Preparation and Characterization of Chitosan Nanofibers Containing Silver Nanoparticles

Chitosan(CS)nanofibers containing silver nanoparticles(AgNPs)were prepared by in-situ reducing method.A water soluble carboxymethyl chitosan(CMCT)was applied for the preparation of AgNPs.The impact factor such as the concentration of CMCT,silver nitrate(AgNO_3)content,temperature and the heating time during the preparation of AgNPs were studied.The result showed that the proper value of the concentration of CMCT,AgNO_3content,temperature and the heating time were set as0.1%,20μL AgNO_3(1.7 mol/L),90°and 3 h,separately and the maximum concentration of AgNPs could be acquired.To solve the spinnability of chitosan nanofiber,a super high molecular weight polyethylene oxide(PEO)was introduced to the system,and a new mixed solvent system was prepared by adding acetic acid,dimethyl sulfoxide(DMSO)and several drops of Triton X-100TMto distilled water.CS/PEO(80/20)with the concentration of 3%was dissolved in the mixed solvent to prepare electrospinning solution for CS/PEO(80/20)nanofiber fabrication.The CS containing AgNPs electrospun solution could be prepared by replacing the distilled water to silver nanoparticle solution during the preparation of mixed solvent.Ultraviolet visible(UV-Vis)spectra and transmission electron microscope(TEM)results showed that silver nanoparticles were prepared successfully.CS membranes with and without AgNPs were acquired via a traditional electrospinning equipment.These two nanofiber membranes were characterized by scanning electron microscope(SEM)images and mechanical testing.It could be noticed from the SEM images that there was a good morphology and random distribution for the nanofibers with an average fiber diameter of 180 nm.The mechanical property results showed that the addition of AgNPs decreased the mechanical strength significantly but the mechanical strength could still support wound dressing application.

Effects of silver nanoparticles on resistance characteristics of the wetland plant Typha orientalis in a hydroponic system

To probe the influence and the adverse-resistance characteristics of wetland plants in presence of silver nanoparticles (AgNPs), the changes in the physiological and biochemical characteristics (including the superoxide dismutase (SOD) activity, catalase (CAT) activity, peroxidase (POD) activity, soluble protein content, and chlorophyll content) of Typha orientalis exposed to different concentrations of AgNPs solutions (0, 0.1, 1, 20 and 40 mg/L) were explored. Meantime, the accumulation of silver content in these plants was revealed. The results show that under low concentrations of AgNPs, the SOD and POD activities in the leaves of Typha orientalis are strengthened to different degrees. However, high concentrations of AgNPs inhibit the activities of SOD and POD. Under the stress of different concentrations of AgNPs, the CAT activities are inhibited initially and later recovered to some extent. Under the stress of low concentrations of AgNPs, the soluble protein content in the leaves of Typha orientalis increases significantly, but decreases more significantly with increasing concentrations of AgNPs. Low concentrations of AgNPs promote chlorophyll synthesis in the leaves of Typha orientalis , but the chlorophyll content subsequently falls to pre-stress levels. In contrast, high concentrations of AgNPs cause a certain inhibition to generate chlorophyll. Meanwhile, the results show that the silver concentrations of plant tissues increase with the exposure of concentrations of AgNPs and they have a positive relationship with the exposure of concentrations of AgNPs.

Biosynthesis of Silver Nanoparticles from <i>Allium ampeloprasum</i>Leaves Extract and Its Antifungal Activity

Development of natural based nanomaterial immense interest of researchers involved in eco-friendly biosynthesis of nanoparticles. This research set out to investigate the potential of Allium ampeloprasum leaves extract to synthesize silver nanoparticles (AgNPs), and evaluate their antifungal activity against some toxigenic strains of Aspergillus isolates. In order to achieve this, AgNPs were prepared using plant extracts at room temperature and the formation of AgNPs was visually detected after the color changed to dark brown within few minutes. The biosynthesized AgNPs were characterized using the UV-vis spectroscopy, which confirmed the formation of AgNPs with a maximum peak at 437 nm due to the Plasmon resonance. The main active reduction agents were detected by Fourier Transmission infrared spectroscopy (FTIR). Also, the nanoparticles were characterized using Scanning electron microscope (SEM). The antifungal activity of AgNPs was investigated by agar well diffusion method, which revealed inhibition zones of 8 mm, 10 mm, 11 mm, 11 mm and 14 mm against Aspergillus flavus 1, A. parasiticus, A. flavus 2, A. ochraceus, and A. niger. The minimum inhibition concentration (MIC) was determined using micro broth dilution method. MIC values of AgNPs ranged from 652 - 2500 μg/ml. The fungi treated with AgNPs, were examined with (SEM), it was observed that the treated fungi were damaged. These results suggest that AgNPs have the potential to be used as an ideal eco-friendly approach to control toxigenic fungi.

Comparison of Antioxidant Activities of Silver Nanoparticles and Methanol Extracts of Three Indigenous Nigeria Herbal Seeds

The antioxidant of seeds was carried out using extracts from methanol and Silver Nanoparticles from the spice. The SEM shows the shapes, dispersion and agglomeration of the sample, while the EDX confirms the SEM and the presence of some compounds. The FT-IR reveals the AgNPs capping and reducing the particular biomolecule from the functional group for identification. Compounds found in the FT-IR seeds of Capsicum annum are Ag L (Silver iodide), C K (Cyanogen chloride), P K (Phenol). Monodora myristica are Mo L (Molybdenum), Ag L (Silver iodide), C K (Cyanogen chloride), P K (Phenol), Mg K (Magnesium). Piper guineense are Ag L (Silver iodide), Ci K (Potassium chloride), C K (Cyanogen chloride), P K (Phenol). The seeds show that the AgNPS of CA and MM has a better antioxidant activity than the methanol of CA and MM, while the PG methanol has a better activity than the AgNPS PG. The control (Catechin and Galic acid) has a slight overall better DPPH activity than the AgNPS. It is important to note that there is a concentration dependency in CA, MM AgNPS, PG methanol respectively. Notably, at CA methanol, the conc. at 125 was higher than the conc. at 250. Hence, there is need to create a great part in using plant samples for making tabulated or capsulated drugs for treatment of diseases and using plant silver nanoparticles to develop a healthy food/drug preservative package material “smart packaging” that will enhance shelf-life.

PAN/AgNPs/TiO_(2)纳米纤维膜结构性能优化

将纳米银颗粒(AgNPs)和二氧化钛(TiO_(2))加入聚丙烯腈(PAN)溶液中,在保证静电纺丝正常进行的基础上,按照L9(34)正交试验方案,制备试验用PAN/AgNPs/TiO_(2)纳米纤维膜,测试其微观形貌、防紫外线性能、防电磁辐射性能和拉伸性能,并进行直观分析和方差分析。结果表明:TiO_(2)质量分数对纳米纤维膜纤维直径影响显著,对其防紫外线性能和拉伸性能影响非常显著;AgNPs质量分数对纳米纤维膜的防电磁辐射性能影响非常显著;最优纳米纤维膜制备方案为AgNPs质量分数1.60%、TiO_(2)质量分数0.75%,此时PAN/AgNPs/TiO_(2)纳米纤维膜纤维的平均直径为311.16 nm,紫外线防护系数为1060.60,辐射量为0.40μW/cm^(2),断裂强力为74.96 cN。

PAN/AgNPs/UV531复合纳米纤维膜的制备及防护性能分析

为制备具有防电磁辐射、防紫外线功能的纳米纤维膜,文章在聚丙烯腈(PAN)溶液中加入纳米银颗粒(AgNPs)和紫外线吸收剂UV531,利用静电纺丝技术制备纯PAN和PAN/AgNPs、PAN/AgNPs/UV531复合纳米纤维膜,测试分析纳米纤维膜的微观形貌、红外光谱、防电磁辐射性能、紫外线防护性能和紫外线吸收性能。结果表明:AgNPs和UV531的加入没有改变PAN的大分子结构;将质量分数分别为1.2%、0.5%的AgNPs和UV531加入纯PAN溶液中,制备得到的PAN/AgNPs/UV531复合纳米纤维膜,纤维直径较小且分布较均匀,防电磁辐射功能和紫外线防护功能优良,可用于开发防电磁辐射/防紫外线纳米纺织品。

Coating independent cytotoxicity of citrate-and PEG-coated silver nanoparticles on a human hepatoma cell line

The antibacterial potential of silver nanoparticles（AgNPs） resulted in their increasing incorporation into consumer,industrial and biomedical products.Therefore,human and environmental exposure to AgNPs（either as an engineered product or a contaminant）supports the emergent research on the features conferring them different toxicity profiles.In this study,30 ran AgNPs coated with citrate or poly（ethylene glycol）（PEG） were used to assess the influence of coating on the effects produced on a human hepatoma cell line（HepG2）,namely in terms of viability,apoptosis,apoptotic related genes,cell cycle and cyclins gene expression.Both types of coated AgNPs decreased cell proliferation and viability with a similar toxicity profile.At the concentrations used（11 and 5 μg/mL corresponding to IC50 and-IC10 levels,respectively） the amount of cells undergoing apoptosis was not significant and the apoptotic related genes BCL2（anti-apoptotic gene）and BAX（pro-apoptotic gene） were both downregulated.Moreover,both AgNPs affected HepG2 cell cycle progression at the higher concentration（11 μg/mL） by increasing the percentage of cells in S（synthesis phase） and G2（Gap 2 phase） phases.Considering the cell-cycle related genes,the expression of cyclin B1 and cyclin E1 genes were decreased.Thus,this work has shown that citrate- and PEG-coated AgNPs impact on HepG2 apoptotic gene expression,cell cycle dynamics and cyclin regulation in a similar way.More research is needed to determine the properties that confer AgNPs at lower toxicity,since their use has proved helpful in several industrial and biomedical contexts.

银纳米粒子涂层根管镍钛器械的抗菌性能及生物相容性研究

目的探讨银纳米粒子涂层根管镍钛器械(silver nanoparticals-coated root canal nickel titanium instruments,AgNPs-NiTi)的抗菌性能及生物相容性。方法利用脉冲电化学沉积技术制备AgNPs-NiTi。场发射扫描电镜观察AgNPs-NiTi的形貌,X射线衍射仪和能谱仪分析涂层的元素组成及含量,万能材料实验机检测AgNPs-NiTi的机械性能。将AgNPs-NiTi与粪肠球菌(E.faecalis)悬液共培养,细菌菌落计数法检测AgNPs-NiTi对E.faecalis的抗菌效果。构建离体牙根管内E.faecalis生物膜模型,将AgNPs-NiTi放入根管内模拟器械分离,用场发射电镜、活死菌染色法观察AgNPs-NiTi对E.faecalis生物膜的抗菌效果。AgNPs-NiTi与Raw264.7细胞共培养,用CCK-8法检测其细胞毒性。结果脉冲电化学沉积法在NiTi器械上构建银纳米粒子涂层,载银后NiTi器械的机械性能无明显变化。AgNPs-NiTi能够明显抑制E.faecalis的增殖,并显著破坏根管内E.faecalis生物膜。AgNPs-NiTi对Raw264.7的增殖无明显影响,无明显细胞毒性。结论AgNPs-NiTi的机械性能与镍钛器械相仿,可抑制E.faecalis及其生物膜的活性,具有良好的生物相容性。

伽师瓜皮银纳米颗粒的合成及其对单偶氮染料的催化降解作用

以硝酸银为前躯物,伽师瓜皮提取物作为还原剂和保护剂制备了伽师瓜皮银纳米颗粒(JM-AgNP)材料。通过单因素法分析了伽师瓜皮提取液的pH值和质量浓度、硝酸银溶液浓度、反应时间与温度对JM-AgNP的影响。采用紫外-可见(UV-Vis)分光光度计、傅里叶变换红外(FTIR)光谱分析仪、X射线衍射仪(XRD)和透射电子显微镜(TEM)等对JM-Ag-NP结构及性能进行表征,并探究了JM-AgNP对单偶氮染料的催化降解性能及机理。研究得到的JM-AgNP最佳合成工艺为:伽师瓜皮提取液pH值为11.5,硝酸银溶液浓度为7 mmol/L,伽师瓜皮提取液质量浓度为5 g/L,反应时间为150 min,反应温度为90℃。所形成的JM-Ag-NP近似为圆球形,粒径在9~46 nm之间。在(CH3COO)3BHNa还原作用下,经过15 min反应时间,JM-AgNP对酸性橙7(AO7)和酸性红13(AR13)染料的降解率分别达到90.48%和88.16%。研究结果可为银纳米颗粒的绿色合成及其在废水处理领域的应用提供方法和思路。

Molecular toxicity and defense mechanisms induced by silver nanoparticles in Drosophila melanogaster

The widely use of silver nanoparticles(AgNPs) as antimicrobial agents gives rise to potential environmental risks. AgNPs exposure have been reported to cause toxicity in animals.Nevertheless, the known mechanisms of AgNPs toxicity are still limited. In this study, we systematically investigated the toxicity of AgNPs exposure using Drosophila melanogaster.We show here that AgNPs significantly decreased Drosophila fecundity, the third-instar larvae weight and rates of pupation and eclosion in a dose-dependent manner. AgNPs reduced fat body cell viability in MTT(3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide)assays. AgNPs caused DNA damage in hemocytes and S2 cells. Interestingly, the mRNA levels of the entire metallothionein gene family were increased under AgNPs exposure as determined by RNA-seq analysis and validated by qRT-PCR, indicating that Drosophila responded to the metal toxicity of AgNPs by producing metallothioneins for detoxification. These findings provide a better understanding of the mechanisms of AgNPs toxicity and may provide clues to effect on other organisms, including humans.

不同表面特性纳米银对铜绿微囊藻的抑制机制

银纳米粒子(AgNPs)会对水生生物产生不利影响,然而这些影响背后的抑制机制仍不清楚。通过测定藻细胞生物量、光合色素、氧化应激水平、细胞膜完整性及胞外聚合物含量等指标,研究了表面修饰不同涂层的AgNPs包括支链聚乙烯亚胺涂层带正电的纳米银(bPEI-AgNPs)和柠檬酸盐涂层带负电的纳米银(Cit-AgNPs)对淡水藻类中的代表性蓝藻铜绿微囊藻(Microcystis aeruginosa)的影响作用机制。数据表明,两种纳米颗粒均对铜绿微囊藻生长起到抑制作用,损害其光合作用,导致大量电子累积从而使藻细胞产生氧化胁迫,细胞分泌大量胞外聚合物来减缓损伤,且抑制程度随着颗粒投加量的增加而增大,特别是带负电荷的Cit-AgNPs对藻细胞的抑制效应更明显,其抑制程度是同质量浓度带正电荷的bPEI-AgNPs的4~5倍。总的来说,该研究结果为不同表面电特性纳米银与铜绿微囊藻的相互作用提供了新的见解,促进了对于纳米银在淡水藻类中的抑制机制的理解,同时有助于后续研究不同表面电性纳米银颗粒在水环境中的迁移转化规律。

微型球状光学免疫传感器的构建及其在CA125检测中的应用

金纳米粒子(AuNP)和银纳米粒子(AgNP)受到光子作用发出强烈的散射光,在暗场显微镜中可观察到清晰的单纳米粒子图像。以金纳米粒子耦合抗体分子作为球状传感器核心,银纳米粒子作为抗原标记物,构建微型球状光学免疫传感器。研究结果显示,在暗场显微镜中观察到抗体耦合的金纳米粒子为金黄色光点,银纳米粒子为绿色光点。当溶液中癌抗原CA125浓度为35 U/mL时,银纳米粒子耦合到金纳米粒子表面,金黄色的暗场图像转变成绿色,散射光强度增强至68720,表明通过暗场显微镜观察传感器的颜色变化可定量检测生物分子。该光学免疫传感器体积小、灵敏度高,可进一步应用于临床疾病诊断。

Long-term effects of silver nanoparticles on performance of phosphorus removal in a laboratory-scale vertical flow constructed wetland

Silver nanoparticles(AgNPs)have been widely used in many fields,which raised concerns about potential threats to biological sewage treatment systems.In this study,the phosphorus removal performance,enzymatic activity and microbial population dynamics in constructed wetlands(CWs)were evaluated under a long-term exposure to Ag NPs(0,50,and 200μg/L)for 450 days.Results have shown that Ag NPs inhibited the phosphorus removal efficiency in a short-term exposure,whereas caused no obviously negative effects from a long-term perspective.Moreover,in the coexisting CW system of Ag NPs and phosphorus,competition exhibited in the initial exposure phase,however,cooperation between them was observed in later phase.Enzymatic activity of acid-phosphatase at the moderate temperature(10–20℃)was visibly higher than that at the high temperature(20–30℃)and CWs with Ag NPs addition had no appreciable differences compared with the control.High-throughput sequencing results indicated that the microbial richness,diversity and composition of CWs were distinctly affected with the extension of exposure time at different Ag NPs levels.However,the phosphorus removal performance of CWs did not decline with the decrease of polyphosphate accumulating organisms(PAOs),which also confirmed that adsorption precipitation was the main way of phosphorus removal in CWs.The study suggested that Ag NPs and phosphorus could be removed synergistically in the coexistence system.This work has some reference for evaluating the influences of Ag NPs on the phosphorus removal and the interrelation between them in CWs.

纳米银抗菌材料在口腔种植应用中的研究进展

纳米银作为一种高效的新型纳米抗菌材料,在具备抗菌的广谱性、抑菌效率高的特点的基础上,同时也具有良好的抗炎性,目前被广泛应用于口腔医学的各个领域。本文就纳米银抗菌材料在口腔种植领域中的抗菌机制和应用作一综述,并对纳米银的抗菌研究前景进行了展望。

Water chemistry controlled aggregation and photo-transformation of silver nanoparticles in environmental waters

The inevitable release of engineered silver nanoparticles（Ag NPs） into aquatic environments has drawn great concerns about its environmental toxicity and safety. Although aggregation and transformation play crucial roles in the transport and toxicity of Ag NPs, how the water chemistry of environmental waters influences the aggregation and transformation of engineered Ag NPs is still not well understood. In this study, the aggregation of polyvinylpyrrolidone（PVP） coated Ag NPs was investigated in eight typical environmental water samples（with different ionic strengths, hardness, and dissolved organic matter（DOM） concentrations） by using UV–visible spectroscopy and dynamic light scattering. Raman spectroscopy was applied to probe the interaction of DOM with the surface of Ag NPs. Further, the photo-transformation and morphology changes of Ag NPs in environmental waters were studied by UV–visible spectroscopy, inductively coupled plasma mass spectrometry, and transmission electron microscopy. The results suggested that both electrolytes（especially Ca2＋and Mg2＋） and DOM in the surface waters are key parameters for Ag NP aggregation, and sunlight could accelerate the morphology change, aggregation, and further sedimentation of Ag NPs. This water chemistry controlled aggregation and photo-transformation should have significant environmental impacts on the transport and toxicity of Ag NPs in the aquatic environments.

Comparison of cellular responses across multiple passage numbers in Ba/F3-BCR-ABL cells induced by silver nanoparticles

With the rapid development of nanotechnology and increasingly broad bio-application of engineered nanomaterials, their bio- hazards have become a serious public concern. It is believed that the chemical nature, particle size, morphology, and surface chemistry of nanomaterials are key parameters that influence their toxicity. Although cultured ceils have been widely used to evaluate nanomaterial toxicity, it remains unclear whether the passage of these cells affects the evaluation results. In the pre- sent study, Ba/F3 cells transfected with the BCR-ABL gene were subcultured to study the effect of passage number on cell sta- bility and their cellular responses upon exposure to nanomaterials. The results demonstrated that proliferation, cellular senes- cence, BCR-ABL gene expression, cell cycle and apoptosis were stable across multiple passages. Senescence and BCR-ABL gene expression of cells from different passage cells were unchanged when treated with silver nanoparticles （AgNPs）. In addi- tion, the cells at multiple passage numbers were all arrested in the G2/M phase and apoptosis was induced by the AgNPs. These nanoparticles could enter cells via endocytosis and localize in the cndosomes, which were also not influenced by passage number. These data suggest that short-term passage would not affect cultured cell stability and toxicity assessment using these cells would be consistent when maintained appropriately.

Green Synthesis of Silver Nanoparticles and Their Reduced Graphene Oxide Nanocomposites as Antibacterial Agents:A Bio-inspired Approach

In this paper, silver nanoparticles （AgNPs） and AgNPs/reduced graphene oxide （RGO） nanocomposites were prepared using lemon juice under microwave irradiation （MWI） and UV light irradiation. AgNPs with face-centered cubic structure RGO peaks were observed by X-ray diffraction. The UV-Vis spectrum showed modifications in the absorption peaks of the AgNPs with the concentration of the precursor solution and irradiation time, and the optimized condition was obtained for 20 min MWI and 60 s of UV light. Raman analysis confirmed the presence of RGO as D and G bands in the spectrum. Transmission electron microscopy analyses confirmed that the AgNPs of size ranging from 3 to 8 nm were anchored onto the RGO sheets. The antibacterial properties of the AgNPs/RGO nanocomposites were investigated using gram-negative bacteria. The results revealed that AgNPs/RGO nanocomposites consisting of approximately 5 wt% AgNPs can achieve antibacterial performance similar to that of neat AgNPS. This method can be useful for the applications of AgNPs-based nanocomposites, where minute amount of silver will be utilized.

Is there a silver lining? Aggregation and photo-transformation of silver nanoparticles in environmental waters

The nanotechnology industry advances rapidly,and at the vanguard are the promising silver nanoparticles（Ag NPs）,which have diverse applications.These nanometer-sized particles have been shown to inhibit the ability of bacteria to produce adenosine triphosphate（ATP）,a molecule necessary for chemical energy transport in cells.The antimicrobial properties of Ag NPs（and Ag＋）make them valued antibacterial

Effects on cytotoxicity and antibacterial properties of the incorporations of silver nanoparticles into the surface coating of dental alloys

The aim of this study was to research the changes in cytotoxicity and antibacterial properties after silver nanoparticles （AgNPs） were incorporated into the surface coating of dental alloys. AgNPs were attached to cobalt chromium alloys and pure titanium using a hydrothermal method, according to the reaction： AgNO3＋NaBH4-, Ag＋1/2H2＋1/2B2H6＋NaNO3. A 3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyl tetrazolium bromide （MTT） assay was used to evaluate the cytotoxicity of the alloys when in contact with osteogenic precursor cells （MC3T3-E1） from mice and mesenchymal stem cells （BMSC） from rats. The antibacterial properties of dental alloys incorporating three different concentrations （10, 4, and 2 μmol/L）of AgNPs were tested on Staphylococcus aureus （SA）and Streptococcus mutans （MS）. High cytotoxicity values were observed for all dental alloys that contained 0% of AgNPs （the control groups）. The incorporation of AgNPs reduced cytotoxicity values. No significant difference was observed for antibacterial performance when comparing dental alloys containing AgNPs to the respective control groups. The results demonstrated that the cobalt chromium alloys and pure titanium all had cytotoxicity to MC3T3-E1 and BMSC and that the incorpo- ration of AgNPs could reduce this cytotoxicity. The concentrations of AgNPs adopted in this study were found to have no antibacterial action against SA or MS.

生物素修饰纳米银探针的制备及在蛋白芯片可视化检测中的应用

采用寡核苷酸为连接分子成功制备了生物素修饰的纳米银探针,并建立了纳米银催化同种金属离子的特异性还原显色反应.实验采用蛋白质芯片为分析工具,以微量人IgG为蛋白分析模式研究了纳米银探针/氢醌/硝酸银体系的显色分析性能.实验结果表明,上述检测体系可对160 fg～100 pg含量范围内的微量蛋白显示可视化结果,蛋白点的灰度值与其浓度具有良好的相关性,最小蛋白检测量可达160 fg.同时还开展了与商品化链亲和素纳米金/银增强试剂显色方法的对比实验,结果表明,本法制备的探针对蛋白的检出限降低了约40倍,且具有存储稳定、反应快速等优点.