绿色合成桑叶银纳米粒及其抗菌抗癌活性

为了更好地开发出具有良好物理化学及生物活性的银纳米粒,利用桑叶水提取物,通过绿色方法制得桑叶银纳米粒.以AgNO3浓度、反应温度、桑叶水提物与AgNO3溶液体积比、pH以及反应时间为影响因素,优化桑叶银纳米粒最佳合成条件;通过UV-Vis、SEM及FTIR等对产物进行结构表征;通过测定抑菌圈、最小抑菌浓度和细胞毒实验评价其抗菌及抗癌活性.结果显示,最佳制备条件为:AgNO3浓度5 mmol/L、反应温度35℃、桑叶水提液与AgNO3溶液体积比1:5、反应体系pH 11.0及反应时间6 h.在此条件下制备的桑叶银纳米粒为大小均一的球形,平均粒径(48.78±0.39)nm,电位(–27.8±2.00)mV;相比于桑叶水提物,桑叶银纳米粒对大肠杆菌、铜绿假单胞杆菌、金黄色葡萄球菌、枯草芽孢杆菌及白色念球菌均表现出较好的抑菌效果,其抑菌圈分别为(11.39±1.02)、(10.50±0.92)、(10.50±0.61)、(7.90±0.79)和(8.31±0.52)mm;桑叶银纳米粒对人宫颈癌细胞〔半数抑制浓度(IC50)为60.63 mg/L〕、人肝癌细胞(IC50为26.98 mg/L)和人乳腺癌细胞(IC50为18.65 mg/L)有很好的抑制作用.     

银纳米粒子的绿色合成及其光谱特性

以糊精为还原剂和稳定剂,采用微波高压液相绿色合成法制备了黄色银纳米粒子。用吸收光谱和共振散射光谱研究银纳米粒子的光谱特性。结果表明,在优化的最佳条件下,用该法制备的纳米银最大吸收峰在418 nm处,最强共振散射峰在486 nm处,银纳米粒子颗粒呈球形,粒度均匀,平均粒径为20 nm,单分散性较好。该法操作简单反应快速。     

银@石墨烯纳米复合材料的绿色制备及其抑菌性能

以聚乙二醇为还原剂通过水热反应,还原氧化石墨烯同时在石墨烯表面原位生长银纳米粒子,制备银@石墨烯纳米复合材料。采用紫外-可见吸收光谱、X射线衍射、红外吸收光谱、透射电子显微镜对所制备的银@石墨烯纳米复合材料进行了表征。结果表明：银以单质形态成功负载在石墨烯表面,银纳米粒子的平均粒径为30nm。以大肠杆菌为模型对纳米复合材料的抑菌性能进行测试,银@石墨烯纳米复合材料在100µg/mL时可以完全抑制大肠杆菌的生长,是一种效果显著的新型抑菌材料。     

载银纳米二氧化硅抗菌粉体材料的制备

研究了以平均粒径13nm的二氧化硅为载体，银单质为抗菌剂的载银纳米抗菌粉体材料的制备工艺及抗菌性能。通过化学还原法在其表面负载理论含量为0．7％～4％（质量分数）金属银，采用抑菌环法和振荡烧瓶法对其抗菌性能进行了检测，结果表明，载银3％（质量分数）的纳米二氧化硅在80～140℃烧结温度范围内制得抗菌粉体对大肠杆菌和金黄色葡萄球菌的杀菌率几乎达到100％，具有优良的抗菌性能，可用于抗菌塑料、抗菌食品包装和抗菌纺织制品等领域。     

纳米载银抗菌粉体材料的制备工艺与性能

本研究采用纳米粒子制备技术,制成的纳米磷酸锆载银抗菌粉体材料,具有颗粒尺寸小、抗菌谱广、高效、无毒、持久和耐热性。     

纳米银生物法绿色合成及其抗菌应用进展

纳米银是研究和应用最为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,人们在纳米银的绿色合成方向做了诸多研究。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,是下一步的重点。综述了利用植物、细菌和真菌绿色合成纳米银的机制与方法,对各方法进行分析比较,介绍了纳米银的抗菌性能、抗菌机制和具体应用,对于未来发展提出建议。     

载银纳米二氧化钛的制备及抗菌性能研究

以碳酰二胺为沉淀剂与TiOSO4溶液反应生成Ti(OH)2沉积于AgCl晶种表面制备载银纳米二氧化钛,产物对金黄色葡萄球菌(S.aureus)、大肠杆菌(E.coli)和白色念珠菌(C.albicans)达到99%抗菌率的最小浓度分别是90、70、60 mg/L,经电子透射显微镜(TEM)表征,粒径主要分布于100～200 nm。     

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。     

银锌复合抗菌剂及纳米抗菌塑料的制备

采用液相法合成抗菌能力优良的银锌复合沸石抗菌剂，并优化组合相应的关键合成条件。首次采用悬浮法制备分散均匀的抗菌母粒，使用相应的钛酸脂偶联剂提高抗菌剂在苯乙烯中稳定性，获得预期效果。将该母粒用于制备抗菌塑料，通过对力学性能，抗菌能力，白度的检测证明可以达到应用标准。     

葡聚糖存在下微波高压合成银纳米粒子及其光谱特性

以葡聚糖为还原剂和稳定剂,采用微波高压液相绿色合成法制备了黄色银纳米粒子。用吸收光谱和共振散射光谱研究其制备条件的影响。在413nm处产生最大吸收峰,在486nm处产生一个最强共振散射峰。实验表明：该法制备的银纳米粒子粒径均匀,平均粒径为16nm,其稳定性和分散性好,合成方法简便、快捷。     

Effect of accelerator in green synthesis of silver nanoparticles

Silver nanoparticles (Ag-NPs) were successfully synthesized in the natural polymeric matrix. Silver nitrate, gelatin, glucose, and sodium hydroxide have been used as silver precursor, stabilizer, reducing agent, and accelerator reagent, respectively. This study investigated the role of NaOH as the accelerator. The resultant products have been confirmed to be Ag-NPs using powder X-ray diffraction (PXRD), UV-vis spectroscopy, and transmission electron microscopy (TEM). The colloidal sols of Ag-NPs obtained at different volumes of NaOH show strong and different surface plasmon resonance (SPR) peaks, which can be explained from the TEM images of Ag-NPs and their particle size distribution. Compared with other synthetic methods, this work is green, rapid, and simple to use. The newly prepared Ag-NPs may have many potential applications in chemical and biological industries.     

Syzygium cumini leaf and seed extract mediated biosynthesis of silver nanoparticles and their characterization

BACKGROUND: Plant mediated synthesis of metallic nanoparticles has been studied and reported, however, to date, the biomolecules involved in the synthesis of metallic nanoparticles have not been characterized. This study was therefore undertaken to characterize the biomolecules of Syzygium cumini involved in the synthesis of silver nanoparticles. RESULTS: Synthesis kinetics and morphological characterization of silver nanoparticles (SNP) synthesized using leaf extract (LE) and seed extract (SE) as well as their polar (water) fractions from Syzygium cumini were compared. The polyphenols content and high performance liquid chromatography (HPLC) profile of different fractions revealed good correlation between size and synthesis rate of SNP. SE contains more polyphenols and biochemical constituents than LE and therefore, showed higher synthesis rate and bigger sized SNP. To analyse the nature of biomolecules involved in the synthesis of SNP, LE and SE were fractionated on a polarity basis by solvent–solvent partitioning. Only the water fractions of LE and SE showed potential for SNP synthesis. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) analysis of SNP indicated that all fractions catalyze the synthesis of spherical nanoparticles. The average size of SNP synthesized by LE, leaf water fraction, SE and seed water fraction were 30, 29, 92, and 73 nm respectively. CONCLUSION: Results suggest that only highly polar soluble constituents are responsible for SNP synthesis. The size of SNP was found to be directly correlated with the amount of polyphenols as well as surfactants present in the reaction solution. Thus, the amount of polyphenols could be one of the crucial parameters determining the size and distribution of SNP. Copyright © 2010 Society of Chemical Industry     

Synergistic antimicrobial effects of polyaniline combined with silver nanoparticles

Silver/polyaniline nanocomposites (Ag NPs/PANI) containing PANI nanofiber and Ag nanoparticles were synthesized by one-step approach without using any extra reducing agent or surfactant and applied to new antimicrobial agents. Morphologies and crystallinity of the nanocomposites were characterized with SEM and XRD. The results showed that the average diameter of the PANI nanofibers is around 50–150 nm, and the average particle size of Ag NPs is around 100 nm. The crystallinity of PANI gets better with increasing silver nitride concentration. UV–vis absorption spectroscopy analysis indicated that the Ag NPs have some effect on the microstructure of PANI. The antimicrobial properties of Ag NPs/PANI against Gram-negative Escherichia coli, Gram-positive Staphylococcus aureus and fungous Yeast were evaluated using viable cell counts. The test results demonstrated that Ag NPs/PANI have enhanced antimicrobial efficacy compared to that of pure Ag NPs or pure PANI under the same test condition. The mechanism of the synergistic antimicrobial effect of Ag NPs with PANI was also proposed. In addition, thermal gravity analysis indicated that pure PANI and Ag NPs/PANI exhibit better thermal stability. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

纳米铁的绿色合成及其在环境中的应用研究进展

纳米铁（零价铁及铁氧化物）比表面积大、还原能力强、反应活性高,是一种良好的环境功能材料。传统的纳米铁合成方法中,物理方法对反应所需仪器设备要求较高,化学方法使用的还原剂具有毒性,绿色合成方法能够有效克服传统方法的不足之处。本文首先根据合成途径、纳米铁的类型介绍了利用植物和微生物对纳米零价铁（nZVI）及纳米铁氧化物（IONPs）进行绿色合成的方法,同时论述了制备的纳米铁所表现的特征（如形貌、尺寸、聚集倾向、等电位点）。随后总结了纳米铁通过不同反应机制（吸附、还原、催化氧化）去除环境有机、无机污染物（染料、芳香族化合物、硝酸盐、重金属）的应用。最后指出了纳米铁在绿色合成与实际应用过程中存在的挑战性问题及解决方法,以期为纳米铁今后的深入研究和大规模的工业生产应用提供参考依据。     

Size-controlled green synthesis of silver nanoparticles assisted by L-cysteine

A green and size-controlled synthesis of silver nanoparticles (Ag NPs) in aqueous solution with the assistance of L-cysteine is presented. The size of Ag NPs decreases with the increase of L-cysteine concentration, and thus can be controlled by adjusting L-cysteine concentration. TEM analysis shows that Ag NPs with an average size of 3 nm can be produced in the presence of 1.0 mmol/L L-cysteine, about one sixth of the size of Ag NPs obtained in the absence of L-cysteine (17 nm). The as-synthesized silver colloidal solution is stable and can be stored at room temperature for at least two months without any precipitation. This L-cysteine assisted method is simple, feasible and efficient, and would facilitate the production and application of Ag NPs.     

Green synthesis of copper oxide nanoparticles: Characterization and applications for environmental and biomedical fields

In recent years, there has been an increasing interest in the development of plant-based nanoparticles due to their numerous benefits over conventional physio-chemical methods, including sustainability and environmental safety. Green synthesis, a process that produces safe and sustainable goods without the use of harsh chemicals or other harmful processes, is gaining popularity. The current study focuses on the green synthesis of copper oxide nanoparticles using Piper nigrum leaf extracts, their characterization, and applications. The synthesis of nanoparticles was confirmed by changes in colour, further endorsed by UV–visible spectroscopy. Copper oxide (CuO) nanoparticles were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). CuO nanoparticle sizes ranged between 58.23 and 69.89 nm and were spherical in shape. FTIR results indicated a functional group capped on the nanoparticle surface. The antibacterial activity of the copper oxide nanoparticles was tested, and they exhibited the significant decrease in bacterial concentration and the largest zone of inhibition, making them an efficient disinfectant. Antimicrobial activity against Bacillus subtilis and Escherichia coli was observed. Furthermore, the synthesized CuO nanoparticles exhibited a high affinity for safranin dyes and demonstrated maximum removal efficiency. This makes them an effective agent for removing dyes in wastewater from industries such as clothing manufacturing. Safranin dye was successfully removed with an efficiency of 78% using nanoparticles. In conclusion, the green synthesis of copper oxide nanoparticles using plant extracts presents an eco-friendly and sustainable approach for producing nanoparticles with a wide range of potential applications.     

Earthworm extracts utilized in the green synthesis of gold nanoparticles capable of reinforcing the anticoagulant activities of heparin

Gold nanoparticles were obtained using a green synthesis approach with aqueous earthworm extracts without any additional reducing or capping agents. The gold nanoparticles were characterized using UV-visible spectrophotometry, high-resolution transmission electron microscopy, atomic force microscopy, field emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and inductively coupled plasma mass spectrometry. The anticoagulant activity of the gold nanoparticles was assessed using the activated partial thromboplastin time and was mildly enhanced by combining the gold nanoparticles with heparin. In addition to the generation of spherical nanoparticles with an average diameter of 6.13 ± 2.13 nm, cubic and block-shaped nanoparticles with an average aspect ratio, defined as the length divided by width, of 1.47 were also observed.