【作者】 Abbas Babapour；

【导师】 曹文武；

【作者基本信息】 哈尔滨工业大学 ， 光学， 2012， 博士

【摘要】 作为一类能够在纳米尺度上进行光控制和光处理的单元，贵金属纳米结构引起了人们浓厚的兴趣。当贵金属纳米结构表面被电磁辐射激发，传导电子振荡会引起表面等离子体共振（SPR）并产生沿粒子表面传播的表面等离子体。等离子体激发可以提供将光聚焦在亚波长尺寸的方法，这将克服光学衍射极限，使得诸如波导等纳米光学器件的设计成为可能。这种伴有等离子体共振的金属纳米结构产生的强电磁场可以用作表面增强光谱。理论研究和实验工作表明， SPR的确切位置和强度极易受到粒子的大小、形状以及粒子周围介质的光学和电学特性的影响，因此可以通过测试其物理性质，来研究金属粒子以及周围生物环境的变化，为生物治疗及检测等技术的实现提供物理基础。在外科手术中如何防止出现设备对患者产生的感染成为科学和医疗界关注的问题。在增加细菌对抗生素抵抗力的同时，应该防止植入设备产生的感染所引起的健康安全问题以及进而造成的经济负担。为解决以上问题，可以通过将抗菌涂层涂抹在植入设备上，在使用过程中释放内部的杀菌剂，进而在改进现有的医疗技术的同时又不妨碍其整体功能。由此，可将贵金属纳米技术引入生物医学当中，以物理学方法和材料制备技术为指导，研究出适用于生物医学的抗菌材料涂层，以适应生物医学领域的需求。纳米复合材料已得到科学界的极大关注，将纳米粒子添加到涂层中制成复合材料涂层，由于每种组分固有的性质以及它们之间的相互作用，使得这种复合材料涂层具有独特的电学、光学、机械性能，这些性能使得它们在光学、图案成像、传感器设计、催化以及抗菌涂层等领域表现出了极大的应用前景。由于等离子体共振，分散在介质材料中的金属纳米粒子产生了特有的消光峰，峰的形状、强度和位置依赖于纳米簇的大小、形状、浓度和化学态，以及纳米簇之间的相互作用。贵金属纳米簇可以通过不同的技术引入到电介质母体中，如浸渍、蒸发、传统的熔体淬火、离子注入、离子交换法、溶胶-凝胶等方法。溶胶-凝胶法一直被视为制造氧化膜最有效和最通用的技术，这是由于这种方法加工温度低，最终样本具有均一性和好的化学纯度，制备小粒径分布的纳米金属颗粒时容易调整金属注入，并可以在小注入时增加、减小氧化药剂。银已被人们熟知具有很好的杀菌性能，并且不会损害哺乳动物细胞。含有银纳米粒子的纳米复合材料的杀菌性能是通过将银纳米粒子氧化成银离子的方式实现的，由于这种抗菌治疗是集中在患处，所以这种方式抑制感染比口服抗生素药物更为有效。由此我们可通过溶胶-凝胶法制备银粒子，研究出有效的抗菌涂层材料。首先将银盐溶解在前驱体溶胶中，然后用热处理或紫外线照射将银离子还原成金属银粒子。通过热处理形成银胶体的过程中，温度是改变最后产生的银纳米簇的大小、形状和化学状态的重要参数，它会影响银纳米粒子的在光学特性中的光强和光吸收特性。本论文描述了稳定的银纳米粒子溶入到不同的母体中的合成、特性及一体化，以及其潜在的应用。我们将银纳米粒子和4种不同的母体进行合成，研究了不同媒介对含银涂层性能的影响，以及不同的纳米银涂层的抗菌活性的影响。金属纳米粒子通过透射电子显微镜（TEM）、扫描电子显微镜（SEM）、能量色散X射线分析（EDX）、X射线光电子能谱（XPS）和紫外可见光谱进行表征。为了研究内部结构，我们通过透射电镜观察样本的剖面，并得到纳米粒子的大小和形状分布等相关数据。首先，我们采用溶胶-凝胶法将银纳米粒子合成进聚乙烯吡咯烷酮(PVP)和无机母体二氧化硅（SiO2）中，研究了母体对纳米银粒子的大小和光学性质的影响。我们发现可以通过改变纳米银的前驱体AgNO3来调整银粒子的大小。在有相同AgNO3浓度的不同母体中，银纳米粒子以不同的速率增长。为了保持银纳米粒子粒径小于100纳米，我们在每一种母体中为AgNO3浓度设置一个上限，这个上限在二氧化硅母体中是8%，在聚乙烯吡咯烷酮母体中高达50%。由于溶胶-凝胶过程溶胶老化时间是非常重要的，所以我们研究了老化时间对纳米粒子的大小和光学吸收光谱的影响。研究发现，老化时间可以影响银纳米粒子的光吸收强度，说明老化时间在纳米粒子形成中是一个重要因素。由于不同母体的折射率不同，导致不同母体中银纳米颗粒的吸收峰是不同的，在PVP母体中吸收峰在425纳米，而在SiO2母体中吸收峰在442纳米。根据扫描电子显微镜（SEM）和原子力显微镜（AFM）结果可以看到，银纳米粒子很好的分布在膜中，在相同AgNO3浓度情况下，平均粒径在不同母体中以不同速率增加。对于同为1.6％AgNO3浓度，在SiO2平均粒径为65纳米，但在PVP母体中只有10纳米。硅基涂层具有化学耐久性能和生物相容性等独特的性质，使得它更适合作为银抗菌剂的衬底。苯基三乙氧基硅烷(PhTEOS)是另外一种存储纳米银的硅基材料。在第四章中，我们制备了含有银离子抗菌剂的溶胶-凝胶涂层，以此来阻止表面生物膜的形成。对这种涂层进行高温处理会导致纳米银的扩散，并可持续降低可利用的银的数量。在此我们提出可利用低温溶胶-凝胶方法制备含有大量银纳米粒子的硅烷基母体——苯基三乙氧基硅烷。把银盐溶入到溶胶-凝胶母体中会产生所需要的银的释放，即开始会在去离子水中产生高的释放率，然后会产生超过15天低的释放，这些可以通过电感耦合等离子体质谱法（ICP-MS）测得。我们将大约108CFU/ml富含营养的细菌悬液分别培养15和30天，然后把薄膜分别浸入到两种溶液中，通过扫描电镜（SEM）观察浸入前后薄膜的表面形貌。通过扫描电镜图片我们发现，包含35纳米粒子的薄膜可以阻止生物膜的形成长达30天。通过X射线电子能谱（XPS）证实了浸泡3天、9天和15天样品表面银的存在。在第五章中，利用低温溶胶-凝胶方法合成了两种不同的含有银粒子抗菌剂的硅基涂层。利用苯基三乙氧基硅烷和四乙基硅酸盐合成两种不同的硅烷基母体，以此为制备硅基薄膜做准备。利用紫外可见分光光度计、原子力显微镜和扫描电镜分析了这些薄膜的光学性质、表面形貌以及结构特性。分析纳米银在两种母体中的光学特性可以看到不同波长处的吸收峰，这些吸收峰的产生是由于纳米粒子的光吸收是受到周围媒介所影响的。我们同时发现在苯基三乙氧基硅烷母体中的银吸收强度高于四乙基硅酸盐中银的吸收强度，这表明更高浓度的银纳米颗粒注入到了涂层之中。我们通过把薄膜浸入到水中分别放置12天和20天来研究银的释放特性。通过AFM和SEM分析表明，苯基三乙氧基硅烷涂层含有更高的银纳米颗粒的注入以及更小的颗粒尺寸，并且在20天后有更多的颗粒保留在涂层中，从而产生更持久的抗微生物活性。作为单原子层sp2杂化，各碳原子紧密的排列在蜂窝状晶体结构中的一类物质，石墨烯由于它在纳米尺度具有高电流强度、传输特性、化学惰性、高的热导率、光学透射、大的表面积、生物相容性以及很好的疏水性而备受关注。在第六章我们成功制备了银纳米颗粒修饰的石墨烯氧化物层，并将其溶入到PVP薄膜中。通过分析含有银-石墨烯氧化物的PVP膜光学吸收谱可以发现，石墨烯的存在产生了不同位置的吸收峰。与不含有石墨烯氧化物相比，相同注入银并含有石墨烯氧化物PVP的表面等离子体在420纳米处的特征峰发生了蓝移。通过透射电镜观察沉积在石墨烯氧化物上的银纳米粒子可以看到，粒子分布直径范围在5-25纳米，并且受石墨烯层的影响粒子也呈六边形。通过高分辨率透射电镜（HRTEM）观测溶入到石墨烯氧化物层中的银纳米颗粒可以看到，银纳米颗粒在(111)晶面的晶格长度为0.236纳米。通过AFM研究含有氧化石墨烯PVP膜的表面形貌，其中石墨烯氧化物被不同数量的AgNO3修饰，在100℃干燥并加热到200℃。干燥后的薄膜中银的含量升高表明提升银的浓度可以增加银的表面含量和粒子的平均尺寸。0.025和0.08gr浓度的AgNO3对应粒子的平均晶粒大小约为12纳米和16纳米。可以明显看出热处理使得表面粒子扩散进入到了涂层当中，这种扩散现象同样可以在硅基涂层中观察到。用0.02gr AgNO3制得的含有银纳米粒子氧化石墨烯层的PVP涂层在100℃下烘干，在200℃下热处理2小时。以前的研究表明，热处理使得银纳米粒子扩散进入到涂层当中，从而使得涂层表面的粒子数降低。表面颗粒的减少对纳米银抗微生物剂的活性是不利的。在此我们发现银纳米颗粒的分布会随母体的不同而不同中，但是氧化石墨烯的存在使得即使在200℃热处理也会让银纳米颗粒维持在涂层表面。通过以上理论分析及实验研究，制备出了高密度、小粒径、适用于生物医学领域应用的复合材料抗菌涂层，并通过对其结构、物性和抗菌性能等的分析，系统研究了其物性与生物学特性之间的关系，为进一步开展新型抗菌材料的研究提供了支持。更多还原

【Abstract】 Recently, the physical properties of composite materials consisting of nanometre-sizedclusters of free electron metals in a dielectric have attracted much attention due to theirpotential applications in many areas including heterogeneous catalysis, anti-reflective films,biosensors and nonlinear optical devices. Metal nanoparticles dispersed in dielectricmaterials exhibit a strong characteristic extinction peak, due to plasmon resonance. Theshape, intensity and position of the peak can depend on the size, shape, concentration, andchemical state of the nanoclusters and also the possible interaction between them.Preventing device-related infections in surgical patients is a major concern for thescientific and health care communities. In conjunction with increased bacterial resistance toantibiotics, implant related infections cause serious health, safety, and financial burdens thatcould be prevented. Applying antibacterial coatings to implantable devices would be asimple method of improving existent medical technologies without hindering their overallfunction. A new trend of antibacterial coating includes those designed to actively releaseembedded bactericidal agents. With inimitable functionality and versatility, it’s no surprisethat nanocomposite materials have received a great deal of attention in the scientificcommunity. Silver is historically known to have extensive bactericidal properties withoutotherwise harming mammalian cells. Silver nanoparticles (Ag NPs) afford thesebactericidal properties to nanocomposites via the oxidation of Ag NPs into silver ions. Theions released from these coatings inhibit infection more efficiently than oral antibioticsbecause the antibacterial therapy is concentrated at the implant site, where it is needed.The present dissertation describes the synthesis, characterization, and incorporation ofstabilized silver nanoparticles into different matrices as well as their potential applications.Silver nanoparticles were synthesized into4different matrices and the effect of differentmedium on properties of silver containing coating as well as antibacterial activity ofdifferent coating containing nanosilver was extensively investigated.At the first step, a facile route has been developed to synthesis silver nanoparticles intopolyvinylpyrrolidone (PVP) as an organic storage for silver and silica (SiO2) as aninorganic matrix using sol-gel method. The influence of matrices on the size and opticalproperties of silver nanoparticles were studied. It is found that the particle size can betailored by changing the AgNO3as a nanosilver precursor. It was observed that silvernanoparticle size increases at different rate with silver nitrate (AgNO3) concentration indifferent matrices; there is an up-limit for AgNO3concentration in each given matrix tokeep the particle size below100nm. This limit is8%in silica matrix and can be as high as 50%for PVP matrix. Because the aging time of sol in sol-gel process is significant, theeffects of aging time on the size of nanoparticle and optical absorption spectrum were alsostudied. It is determined that aging time can affect the optical absorption intensity of silvernanoparticles which means that certain time is necessary in the formation of nanoparticles.The absorption peak is varied for different matrix and occurs at425in PVP matrix and at442in SiO2matrix because of the difference in refractive index of these two matrices.Based on Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM)images, Ag nanoparticles are well-dispersed into the film and the mean particle size of thenanosilver increases with the AgNO3content at different rate in different matrix. For thesame1.6%Ag NO3concentration, the mean particle size is65nm in SiO2matrix but only10nm in PVP matrix.Silica-based coatings are interesting substrates for biocide silver because of theirunique properties like chemical durability and biocompatibility.PhTEOS was another silica-based material which was selected for nanosilver storage.In Chapter4, Sol–gel coatings containing biocide silver ions are prepared for the preventionof biofilm formation on implanted surfaces. High-temperature processing of such coatingscan lead to diffusion of nano silver and reduce the amount of available silver for lastingeffect. Here, we present the preparation of silane based matrices, phenyltriethoxysilane(PhTEOS), containing different amount of Ag nanoparticles, using a low-temperature sol–gel method. The incorporation of a silver salt into sol–gel matrix resulted in a desired silverrelease scheme, i.e., with high initial release rate in de-ionized water followed by a lowersustained release for more than15days, as determined by inductively coupled plasma massspectrometry (ICP-MS). Scanning Electron Microscopy (SEM) has been employed toinvestigate the morphology of the film surfaces before and after immersion in a nutrient-rich bacterial suspension of approximately108CFU/ml, which was incubated for15and30days at37°C. From SEM images, it was found that thin films containing35nm particlescould prevent formation of biofilm for over30days. The presence of surface silver beforeand after3,9and15days immersion was confirmed by X-ray photoelectron spectroscopy(XPS).In chapter5, two different silica-based coatings containing biocide silver nanoparticleshave been synthesized using low temperature sol-gel method. Two different silane basedmatrices, were synthesized by applying phenyltriethoxysilane (PhTEOS) and tetraethylorthosilicate (TEOS) as precursor to prepare silica-based film. The films were analyzed byusing UV–visible spectrophotometry, atomic force microscopy (AFM) and scanningelectron microscopy (SEM) for their optical, surface morphological as well as structuralproperties. Optical properties of nanosilver in these two matrices showed that the peak absorption occurred at different wavelengths because; optical absorption of nanoparticles isaffected by the surrounding medium. It was also found that the silver absorption has higherintensity in PhTEOS than in TEOS matrix, indicating higher concentration of silvernanoparticles being loaded into the coating. To study silver release property, the films wereimmersed in water for12and20days. AFM and SEM analyzes showed that higherconcentration of silver nanoparticles and smaller particle sizes were synthesized intoPhTEOS coating and consequently, more particles remains on the surfaces after20dayswhich leads to longer antibacterial activity of PhTEOS coating.Graphene, a one-atom-thick planar sheet of sp2bonded carbon atoms densely packedin a honeycomb crystal lattice, has grabbed appreciable attention due to its exceptionalproperties including high current density, ballistic transport, chemical inertness, highthermal conductivity, optical transmittance, high surface area, biocompatibility and superhydrophobicity at nanometer scale. Decorating silver nanoparticles on the surface ofgraphene improves its antibacterial activity. In chapter6, we show the successfulpreparation of silver nanopartcle decorated graphene oxide sheets and embed them intoPVP film. Optical absorption spectra of PVP film containing Ag-GO shows that thepresents of graphene leads the shift of absorption peak of Ag-PVP film in the presence ofGO. The appearance of characteristic surface plasmon band at420nm, leads to a blue-shiftfor the absorption peak at the same concentration of silver in PVP without GO. TEMmicrograph of silver nanoparticles deposited on grapheme oxide sheets shows a wide sizedistribution of particles ranging from5–25nm and the particles are hexagonal in shape thatcould be the result of the deposition of the particles on the graphene sheets. Base on thefringe pattern of the HRTEM images, the lattice spacing of Ag nanoparticle deposited onthe GrO sheets is0.236nm, which corresponds to the (111) crystal plane.Atomic Force Microscopy (AFM) was employed to study the surface topography ofPVP film containing GO decorated by different amount of AgNO3dried at100°C and heat-treated at200°C. AFM images of the dried films containing higher Ag concentrationsdemonstrate that surface concentration and the mean particle size are increased by raisingthe Ag concentration. The mean particle size was measured to be about12nm for0.025and16nm for0.08gr AgNO3concentrations, respectively. It was observed that heat-treatmentcauses surface particles diffusion into the coating. This diffusion was also observed for Ag-Silica based coating. PVP coating containing grapheme oxide sheets embedded silvernanoparticles with0.02AgNO3was also dried at100°C and annealed at200°C for2hours.Previous studies showed that, heat-treatment leads diffusion of nanosilver into the coatingwhich causes surface particles reduction. Reduction of surface particle is undesired forantibacterial activity of biocide nanosilver. Here, we found silver nanoparticles concentration varies when embedded in different matrices, GO matrix causes silvernanoparticles to sustain on the surface of coating even being treated at200°C.Through this thesis work, we have successfully fabricated high concentration,silver nano-composite antibacterial coatings, which can be used in bio-medicalapplications. Based on structural analyses, property evaluation and biocide tests,we have given the correlation between physical properties and biocidecharacteristics, which laid the foundation for new bio-coating materials.更多还原