具有核-壳结构的金纳米包覆磁性纳米复合颗粒的研究进展

具有核-壳结构的金纳米包覆的磁性纳米粒子,既具有磁性纳米粒子的特点又增加了金纳米的表面化学性质,近年来受到研究人员的广泛关注。简要综述了近年来国内外制备2类核-壳结构的金包铁磁性纳米复合材料的研究进展及相关应用,并对其应用前景进行了展望。     

Au/锗/氧化硅纳米多层膜/p-Si结构的电致发光机制研究

用射频磁控溅射法制备了锗/氧化硅纳米多层膜,在室温下测量了Au/锗/氧化硅纳米多层膜/pSi结构的电致发光.利用位形坐标模型分析了锗/氧化硅纳米多层膜的发光中心,并用量子限制-发光中心模型对该纳米结构的电致发光过程作了研究,研究表明锗/氧化硅纳米多层膜的电致发光主要来自SiO2层的发光中心.     

细乳液法合成单核核壳结构氧化硅/聚苯乙烯复合微球

采用细乳液聚合法,以3-甲基丙烯酰氧基丙基三甲氧基硅烷(KH570)表面改性的直径50nm的氧化硅粒子为核,在乳化剂、助乳化剂、引发剂存在的情况下制备了小粒径、单核核壳结构氧化硅/聚苯乙烯纳米复合微球.研究表明,苯乙烯的浓度、超声细乳化时间,是制备这种小粒径、单分散、单核核壳结构的氧化硅/聚苯乙烯纳米复合微球的关键因素.透射电镜(TEM)的观察显示,在优化的实验条件下,可以制得平均粒径95nm,壳厚20nm,粒径均一、球形规整度较好、单核核壳结构的氧化硅/聚苯乙烯纳米复合微球.其平均粒径远低于用其它聚合方法制备的复合微球.     

核壳结构二氧化硅/磁性纳米粒子的制备及应用

核壳结构二氧化硅/磁性纳米粒子作为一种新型功能复合材料在生物医学方面有重要应用前景.综述了核壳结构二氧化硅/磁性纳米粒子的各种制备方法以及国内外在核壳结构二氧化硅/磁性纳米粒子制备方面的研究新进展,并对其在生物医学上的应用作了介绍.     

可控制备磁性四氧化三铁-金纳米复合颗粒及其催化性能研究

随着纳米催化剂的不断发展, 基于纳米金的多功能复合材料以其高效的催化性能而受到广泛关注。本研究采用简单可控的原位还原法, 制备了一种粒径均一、分散性良好、可快速磁分离且具有高催化活性与催化稳定性的磁性四氧化三铁-金纳米复合颗粒。首先用有机硅源-巯丙基三乙氧基硅烷(MPTES)水解得到的有机硅层来包覆粒径约100 nm的亲水四氧化三铁(Fe₃O₄)纳米颗粒, 再通过有机硅层表面的巯基来锚定原位还原生成的尺寸可控的金纳米颗粒(2 nm或6 nm), 得到内核为四氧化三铁、壳层为金纳米颗粒均匀修饰有机硅层的磁性氧化硅复合颗粒。利用透射电子显微镜(TEM)、动态光散射仪(DLS)和振动样品磁强计(VSM)等对所合成材料进行系统表征, 结果表明: 合成的磁性氧化硅复合颗粒核壳结构明显, 分散性良好, 粒径约为150 nm; 饱和磁强度为32.1 A•m²/kg, 具有良好的超顺磁特性。将其应用于4-硝基苯酚的催化还原, 转化频率(TOF)值高达70 s^-1, 远高于文献报道值, 五次循环反应后的转化率依然高达98%, 证实其具备高催化活性及良好的循环催化性能。     

氧化硅包覆铁“壳/核”型纳米复合粒子的制备及其吸波特性研究

采用非平衡物理气相蒸发法在氢气氩气混合气氛下制备了氧化硅包覆铁“壳/核”型纳米复合粒子. 通过X射线衍射(XRD)、透射电子显微镜(TEM)和能谱分析(EDS)等方法表征了纳米复合粒子的相组分、结构以及颗粒形貌. 结果表明,制备的氧化硅包覆铁纳米复合粒子的尺寸在50nm左右,在铁纳米粒子的表面还出现了非晶态的氧化硅纳米棒,长度为150~200nm. 利用电磁参数模拟微波吸收特性得出,涂层厚度为1.79mm时,在15.4GHz频率处达到最小反射损耗值为-14.5dB,反射损耗在8~18GHz的频段低于-10dB,且损耗机制为自然共振.     

小分子化合物表面修饰对金/二氧化硅纳米核壳粒子结构的影响

分别使用带有巯基的化合物半胱胺(Cys)、胱胺(CYS)、巯基丁二酸(MSA)和巯基乙醇(ME)对金/二氧化硅纳米核壳粒子(GNs)进行表面化学修饰。利用动态光散射(DLS)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)和紫外-可见吸收光谱(UV-Vis)对修饰后的GNs进行表征。研究结果显示Cys和CYS修饰后GNs胶体溶液稳定性下降,核壳结构完整性破坏,从而导致其在近红外区最大吸收峰消失。而MSA和ME修饰的GNs胶体溶液稳定,金壳结构完整,光学性质稳定。这可能是由于Cys和CYS的胺基通过与金壳之间产生静电力作用和配位作用,破坏了GNs表面金壳。     

炭化聚甲基丙烯酸甲酯／聚丙烯腈核壳聚合物制备炭纳米空心球

采用炭化聚甲基丙烯酸甲酯(PMMA)/聚丙烯腈(PAN)核壳聚合物的方法制备了炭纳米空心球.以两步无皂乳液聚合法制备了PMMA/PAN核壳粒子:首先以间歇无皂乳聚合法制备出直径约200 nm的PMMA粒子乳液,再以其作为种子乳液,以饥饿滴定法在PMMA外表而聚合一层厚度约30 nm的PAN外壳.将制备的PMMA/PAN乳液冷冻干燥后,分别经过250℃预氧化及1000℃炭化工艺,制备了炭纳米空心球.透射电镜结果显示所有核壳粒子均炭化成空心球并呈现交联状态.     

ZnS包覆 SiO2核壳和空腔结构纳米球制备研究

ZnS包覆SiO2三维核壳结构或空腔结构纳米球可用于光子晶体的组装.本实验采用层层自组装法,利用二氧化硅模板表面的静电作用吸附纳米晶粒子,生成纳米晶包覆层,制备核壳结构的SiO2@ZnS和SiO2@ZnS：Mn^2＋纳米球.控制氢氟酸对二氧化硅的蚀刻程度,制备了空腔型硫化锌纳米球.采用XRD、UV、PL、TEM、SEM、AFM等测试手段对核壳结构和空腔型硫化锌纳米球进行了表征.结果表明ZnS纳米晶包覆SiO2后,在其表面形成了包裹紧密、形貌规整、粒径均一的ZnS壳层;经5%氢氟酸蚀刻得到的空腔纳米球结构完好、厚度均匀.     

核壳结构纳米复合材料的研究进展

纳米粒子由于具有大量的潜在应用,近年来已引起人们极大的关注.通过制备具有核壳结构的纳米复合材料可以使其获得更多特殊的性质.综述了最近几年制备壳核结构纳米粒子的方法,根据其核、壳的不同材料分了4类,并对其中某些方法进行了比较,同时指出了目前该领域的应用前景、存在的不足和今后的研究发展方向.     

Scalable routes to gold nanoshells with tunable sizes and response to near-infrared pulsed-laser irradiation

A simplified synthesis of hollow gold nanoshells 20-50 nm in diameter via the well-established templated galvanic replacement reaction of silver for gold is presented. The surface plasmon resonance absorbance of the nanoshells is tuned using basic colloid chemistry to control the size of the silver templates. The gold nanoshells have an aqueous core and are varied in size and shell thickness depending on the silver/gold reagent ratios. The template replacement chemistry is rapid, highly scalable, uses minimal amounts of toxic reagents, and in many cases is a true one-pot synthesis. The smallest nanoshells (20-nm diameter, 7-nm wall thickness) reach the highest temperature on irradiation with femtosecond light pulses in the near infrared and anneal to form spherical nanoparticles fastest, even though their plasmon resonance does not overlap as well as the larger nanoshells (50-nm diameter, 7-nm wall thickness) with 800-nm wavelength excitation.     

Metal nanoshell assembly on a virus bioscaffold

Chilo iridescent virus is demonstrated as a useful core substrate in the fabrication of metallodielectric, plasmonic nanostructures. A gold shell is assembled around the wild-type viral core by attaching small, 2-5-nm gold nanoparticles to the virus surface by means of the chemical functionality found inherently on the surface of the proteinaceous viral capsid. The density of these nucleation sites was maximized by reducing the repulsive forces between the gold particles through electrolyte addition. These gold nanoparticles then act as nucleation sites for the electroless deposition of gold ions from solution around the biotemplate. The optical extinction spectra of the metalloviral complex is in quantitative agreement with Mie scattering theory. Overall, the utilization of a native virus and the inherent chemical functionality of the capsid afford the ability to grow and harvest biotemplates for metallodielectric nanoshells in large quantities, potentially providing cores with a narrower size distribution and smaller diameters (below 80 nm) than for currently used silica.     

Immunotargeted nanoshells for integrated cancer imaging and therapy

Nanoshells are a novel class of optically tunable nanoparticles that consist of a dielectric core surrounded by a thin gold shell. Based on the relative dimensions of the shell thickness and core radius, nanoshells may be designed to scatter and/or absorb light over a broad spectral range including the near-infrared (NIR), a wavelength region that provides maximal penetration of light through tissue. The ability to control both wavelength-dependent scattering and absorption of nanoshells offers the opportunity to design nanoshells which provide, in a single nanoparticle, both diagnostic and therapeutic capabilities. Here, we demonstrate a novel nanoshell-based all-optical platform technology for integrating cancer imaging and therapy applications. Immunotargeted nanoshells are engineered to both scatter light in the NIR enabling optical molecular cancer imaging and to absorb light, allowing selective destruction of targeted carcinoma cells through photothermal therapy. In a proof of principle experiment, dual imaging/therapy immunotargeted nanoshells are used to detect and destroy breast carcinoma cells that overexpress HER2, a clinically relevant cancer biomarker.     

Facile control of DNA-templated inorganic nanoshell size

We elaborated a facile method to control the size of CdS nanoshells obtained by DNA assisted "double templating" approach. By changing the concentration of NaCl in solution to vary the extent of DNA electrostatic deposition on cationic silica beads, we succeeded to control the density of DNA adsorbed on the beads, and further the density of CdS material grown on DNA. Further dissolution of the silica core triggers shrinking of CdS shell to a different extent depending on the CdS shell density and results in formation of CdS nanoshells of different sizes from ca. 100 nm to ca. 400 nm. Therefore, the main advantage of the proposed method is that it can be used to synthesize hollow nanoshells of various sizes, from ca. 25% to ca. 75% size of the primary template (silica bead), by using only one single primary template.     

Gold nanoshell photomodification under a single-nanosecond laser pulse accompanied by color-shifting and bubble formation phenomena

Laser-nanoparticle interaction is crucial for biomedical applications of lasers and nanotechnology to the treatment of cancer or pathogenic microorganisms. We report on the first observation of laser-induced coloring of gold nanoshell solution after a one nanosecond pulse and an unprecedentedly low bubble formation (as the main mechanism of cancer cell killing) threshold at a laser fluence of about 4?mJ?cm(-2), which is safe for normal tissue. Specifically, silica/gold nanoshell (140/15?nm) suspensions were irradiated with a single 4?ns (1064?nm) or 8?ns (900?nm) laser pulse at fluences ranging from 0.1?mJ?cm(-2) to 50?J?cm(-2). Solution red coloring was observed by the naked eye confirmed by blue-shifting of the absorption spectrum maximum from the initial 900?nm for nanoshells to 530?nm for conventional colloidal gold nanospheres. TEM images revealed significant photomodification of nanoparticles including complete fragmentation of gold shells, changes in silica core structure, formation of small 20-30?nm isolated spherical gold nanoparticles, gold nanoshells with central holes, and large and small spherical gold particles attached to a silica core. The time-resolved monitoring of bubble formation phenomena with the photothermal (PT) thermolens technique demonstrated that after application of a single 8?ns pulse at fluences 5-10?mJ?cm(-2) and higher the next pulse did not produce any PT response, indicating a dramatic decrease in absorption because of gold shell modification. We also observed a dependence of the bubble expansion time on the laser energy with unusually very fast PT signal rising (～3.5?ns scale at 0.2?J?cm(-2)). Application of the observed phenomena to medical applications is discussed, including a simple visual color test for laser-nanoparticle interaction.     

Reversible shape transition: Plasmonic nanorods in elastic nanocontainers

We demonstrate the reversible rod-to-sphere shape transition of gold/mesoporous silica core/shell nanorods, where the shell acts as an elastic nanocontainer during the shape change. It is shown, that elongated core/shell nanorods are transformed into spherical core/shell particles at 300 °C. The anisometric shape of the composite particles can be recovered upon in-situ seeded growth of the gold core. The mesoporous silica shell acts as a nanoscale confinement, enabling control over the growth procedure during the chemical reaction. The shell of the particles was found to be elastic; it shows conformal shape-change with the core material during the heating and the subsequent seeded growth process. The effect of the reaction conditions during the seeded growth on the resulting particle morphology was also investigated. It is demonstrated, that depending on the growth conditions, core/shell nanorods or larger core/shell nanospheres can be obtained. The shape transformation cycle can be repeated for the same system several times, where the break-up of the confining shell represents the physical limit of the process.     

Plasmonic photothermal therapy of colon cancer cells utilising gold nanoshells: an in vitro study

In this study, gold nanoshell (GNS) were synthesised utilising the Halas method. The obtained nanoparticles (NPs) were characterised by Fourier‐transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–Vis spectroscopy and dynamic light scattering. FTIR spectra demonstrated the successful functionalisation of silica NP with 3‐aminopropyl trimethoxysilane. SEM and TEM images showed the morphology and diameter of the synthesised silica NPs (137 ± 26 nm) and GNS. UV–Vis spectrum illustrated the maximum absorbance of the resultant GNS and their average hydrodynamic diameter was 159 nm. For in vitro study, HCT‐116 cells were exposed to gold nanoshells and intense pulsed light in different experiment groups. The results showed that exposing the cells to nanoshells and 30 s irradiation would efficiently decrease the viability percentage of the cells to about 30% compared with the control. A continued exposure of 4 min decreased the viability of the cancer cells to 20%. The results demonstrated that photothermal therapy would be promising in treatment of colon cancer cells utilising gold nanoshells.Inspec keywords: gold, silicon compounds, nanomedicine, plasmonics, radiation therapy, bio‐optics, cancer, cellular biophysics, nanoparticles, Fourier transform spectra, infrared spectra, scanning electron microscopy, transmission electron microscopy, ultraviolet spectra, visible spectraOther keywords: plasmonic photothermal therapy, colon cancer cells, gold‐silica nanoshells, GNS, Halas method, Fourier transform infrared spectroscopy, FTIR, scanning electron microscopy, SEM, transmission electron microscopy, TEM, UV‐vis spectroscopy, dynamic light scattering, FTIR spectra, 3‐aminopropyl trimethoxysilane, morphology, in vitro study, HCT‐116 cells, cell viability, nanoparticles, time 30 s, time 4 min, Au     

Langmuir-Blodgett films of gold/silica core/shell nanorods

We report the preparation of Langmuir- and Langmuir-Blodgett films of mesoporous silica coated gold nanorods. The silica coating on the gold nanorods was found to prevent the aggregation of the plasmonic particles trapped at the air/water interface. Due to the small aspect ratio of the gold core and the presence of the silica shell, the orientational alignment of the nanorods in the Langmuir-Blodgett film is hindered. After particle deposition, no plasmon coupling was observed, which enables the design of the resulting film's optical property at the particle level. By using mesoporous silica as the shell material, the accessibility of the metal core's surface is preserved. Organic dye (Rhodamine 6G) was found to be able to penetrate into the mesoporous shell of the gold nanorods, resulting in a red shift of the longitudinal plasmon mode.     

Selective Patterning of Gold Surfaces by Core/Shell,Semisoft Hybrid Nanoparticles

The generation of patterned surfaces with well‐defined nano‐ and microdomains is demonstrated by attaching core/shell, semisoft nanoparticles with narrow size distribution to microdomains of a gold‐coated silicon wafer. Near monodisperse nanoparticles are prepared using reversible addition‐fragmentation chain transfer (RAFT) polymerization, initiated from a silica surface, to prepare a polystyrene shell around a silica core. The particles are then used as‐prepared, or after aminolysis of the terminal thiocarbonyl group of the polystyrene shell, to give thiol‐terminated nanoparticles. When gold‐coated silicon wafers are immersed into very dilute suspensions of these particles (as low as 0.004 wt%), both types of particles are shown to adhere to the gold domains. The thiolated particles adhere selectively to the gold microdomains, allowing for microdomain patterning, while particles that contain the trithiocarbonate functionality lead to a much more even coverage of the gold surface with fewer particle aggregations.