纳米银的抗菌机理研究进展

纳米银因其高效、广谱、不易产生耐药性、安全性高等优点,成为当前抗菌材料的研究热点之一,但目前对纳米银的抗菌机理仍有不同的认识.本文首先综述了国内外纳米银抗菌机理的研究进展和主要成果,主要从影响细菌生活环境、破坏细菌的细胞壁和细胞膜、抑制DNA复制、抑制酶呼吸作用和抑制其他酶活性5个方面分析了纳米银的抗菌机理.并且纳米银的抗菌过程受多种因素影响,文中详细阐述了纳米银的尺寸分布、形貌以及稳定剂、活性氧、菌种和培养基等因素对纳米银抗菌性的影响.最后指出纳米银的抗菌过程复杂,进一步研究其具体作用方式和机理以及影响抗菌作用的主要因素都将有助于纳米银抗菌材料的广泛应用.     

中草药还原法制备银纳米颗粒及其抗菌性能表征

分别以中草药丁香、山茱萸、地榆和乌梅的提取液为还原剂和保护剂合成银纳米颗粒,利用紫外-可见吸收光谱(UV-vis)、透射电镜(TEM)以及X射线粉末衍射(XRD)对产物进行了表征。结果表明,所得银纳米颗粒呈近球形,提高提取液的pH有利于获得粒径较小、分散性好、稳定性高的银纳米颗粒。进一步考察制得的银纳米颗粒的抗菌性能,结果表明,其对大肠杆菌和金黄色葡萄球菌有很强的抑制作用,最小抑菌质量浓度(M IC)分别可达1.69和3.38 mg/L。     

Sol‐gel preparation and properties of Ag‐containing bioactive glass films on titanium

Ag‐containing bioactive glass films (Ag/Ca atomic ratios of 0, 5% and 10%) were sol‐gel prepared for bioactive and antibacterial modification of titanium. The gel powders calcined at 610°C are mainly amorphous confirmed by x‐ray diffraction, but small diffraction peaks of Ca₃SiO₅ and silver are detected. The film surface is porous with the pore size of ~200 nm. Silver‐rich sub‐micro particles with sizes of 100‐480 nm are present at the surface of Ag‐glass films. CaP phase, metallic silver and silica are detected by x‐ray photoelectron spectroscopy. The mean apparent bonding strength of the films is as high as 21±1 MPa measured by the pull‐off test. The potentiodynamic polarization test shows that the coated samples have better corrosion resistance than the polished sample. The Ag‐glass coatings and their wafer samples exhibit antibacterial activity against S. aureus. The coated samples are covered by apatite layer after soaked in the simulated body fluid for 2 weeks, demonstrating their bioactivity.     

Preparation and characterization of hydrophilic and antibacterial silver decorated silica-grafted-poly(vinylpyrrolidone) (Ag-SiO2-PVP) nanoparticles for polymeric nanocomposites

Hydrophilic antibacterial silver decorated silica-grafted-poly(vinylpyrrolidone) (Ag-SiO₂-PVP) nanoparticles were successfully synthesized in multiple steps. In this regard, silanization of the silica nanoparticles was performed with different concentrations of vinyltrimethoxysilane (VTS) to generate vinyl groups onto the nanoparticles surface. Obtained results showed that by increasing the VTS concentration the amount of vinyl groups on the surface of the silica nanoparticles increased while nanoparticles agglomeration did not occur. Then, poly(vinylpyrrolidone) PVP brushes were grafted onto the silanized silica nanoparticles (SiO₂-VTS) via grafting-through polymerization method to obtain PVP-grafted silica nanoparticles (SiO₂-PVP). Fourier transform infrared spectroscopy, thermal gravimetric analysis, and dynamic light scattering confirmed the successful generation of the vinyl groups and PVP brushes onto the silica nanoparticles. Finally, Ag-SiO₂-PVP nanoparticles were prepared by synthesizing silver nanoparticles onto the SiO₂-PVP nanoparticles to render them antibacterial. Energy dispersive X-ray spectroscopy showed that highest grafting of silver nanoparticles onto the SiO₂-PVP nanoparticles was obtained for the nanoparticles with highest content of vinyl groups. X-ray photoelectron spectroscopy was used to identify the elements and their chemical structure for the synthesized nanoparticles. Plate colony counting method was applied to assess the antibacterial effects of the Ag-SiO₂-PVP nanoparticles which revealed outstanding bactericidal properties of them.     

Synthesis, characterization and microbiological response of silver doped bioactive glass nanoparticles

Glass nanoparticles containing 1, 3, 5, and 10 wt% of Ag₂O (coded; GAg1%, GAg3%, GAg5%, and GAg10%, respectively) were synthesized through a quick alkali mediated sol-gel method and were characterized by TEM, XRF, FT-IR, XRD, TGA, and DSC. Thermal analysis showed that all organic and inorganic by-products were completely decomposed before 700 °C and, hence, all glass samples were stabilized at this temperature. XRD confirmed the amorphous nature of all glasses after stabilization. TEM micrographs showed that the average particle sizes of all samples were less than 100 nm in diameter and the XRF showed that the compositions of the obtained glasses were almost consistent with the designed ones. The samples GAg1%, GAg3%, GAg5%, and GAg10%, showed average pore diameters of 19.85, 18.22, 13.32, and 19.62 nm and specific surface areas of 73.18, 100.38, 192.6, and 55.7 m²/g, respectively. In addition, their porosity% was 76.53, 83.20, 77.97, and 79.61%, respectively. The FT-IR spectra of all glasses showed bands located in the range of 1000-1200, 725-800, and 450-480 cm⁻¹ that correspond to the Si-O-Si asymmetric stretching vibration, the Si-O-Si symmetric stretching vibration, and the Si-O-Si bending mode, respectively. Finally, all samples had an anti-bacterial effect against different types of bacteria and the extraction of silver ions from them followed a diffusion-controlled mechanism, which could demonstrate their ability to treat bone infection.     

A sweet killer: mesoporous polysaccharide confined silver nanoparticles for antibacterial applications

Silver nanoparticles (AgNP) confined within porous starch have been prepared in a simple, green and efficient manner, utilising the nanoporous structure of predominantly mesoporous starch (MS) to act as nanoparticle stabiliser, support and reducing surface. MS/AgNP materials present high surface areas (S(BET) > 150 m(2) g(-1)) and mesopore volumes (V(meso) > 0.45 cm(3) g(-1)). The interaction of the AgNP precursor and forming nanoparticle nuclei with the mesoporous domains of the porous polysaccharide, direct porosity to increasingly narrower and more defined pore size distributions, indicative of a degree of cooperative assembly. Transmission electron microscopy images indicated the presence of spherical AgNP of a size reflective of the porous polysaccharide mesopore diameter (e.g., 5-25 nm), whilst XPS analysis confirmed the metallic Ag(0) state. Materials were prepared at relatively low Ag loadings (<0.18 mmol g(-1)), demonstrating excellent antimicrobial activity in solid and liquid phase testing against Gram negative (E. coli) and positive (S. aureus) model bacteria. The resulting materials are biocompatible and present a useful solid porous carbohydrate-based polymer vehicle to control the AgNP size regime and facilitate transference to a biological environment.     

Ag NPs改性鱼鳞明胶-琼脂复合膜的制备及性能表征

利用鱼鳞明胶作为还原剂和稳定剂制备银纳米颗粒（silver nanoparticles, Ag NPs），研究Ag NPs添加量（0.04wt%-0.2wt%）对鱼鳞明胶-琼脂复合膜的理化性能和抗菌性能的影响。通过透射电子显微镜和X射线粉末衍射对合成的Ag NPs进行表征，结果表明制得Ag NPs为球形形貌，平均粒径为9.3 ?1.8 nm。随着Ag NPs添加量的增加，鱼鳞明胶-琼脂复合膜的色泽变黄渐深，透明度下降，对紫外和可见光的吸收增强，同时，复合膜的断裂延展性、水蒸气阻隔性能和耐水性能显著增强，而厚度和抗拉强度却无明显变化。FTIR和热重分析结果表明，Ag NPs与膜基质间存在化学相互作用，并在一定程度上改善了复合膜的热稳定性。抑菌环实验结果显示，复合膜可以在0.04wt%-0.2wt%较低的银浓度下实现良好的抗菌效果。研究结果将为鱼鳞明胶可降解抗菌包装材料的开发提供新思路。     

基于植物质还原的银纳米颗粒的制备及在织物抗菌整理上的应用

纳米银是以纳米技术为基础研制而成的新型抗菌产品,由于量子效应和尺寸效应具有普通银系抗菌剂无法比拟的抗菌效果。本研究以黄芩、丁香、洋浦桃、芳樟4种植物质提取液制备银纳米颗粒,并借助于UV-Vis、TEM以及XRD对产物进行表征,结果表明增加植物质提取液浓度或增大NaOH加入量,均有利于制得粒径较小的银纳米颗粒。SEM图片表明采用浸渍法可将所得纳米银颗粒负载于纯棉织物上,通过考察浸渍时间、温度、浴比对织物上载银量的影响,确定较优的浸渍条件为时间30 h,温度55℃,浴比为1:25。分别考察了银纳米颗粒粒径和植物质种类对所得载银织物抗菌性能的影响,发现负载到织物上的纳米银粒径越小,织物抑菌效果越好;利用本身具有抑菌效果的黄芩、丁香来制备银纳米颗粒,有利于增强所得载银织物的整体抗菌性能;4种植物质中以黄芩制得的载银织物抗菌效果最优,对金黄色葡萄球菌、大肠杆菌等实验菌株均有强烈的抑制作用。     

负载纳米银的埃洛石纳米管/聚醚砜杂化超滤膜的制备

以聚醚砜(PES)为膜材料,N, N-二甲基乙酰胺(DMAc)为溶剂,聚乙烯吡咯烷酮(PVP)和负载纳米银的埃洛石纳米管(Ag- HNTs)为添加剂,采用相转化法制备聚醚砜超滤膜。系统地考察了添加剂(Ag- HNTs)含量对膜性能的影响,并用抑菌圈试验研究了所制膜的抗菌效果。结果表明：硅烷偶联剂KH-792中的甲氧基与HNTs上的羟基成功地发生反应,并且接枝量为0.105g (KH-792)?g -1 (HNTs);改性后的HNTs与Ag成功地发生络合反应,并且络合量近似为0.145g (Ag)?g -1 (HNTs);溶剂中负载纳米银的埃洛石纳米管(Ag- HNTs)所占比例的增加能提高膜的水通量,而截留率保持在95%左右。所制备的膜对大肠杆菌和金黄色葡萄球菌有较强的抑制作用。     

Fabrication and characterization of ZnO modified bioactive glass nanoparticles

Bioactive glass nanoparticles in the system (SiO₂-CaO-P₂O₅-ZnO) were synthesized following the sol-gel technique. The prepared glass nanoparticles of 1, 3 and 5 wt% of ZnO (coded: GZ1, GZ3 and GZ5, respectively) were characterized by TEM, FTIR, XRF, TGA and DSC. All glass powders had particle sizes less than 100 nm. Textural analysis revealed that for GZ1, GZ3 and GZ5, the average pore diameters, measured by the high-speed gas sorption analyzer, were 15.9, 15.4 and 15.2 nm, respectively, while the average pore diameters measured by the mercury intrusion porosimetry were 47, 50 and 63 nm, respectively. All glass powders were highly porous (75, 76 and 75%) with surface areas of 233, 94 and 118 m²/g for GZ1, GZ3 and GZ5, respectively. All glass powders induced an apatite layer on their surfaces upon immersion in simulated body fluid (SBF) as verified by SEM and TF-XRD.     

Preparation of bicontinuous mesoporous silica and organosilica materials containing gold nanoparticles by co-synthesis method

Catalytic activities of gold strongly depend on its particle size. It is necessary to have homogeneous distributions of small gold nanoparticles with diameters between 2 and 5 nm for excellent catalytic activities. In this study, gold-containing mesoporous silica materials were prepared by a co-synthesis method. The essence of this sol–gel co-synthesis method is to combine together neutral surfactant template synthesis of mesoporous silica materials with the introduction of metal ions via bifunctional silane ligands, so that the formation of mesostructures and metal–ion doping occur simultaneously. The formation of gold nanoparticles with size less than 5 nm inside mesoporous materials (HMS, MSU, and PMO) has been achieved by this co-synthesis sol–gel process. In addition, the effects of post-treatments, such as calcination and reduction, on pore structures and nanoparticle size distributions were also investigated.     

Fabrication and in vitro characterization of antibacterial magneto-luminescent core-shell bioactive glass nanoparticles

When nanomaterials with antibacterial properties were sent to the infected area, it was predicted that infection and related complications could be prevented. The nanoparticles can be designed to possess magnetic and luminescence (magneto-luminescent) properties to be effectively targeted and localized at the infection foci without dispersing into the body. Simultaneously, the magneto-luminescent characteristic of particles allows visualization and confirmation of localized particles at the desired area. In this regard, there are no studies on the use of antibacterial magneto-luminescent bioactive glass for orthopedic applications and the treatment of orthopedic device-related infections. In this study, antibacterial magneto-luminescent 58S bioactive glasses were synthesized by the modified Stöber using coupled with a layer-by-layer assembly approach to possess core/shell particle morphology. SPION/Bioactive glass nanoparticles had an average size of 50 nm and displayed superparamagnetic behavior. While the saturation magnetization value (σ_s) of the undoped 58S sample was 25.32 emu/g, that of the co-doped sample (2% Eu, 2% Zn) was 21.74 emu/g; this showed that the doping slightly reduced the magnetization value. Europium (Eu) doping of SPION/Bioactive glass nanoparticles induced characteristic red emission originating from Eu emissions belonging to ⁵D₀–⁷F_J (J = 1–4) transitions and the strongest peak was at 612 nm (electric-dipole transition, ⁵D₀–⁷F₂). Color chromaticity coordinates confirmed emission in the red region. XPS spectrum revealed the existence of Eu and Zn dopant elements in 58S bioactive glass. After soaking characteristic peaks at 31.74° and 45.43° belonging to the hexagonal hydroxyapatite phase were detected in the XRD data, confirming the SEM images. 2% Eu doped SPION/Bioactive glass nanoparticles had the highest osteoblast viability up to 7 days in vitro, while doping the samples with 2% zinc did not yield bone cell viability as high as the Eu doped ones. Importantly, Eu doped SPION/Bioactive glass nanoparticles inhibited gram-positive Staphylococcus aureus (S. aureus) and gram-negative Escherichia coli (E. coli) growth up to 48 h in vitro. The results showed that Eu doping of SPION/Bioactive glass nanoparticles increased osteoblast viability and inhibited bacterial growth, while possessing superparamagnetic properties and exhibiting red luminescence.     

Antibacterial poly(vinyl alcohol) film containing silver nanoparticles: Preparation and characterization

The importance of antibacterial materials for biomedical applications is growing nowadays. The presented article deals with the characterization of structural, mechanical and thermal properties and of antibacterial polymeric films based on polyvinyl alcohol (PVA) and silver nitrate, which can find their applicability in wound dressing components and protective coating. The methods of transmission electron microscopy, UV–vis and XRD spectroscopy, optical microscopy, differential scanning calorimetry, stress–strain analysis, and agar diffusion test were used to characterize the polymer films prepared. The results showed strong antibacterial activity against Escherichia coli and Staphylococcus aureus already at the lowest addition level of silver nitrate. An improvement of mechanical properties (Young's modulus) was also noticed due to a modification of PVA with silver nitrate up to 1 wt. % of silver content. Furthermore, the results show a strong effect of the thermal history of the sample preparation on the degree of silver‐ion reduction and formation of nanoparticles. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Structural and luminescence properties of silica powders and transparent glass‐ceramics containing LaF3:Eu3+ nanocrystals

In this work, silica powders and transparent glass‐ceramic materials containing LaF₃:Eu³⁺ nanocrystals were synthesized using the low‐temperature sol‐gel technique. Prepared samples were characterized by TG/DSC analysis as well as X‐ray diffraction and IR spectroscopy. The transformation from liquid sols toward bulk powders and xerogels was also examined and analyzed. The optical behavior of prepared Eu³⁺‐doped sol‐gel samples were evaluated based on photoluminescence excitation (PLE: λ_em = 611 nm) and emission (PL: λ_exc = 393 nm, λ_exc = 397 nm) spectra as well as luminescence decay analysis. The series of luminescence lines located within reddish‐orange spectral scope were registered and identified as the intra‐configurational 4f⁶‐4f⁶ transitions originated from Eu³⁺ optically active ions (⁵D₀ → ⁷F_J, J = 0‐4). Moreover, the R/O‐ratio was also calculated to estimate the symmetry in local framework around Eu³⁺ ions. The luminescence spectra and double‐exponential character of decay curves recorded for fabricated nanocrystalline sol‐gel samples (τ₁(⁵D₀) = 2.07 ms, τ₂(⁵D₀) = 8.07 ms and τ₁(⁵D₀) = 0.79 ms, τ₂(⁵D₀) = 9.76 ms for powders and glass‐ceramics, respectively) indicated the successful migration of optically active Eu³⁺ ions from amorphous silica framework to low phonon energy LaF₃ nanocrystal phase.     

Nanocomposite of chitosan and silver oxide and its antibacterial property

An aqueous emulsion of chitosan nanoparticles encapsulating silver oxide is prepared from silver nitrate and chitosan. The nanoparticles are positively charged with an average diameter of 300 nm. The dried particle has a spherical shape with a 100 nm diameter. The emulsion is applied onto cotton and delivers a durable antibacterial activity against S. aureus and E. coli, after 20 washings. The coefficient of friction of the treated fabric is similar to that of the untreated cotton fabric. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Facile preparation of silver/reduced graphene oxide/chitosan colloid and application of the nanocomposite in antibacterial and catalytic activity

Reduced graphene oxide (RGO) decorated with silver nanoparticles (AgNPs) was synthesized by a facile solution‐based approach in chitosan (CS) solution. The morphology and elemental composition of as‐prepared Ag/RGO/CS colloid were characterized by SEM and energy dispersive X‐ray spectroscopy, respectively. TEM images show that most of the AgNPs are uniformly dispersed in the CS matrix while the other nanoparticles are decorated on the RGO nanosheets. XRD indicates that the interlayer distance of RGO is between 0.34 and 1.87 nm while the diameter of face‐centered cubic AgNPs is no more than 30 nm. Fourier transform infrared spectroscopy of the Ag/RGO/CS colloid confirms the formation of AgNPs and RGO. X‐ray photoelectron spectroscopy proves that both the Ag ? O bond and the C ? N bond exist in the nanocomposite. Antimicrobial assays were performed using the most common species of Gram bacteria. The inhibitory effect indicates that the incorporation of AgNPs and RGO significantly improves the antimicrobial activity of CS colloid. In addition, the nanocomposite colloid exhibits significant catalytic activity toward the reduction of 4‐nitrophenol by NaBH₄. © 2018 Society of Chemical Industry     

Electrospinning of antibacterial poly(vinylidene fluoride) nanofibers containing silver nanoparticles

Poly(vinylidene fluoride) (PVDF) nanofibrous mats containing silver nanoparticles were prepared by electrospinning. The diameter of the nanofibers ranged between 100 and 300 nm, as revealed by scanning electron microscopy. The silver nanoparticles were dispersed, but some aggregation was observed with transmission electron microscopy. The content of silver nanoparticles incorporated into the PVDF nanofibrous mats was determined by inductively coupled plasma and X‐ray photoelectron spectroscopy. The antibacterial activities of the samples were evaluated with the colony‐counting method against Staphylococcus aureus (Gram‐positive) and Klebsiella pneumoniae (Gram‐negative) bacteria. The results indicate that the PVDF nanofibrous mats containing silver nanoparticles showed good antibacterial activity compared to the PVDF nanofiber control. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

金纳米微粒修饰几丁聚糖微胶囊新方法

制备了金-海藻酸钙-几丁聚糖微胶囊,提出了修饰用于蛋白质药物靶向传输的多糖载体-几丁聚糖的新方法,该方法通过在几丁聚糖微胶囊表面结合金的纳米微粒使微胶囊表面结构发生变化,从而改变微胶囊的性质,这种修饰方法目前未见报道.文中对制备条件进行了优化,并对金-海藻酸钙-几丁聚糖微胶囊的粒径分布进行了表征.文中选择在pH值为5时反应2 h,制得的柠檬酸体系和丙烯酸体系的金-海藻酸钙.几丁聚糖微胶囊的平均直径分别为216.686um和196.850um.     

Mussel-inspired synthesis of silver nanoparticles as fillers for preparing waterborne polyurethane/Ag nanocomposites with excellent mechanical and antibacterial properties

Silver nanoparticles (AgNPs) were synthesized by a facile, mild and green method using dopamine as a reducing and stabilizing agent and were introduced to waterborne polyurethane (WPU) via an in situ emulsification method to prepare antibacterial nanocomposite films. The formation of AgNPs was characterized by UV–visible spectroscopy and XRD. The dispersion of AgNPs was confirmed by TEM and the thermal stability of WPU/Ag nanocomposites was confirmed by TGA. The results showed that AgNPs were uniformly dispersed in the WPU matrix. The introduction of AgNPs significantly improved the thermal stability of WPU films. With incorporation of 0.1 wt% AgNPs, a five-fold increase in the tensile strength was achieved without sacrificing the ultimate strain. The WPU/Ag nanocomposite films showed antibacterial activity against Escherichia coli and Staphylococcus aureus. © 2021 Society of Industrial Chemistry.