Antimicrobial Activity, Structural, Crystallographic and Thermal Characteristics of Alpha-Titanium Phosphate Promoted by Silver Ions

The recent global spread of the pandemic underscores the necessity of seeking new materials effective against microorganisms. Nanotechnology offers avenues for developing multifunctional materials. In this study, alpha-titanium phosphate (α-TiP) nanoparticles were synthesized and treated with silver salt to enhance their antimicrobial properties. The physicochemical characteristics and antimicrobial activity were evaluated. It was revealed by X-ray diffraction analysis that the structural integrity of α-TiP was influenced by ethylenediamine and silver ions. Distinct degradation profiles for each chemical modification were shown by thermogravimetric analysis. Infrared spectroscopy detected shifts and new absorption peaks in the spectra depending on the type of modification. Energy dispersive spectroscopy confirmed the disaggregation of α-TiP galleries following the addition of silver salt, which increased their effectiveness against microorganisms. Notably, only the sample treated with silver ions exhibited antimicrobial action. Antimicrobial activity was tested against the bacteria of medical importance Escherichia coli, Salmonella Enteritidis, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus cereus, Listeria momocytogenes and the yeast Candida albicans. All microorganisms were inhibited by sample containing silver. Minor inhibition was observed against the Gram-positive bacteria L. monocytogenes and Bacillus cereus, while the greatest inhibition occurred against the fungus (yeast) C. albicans. The results revealed a potential application of the nanoparticles for control of microorganisms in public health.

Biosynthesis of Silver Nanoparticles with Clerodendron phlomoides Leave Extract:Particle Morphology,Antimicrobial Potential and Application

Silver nanoparticles are versatile nanomaterials that have found numerous applications in various fields.The use of plant extract for the synthesis of silver is a green and sustainable approach.Clerodendron phlomoides leaves extract has been found to contain various phytochemicals,such as phenols,flavonoids,tannins,and alkaloids,which possess reducing and stabilizing properties that can aid the production of silver particles.In this paper,morphological and topographical analyses were performed on silver nanoparticles.The biosynthesized silver nanoparticles showed antimicrobial potential against wound pathogens.SEM and TEM micrographs revealed that the particles were sphere and nanosized,which makes them suitable for various biomedical applications.

Green synthesis,antimicrobial and cytotoxic effects of silver nanoparticles using Eucalyptus chapmaniana leaves extract

Objective:To synthesize silver nanopaticles from leaves extract of Eucalyptus chapmaniana(E.chapmaniana)and test the antimicrobial of the nanoparticles against different pathogenic bacteria,yeast and its toxicity against human acute promyelocytic leukemia(HL-60)cell line.Methods:Ten milliliter of leaves extract was mixed with 90 mL of 0.01 mmol/mL or 0.02 mmol/mL aqueous AgNO_3 and exposed to sun light for 1 h.A change from yellowish to reddish brown color was observed.Characterization using UV-vis spectrophotometery and X-ray diffraction analysis were performed.Antimicrobial activity against six microorganisms was tested using well diffusion method and cytoxicity test using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide,a yellow tetrazole was obtained on the human leukemia cell line(HL-60).Results:UV-vis spectral analysis showed silver surface plasmon resonance band at 413 nm.X-ray diffraction showed that the particles were crystalline in nature with face centered cubic structure of the bulk silver with broad beaks at 38.50°and 44.76°.The synthesized silver nanoparticles efficiently inhibited various pathogenic organisms and reduced viability of the HL-60 cells in a dose-dependent manner.Conclusions:It has been demonstrated that the extract of E.chapmaniana leaves are capable of producing silver nanoparticles extracellularly and the Ag nanoparticles are quite stable in solution.Further studies are needed to fully characterize the toxicity and the mechanisms involved with the antimicrobial and anticancer activity of these particles.

Green synthesis, antimicrobial and cytotoxic effects of silver nanoparticles mediated by Eucalyptus camaldulensis leaf extract

Objective: To investigate the environmental-friendly extracellular biosynthetic technique for the production of the silver nanoparticles(AgN Ps) by using leaf extract of Eucalyptus camaldulensis(E. camaldulensis). Methods: The NP were characterized by colour changes and the UV-visible spectroscopy. The cytotoxic effects of prepared AgN Ps was detected against four types of pathogenic bacteria, including two Gram-negative bacteria(Pseudomonas aeruginosa and Escherichia coli) and two Gram-positive bacteria(Staphylococcus aureus and Bacillus subtilis) by using agar well diffusion method. Results: A peak absorption value between 400-450 nm for the extract and the colour change to dark brown were corresponding to the plasmon absorbance of AgN Ps. On the other hand, aqueous extract of E. camaldulensis leaves could be effective against tested microorganisms which showed inhibition zones of 9.0-14.0 mm. Furthermore, biologically synthesized AgN Ps had higher ability to suppress the growth of the tested microorganisms(12.0-19.0 mm). Conclusions: Our findings indicated that extracellular synthesis of Ag NPs mediated by E. camaldulensis leaf extract had an efficient bactericidal activity against the bacterial species tested. The exact mechanism of the extracellular biosynthesis of metal NP was not well understood. Further studies are needed to highlight the biosynthesis process of AgN Ps and also to characterize the toxicity effect of these particles.

Antimicrobial activity of latex silver nanoparticles using Calotropis procera

Objective:To synthesize silver nanoparticles(AgNPs) by green methods using scrum latex of Calotropis procera at 80 ℃ and evaluate them against bacteria,dermatophytes and phytopathogenic fungi comparing with the activity of untreated latex.Methods:The synthesis of AgNPs was performed by mixing 3%latex scrum extract with the same volume of silver nitrate(2 mmol/L) solution in round flask and heating in water bath at80 ℃.Characterization of silver particles were determined using UV-vis spectrophotometer,transmission electron microscopy(TEM),X-ray diffraction and Fourier transform infrared spectroscopy.The antimicrobial activity of the green synthesized AgNPs was determined against bacteria,dermatophytes and phytopathogenic fungi and compared to the crude untreated latex by agar-well diffusion methods.Results:Biosynthesis of latex silver nanoparticles was successfully obtained by green method.The formation of AgNPs has been confirmed by UV-vis,TEM microscopy.X-ray diffraction and Fourier transform infrared spectroscopy.TEM analysis showed that synthesized AgNPs are highly stable spherical shaped particles,well dispersed with a diameter ranged from 4 nm up to 25 nm and an average size of 12.33 nm.AgNPs showed strong antibacterial activity against Gram-negative bacteria(Escherichia coli,Pseudomonas aeruginosa and Serratia sp.) and antifungal activity against Trichophyton rubrum,Candida albicans and Aspergillus terreus.Conclusions:It can be concluded that serum latex of Calotropis pmcera was found to display strong potential for the synthesis of AgNPs as antimicrobial agents through rapid reduction of silver ions(Ag^+ to Ag^0).The green synthesized AgNPs were found to show higher antimicrobial efficacy than crude latex.

Synthesis of Stable Silver Nanoparticles with Antimicrobial Activities in Room-temperature Ionic Liquids

Stable silver nanoparticles was successfully synthesized by chemical reduction of silver nitrate in an ionic liquid,1-n-butyl-3-methylimidazolium tetrafluoroborate（[BMIM]·BF4） at room temperature.Results of UV-Vis diffuse reflectance spectroscopy show as-prepared Ag nanoparticles exhibit a typical emission peak at 400―430 nm.By varying the reaction temperature and the precursor concentration,the size and the shape of the silver nanoparticles could be easily controlled under mild conditions.Analyses of transmission electron micrographs,X-ray diffraction pattern and X-ray photoelectron spectrum further reveal that the silver nanoparticles were coated incompletely by [BMIM]·BF4.Microbial experiments indicate that as-prepared silver nanoparticles show a wide spectrum of antimicrobial activities and have better antimicrobial activities to Pseudomonas aeruginosa than silver nitrate with the same concentration of silver.

Extracellular synthesis of silver nanoparticles by Pseudomonas sp. THG-LS1.4 and their antimicrobial application

Silver nanoparticles（Ag NPs） are known to have bacteriostatic and bactericidal effects. The present study highlights the extracellular synthesis of Ag NPs and its antibacterial properties. The Ag NPs were synthesized using Pseudomonas sp. THG-LS1.4 strain which had been isolated from soil. The Ag NPs were characterized by field emission-transmission electron microscopy（FE-TEM）, X-ray diffraction（XRD）,Fourier transform-infrared（FT-IR） spectroscopy, and particle size distribution（DLS）. The Ag NPs displayed maximum absorbance at 412 nm and were irregular in shape ranging from 10 to 40 nm. The XRD spectroscopy results demonstrated the crystalline nature of nanoparticles. The Ag NPs showed antimicrobial activity against Bacillus cereus, Staphylococcus aureus, Candida tropicalis, Vibrio parahaemolyticus, Escherichia coli and Pseudomonas aeruginosa. Furthermore, the Ag NPs were also evaluated for their increased antibacterial activities with various antibiotics against Escherichia coli, Pseudomonas aeruginosa and Salmonella enterica. Additionally, Ag NPs showd biofilm inhibition activity. The biosynthesized Ag NPs were found to be a potent agent against tested pathogens. More importantly, we highlight the applications of Ag NPs as an antimicrobial agent.

Antimicrobial Effect of Silver Ionised Water Prepared with the Sintering Coating Method—Effect on Acid Production in Plaque

Purpose: To investigate the effect of silver ionised water on acid production in plaque. Methods: After injecting 0.5 mL of silver ionised water (concentration: 5 ppm) produced with the sintering coating method in the sensor part of the pH metre, plaque collected from the oral cavity by one platinum loop was mixed in. Immediately after that, a 5% sucrose solution (1 g/20 mL) was added and the pH was continuously measured for 30 minutes at 1-minute intervals (A). Similarly, silver ionised water was mixed with 5% sucrose solution in the same way as in (A) at 3 (B), 5 (C), 10 (D) and 15 minutes (E) after plaque contamination. The pH was measured at 1-minute intervals. The pH of the purified water containing no silver ionised water mixed with plaque and sugar solution at the same time was measured and used as a control. Each experiment was conducted three times, and the pH measured every minute was compared as a percentage of the pH at the beginning of the measurement (100%). Results: Analysis of variance of the repeated measurements to determine the effect of silver ionised water on the decrease in pH revealed a main effect of silver ionised water and an interaction between time and group [F(1.302,20.826) = 39.145, p < 0.01]. Multiple comparisons using Dunnett’s method showed a significant decline in the rate of decrease in pH from B to E as compared with that in the control (p < 0.01). Conclusion: Silver ionised water was found to inhibit the acid production in plaque.

Structure, properties and application to water-soluble coatings of complex antimicrobial agent Ag-carboxymethyl chitosan-thiabendazole

The structure, properties and application to water-soluble coatings of a new complex antimicrobial agent Ag-carboxylmethyl citosan-thiabendazole （Ag-CMCTS-TBZ） prepared from different materiel ratios were reported. The silver ions were preferably coordinated with the free-NH2 groups and the -OH groups of secondary alcohol and carboxyl in CMCTS. TBZ preferably bonded to carboxyl group in CMCTS by electrostatic force and hydrogen bonding. Increase in silver ions content in the complex agent improved to some limited extent the antibacterial activity, but enhanced coloring and cost of the complex agent. Increase in TBZ content resulted in increase of antifungal activity, but decrease of water solubility of the complex agent. The antimicrobial MICs of the complex agent to Esherichia coil, Staphylococcus aureus, Candida albicans, Aspergillus niger, Mucor sp. were 20 -80, 15 -60, 20 - 55, 40 - 250, and 400 - 1700 mg/kg, respectively. Addition of 0.1% of this complex agent to acrylic emulsion paint made the paint without substantial change in color, luster, viscosity, odor or pH value, but with an excellent and chronically persisting broad-spectra antimicrobial activity.

Structural,optical and antimicrobial properties of pure and Agdoped ZnO nanostructures

In the present work,zinc oxide(ZnO)and silver(Ag)doped ZnO nanostructures are synthesized using a hydrothermal method.Structural quality of the products is attested using X-ray diffraction,which confirms the hexagonal wurtzite struc-ture of pure ZnO and Ag-doped ZnO nanostructures.XRD further confirms the crystallite orientation along the c-axis,(101)plane.The field emission scanning electron microscope study reveals the change in shape of the synthesized ZnO particles from hexagonal nanoparticles to needle-shaped nanostructures for 3 wt%Ag-doped ZnO.The optical band gaps and lattice strain of nanostructures is increased significantly with the increase of doping concentration of Ag in ZnO nanostructure.The anti-microbial activity of synthesized nanostructures has been evaluated against the gram-positive human pathogenic bacteria,Staphylococcus aureus via an agarose gel diffusion test.The maximum value of zone of inhibition(22 mm)is achieved for 3 wt%Ag-doped ZnO nanostructure and it clearly demonstrates the remarkable antibacterial activity.

Silver nanoparticle technology in orthopaedic infections

The irrational and prolonged use of antibiotics in orthopaedic infections poses a major threat to the development of antimicrobial resistance.To combat antimi-crobial resistance,researchers have implemented various novel and innovative modalities to curb infections.Nanotechnology involves doping ions/metals onto the scaffolds to reach the target site to eradicate the infective foci.In this conno-tation,we reviewed silver nanoparticle technology in terms of mechanism of action,clinical applications,toxicity,and regulatory guidelines to treat ortho-paedic infections.

Antimicrobial technology in orthopedic and spinal implants

Infections can hinder orthopedic implant function and retention.Current implant-based antimicrobial strategies largely utilize coating-based approaches in order to reduce biofilm formation and bacterial adhesion.Several emerging antimicrobial technologies that integrate a multidisciplinary combination of drug delivery systems,material science,immunology,and polymer chemistry are in development and early clinical use.This review outlines orthopedic implant antimicrobial technology,its current applications and supporting evidence,and clinically promising future directions.

生物法绿色合成纳米银及其抗菌应用进展

纳米银是研究和应用最广泛的纳米材料之一。近年来,为避免纳米银合成过程中产生有毒副产物,研究者在纳米银的绿色合成方面进行了诸多研究。首先,综述了生物法绿色合成纳米银,重点介绍了微生物法、植物提取物法;接着,介绍了纳米银抗菌性的机理和影响因素;然后,总结了纳米银的抗菌应用;最后,指出植物各组织和微生物细胞中富含的各类天然化合物均可完成纳米银的绿色合成,不同生物源合成纳米银的潜力有待进一步发掘。纳米银尺寸和形状的可控化以及在使纳米银发挥抗菌作用的前提下减少迁移、减少副作用是下一步的研究重点,对未来发展提出了建议。

羧甲基壳聚糖/纳米银抗菌剂的制备及缓释性能研究

以羧甲基壳聚糖(CMCS)、银氨溶液为主要原料,采用微波辐射法合成具有缓释抗菌作用的羧甲基壳聚糖/纳米银(CMCS-Ag)抗菌剂。研究反应时间与温度对CMCS-Ag抗菌剂中纳米银生成量的影响,以较优条件制备抗菌剂并通过紫外-可见光谱、X射线衍射、透射电镜及红外光谱对抗菌剂进行结构表征,与商用纳米银进行对比测试,对CMCS-Ag抗菌剂的抗菌性能与Ag^(+)缓释性能进行评价。结果表明:羧甲基壳聚糖与银氨溶液比例为100mg∶0.4mmol时,在70℃、40min条件下制备出CMCS-Ag抗菌剂的纳米银含量最高,纳米银浓度为(1250±2.8)mg/L;CMCS-Ag抗菌剂中纳米银晶型良好且粒径较小,平均粒径为(26±0.12)nm,能够均匀地负载于CMCS网状结构中;CMCS-Ag抗菌剂对大肠杆菌最小抑菌浓度为7.81mg/L、对金黄色葡萄球菌为15.63mg/L,抗菌效果优于商用纳米银;CMCS-Ag抗菌剂240h累计Ag^(+)释放浓度为(26±0.5)μg/L,Ag^(+)释放总量低于商用纳米银,Ag^(+)缓释性能优于商用纳米银。

海藻基纳米银研究进展

病原菌对抗生素多重耐药性的增加而引发的持续感染、高医疗成本使公共卫生领域面临着巨大挑战。新型海藻基纳米银(Silver nanoparticles,AgNPs)抗菌剂的开发研究对病原菌的控制意义重大。文章对海藻基AgNPs的生物合成、表征方法、抗菌活性进行了综述,强调了海藻基AgNPs抗菌活性可能的作用机制,并对其未来的研究方向进行展望,旨在为海藻基AgNPs抗菌新材料的深度开发与应用提供研究思路和方向。

植物提取物合成银纳米粒子在龋齿治疗中应用的研究进展

口腔疾病如龋齿是世界上最常见的非传染性疾病。如果不及时治疗,会发展为系统性疾病。龋齿的预防传统上依赖于口腔卫生和饮食控制,以及其他预防措施。在无机纳米材料中,银纳米粒子(AgNPs)由于其独特的物理化学性质和较强的抗菌活性,在牙科治疗中应用前景十分广阔。因此,AgNPs可能为治疗和预防牙齿感染提供新的策略。然而,人们对纳米材料的化学合成存在很多弊端,如有毒还原剂的使用。这也激发了研究者开发使用天然产物作为还原剂的绿色合成路线。与化学合成的AgNPs相比,生物源AgNPs具有良好的生物相容性。因此,采用植物合成的AgNPs具有抗菌、防污和再矿化的作用,是用于治疗龋齿和口腔疾病有前景的药物。

活性屏等离子表面改性技术制备纳米银涂层不锈钢的体外抗菌性能

背景:既往利用活性屏等离子技术制备的银涂层大都不涉及纳米领域,形成的银涂层为“薄膜样”,被覆基质表层且表面银颗粒分布不均,其长效抗菌能力受到挑战。目的:采用活性屏等离子体表面改性(ASPSM)技术制备可“埋入”不锈钢(SS)基质内部的纳米银涂层,观察其抗菌能力。方法:以不锈钢为基体,采用ASPSM技术制备纳米银涂层,其中通过调整轰击时间(1,2,4 h)制备3组涂层样品,分别记为1 h-Ag-ASPSM@SS、2 h-Ag-ASPSM@SS和4 h-Ag-ASPSM@SS,通过抑菌环实验、革兰染色分析3组涂层的抗菌能力。以不锈钢为基体,制备庆大霉素联合万古霉素抗生素涂层样品,记为ACNs。将不锈钢、2 h-Ag-ASPSM@SS、ACNs分别插入金黄色葡萄球菌或铜绿假单胞菌悬液中,采用涂布平板法分析样品长效(84 d)抗菌能力。将骨髓间充质干细胞分别与不锈钢、2 h-Ag-ASPSM@SS、ACNs共培养,进行CCK-8、活死染色与细胞上清乳酸脱氢酶活性检测。取连续暴露于金黄色葡萄球菌悬液12周后的不锈钢、2 h-Ag-ASPSM@SS、ACNs,采用滚平板法评估材料表面残留活菌量,采用万古霉素药敏纸片法评估材料表面残留活菌耐药性。结果与结论:①随着轰击时间的延长,样品表面纳米银的直径与含量逐渐增加,其中2 h-Ag-ASPSM@SS在形成了均匀球形纳米颗粒的情况下表面银含量较高。②抑菌环实验、革兰染色显示,相较于1 h-Ag-ASPSM@SS、4 h-Ag-ASPSM@SS,2 h-Ag-ASPSM@SS对金黄色葡萄球菌与铜绿假单胞菌有更好的抑制效果。与两种细菌共培养42,84 d后,2 h-Ag-ASPSM@SS组洗脱液涂布平板上的活菌数量显著少于不锈钢组、ACNs组;与金黄色葡萄球菌共培养84 d后、与铜绿假单胞菌共培养42 d后,ACNs组洗脱液涂布平板上的活菌数量多于不锈钢组。③CCK-8、活死染色与细胞上清乳酸脱氢酶活性检测显示,2 h-Ag-ASPSM@SS无明显的细胞毒性,ACNs具有明显的细胞毒性。④与金黄色葡萄球菌共培养12周后,2 h-Ag-ASPSM@SS组表面残留活菌量少于不锈钢组,ACNs组表面残留活菌量多于不锈钢组;与不锈钢组比较,ACNs组表面残留活菌株对万古霉素的敏感性显著下降(P<0.001),2 h-Ag-ASPSM@SS组表面残留活菌株对万古霉素的敏感性无明显变化(P>0.05)。⑤结果表明,ASPSM技术制备的纳米银涂层提高了不锈钢表面纳米银含量的沉积效率,并且具有持久的抗菌特性、良好的细胞相容性。

Antibacterial screening of silver nanoparticles synthesized by marine micro algae

Objective:To explore the biosynthesis of silver nanoparticles synthesized by marine microalgae. Methods:Marine microalgae was collected from Central Marine Fisheries Research Institute (CMFRI,tuticorin) and cultured in the lab.Silver nanoparticles synthesis were observed in normal and microwave irradiated microalgae and screened against human pathogens for the presence of antimicrobials.Results:The presence of silver nanoparticle was confirmed by UV-Visible spectroscopy at 420 nm by the presence of plasmon peak.Further confirmation was done by scanning electron microscope(SEM).Conclusions:These results not only provide a base for further research but are useful for drug development in the present and future.

Electrospinning of Gelatin Functionalized with Silver Na-noparticles for Nanofiber Fabrication

The present paper deals with gelatin nanofibres functionalized with silver nanoparticles, prepared by electrospinning using solutions of gelatin mixed with silver nitrate (AgNO3). As a common solvent for gelatin and silver nitrate (AgNO3), a mixture of acetic acid and water (70:30 v/v) was selected. In this system, acetic acid was used as a solvent for gelatin, and at the same time reducing agent for silver ions in solution. Silver nanoparticles (nAg) were stabilized through a mechanism that involves an interaction of the oxygen atoms of the carbonyl groups of gelatin. The viscosity and the conductivity of the gelatinous solutions were found to increase with the solution concentration. There is an observed decrease in the viscosity of the nAg containing gelatin solutions with the aging time increasing, whereas the conductiity of the AgNO3—containing gelatin solutions was greater than that of the base gelatin solution. The gelatin nanofibres functionalized with silver nanoparticles were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and antimicrobial test. The results of investigations by TEM and XRD confirmed the presence of silver nanoparticles with diameters in the range of (2 - 10 nm), uniformly distributed over the surface of smooth nanofibres with an average diameter of 70 nm. The release of silver ions from both the 2- and 4-hrs crosslinked nAg containing gelatin fiber mats by a total immersion method in buffer and distilled water occurred rapidly during the first 60 minutes, and increased gradually afterwards. Lastly, the tests demonstrated that gelatin/Ag nanofibers have a good antimicrobial activity against some common bacteria found on burned wounds. The anti-bacterial activity of these materials was greatest against Staphylococcus aureus, followed by Escherichia coli, and Pseudomonas aeroginosa ≈ Candida albicans.

Antibacterial Action and Physicochemical Properties of Stabilized Silver and Gold Nanostructures on the Surface of Disperse Silica

This work is devoted to the synthesis and stabilization of nanosized Ag/SiO2 and Au/SiO2 disperse materials and investigation their morphology, optical and antimicrobial properties. First, Ag and Au nanoparticles (NPs) were produced in colloids via chemical (Ag) or photochemical (Au) reduction of appropriate ions. To prevent the oxidation of Ag NPs in colloid solution, external binary stabilizing agents PVP and SDS were used. Then, Ag and Au NPs (0.01-0.05% wt) were adsorbed from their colloid solutions on high disperse silica surface (Ssp=260m2/g) and samples prepared were dried. Materials obtained were studied by UV-vis, XRD, and TEM methods. Ag and Au NPs adsorbed on silica demonstrated a fair crystallinity in XRD. The surface plasmon resonance (SPR) band positions inherent to Ag and Au NPs on silica surface as well as the intensities of optical spectra were stable during 7 month and more. Obtained Ag NPs in colloids and Ag/SiO2 composites demonstrated excellent antimicrobial activity against a series of the microorganisms (Escherichia coli, Staphylococcus aurous, and Candida albicans). Au/SiO2 samples did not reveal any bactericide properties relative to the test microorganisms grown. The mechanisms of Ag(Au) NPs interaction with silica surface were analyzed.