Antibacterial properties of polypropylene textiles modified by poly(2-(N,N-dimethyloamino ethyl) methacrylate)

Polypropylene nonwoven fabrics samples were modified using poly(2-(N,N-dimethyloamino ethyl) methacrylate) (PDAMA) and silver-containing layers. The structure of the material after modification was confirmed using scanning electron mocroscope, energy-dispersive X-ray spectroscopy, Fourier Transfer Infrared Spectroscopy (FTIR), and electro-kinetic measurements. It was found that samples with external PDAMA layers have excellent activity against Staphylococcus aureus under dynamic contact conditions. In contrast, samples finished with deposited silver showed little antimicrobial effect. Antibacterial tests conducted under static conditions showed no antibacterial activity irrespective of the deposited layers.     

Silver nanoparticle-algae interactions: oxidative dissolution, reactive oxygen species generation and synergistic toxic effects

The short-term toxicity of citrate-stabilized silver nanoparticles (AgNPs) and ionic silver Ag(I) to the ichthyotoxic marine raphidophyte Chattonella marina has been examined using the fluorometric indicator alamarBlue. Aggregation and dissolution of AgNPs occurred after addition to GSe medium while uptake of dissolved Ag(I) occurred in the presence of C. marina. Based on total silver mass, toxicity was much higher for Ag(I) than for AgNPs. Cysteine, a strong Ag(I) ligand, completely removed the inhibitory effects of Ag(I) and AgNPs on the metabolic activity of C. marina, suggesting that the toxicity of AgNPs was due to the release of Ag(I). Synergistic toxic effects of AgNPs/Ag(I) and C. marina to fish gill cells were observed with these effects possibly attributable to enhancement in the generation of reactive oxygen species by C. marina on exposure of the organism to silver.     

Humic acid-induced silver nanoparticle formation under environmentally relevant conditions

The formation of silver nanoparticles (AgNPs) via reduction of silver ions (Ag(+)) in the presence of humic acids (HAs) under various environmentally relevant conditions is described. HAs tested originated from the Suwannee River (SUW), and included samples of three sedimentary HAs (SHAs), and five soils obtained across the state of Florida. The time required to form AgNPs varied depending upon the type and concentration of HA, as well as temperature. SUW and all three SHAs reduced Ag(+) at 22 °C. However, none of the soil HAs formed absorbance-detectable AgNPs at room temperature when allowed to react for a period of 25 days, at which time experiments were halted. The appearance of the characteristic surface plasmon resonance (SPR) of AgNPs was observed by ultraviolet-visible spectroscopy in as few as 2-4 days at 22 °C for SHAs and SUW. An elevated temperature of 90 °C resulted in the accelerated appearance of the SPR within 90 min for SUW and all SHAs. The formation of AgNPs at 90 °C was usually complete within 3 h. Transmission electron microscopy and atomic force microscopy images showed that the AgNPs formed were typically spherical and had a broad size distribution. Dynamic light scattering also revealed polydisperse particle size distributions. HAs appeared to colloidally stabilize AgNPs based on lack of any significant change in the spectral characteristics over a period of two months. The results suggest the potential for direct formation of AgNPs under environmental conditions from Ag(+) sources, implying that not all AgNPs observed in natural waters today may be of anthropogenic origin.     

Differential effect of common ligands and molecular oxygen on antimicrobial activity of silver nanoparticles versus silver ions

The antibacterial activity of silver nanoparticles (AgNPs) is partially due to the release of Ag(+), although discerning the contribution of AgNPs vs Ag(+) is challenging due to their common co-occurrence. We discerned the toxicity of Ag(+) versus a commercially available AgNP (35.4 ± 5.1 nm, coated with amorphous carbon) by conducting antibacterial assays under anaerobic conditions that preclude Ag? oxidation, which is a prerequisite for Ag(+) release. These AgNPs were 20× less toxic to E. coli than Ag(+) (EC??: 2.04 ± 0.07 vs 0.10 ± 0.01 mg/L), and their toxicity increased 2.3-fold after exposure to air for 0.5 h (EC??: 0.87 ± 0.03 mg/L) which promoted Ag(+) release. No significant difference in Ag(+) toxicity was observed between anaerobic and aerobic conditions, which rules out oxidative stress by ROS as an important antibacterial mechanism for Ag(+). The toxicity of Ag(+) (2.94 μmol/L) was eliminated by equivalent cysteine or sulfide; the latter exceeded the solubility product equilibrium constant (K(sp)), which is conducive to silver precipitation. Equivalent chloride and phosphate concentrations also reduced Ag(+) toxicity without exceeding K(sp). Thus, some common ligands can hinder the bioavailability and mitigate the toxicity of Ag(+) at relatively low concentrations that do not induce silver precipitation. Furthermore, low concentrations of chloride (0.1 mg/L) mitigated the toxicity of Ag(+) but not that of AgNPs, suggesting that previous reports of higher AgNPs toxicity than their equivalent Ag(+) concentration might be due to the presence of common ligands that preferentially decrease the bioavailability and toxicity of Ag(+). Overall, these results show that the presence of O? or common ligands can differentially affect the toxicity of AgNPs vs Ag(+), and underscore the importance of water chemistry in the mode of action of AgNPs.     

Fabrication of Novel Antimicrobial Bio-Fibers Using Silk Wastage,Study of Poly (hexamethylene) Biguanide,and Silver Nanoparticles Interaction

Regenerated silk fibers were fabricated through dry-wet spinning process using N-methyl morpholine N-oxide and methanol as solvent and coagulant, respectively. Several concentrations of poly (hexamethylene) biguanide (PHMB) (0.27, 0.41, and 0.55 mL per 1 g of fibroin) and silver nanoparticles (AgNPs) (0.0005, 0.0015, 0.0055, 0.0095, and 0.0135% (w/v) were used as antibacterial agents. Antibacterial property of bio-fibers produced by either master batch or dipping methods was compared to each other against a gram-positive bacterium, Staphylococcus aurous. Master batch process indicated the dependency of antibacterial effect on the concentration of antibacterial agents as well as particle size. Maximum bactericidal activity in this process was obtained at concentrations of 0.0055% of AgNPs and 0.55 mL of PHMB per 1 g of fibroin. However for long-lasting effect and from toxicity aspect PHMB with lower concentration (0.27 mL) and with 0.0055% AgNP was seemed to be ideal. The result from dipping process showed that various concentrations of PHMB can greatly influence on the results; the interaction of 0.0055% AgNPs and 0.41 mL of PHMB offered good antibacterial properties with the least amount of toxicity effect in human cells.     

等离子体引发丙烯酰胺接枝改性聚丙烯非织造布

采用常压等离子体设备,以空气为介质对聚丙烯(PP)熔喷非织造布进行处理,并在15%的丙烯酰胺水溶液中进行接枝聚合。表面衰减全反射红外光谱(ATR-FTIR)分析的结果表明,等离子体处理后,非织造布已接枝上聚丙烯酰胺(PAM)。经接枝改性的样品,亲水性得到持久提高,接触角由处理前的135°降低至110°,放置后接触角不变。未经接枝PAM的样品,放置后接触角回复至130°。扫描电镜观察的结果表明,等离子体处理对PP纤维产生明显的刻蚀,接枝后的PP纤维表面有突出物。     

Development of antibacterial fabrics by treatment with Ag-doped TiO2 nanoparticles

This paper deals with the antibacterial properties of nonwoven Co/PET and PP fabrics and woven cotton fabrics treated with the pad-dry-cure (PDC) and electrospray processes. Firstly, the surface modification of nonwoven Co/PET and PP fabrics was carried out to obtain their hydrophilicity by RF-plasma system using acrylic acid as the monomer. Subsequently, Ag-doped TiO₂ nanoparticles prepared by sol–gel and chemical reduction processes using titanium isopropoxide and silver nitrate as precursor were applied to the fabric samples by PDC and electrospray processes. The effect of different synthesis processes of the nanoparticles and various application processes on their antibacterial efficiency was investigated. After RF-plasma pretreatment, the absorbency properties of the fabric samples were measured. The antibacterial activity of fabric samples against Escherichia coli and Staphylococcus aureus was determined qualitatively and quantitatively according to AATCC Method 147 and AATCC Method 100, respectively. The microstructural characteristics and surface morphology of the fabric samples were investigated by SEM-EDX and FTIR-ATR analyses. These results suggest that Ag-doped TiO₂ nanoparticles synthesized by the chemical reduction process imparted good and durable antibacterial activity to nonwoven Co/PET and PP fabrics and woven cotton fabrics for use in wall textiles.     

负载小麦醇溶蛋白纳米银胶体颗粒的抗菌壳聚糖复合膜构建及表征

本研究采用浇筑法,成功构建了Ag NPs/小麦醇溶蛋白/壳聚糖复合抑菌膜,实现了Ag NPs的稳态化和协同增效。自组装的小麦醇溶蛋白(gliadin),同时充当AgNPs的螯合剂和稳定剂,有效抑制了纳米银颗粒(AgNPs)团聚。与其他复合膜相比,gliadin/Ag NPs复合膜透明度良好。SEM和EDS证实Ag NPs均匀分布于复合膜。此外,gliadin/AgNPs复合颗粒具有优异的缓释特性。人皮肤成纤维细胞评估结果表明复合膜具有更好的生物相容性,激光共聚焦显微镜(CLSM)显示gliadin/Ag NPs复合膜对大肠杆菌与金黄色葡萄球菌具有更强的抗菌效果。这些薄膜在抗菌食品包装材料、伤口敷料以及植入物的开发方面极具应用价值。     

Measurement of engineered nanoparticles in consumer products by surface-enhanced Raman spectroscopy and neutron activation analysis

There has been an increasing number of consumer and food products sold on the market that contain various engineered nanomaterials (ENMs) such as silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs). These nanomaterials possess novel physical and chemical properties that can be used for wide applications in agriculture and food safety. However, current analytical methods to detect and measure ENMs are time-consuming, labor-intensive, and expensive. The objective of this study was to develop a novel, simple, rapid, and accurate method to detect AgNPs and AuNPs in consumer products using surface-enhanced Raman spectroscopy (SERS). SERS measurement was conducted to detect AgNPs and AuNPs using an effective Raman indicator, 4-aminothiophenol (pATP). The pATP can strongly bind onto nanoparticles, generating greatly enhanced Raman signals that can be used for measurement. The pATP was combined with Ag or Au stock solution, AgNO₃, citrate-coated AgNPs, citrate-coated AuNPs, AuCl, AgNPs, AuNPs, and five commercial products to study the differences in their SERS spectral data. The observed spectra of AgNPs and AuNPs have similar peaks at ~?390, ~?1087, and ~?1590 cm^?1 that can be attributed to the C–S stretching vibration, C–C stretching vibration, and C–H stretching vibration, respectively. Neutron activation analysis (NAA) and electron microscopy was used to characterize and quantify AgNPs and AuNPs in the consumer products. The results demonstrate that SERS method in combination with NAA can be an effective method for detection of ENMs, and it can easily distinguish AgNPs and AuNPs from other non-nanoparticle species in the complex matrices.     

Facile synthesis of silver nanoparticles using Tribulus longipetalus extract and their antioxidant and antibacterial activities

In this study, the preparation of silver nanoparticles (Ag NPs) using Tribulus longipetalus Viv. leaf extract was evaluated. Additionally, the in vitro antioxidant and antibacterial activities of the extract were evaluated. The antioxidant activity was assessed by two different approaches based on 2,2-diphenyl-1-picryl-hydrazyl and reducing power assay. The antibacterial activity of the extract, on the other hand, was determined against gram positive and gram negative microorganisms. The AgNPs prepared under the optimal conditions were found to be 15 nm in size and were characterized by ultraviolet–visible spectroscopy, dynamic light scattering, X-ray diffraction and transmission electron microscopy.     

Long-term transformation and fate of manufactured ag nanoparticles in a simulated large scale freshwater emergent wetland

Transformations and long-term fate of engineered nanomaterials must be measured in realistic complex natural systems to accurately assess the risks that they may pose. Here, we determine the long-term behavior of poly(vinylpyrrolidone)-coated silver nanoparticles (AgNPs) in freshwater mesocosms simulating an emergent wetland environment. AgNPs were either applied to the water column or to the terrestrial soils. The distribution of silver among water, solids, and biota, and Ag speciation in soils and sediment was determined 18 months after dosing. Most (70 wt %) of the added Ag resided in the soils and sediments, and largely remained in the compartment in which they were dosed. However, some movement between soil and sediment was observed. Movement of AgNPs from terrestrial soils to sediments was more facile than from sediments to soils, suggesting that erosion and runoff is a potential pathway for AgNPs to enter waterways. The AgNPs in terrestrial soils were transformed to Ag(2)S (~52%), whereas AgNPs in the subaquatic sediment were present as Ag(2)S (55%) and Ag-sulfhydryl compounds (27%). Despite significant sulfidation of the AgNPs, a fraction of the added Ag resided in the terrestrial plant biomass (~3 wt % for the terrestrially dosed mesocosm), and relatively high body burdens of Ag (0.5-3.3 μg Ag/g wet weight) were found in mosquito fish and chironomids in both mesocosms. Thus, Ag from the NPs remained bioavailable even after partial sulfidation and when water column total Ag concentrations are low (<0.002 mg/L).     

剑麻载银复合抗菌纤维的制备及其性能

以自制纳米银粒子为抗菌剂,基于膜自组装原理,采用Nβ--(氨乙基)-γ-氨丙基甲基二甲氧基硅烷偶联剂(YDH602)为架桥剂,制备了键合型载银剑麻复合抗菌纤维。以纤维载银量为指标,考察了纳米银溶胶质量浓度、反应时间、pH值对载银效果的影响。利用TEM、紫外光谱仪、SEM、X-射线能谱仪等对纳米银粒子和剑麻抗菌纤维结构进行了表征。结果表明,所制备的剑麻抗菌纤维载银量较多,并且分布比较均匀,在48 h内,银释放量为0.17%,说明银与剑麻的结合能力较强,并且会持续稳定地释放出银。此外,载银剑麻纤维对金黄色葡萄球菌和肺炎克雷伯菌的抗菌效果较好。     

Ag nanoparticles-coated cotton fabric for durable antibacterial activity: derived from phytic acid–Ag complex

Abstract

This study focuses on the preparation of functional cotton with high and durable antibacterial activity by in situ formation of Ag nanoparticles (NPs) onto cotton fabric derived from phytic acid-Ag complex. The route can be divided into two simple steps, adsorption of silver ions onto cellulose matrix with phytic acid as a capture agent and subsequent reduction of Ag⁺ to Ag NPs by sodium borohydride. The successful deposition of Ag NPs on cotton fabric was verified by SEM, EDS and XPS. The bacterial reduction rate against E. coli and S. aureus for the as-treated fabrics was above 99%, even after 10 laundry cycles. The phytic acid was found of benefit to distribution and bonding of silver on the cotton fabric, which might lead to the enhancement of antibacterial property and durability against wash. This study may provide a green, novel and simple strategy to manufacture Ag-based antibacterial cotton for potential applications in textile industry.     

Antimicrobial and physicomechanical natures of silver nanoparticles incorporated into silicone-hydrogel films

PurposeThe effects of silver nanoparticles (AgNPs) incorporated in silicone-hydrogel films on their physicochemical properties and microbial activity were investigated.MethodsSilicone-hydrogel composite films (SiHCFs) were prepared by in-situ chemical reduction of silver ions added in different concentrations (0, 10, 20, 30, 40, 60, and 80 ppm) followed by ultraviolet (UV) casting. The reduction of silver ions into AgNPs was confirmed by transmission electron microscopy (TEM) and absorption spectroscopy over ultraviolet and visible (UV–vis) wavelengths. Incorporation of AgNPs into SiHCFs was confirmed by UV–vis absorption spectroscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) spectroscopic mapping. The physico- mechanical properties of the SiHCFs were evaluated. Antimicrobial activity and biofilm formation of Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus were assessed.ResultsTEM, UV–vis absorption, SEM, and EDX mapping showed that silver ions were reduced in the mixture of co-polymerizing monomers and incorporation of AgNPs into SiHCFs was achieved. Mechanical properties of the SiHCFs were enhanced with increasing AgNPs concentration without affecting their chemical and thermal properties. SiHCFs exhibited transmittance greater than 90% at a wavelength 600 nm. Bacterial growths in the solutions bathing the SiHCFs with increasing silver concentration were 95, 78, 4, 2, 0, 0, 0% respectively, for Escherichia coli; 95, 82, 4, 0.6, 0, 0, 0% for Pseudomonas aeruginosa; and 93, 79, 4, 0.5, 0, 0, 0% for Staphylococcus aureus.ConclusionsIncorporation of AgNPs into SiHCFs demonstrated sufficient release of AgNPs to inhibit bacterial growth and reduce biofilm formation, with collateral enhancement of some mechanical properties of SiHCFs.     

Development of Antibacterial Carboxymethyl Cellulose‐Based Nanobiocomposite Films Containing Various Metallic Nanoparticles for Food Packaging Applications

In this study, silver (Ag), zinc oxide (ZnO), and copper oxide (CuO) metallic nanoparticles were used in preparation of carboxymethyl cellulose (CMC) nanobiocomposite films. Scanning electron microscopy (SEM), X‐ray diffraction (EDXA), water vapor permeability (WVP), ultraviolet and visible light (UV–Vis) spectroscopy, and mechanical and microbial tests were used to determine the characteristics of the obtained active films. SEM results showed that the CMC nanobiocomposite films had roughness deflection levels and the EDXA test confirmed the presence of Ag, ZnO, and Cuo nanoparticles in the biopolymer tissue. UV–Vis spectroscopy confirmed that with addition of metallic nanoparticles to the pure CMC film, absorption rate increased and WVP decreased. In the mechanical tests, addition of nanoparticles also increased the tensile strength of the films, and the nanobiocomposite films exhibited higher resistance compared to the pure CMC film. Films incorporating metallic nanoparticles showed antibacterial properties against Escherichia coli and Staphylococcus aureus growth. Thus, nanobiocomposite films can be used as active packaging films and could increase the shelf‐life of the food.     

Potential silver nanoparticles migration from commercially available polymeric baby products into food simulants

In recent years, silver nanoparticles (AgNPs) have been extensively employed in food packaging systems as a potential antibacterial agent. Although proven to be highly effective, the increased number of AgNP-containing products raises concerns among consumers regarding the migration of AgNPs from the packaging material into foods, which may exert toxic effects. To address this, five baby products were chosen (baby bottle A, baby bottle B, pacifier A, pacifier B and breastmilk storage bag) to investigate AgNPs migration into three food simulants (deionised water, 4% acetic acid (w/v) and 50% ethanol (v/v)) using inductively coupled plasma mass spectrometry (ICP-MS). As a result, the highest level of migrated Ag was observed for 4% acetic acid in the case of baby bottle B, pacifier A, pacifier B and the breastmilk storage bag, with the detection amount ranging from 1.05–2.25 ng/mL. On the other hand, baby bottle A showed the maximum migration for 50% ethanol due to the polymer nature. Finally, a centrifugal ultrafiltration experiment was conducted to determine the fraction of dissolved Ag in acidic simulant and it was found that migrated Ag was predominantly in Ag⁺ form, with a small fraction of non-ionic AgNPs. Thus, it has been found that the amount of migrated Ag in baby products was low; however, the migration was dependent on the type of food simulant and polymer nature.     

衣康酸/丙烯酸与聚酯织物接枝共聚性能

研究了在水溶液中以过氧化苯甲酰为引发剂,衣康酸/丙烯酸为单体与碱处理后的三叶形聚酯(PET)平纹织物接枝共聚;对共聚条件如聚合温度、时间、引发剂浓度、单体物质的量比等进行研究,得出最佳聚合条件。电子扫描电镜照片和傅里叶红外变换光谱显示衣康酸/丙烯酸共聚到聚酯大分子上。研究结果表明随着接枝率的上升,织物吸湿快干性能提高;阳离子染料上染率大幅度提高,织物色光鲜艳。     

Development of cellulose-based bactericidal nanocomposites containing silver nanoparticles and their use as active food packaging

The use of nanomaterials, including metallic as active fillers in polymeric nanocomposites for food packaging has been extensively investigated. Silver nanoparticles (AgNPs), in particular, have been exploited for technological applications as bactericidal agents. In this paper, AgNPs were incorporated into a hydroxypropyl methylcellulose (HPMC) matrix for applications as food packaging materials. The average sizes of the silver nanoparticles were 41 nm and 100 nm, respectively. Mechanical analyses and water vapor barrier properties of the HPMC/AgNPs nanocomposites were analysed. The best results were observed for films containing smaller (41 nm) AgNPs. The antibacterial properties of HPMC/AgNPs thin films were evaluated based on the diameter of inhibition zone in a disk diffusion test against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The disk diffusion studies revealed a greater bactericidal effectiveness for nanocomposites films containing 41 nm Ag nanoparticles.     

聚乙烯醇-乙烯共聚物纳米纤维增强聚丙烯微米纤维复合空气过滤材料的结构与性能

为提高常规纤维基空气过滤材料的过滤性能,采用熔融共混相分离法制备得到聚乙烯醇-乙烯共聚物(PVA-co-PE)纳米纤维并制成悬浮乳液,将聚丙烯(PP)针刺基材浸渍到悬浮乳液中进行冷冻干燥处理,得到PVA-co-PE纳米纤维增强PP微米纤维骨架复合空气过滤材料。借助傅里叶变换红外光谱仪、扫描电子显微镜、静电电位计、孔径分析仪及滤料综合测试台对过滤材料的结构及性能进行表征。结果表明:当纳米纤维的面密度为9.34 g/m²时,复合空气过滤材料对尺寸为0.3 μm的NaCl气溶胶粒子的过滤效率为99.936%,阻力压降为81 Pa,品质因数为0.091 9 Pa^-1,且复合过滤材料的拉伸强度及拉伸模量相比PP针刺基材均增加50%。     

基于共价结合的纳米银抗菌棉织物研究进展

针对棉织物与纳米银之间缺乏亲和性,主要依靠物理吸附结合,水洗牢度差等问题,总结了基于共价结合的纳米银抗菌棉织物的最新研究进展,探讨了席夫碱反应和酯化反应这2种共价结合机制。以纳米银与棉织物之间的共价交联剂(超支化聚合物、树状大分子、丝素、丝胶、半胱氨酸、蛋氨酸、巯基乙酸、壳聚糖衍生物、聚苯乙烯-b-聚丙烯酸、丁烷四羧酸)种类进行分类介绍,结合抑菌率和银含量的数据讨论了基于共价结合的纳米银抗菌棉织物的制备工艺、抗菌性能和抗菌耐洗性能。最后对基于共价结合的纳米银抗菌棉织物领域存在的不足和未来需要深入关注的地方进行了探讨。研究指出,共价交联法大幅提高了纳米银的抗菌耐洗性能,为开发环境友好和长效抗菌的纳米银纺织品提供了新思路和新途径。