulsion solvent evaporation method, using ammonium bicarbonate as a porogen. The microparticle possessed highly porous surface, suitable aerodynamic diameter for inhalation (8.31±1.33 µm), favorable drug loading (4.09%±0.11%), and sustained release profile. The antiproliferation effect of release supernatant was detected through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay using non-small-cell lung cancer A549 as a model, with only 13.3% of cell viability observed for the release supernatant at 7 days. The antiproliferation mechanism was elucidated to be associated with the enhanced induction of cell apoptosis and cell cycle arrest at S phase through flow cytometry and Western blotting analysis. Finally, wound healing and transwell migration assay showed that they could efficiently inhibit the cell migration. These results demonstrated that disulfiram-loaded porous PLGA microparticle could achieve favorable antitumor efficiency, implying the potential of treating non-small-cell lung cancer in a pulmonary administration.

[A qualitative research on impact factors for the effectiveness of pit and fissure sealing in Xi'an city].

PURPOSE: To explore the factors influencing the effectiveness of pit and fissures sealing in order to provide suggestions to policy makers for quality promotion of pit and fissure program. METHODS: After developing outline of the qualitative interview, the method of focus group discussion was applied in this study. A total of 32 persons including dental clinical experts, dentists who operated pit and fissure sealing and program managers were interviewed. The data was collected, marked and classified by using MAXqda software. RESULTS: The main factors influencing the effectiveness of pit and fissure sealing in Xi'an city were the service providers, the service needers and the management of external organization. CONCLUSIONS: In order to promote the preventive effect of pit and fissure sealing, attention should be paid to increase investment from the government, promote school-based program mode, strengthen the supervision of designated medical institutions and the external management.

Response surface methodology for the optimization of beta-lactoglobulin nano-liposomes.

Response surface methodology based on a central composite rotatable design has been successfully used to model and optimize biochemical and biotechnological processes. Heat treatment could have an effect on beta-lactoglobulin (ß-Lg) and lead to allergic reaction. To reduce this phenomenon, liposomes were used as carriers in this research. The mass ratio of phosphatidylcholine and cholesterol (2.5-12.5), ß-Lg concentration (2.5-12.5 mg mL(-1)), sonication time (5-25, min) and temperature (25-40 °C) were selected as independent variables with encapsulation efficiency as a dependent variable. For each response, a second-order polynomial model was developed using multiple linear regression analysis. Applying a desirability function method the optimum parameters were: phosphatidylcholine to cholesterol ratio of 8.05, ß-Lg concentration of 9.09 mg mL(-1), sonication time of 17.71 min and temperature of 30 °C. The particle size and encapsulation efficiency were found to be 189 nm and 61.55%, respectively. Furthermore, the in vitro stability of ß-Lg nano-liposomes in simulated gastrointestinal juice was evaluated. The nano-liposomes showed an acceptable stability in simulated gastrointestinal juice at 37 °C for 4 h.

Nanocrystalline ß-Ti alloy with high hardness, low Young's modulus and excellent in vitro biocompatibility for biomedical applications.

High strength, low Young's modulus and good biocompatibility are desirable but difficult to simultaneously achieve in metallic implant materials for load bearing applications, and these impose significant challenges in material design. Here we report that a nano-grained ß-Ti alloy prepared by high-pressure torsion exhibits remarkable mechanical and biological properties. The hardness and modulus of the nano-grained Ti alloy were respectively 23% higher and 34% lower than those of its coarse-grained counterpart. Fibroblast cell attachment and proliferation were enhanced, demonstrating good in vitro biocompatibility of the nano-grained Ti alloy, consistent with demonstrated increased nano-roughness on the nano-grained Ti alloy. Results suggest that the nano-grained ß-Ti alloy may have significant application as an implant material in dental and orthopedic applications.

Ti-Ge binary alloy system developed as potential dental materials.

As-cast Ti-xGe (x = 2, 5, 10, 20 wt %) binary alloys were produced in this work, and various experiments were carried out to investigate the microstructure, mechanical properties, in vitro electrochemical and immersion corrosion behaviors as well as cytotoxicity with as-cast pure Ti as control, aiming to study the feasibility of Ti-xGe alloy system as potential dental materials. The microstructure of Ti-xGe alloys changes from single α-Ti phase to α-Ti + Ti(5)Ge(3) precipitation phase with the increase of Ge content. Mechanical tests show that Ti-5Ge alloy has the best comprehensive mechanical properties. The corrosion behavior of Ti-xGe alloys in artificial saliva with different NaF and lactic acid addition at 37°C indicates that Ti-2Ge and Ti-5Ge alloys show better corrosion resistance to fluorine-containing solution. The cytotoxicity test indicates that Ti-xGe alloy extracts show no obvious reduction of cell viability to L-929 fibroblasts and MG-63 osteosarcoma cells, similar to pure Ti which is generally acknowledged to be biocompatible. Considering all these results, Ti-2Ge and Ti-5Ge alloys possess the optimal comprehensive performance and might be used as potential dental materials.

[Differential scanning calorimetry analyses of phase transformations in different nickel-titanium orthodontic wires].

OBJECTIVE: To characterize austenite, martensite and R phase temperatures as well as transition temperature ranges of the commonly used nickel-titanium (NiTi) orthodontic arch wires selected from several manufacturers. METHODS: Differential scanning calorimetry (DSC) method was used to study the phase transformation temperatures and the phase transition processes of 9 commonly used NiTi alloys (types: 0.406 mm, 0.406 mm x 0.559 mm). RESULTS: The austenite finish temperatures of A, B, D NiTi wires were 22.4 CT, 21.9 degrees C, 22.5 degrees C, respectively. No phase transformation was detected during oral temperature. It indicated that these types of NiTi wires did not possess shape memory property. For C and H NiTi wires, no phase transformation was detected during the scanning temperature range, suggesting that these two types of wires did not possess shape memory either. The austenite finish temperatures of E, G and I NiTi wires were 34.3 degrees C, 36.6 degrees C, 38.5 degrees C, respectively, which were close to the oral temperature and presented as martensitic-austenitic structures at room temperature, suggesting that the NiTi wires listed above had good shape memory effect. Although F NiTi wire also showed martensitic-austenitic structures at room temperature, its austenite finish temperature (61.5 degrees C) was much higher than oral temperature. CONCLUSIONS: The transformation phase temperatures and transformation behavior were varied among different NiTi alloys, leading to variability in shape memory effect.