Effect of metal oxide as antibacterial agent on thermoplastic starch/metal oxide biocomposites properties

ABSTRACT

This research was purposed at studying the effect of the addition of metal oxide (MO) as antibacterial agent on thermoplastic starch (TPS) properties. TPS/MO biocomposites with 0.1 until 2.0 phr of metal oxide were prepared. Antibacterial activity of TPS and TPS/MO biocomposites against bacteria was investigated. The inhibition zone of biocomposite films was dramatically increased along with the increasing of metal oxides contents. The addition of ZnO content resulted in an increase in inhibition zone for E. coli and S. aureus. The incorporation of MO into TPS/MO biocomposites tends to reduce mechanical properties, the mass loss and T50% of TPS/MO biocomposites.     

Multifunctional ceramic-metal biocomposites with Zinc containing antimicrobial glass coatings

A biocompatible glassy coating with a high antimicrobial activity (>3 log of reduction) versus the gram-bacterium Escherichia coli has been obtained. The substrates are based on new zirconia ceramic matrix composites reinforced with biological tolerant metals (3Y-TZP/Ta and 3Y-TZP/Nb biocermets). Biocompatibility was studied using NIH-3T3-cells (mouse embryonic fibroblast) and >70% viability was found. These results open up the possibility of using these materials in large panoply in orthopaedics, dentistry and other hard tissue replacement applications where biofunctional, structural and antimicrobial properties are required.     

Hierarchical MnNiCo ternary metal oxide/graphene nanoplatelets composites as high rated electrode material for supercapacitors

For achieving a higher supercapacitor performance, electrode material with high surface area and conductivity such as graphene, graphene nanoplatelets (GNP), and carbon nanotubes along with Transition Metal oxides (TMO) can be used. Herein, the composite of graphene nanoplatelets with ternary metal oxide of manganese, nickel, and cobalt (MNC) is synthesized through a facile cost-effective hydrothermal process and its compositional, morphological, and electrochemical properties are investigated. As-synthesized MNC-GNP composite showed excellent electrochemical properties owing to the high porosity offered by graphene nanoplatelets and synergistic effects produced by individual components of the composite. For comparative studies, ternary oxide MNC was prepared by the same hydrothermal route. The cubic structure of the MNC-GNP composite is confirmed by X-ray diffraction (XRD). Scanning Electron Microscope (SEM) showed distinct hierarchical dendritic structures which showed an increase in density by the addition of graphene nanoplatelets. Electrochemical testing revealed that MNC-GNP exhibited an enhanced specific capacity of 605 mAh g^-1 which is higher compared to MNC which exhibited 243 mAh g^-1 at a current density of 2 mV s^-1. GCD also depicted an increased charge-discharge time in the case of MNC-GNP as compared to its counterpart. MNC-GNP has also shown charge stability up to 99.5 % of capacity retention up to 1000 cycles. Hence, synthesized composite shows to be an effective electrode material for supercapacitors owing to enhanced electrochemical properties.     

Work of adhesion in ceramic oxide/liquid metal systems

On the basis of experimental data given in the literature, a model for the determination of the work of adhesion was successfully applied in non-reactive oxide Al₂O₃ ZrO₂ UO₂/liquid metal systems. According to this model, the non-transition metals interact with oxides via dispersion forces, whilst the transition metals additionally establish chemical-type equilibrium bonds with the oxide surface. The assumptions of the model for both system categories are discussed and they are in good agreement with other theoretical and experimental findings.     

Comparing digital light processing and stereolithography vat polymerization Technologies for antimicrobial 3D printing using silver oxide as an antimicrobial filler

Vat polymerization technology allows filler particles to be incorporated into photosensitive 3D printing resin to improve the properties of the printed material. This method can be used to produce medical devices with an antimicrobial effect that can reduce biofilm formation and reduce infections due to indwelling devices. Metal oxides have the potential to combat antibiotic-resistant bacteria, further lowering the risk of hospital-acquired infections. The antimicrobial agent in this study, silver oxide, was evaluated for its antimicrobial effect against gram-positive bacteria (Staphylococcus epidermidis) as these are the main cause of biofilm formation. The 3D printed samples demonstrated a strong antimicrobial effect at low concentrations of 1 wt.%. Two vat polymerization technologies, stereolithography (SLA) and digital light processing (DLP), were compared for their suitability for producing 3D printed samples with an antimicrobial effect. DLP successfully produced samples with mechanical properties comparable to the base resin, whereas SLA samples had reduced mechanical strength at higher concentrations of silver oxide filler. Neither printing technology nor silver oxide concentration had a statistically significant effect on the mechanical properties of the printed materials.     

三维金属氧化物纳米材料的研究进展

三维金属氧化物纳米材料（3D-MONs）具有独特的连续多孔网络结构特点,不仅使其保留了金属氧化物特有的化学性质,而且表现出低密度、高比表面积、高孔隙率、低热导率等优异的物理性能,是近年来纳米材料领域一个新的研究热点。综述了3D-MONs制备方法的研究进展,重点介绍了水热合成法、溶胶-凝胶法、模板法、溶液喷射法、直接发泡法,并对其共性与差异进行了讨论;探讨了3D-MONs在污水治理、空气净化、储能、隔热领域应用的研究进展;在此基础上,提出了合成3D-MONs需要解决的问题及其应用展望。     

Coating metal oxide particles via the combustion of deposited polymer precursors

Water-swellable chelated polymers were synthesized, starting either from (1) In(III) or In(III) and Sn(II) as central ions and N-trimethoxysilylpropylethylenediamine or ethylenediamine each together with ethylenediaminetetraacetic acid (EDTA) as coordination ligands, or from (2) Ag(I) as the central ion and ethylene glycol (EG) and EDTA as coordination ligands, as follows: The nitrate(s) of the above metal ions together with the corresponding ligands were dissolved in water, and the solution was concentrated by heating to carry out the chelating polymerization. After cooling, the polymer was dried and ground to a fine powder, which was then mixed with a metal oxide powder by grinding in the presence of a small amount of water. A paste was thus obtained, which, after drying, was calcined at 200°C and subsequently at 750°C. The polymer became a sticky gel at 200°C, which adhered to the surface of the metal oxide particles; it was converted to an inorganic coating, In₂O₃—SnO₂—SiO₂, In₂O₃—SnO₂, SnO₂, or Ag, during the subsequent calcination at 750°C. Two metal oxide powders, namely, the electrically conductive In₂O₃ and the nonconductive SnO₂, were used as substrates. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) indicated that the substrate particles were coated after calcination by a multicomponent oxide or silver layer. Temperature-resistant electrically antistatic film could be prepared by using the metal oxide coated In₂O₃ particles as pigments and polypropylsiloxane as the binder. The Ag-coated SnO₂ powder had a conductivity σ = 1.0 × 10⁻³ S cm⁻¹ at 8.6 vol % Ag, while the mechanically mixed powders of Ag and SnO₂ exhibited a conductivity of 2.0 × 10⁻⁷ S cm⁻¹ at 16 vol %. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1891–1903, 1998     

过渡金属氧化物修饰的金纳米催化剂苯甲醇氧化性能

采用一步法合成介孔二氧化硅负载的金纳米催化剂,以氯化锡为前驱体,通过浸渍法向金纳米催化剂中引入助剂氧化锡,得到过渡金属氧化物修饰的金纳米催化剂。通过N2吸附-脱附、X射线衍射、透射电镜和固体紫外漫反射光谱等对催化剂结构进行表征。将所合成的催化剂用于苯甲醇选择性氧化反应,考察助剂组分对催化剂性能的影响,结果表明,氧化锡的引入改变了金纳米颗粒的表面电子结构,增加了催化剂活性与选择性;但随着氧化锡含量继续增加,催化剂活性降低,这主要是因为金纳米颗粒表面过渡金属氧化物覆盖度增加,减少了催化剂活性组分与苯甲醇的接触。当氧化锡质量分数0.2%时,催化剂效果最佳,在100℃和氧气压力0.2 MPa下反应3 h,苯甲醇转化率25.7%,苯甲醛选择性75.9%,苯甲酸选择性15.8%,苯甲酸苄酯选择性6.3%。     

Solid state chemistry of bulk mixed metal oxide catalysts for the selective oxidation of propane to acrylic acid

Syntheses of Mo–V–Sb–Nb–O bulk materials, which are candidate catalyst systems for the selective oxidation of propane to acrolein and acrylic acid, were made using soluble precursor materials. The products were characterized by X-ray powder diffraction and Raman spectroscopic studies. The objectives of this work were to explore the utility of liquid phase automated synthesis for the preparation of bulk mixed metal oxides, and the identification of the oxide phases present in the system. This is the first published study of the phase composition for these materials. After calcination of these bulk oxides under flowing nitrogen at 600°C, and using stoichiometric ratios of Mo–V–Sb–Nb (1:1:0.4:0.4) and Mo–V–Sb–Nb (3.3:1:0.4:0.4) it was demonstrated that a mixture of phases were obtained for the syntheses. X-ray powder diffraction studies distinguished SbVO₄, Mo₆V₉O₄₀, MoO₃, and a niobium-stabilized defect phase of a vanadium-rich molybdate, Mo_0.61–0.77V_0.31–0.19Nb_0.08–0.04O_x, as the major phases present. Complementary data were provided by the Raman spectroscopic studies, which illustrated the heterogeneity of the phases present in the mixture. Raman also indicated bands attributable to the presence of phases containing terminal M=O bonds as well as M–O–M polycrystalline phases. Previous studies on this system have identified SbVO₄ and niobium-stabilized vanadium molybdate species as the active phases necessary for the selective oxidation of alkanes.     

Manufacturing and structural analysis of antimicrobial kefiran/polyethylene oxide nanofibers for food packaging

Kefiran, a branched glucogalactan, is a useful microbial polysaccharide produced by lactic acid bacteria. The aim of this study was to evaluate the antimicrobial activity of kefiran nanofibers as a biocontrol agent for food packaging as well as food preservation. Thus, kefiran/polyethylene oxide (PEO) nanofibers were fabricated using the electrospinning method. Kefiran was produced from raw milk with 0.5% fat and 10 g of kefir grain and was separated from it by ethanol. Structural analysis of kefiran was detected by means of nuclear magnetic resonance and Fourier transforms infrared spectroscopy (FTIR). Antimicrobial properties of kefiran were assayed against Rhizoctonia, Pseudomonas sp. (isolated from soil at Isfahan University) and Staphylococcus aureus (S. aureus). Electrospun kefiran/PEO nanofibers were characterized by scanning electron microscopy, optical microscopy and ATR-FTIR techniques. Hydrophilicity and in vitro biodegradation of the kefiran/PEO nanofibers were investigated, as well. The results showed that the mean diameter of the nanofibers was 607.5 nm. The contact angle measurement result was 51.5° ± 0.71 with normal hydrophilicity. First of all, antimicrobial properties of kefiran were confirmed against different types of microorganisms. Moreover, the result obtained in this study showed that kefiran/PEO nanofibers with oxidizing functional groups on them have antimicrobial activity against S. aureus. Biodegradation of kefiran/PEO nanofibers was also confirmed by FTIR.     

Porous chitosan/graphene oxide biocomposites for tissue engineering

Porous chitosan/graphene oxide (CHT/GO) biocomposites with 0.5, 1, 2, and 3 wt% GO were prepared by freeze‐drying method. The biocomposites were characterized regarding structural, morphological, and thermal properties, degradation, and swelling responses. Raman spectroscopy and scanning electron microscopy (SEM) results indicated good GO dispersion within the polymer host and highly porous structure for the obtained biocomposites. The GO presence has a profound effect on the structural features of the biocomposites generating decrease of swelling degree and enzymatic biodegradation rate. Conversely, the thermal stability of the biocomposites was significantly improved, and the decomposition temperature at which the mass loss is 3% (T _d,3%) was increased with 64°C by adding 3 wt% GO within the CHT. The ability of the biocomposites to form apatite‐like crystals was also investigated. X‐ray diffraction and SEM analyses indicated the formation of apatite deposits on the CHT/GO biocomposites. POLYM. COMPOS., 38:363–370, 2017. © 2015 Society of Plastics Engineers     

PLA抗菌/抗氧化活性包装薄膜在食品中的应用及其安全性评价

综述了聚乳酸（PLA）抗菌/抗氧化活性薄膜在食品包装中的应用及其安全性评价的研究进展,主要从PLA抗菌/抗氧化活性薄膜及其在食品包装中的应用和PLA材料的安全性评价3个方面进行了归纳总结,旨在为PLA抗菌/抗氧化活性包装薄膜研究提供参考。     

植酸在金属防护中的应用新进展

植酸是一种新型金属多齿螯合剂 ,可在金属表面形成一层致密的单分子有机保护膜 ,从而防止金属的腐蚀。介绍了植酸在金属防腐、磷化和钝化等工艺中的应用。     

活性炭担载金属氧化物用于热煤气脱硫

以热煤气脱硫并回收单质硫为目的,考察了活性炭担载金属氧化物(M/AC)在中温范围150—250℃内,催化氧化硫化氢生成单质硫的研究。担载量1%(质量分数)的M/AC通过等体积浸渍法制得,在固定床上评价了其脱硫活性,并考察了温度、反应气氛等工艺条件对脱硫效果的影响。M/AC脱硫的活性顺序为:Mn/ACCu/ACCe/ACFe/ACCo/ACV/AC。通过DTG分析,硫化氢选择性氧化的主要产物是单质硫。M/AC上金属氧化物起主要的催化作用,催化硫化氢和氧气反应生成单质硫,生成的单质硫被吸附在活性炭的孔道中。     

基于表/界面调控的金属氧化物半导体光催化剂的理性构筑

近年来半导体光催化作为一种绿色技术在解决环境问题和提供可再生能源方面获得了广泛关注,然而较低的催化效率限制着它的实际应用。合理设计金属氧化物半导体的表/界面结构,是提升光催化剂性能的有效手段。对近年来半导体光催化剂的表/界面结构调控以及构-效关系的研究进行了梳理,介绍了在单一组分体系中利用晶面效应优化光催化性能的可行措施。在此基础上,总结了晶面/界面结构调控在复合光催化剂体系中的应用。最后,总结了该领域面临的挑战与未来的前景。     

Ce-Cu-Al-O复合金属氧化物吸附剂低温脱除H2S

用共沉淀法制备了一系列Ce-Cu-Al-O复合金属氧化物吸附剂,用于低温下脱除CO₂气体中的微量H₂S。采用XRD、N₂物理吸附、SEM及XPS等手段对脱硫前后的吸附剂结构进行表征。研究了Ce含量、煅烧温度、气体空速、杂质气体及吸附温度对吸附剂脱除H₂S性能的影响。结果表明,Ce-Cu-Al-O系列吸附剂在40℃条件下可有效脱除CO₂气体中的H₂S,Ce含量为10%的吸附剂（10Ce-Cu-Al-O）具有最大H₂S穿透吸附量,为94.1mg/g。研究发现,引入CeO₂能有效改善CuO的分散性,提高吸附剂的比表面积和孔容。提高煅烧温度,较大空速均不利于吸附剂的脱硫效果;平衡气CO₂会抑制H₂S的吸附;吸附温度不高于100℃时,10Ce-Cu-Al-O的穿透吸附量随温度升高而增加且不会生成COS副产物。表征结果显示,硫化后吸附剂的组分团聚导致了比表面积和孔容降低。此外,失活后的脱硫剂可在100℃用空气再生。     

纳米MgO增强聚乳酸薄膜在食品包装领域的应用

采用溶液流延工艺制备了纳米MgO增强聚乳酸(PLA)薄膜。研究了纳米MgO质量分数分别为0.5%,2.0%,3.5%,6.0%的PLA/MgO薄膜的力学性能、阻隔性能、热性能等。结果表明:与PLA薄膜相比,纳米MgO质量分数为2.0%时,所制PLA/MgO薄膜具有最高的拉伸强度和断裂伸长率,这归功于纳米MgO在PLA基体内的分散均一性。     

银系抗菌剂的研发及其市场应用现状

总结了当前抗菌剂的分类,根据载体的不同,分别概述了当前不同类的银系抗菌剂的制备方法和研究现状,还报道了相关银系抗菌剂制备的专利技术,同时通过对银系抗菌剂市场的了解,对银系抗菌剂的市场应用现状作了相关报道。     

Preparation,characterization and the antimicrobial properties of metal ion-doped TiO2 nano-powders

TiO₂ samples doped with lithium, sodium, magnesium, iron or cobalt were prepared by high-energy ball milling for different periods of time. The crystalline phase, chemical composition, crystalline size and photo-absorption were characterized by X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS) and Ultraviolet visible diffuse reflectance spectroscopy (UV - Vis - DRS), Fourier transform infrared spectroscopy (FT - IR) and scanning electron microscopy (SEM). The antimicrobial properties of the modified TiO₂ samples were evaluated with E. coli and S.aureus assays. The results of the XRD show that the TiOSO₄, Ti₃O₅, Li₂TiO₃ and NaTi₂O₄ phases appear along with Li, Na and Mg doped TiO₂. However, XPS spectra indicated that Ti exists as both Ti³⁺ and Ti⁴⁺ in Na-doped TiO₂ samples. Ti³⁺, due to its narrow band gap, is highly active in promoting visible light-induced photocatalytic activity. SEM images showed that the crystalline size of TiO₂ is reduced and has a common-round and hexagonal plate morphology after milling. The modified TiO₂ samples had the best antimicrobial activities after 3 h of milling. In particular, the antimicrobial rate of TiO₂ 5% doped with transition metals (Co, Fe) reached 100% against E. coli, but the antibacterial rate against S. aureus for Co and Fe dopants was 98.4% and 98.2%, respectively.     

Catalytic combustion of solvent containing air on base metal catalysts

Complete oxidation of solvents (e.g., acetone, butyl acetate and isopropanol) over base metal oxides was investigated using a fixed bed reactor. Mixed oxides with perovskite (e.g. LaMnO₃) or spinel structure (e.g. CuMn₂O₄) have been prepared and characterized by BET surface area measurements and X-ray diffraction. The influence of catalyst type and composition, reaction temperature and feed composition on the formation of CO₂ and partially oxidized intermediates has been examined.