不同还原剂对银粒子生长形貌的影响

目的探究不同还原剂在纳米银粒子合成过程中对其粒径、尺寸分布和形貌的影响。方法以聚乙烯吡咯烷酮(PVP)为分散剂,选择葡萄糖、抗坏血酸、柠檬酸钠、乙二醇作对照,通过化学还原的方法,并将反应温度控制在60℃来制备纳米银粒子。通过马尔文激光粒度仪、X-射线衍射光谱(XRD)、扫描电镜(SEM)、紫外-可见光谱(UV-vis)等对所制备银粒子进行表征。结果采用葡萄糖为还原剂时,制备出了粒径较小(平均粒径为51 nm)且分布均匀的球形纳米银;将抗坏血酸作为还原剂时,出现了晶体颗粒聚集而成的球状团聚体,平均粒径为67 nm;柠檬酸纳还原出的纳米银粒子集中分布在15 nm左右以及100nm左右,平均粒径为57nm;乙二醇在相同条件下还原出了球形、棒状、三角片等形状的纳米银粒子,平均粒径为107 nm。结论采用葡萄糖作为还原剂,更容易制备出球形、粒径小且分散均匀的纳米银粒子。     

新型湿法纳米银制备技术及其毒性行为

针对目前纳米银(AgNPs)制备方法中存在的纳米银颗粒粒度分布不均,稳定性较差的问题,利用柠檬酸钠和无水乙醇作还原剂,以柠檬酸钠和聚乙烯吡咯烷酮(PVP)作为保护剂制备纳米银.利用紫外吸收光谱分析、XRD、SEM、TEM、EDS、Zeta电位仪等多种技术表征所制备纳米银的特征,结果表明纳米银颗粒为球形面心立方结构,粒径...     

化学还原法制备小粒径金纳米粒子

以聚乙烯吡咯烷酮(PVP)为保护剂,用硼氢化钠还原氯金酸制备出金纳米颗粒,研究了还原剂和保护剂用量、反应温度及试剂加入顺序对金纳米颗粒粒径、形貌、分散性的影响。利用透射电子显微镜和紫外分光光度计对纳米金颗粒的形貌、分散性及尺寸进行表征。结果表明:采用硼氢化钠为还原剂时,硼氢化钠与氯金酸的摩尔比为3.75∶1,PVP与氯金酸的质量比为1∶1,反应温度为100℃并且在氯金酸和PVP的混合溶液中迅速加入硼氢化钠制备的金纳米颗粒均一、平均粒径在4.3nm、分散性好。同时研究了各个影响因素的作用方式并分析了原因。     

具有自相似结构纳米银粉的制备及表征

采用液相化学还原法,以改性聚乙烯吡咯烷酮为分散稳定剂,用抗坏血酸还原硝酸银得到银溶胶,将银溶胶经离心分离、洗涤和真空干燥处理,得到规则球形纳米银粉.用动态光散射法激光粒度仪考察反应温度和溶液的pH值对纳米银粉粒度的影响.用扫描电镜(SEM)观察纳米银粉的形貌.用X 射线衍射(XRD)表征纳米银粉的晶体结构.研究结果表明,反应温度为40 ℃、w(PVP):w(AgNO3)=0.8、AgNO3浓度为0.24 mol/L、抗坏血酸溶液pH值=10,可得到具有至少3级循环套嵌自相似结构的规则球形纳米银粉;纳米银粉聚集体纯净无杂质,粒径在500～1 000 nm之间;粉体一次颗粒粒径为9～20 nm.     

焦性没食子酸还原制备纳米银

以三聚磷酸钠为保护剂,用焦性没食子酸还原硝酸银得到了纳米银溶胶。利用X射线衍射、紫外-可见吸收光谱、透射电镜、粒度分析对得到的纳米银溶胶进行了表征。结果表明,通过改变体系中保护剂的含量、反应时间和反应温度,制备了平均粒径分别为15、17、22、25、26nm的均匀球形纳米银;用不同的焦性没食子酸衍生物(没食子酸甲酯和没食子酸月桂酯)作还原剂分别得到了多形貌纳米银和平均粒径为7nm且尺寸均一的球形纳米银。     

微米级球形银粉的可控制备

摘要采用化学还原法,以七水硫酸亚铁（FeS04·7H20）为还原剂,在室温条件下搅拌还原硝酸银溶液制备了表面粗糙度高、粒度分布窄的微米级球形银粉。结果表明,通过控制还原剂与氧化剂物质的量比可以制备出粒径范围在1-4μm、尺寸可调的单分散球形银粉。     

微波辐照纳米银的制备与表征

在微波辐照下,以硝酸银为银源,水为溶剂,聚乙烯吡咯烷酮(PVP)为稳定剂和还原剂,不加入其他还原剂的条件下,快速制备出纳米银胶体。利用紫外光谱法,对微波制备纳米银粒子的条件进行了一系列研究,得出了先40℃下预热15min,再微波辐照30min,微波功率为260W,AgNO3∶PVP=1∶3(质量比)为最佳制备条件。对制得的纳米银粒子进行了TEM、SPM、DTA表征,发现制得的纳米银粒子为球形粒子,粒径较小,且粒径分布较窄,为18~25nm。对PVP的作用机理研究认为:主要是由于Ag离子与PVP的配位作用和PVP的空间位阻效应,使得能够制备出纳米球形银粒子。     

水热法制备纳米银颗粒的试验研究

以AgNO_3和NaHCO_3为反应原料,以PVP为保护剂,用水热法制备出纳米银颗粒。研究了AgNO_3浓度和分散剂PEG的加入对反应生成纳米银颗粒形貌的影响。结果表明,在AgNO_3浓度为0.06 mol/L,NaHCO_3浓度为0.15 mol/L,PVP为0.03 mol/L,PEG为0.05 mol/L,反应温度为200℃,反应时间4 h的工艺条件下,可得到平均粒径尺寸约50 nm、分散性好、尺寸均一的近球形纳米银颗粒。     

液相还原法制备不同粒度分布的规则球形纳米银粉研究

采用液相还原法，分别以水合肼、次磷酸钠和硼氢化钠为还原剂，聚乙二醇和聚乙烯吡咯烷酮为分散剂和保护剂，硝酸银被还原制备球形纳米银粉。通过透射电镜（TEM）和X射线衍射（XRD）进行表征，得到在10～60nm之间不同粒度分布的规则球形、纯相面心立方晶系纳米银粉。     

医用聚氨酯材料化学镀纳米银工艺

为提高医用聚氨酯材料留置人体内时的生物抗茵性能,需在其表面化学镀银.以次磷酸钠为还原剂,聚乙烯吡咯烷酮(PVP)为高分子保护剂,六偏磷酸钠为分散荆,还原硝酸银,将纳米银颗粒还原并沉积在医用聚氨酯内支架管表面,形成纳米银涂层.获得了最佳的化学镀银工艺:0.25 mol/,L AgNO3,AgNO3与还原剂次磷酸钠的摩尔比为2:1,温度40℃,时间30 min.采用本工艺,纳米银颗粒平均粒径为20～30 nm,镀液中添加高分子保护剂和分散剂可以阻止颗粒长大.提高纳米银颗粒的分散均匀性.本工艺在医用领域具有较好的前景.     

Silver nanoparticles: Ultrasonic wave assisted synthesis, optical characterization and surface area studies

Silver nanoparticles have been successfully synthesized by the sonochemical route using sodium borohydride and sodium citrate as the reducing agents. The effect of the reducing agents on the particle size and morphology has been studied by carrying out the two reactions at the same ultrasound frequency (20 KHz). The strong reducing agent (NaBH₄) produced spherical silver nanoparticles of sizes 10 nm whereas sodium citrate led to much smaller silver nanoparticles of ~ 3 nm diameter. Powder X-ray diffraction studies reveal a high degree of crystallinity and monophasic silver particles. UV-Visible studies show the presence of a surface plasmon band at 405 nm. However the reflectance spectra give a broad band between 340 and 360 nm which is characteristic for the quasi-spherical silver nanoparticles. The specific surface area was found to be 2.6 and 13.1 m²/g and the pore radius was found to be 15.2 and 12.3 Å for silver nanoparticles obtained by the sodium borohydride and sodium citrate reduction respectively.     

pH effect on the aggregation of silver nanoparticles synthesized by chemical reduction

Silver colloidal nanoparticles were prepared according to the chemical reduction method in which the ascorbic acid was used as a reducing agent and sodium citrate as a stabilizing agent. The absorption spectra of all prepared samples obtained using the UV-Vis spectrophotometer showed a surface plasmon peak at a wavelength of about 420 nm. The size of the silver nanoparticles was controlled by changing the pH values of the reaction system. At high pH, smaller size silver nanoparticles were obtained compared to low pH values. This difference can be attributed to the difference in the reduction rate of the precursor. In addition to the inverse proportionality between the size and the pH value it is clear that increasing the pH value enables us to obtain spherical nanoparticles while at low pH, rods and triangular particle shapes were formed. Poor balance between nucleation and growth processes could be the cause of this result.     

纳米银粒子在微乳液中的制备及其抗菌性能

在以二丁酸二异辛酯磺酸钠为表面活性剂、异辛烷为油相形成的W／O型微乳体系中,以AgNO3为银源、抗坏血酸为还原剂,讨论了AgNO3浓度、抗坏血酸浓度以及水核半径（W）对制备纳米银粒子的影响。利用紫外一可见光谱分析（UV-Vis）、透射电镜（TEM）和纳米粒度仪对制得的纳米银进行表征。结果表明,在AgNO3浓度为0．2mol／L,抗坏血酸浓度为0．2mol／L,W值为10的条件下,得到大小为10nm左右,单分散性好的均匀球状纳米银溶胶。抗菌性能测试表明,当纳米银粒子质量浓度为10μg／mL时,对大肠杆菌的杀菌率达98％以上。     

Synthesis of Starch-Stabilized Silver Nanoparticles and Their Antimicrobial Activity

In this study, silver nanoparticles were prepared using silver nitrate as the metal precursor, starch as protecting agent, and sodium borohydride (NaBH₄) as a reducing agent by the chemical reduction method. The formation of the silver nanoparticles was monitored using ultraviolet-visible absorption spectroscopy, cyclic voltammetry, and particle size analyzer and characterized by transmission electron microscopy (TEM) and x-ray diffraction (XRD). Synthesis of nanoparticles were carried out by varying different parameters, such as reaction temperature, concentration of reducing agent, concentration of silver ion in feed solution, type and concentration of the stabilizing agent, and stirrer speed expressed in terms of particle size and size distribution. Dispersion destabilization of colloidal nanoparticles was detected by Turbiscan. It was observed that size of the starch stabilized silver nanoparticles were lower than 10 nm. The microbial activity of synthesized silver nanoparticles was examined by modified Kirby-Bauer disk diffusion method. Silver nanoparticles were tested for their antibacterial activity against Gram negative bacteria such as Escherichia coli, Pseudomonas aeruginosa, and Gram positive bacteria such as Staphylococcus aureus and Staphylococcus epidermidis. High bacterial activity was observed at very low concentrations of silver (below 1.39 μg/ml). The antifungal activity of silver nanoparticles has been assayed against Candida albicans.     

Water based simple synthesis of re-dispersible silver nano-particles

Successful experiments with tri-sodium citrate as initial surfactant-cum-reducing agent followed by a secondary reducing agent i.e. sodium formaldehyde sulphoxylate (SFS) to silver nitrate were performed which established a clear large-scale method for the preparation of silver nano-powder of particle size of less than 50 nm. The citrate ions also create hydrophilic capping to in-situ generated zero-valent silver, thus leading to surfactant capped particles. Partial re-dispersion of such nano-powder in aqueous medium leads to colloidal silver which can be loaded in water friendly polymers such as polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP). UV-Visible absorption band at about 275 and 400 nm of colloidal silver in water can be retained even after loading in polymer. Transmission electron microscopy (TEM) of the colloidal solution showed a particle of the size < 30 nm. Particle size distribution by dynamic light scattering technique (DLS) showed that the particles are in the range of 10-40 nm. The elemental composition was studied by energy dispersive analysis of X-rays (EDS).     

液相化学还原法制备纳米银及抗菌性能研究

选用液相化学还原法,分别在以羧甲基纤维素钠(Carboxymethyl cellulose sodium,CMC)和葡萄糖为还原剂的体系下制备纳米银颗粒,并进行了对比分析。通过紫外分光光度计、X射线衍射和透射电镜等测试手段对其进行了表征。结果表明,用CMC体系制备的纳米银粉末平均粒径为20～30nm,为多晶结构;用葡萄糖体系制备的纳米银粉末平均粒径为25～35nm,为面心结构。利用抑菌圈法对纳米银的抗菌性能进行测试,结果显示2种体系下制备的纳米银对海洋芽孢杆菌都有很好的抑制作用。     

Effect of citrate on poly(vinyl pyrrolidone)-stabilized gold nanoparticles formed by PVP reduction in microwave (MW) synthesis

Colloidal PVP (poly(vinyl pyrrolidone))–stabilized gold nanoparticles (PVP–AuNPs) are synthesized in aqueous solution with PVP as a reducing and stabilizing agent using a short microwave (MW) heating duration of 1 min. The size and uniformity of the synthesized PVP–AuNPs can be varied by modifying the concentration of sodium citrate (Na₃Ct), which acts predominantly as mediator of the stability of PVP–AuNP formation during the rapid synthesis. Due to the increase in the Na₃Ct concentration, the number of citrate ions adsorbed on the growing surface of AuNPs increase, and less reactive gold solute complexes are formed, leading to slow stable reactions that produce small, uniform colloidal PVP–AuNPs. We therefore demonstrate that by adjusting the Na₃Ct concentration used in the PVP reduction, the diameter of PVP–AuNPs was varied from 19.47 ± 3.97 nm to 7.94 ± 0.14 nm when using constant concentrations of chloroauric acid (HAuCl₄) and PVP.     

纳米银/聚乙烯醇复合物的生物合成及其对6种水产病原菌的抑菌活性

纳米银作为一种新型抑菌剂有望成为传统抑菌剂的替代品,制备稳定、高效、环保的新型纳米银抑菌产品成为当今的研究热点。本研究以葡萄籽提取液为还原剂和稳定剂,聚乙烯醇(PVA)为载体,采用一步法“绿色”生物合成出一种纳米银/聚乙烯醇复合物(AgNPs/PVA)。通过紫外-可见(UV-Vis)吸收光谱、透射电镜(TEM)、X射线衍射(XRD)等手段对合成产物进行了表征。结果表明银离子被葡萄籽提取物成功还原成纳米银并附着在PVA的表面,纳米银颗粒均匀,呈现单分散状态,粒径较小,平均粒径为14 nm左右。AgNPs/PVA对鳗弧菌、溶藻弧菌、副溶血弧菌、哈维氏弧菌、灿烂弧菌及点状气单胞菌等6种典型的水产病原菌均有显著的抑菌效果。以溶藻弧菌为指示菌,AgNPs/PVA的最小抑菌浓度(MIC)为1.1 μg/mL,最小杀菌浓度(MBC)为2.2 μg/mL。AgNPs/PVA的Zeta电位为?24.1 mV,表明纳米银颗粒间有很强的排斥力,为其稳定分散提供保障,后续实验证明制备的AgNPs/PVA具有良好的稳定性和热稳定性。以上研究结果表明,AgNPs/PVA复合材料在水产养殖病害防治中具有广阔的应用前景。      

Synthesis and characterization of silver nanoparticles impregnated into bacterial cellulose

This article presents a study about the synthesis of colloidal silver (Ag)/biopolymer where Ag submicron particles were prepared in situ on bacterial cellulose (BC) produced by Gluconacetobacter xylinus. Different reducing agents were compared (hydrazine, hydroxylamine or ascorbic acid) together with the influence of gelatin or polyvinylpyrrolidone (PVP) employed as colloid protectors. Particle size distribution and morphology were investigated by scanning electron microscope (SEM). SEM images show silver nanoparticles (40–100 nm) size range attached on (BC) microfibrils. XRD analyses confirmed the Ag cubic phase deposited on to BC fibrils. The ash contents determined by thermogravimetric analyses have indicated high level of silver loading on the obtained composites.     

Spontaneous formation of silver nanoparticles on polymeric supports

Silver nanoparticles with a size range of 2-4 nm were prepared on polyethylene glycol-coupled 2-chlorotrityl resins without using any reducing agents. In contrast to the polyol process, silver nanoparticles were simply reduced in the tetrahydrofuran/chloroform system on the resin without using any alcohols, and the resulting silver nanoparticles exhibited a uniform size distribution. The polyethylene glycol spacer on the resin played an important role in obtaining silver nanoparticles, probably acting as a polydentate-chelating agent for the silver ions.