Isolation of antibacterial components from infusion of Caesalpinia paraguariensis bark. A bio-guided phytochemical study

The antimicrobial activities and toxicity of infusion, decoction and tincture of Caesalpinia paraguariensis Burk. bark (CPBEs) were investigated to validate its traditional use as drink additive and to identify microbicidal component(s). The minimum inhibitory concentrations (MIC) of CPBEs against aerobic bacteria (Gram-negative and Gram-positive species) were determined using standardised dilution methods. The LC₅₀ were determined by Brine Shrimp Test. CPBEs showed bacteriostatic and bactericidal activity against tested strains. The highest activity was observed for infusion (MIC:200 μg/mL) against Morganella morganii, Erwinia carotovora, Bacillus spp., Staphylococcus spp. and Enterococcus spp. The bacterial species were susceptible to CPBEs (MIC:200–1993 μg/mL) at lower concentration than sodium benzoate, a known food preservative. Two bioactive components were isolated from liophylised infusion by bio-guided chromatographic procedures; these were identified by spectrometric techniques as ellagic and 3-O-methylellagic acids. This study demonstrated that C. paraguariensis bark infusion it is safe for human consumption and a possible source of food natural preservatives.     

桑蚕丝织物HSDA-HTC抗菌整理性能研究

用实验室自制的聚合季铵盐(HSDA-HTC)对桑蚕丝织物进行抗菌整理,测试并分析了整理织物的抗菌性能、抗菌耐洗性及力学和吸湿性能.结果表明,经10 g/L的HSDA-HTC水溶液整理后的桑蚕丝织物对金黄色葡萄球菌和大肠杆菌的抑菌率分别为99.62%和99.44%,并具有优良的抗菌耐洗性,洗涤50次后其抑菌率仍超过99....     

镀银纤维分布均匀性与织物抗菌性的关系

探讨镀银纤维在纱线、织物中的分布均匀性对抗茵性的影响.采用琼脂平皿法分别对镀银纤维、镀银纤维介入织物不同技术路线的纱线及其嵌织织物试样的抗茵性进行了测试与分析,结果表明:镀银纤维具有良好的抗菌溶出性,进行抗菌织物设计时,在满足临界用量要求的前提下,可选择混纺、包芯、交捻、交织等多种技术手段开发抗茵织物,但应注意不同的技术手段对分布均匀性要求的差异.     

纳米Ag@TiO2、Fe@TiO2和Zn@TiO2的抑菌活性比较研究

探索常见金属离子掺杂对抑菌片的抑菌性能的影响,为新型纳米TiO₂抑菌片的制备与改善提供技术基础。选择固定质量分数的Ag⁺、Zn²⁺和Fe³⁺掺杂TiO₂,通过抑菌圈、MIC与MBC方法综合评价其抑菌性能,对微观结构进行表征分析,探讨抑菌性能差异的原因。结果表明:抑菌性能大小顺序为Ag@TiO₂> Zn@TiO₂> Fe@TiO₂,Zn@TiO2 的抑菌活性较好但抑菌稳定性差Ag@TiO2对大肠杆菌和金黄色葡萄球菌的MIC、MBC均是10、20 mg/L,Zn@TiO₂对大肠杆菌和金黄色葡萄球菌的MIC、MBC均是30、50 mg/L。表征发现抑菌活性强弱主要归因于纳米TiO₂表面与金属离子共同产生的活性位点数量及稳定性,与孔结构或表面宫能团的关联不大。     

1D sub 10 nm nanofabrication of ultrahydrophobic Ag@TiO2 nanowires and their photocatalytic,UV shielding and antibacterial properties

Here we report the synthesis of 1D TiO₂ sub 10 nm nanowires through one pot hydrothermal method in an alkaline NaOH medium at 95 °C for 36 h. Further, these TiO₂ nanowires were embellished with silver (Ag) using polyvinylpyrrolidone (PVP) and ethylene glycol (EG) based solvothermal route at 160 °C for 4 h. With Ag decoration the photocatalytic activity was enhanced and the complete photooxidation of Methylene Blue (MB) was achieved in 35 min under optimized conditions. Super- and ultra-hydrophobic coating on cotton fabric exhibited a consistent antibacterial activity with enhanced UV-blocking property. Enhanced multifunctional properties observed were primarily attributed to the formation of Ag decorated 1D sub 10 nm TiO₂ nanowires heterojunctions achieved using facile chemical route. Hence, such multiple functionalities make the 1D sub 10 nm TiO₂ nanowires good candidate for industrial and domestic wastewater treatment.     

TiO2 hollow spheres as a novel antibiotic carrier for the direct delivery of gentamicin

The TiO₂ hollow spheres were synthesized using a green, cheap, and easy process, in which carbonaceous spheres were chosen as the removable template. The prepared materials were characterized by X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EDX), Atomic force microscopy (AFM), Fourier Transform Infrared Spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET) analysis. According to the results, the obtained mesoporous TiO₂ hollow spheres demonstrated an external diameters less than 200?nm with shell thickness around 40?nm. The antibacterial activities of the TiO₂ hollow spheres were evaluated against gram-positive (Bacillus subtilis and Staphylococcus aureus) and gram-negative (Escherichia coli and Pseudomonas aeruginosa). No antibacterial activity was found for TiO₂ hollow spheres in the used concentrations. TiO₂ hollow spheres were loaded with gentamycin as a selected antibiotic to magnify their benefits in biomedical applications. TiO₂ hollow spheres exhibited good antibiotic carrier activity for the direct delivery of gentamicin, which was attributed to interaction between gentamicin and surface due to their larger specific surface area, more abundant porous structure, and their spherical morphology. The application of TiO₂ hollow spheres as gentamicin carrier undoubtedly opens an avenue to use hollow sphere materials in other drug delivery applications.     

Chemical composition,antibacterial and antioxidant activity of the essential oils of Metaplexis japonica and their antibacterial components

The aim of this research was to determine the chemical composition, antioxidant and antibacterial properties of the essential oils from Metaplexis japonica and isolation of antibacterial constituents from the essential oils. Results showed that 63 components were identified in essential oils. Phenylethyl alcohol (77.978%), α‐terpineol (31.810%) and docosane (21.644%) were the most abundent constituents of flower oil, leaf oil and fruit oil, respectively. Based on bioactivity‐guided fractionation, three active constituents were isolated and identified as phenylethyl alcohol, α‐terpineol and β‐linalool. Both flower oil and phenylethyl alcohol showed high antibacterial performance, with inhibition zone from 25 ± 0.5 to 11 ± 0.6 mm at highest concentration, and MIC values ranging from 0.125 to 2%. In both DPPH and ABTS assay, the oils showed moderate antioxidant activity. These results indicate potential efficacy of active constituents and essential oils of M. japonica to control food‐borne pathogenic and spoilage bacteria.     

Insight into the impact of zinc doping on the structural,surface, and biological properties of magnasium oxide nanoparticles stabilized by Vateria indica (L.) fruit extract

The present study is an attempt to delineate the effect of zinc doping on the green synthesized magnesium oxide (MgO) NPs. Pure (MgOVI) and zinc doped (ZnMgOVI) NPs were synthesized employing an aqueous fruit extract of V. indica as capping and reducing agents. The various analytical techniques viz. FTIR, PXRD, FESEM, and EDS spectroscopy together with elemental mapping analyses substantiated the formation of pure and doped NPs with crystallite sizes 23.74 and 25.41 nm. The study of surface properties through BET analysis unfolded the formation of mesoporous NPs with a surface area of 7.4 and 5.3 m²g^-1 for pure and doped NPs respectively. Additionally, the refinement of obtained PXRD data through Rietveld refinement corroborated the changes in cell parameters after zinc doping. The anti-inflammatory activity carried out unveiled the biocompatibility of obtained NPs by exhibiting a % HRBCS of 83.65 ± 0.002 and 85.69 ± 0.003 for MgOVI and ZnMgOVI NPs. The in-vitro antidiabetic activity of MgOVI and ZnMgOVI NPs performed revealed their excellent α-amylase inhibition activity (86.29 ± 0.001and 86.44 ± 0.002%). Furthermore, the NPs also displayed anti-microbial activities against Staphylococcus aureus, Bacillus subtulis, Pseudomonas aeroginosa, Pseudomonas syringae, and Escherichia coli. Thus the studies have evinced the superlative antidiabetic and antimicrobial potentialities of MgOVI and ZnMgOVI NPs with high biocompatibility.     

Effect of ZrO2 nanoparticles addition to PEO coatings on Ti–6Al–4V substrate: Microstructural analysis,corrosion behavior and antibacterial effect of coatings in Hank's physiological solution

In this study, plasma electrolyte oxidation (PEO) method was employed to modify the surface of Ti–6Al–4V. Effects of different concentrations of ZrO₂ nanoparticles (0, 1, 3 and 5 g/l) into a phosphate-based electrolyte on the morphology, wettability, antibacterial and corrosion behaviors of coatings were investigated. Microstructural analyses of coatings were evaluated using scanning electron microscopy with an energy dispersive spectrometer. Also, X-ray diffraction, contact angle instrument and profilometry were respectively used to perform phase analysis, wettability, and surface roughness of the coatings. The antibacterial test was conducted with spot inoculation method on four pathogenic bacteria. Polarization and impedance spectroscopy measurements were performed in Hank's solution to investigate the corrosion behavior of coatings. The results revealed that PEO coatings without nanoparticles and by increasing the concentration of the ZrO₂ nanoparticles up to 3 g/l in the electrolyte led to a significant improvement in the antibacterial activities of gram-negative bacteria (P. aeruginosa and E. Coli). In the case of gram-positive bacteria, the PEO coated samples demonstrated improved antibacterial effects but addition of ZrO₂ nanoparticles in the PEO coatings resulted in deterioration of antibacterial effect. The sample coated with 3 g/l ZrO₂ nanoparticles showed the peak corrosion resistance compared to its counterparts.     

Preparation and photocatalytic antibacterial mechanism of porous metastable β-Bi2O3 nanosheets

Effective and safe application of antibacterials has always been an important aspect for their usage. High-efficiency photocatalytic technology driven by visible light for antibacterial action constitutes a practical solution for antibacterial agents and will not harm the human body or the environment. While most studies on β-Bi₂O₃ materials with good photocatalytic properties under visible light are conducted in the field of optoelectronics, their potential and mechanism as photocatalytic antibacterial agents have not yet been fully explored. Herein, we report the performance of sheet-like metastable β-Bi₂O₃ material with rich oxygen vacancies and high electron-hole separation efficiency in antibacterial processes, as well as a preliminary exploration of its antibacterial mechanism. The results revealed that the antibacterial activity of the product against E. coli greatly improved in comparison with commercially available α-Bi₂O₃ owing to its excellent structure and optical properties. In addition, gradient experiments and scavenger experiments have confirmed that the main antibacterial effect of β-Bi₂O₃ originates from reactive oxygen species (ROS), and the superoxide radical, ·O₂⁻, of generated ROS is the key reactive species in the antibacterial process. Through the detection of lipid peroxidation and bacterial respiratory-chain dehydrogenase activity, several pathways were identified for the excellent antibacterial activity of the product.