光学仪器 眼镜、放大镜、显微镜、望远镜

TH742.642006054715激光共聚焦显微镜观察光敏剂ALA和HMME在肿瘤细胞的胞内分布=CLSMi maging of5-ALA and HMMEintumor cells[刊,中]/肖卫东(第三军医大学新桥医院.重庆(400038)),陈炜…//激光杂志.—2006,27(2).—95使用激光共聚焦显微镜观察光敏剂5-ALA和HMME在结肠癌SW480细胞及红白血病K562细胞的胞内分布。5-ALA及HMME进入肿癌细胞早期主要分布于胞膜,而在后期主要以颗粒状荧光分布于胞质,5-ALA分布相对弥散,HMME分布相对集中,核内分布极少。光敏剂5-ALA和HMME主要分布于肿瘤细胞的胞质,表明它们的光化学作用位…     

Au@TiO_2纳米核壳与HMME结合体的制备及其光动力疗效初探

光动力疗法(PDT)是一种高效、安全、微创的新型治疗方法,国产光敏剂血卟啉单甲醚(HMME)介导的光动力疗法由于其成分单一、单态氧产量高及光敏周期短,临床上已用于脑胶质瘤和鲜红斑痣的治疗。为了进一步提高光动力疗效,本研究基于晶种生长法制备稳定粒径均一的吸收峰在530nm的阳离子金纳米球。采用毒性低且阴离子电解活化作用强的聚(四-苯乙烯磺酸钠)(PSS)进行修饰。利用静电吸引力将钛源TiCl_3水解的TiOH~(2+)与其结合并氧化制备AuNP@TiO_2核壳,通过改变NaHCO_3量制得不同TiO_2壳层厚度的AuNP@TiO_2核壳,并进一步将其与HMME结合制备结合体。采用紫外-可见吸收光谱、红外光谱、激光纳米粒度仪和透射电镜对所制样品进行表征。结果表明新型的光敏剂粒径均匀,结构稳定。最后采用细胞实验验证了其光动力疗效。总之,该研究合成了新型的Au@TiO_2-HMME纳米光敏剂,通过人口腔表皮样癌细胞系KB细胞与新型核壳纳米结构的光动力作用,与纯HMME相比,在最优条件下可提高约35%的细胞杀伤率。     

硫醇衍生化的纳米金与癌胚抗原相互作用的光学分析

纳米金已在在药物靶向传输体系、疾病检测、分子识别、生物标签等领域有着广泛的应用,但是,由于纳米金的表面效应,大量的表面原子具有巨大剩余成键能力,使得纳米金粒子较容易团聚、沉聚,影响了其稳定性。为了实现对肿瘤靶标之一-癌胚抗原的痕量检测,需要制备出对癌胚抗原检测具有良好的增色效应与荧光增敏效应的纳米材料。该工作采用纳米金的硫醇衍生法制备了一种新型的硫醇衍生化的纳米金材料,并对此新型硫醇衍生化的纳米金材料的特性用透射电子显微镜,紫外-可见吸收光谱,荧光发射光谱和红外光谱等方法进行了研究。紫外-可见吸收光谱,荧光发射光谱的实验结果表明,在新的配体乙二硫醇存在下,有更多的电子从配体的轨道跃迁到与中心离子相关的轨道上,导致荧光增强。这种新型硫醇衍生化的纳米金与癌胚抗原作用时表现出增色效应与荧光增敏效应,而纳米金与癌胚抗原作用时看不到这种增色效应与荧光增敏效应。红外方法的研究结果表明,这种材料的蛋白增色机理为当硫醇衍生化纳米金与癌胚抗原蛋白作用时,体系中蛋白的—OH表现出更多的面外弯曲振动,有利于电子从硫醇衍生化纳米金配合物向蛋白转移而导致其增色和荧光增敏效应。因而这种新的硫醇衍生化纳米金材料比纳米金将具有更好的生物检测应用价值。     

聚乙二醇-b-聚(4-乙烯基吡啶)/氢氧化钇杂化纳米管在金纳米粒子负载方面的应用

利用聚乙二醇-b-聚(4-乙烯基吡啶)(PEO-b-P4VP)胶束在氢氧化钇纳米管(YNTs)表面上的吸附,制备出被致密的P4VP内层和伸展的PEO外层包裹的杂化纳米管. 通过小分子交联剂1,4-二溴丁烷交联P4VP层可进一步稳定其结构. 然后将交联的杂化纳米管(CHNTs)作为金纳米粒子(GNPs)催化剂的新型纳米载体. 金纳米粒子被负载在交联杂化纳米管的P4VP层中(GNPs/CHNTs),并应用于催化对硝基苯酚的还原反应. 结果表明,这种新型的纳米载体在水溶液中具有良好的分散性, 对金纳米粒子有很高的负载效率(0.87 mmol/g),负载的金纳米粒子保持了很高的催化活性(12.9 μmol^-1min^-1),且GNPs/CHNTs有较好的可重复使用性.     

半胱氨酸修饰金纳米棒光学性质的研究

采用种子生长法制备了不同长径比的金纳米棒,并通过金硫键的结合在其表面包覆半胱氨酸分子。利用紫外-可见吸收光谱仪,扫描电子显微镜以及拉曼光谱仪等对样品进行分析和表征。实验结果表明金纳米棒产率较高,且一致性较好。表面修饰后的金纳米棒的纵向吸收峰发生蓝移,表明半胱氨酸分子与金纳米棒的结合有助于溶液分散性的提升。以结晶紫为探针分子,随着金纳米棒长径比的增加其拉曼增强效果变强。进一步分析发现,修饰后的金纳米棒的表面增强拉曼光谱的增强效果并未受到影响。通过金纳米棒与半胱氨酸分子牢固的结合,一方面可以提高金纳米棒溶液的分散性与稳定性;另一方面半胱氨酸分子可为金纳米棒修饰其它有机官能团提供了一个牢固的桥梁,有效地拓展了金纳米棒的应用方向。     

十八胺LB膜吸附组装金纳米颗粒研究

制备了十八胺单层、多层LB膜及粒径为几个纳米的金纳米粒子。pH值小于10.3时十八胺带正电荷,将其置于金纳米溶胶(pH值10.3)中,带负电荷的金纳米粒子与带正电荷的十八胺之间通过静电作用,金纳米颗粒被成功地吸附组装到十八胺LB膜中,形成纳米薄膜。紫外-可见光谱、红外光谱及扫描电镜显示:金纳米颗粒通过这种方法能够很好的组装在十八胺LB膜上,且其组装层整齐有序,同时也受十八胺LB膜层数及组装时间的影响。     

金纳米棒核／二氧化硅壳纳米复合结构的可控制备及细胞成像

采用模板合成以及溶胶凝胶方法制备了金纳米棒核／二氧化硅壳（GNR@SiO2）纳米复合粒子,探讨了这种新型纳米复合结构的可控制备、光谱性质、细胞毒性和细胞成像。通过紫外可见分光光度计、透射电镜、共聚焦显微镜对样品进行表征,结果表明：通过对反应时间的调控,获得的纳米复合粒子的二氧化硅壳层厚度可以控制在20～30nm。由于二氧化硅壳层的存在,大大提高了金纳米棒的稳定性,同时降低了金纳米棒的细胞毒性;此外,由于二氧化硅壳层具有良好的化学修饰作用,因此可以将荧光探针分子标记在二氧化硅壳层表面,修饰后的纳米复合粒子可以通过细胞内吞作用进入细胞,从而实现细胞内的光学成像。因此,该纳米粒子复合材料在生物传感、细胞成像以及光热治疗等方面有着良好的应用前景。     

新型膜状金纳米活性基底的制备及拉曼光谱增强研究

贵金属纳米粒子作为增强基底已经广泛应用于表面增强拉曼光谱(SERS)研究,传统的贵金属纳米基底在制备方法、增强能力、准确性等方面仍有待改进和提高。采用一种简易、高效的方法制备出了一种具有膜状结构的新型金纳米增强基底：以聚乙烯吡咯烷酮(PVP)作保护剂和粘结剂,通过化学还原法制备金纳米基底。实验考察了还原剂种类、反应温度、体系pH和柠檬酸钠浓度对反应的影响,制备出增强效果最佳的新型膜状金纳米基底。利用罗丹明B作为探针分子,考察基底的SERS特征,其增强因子可达6.5×105。利用扫描电镜(SEM)对纳米粒子的结构进行了表征,结果表明其具有膜状结构,且比表面积大,利于分子的吸附。相比于传统的贵金属纳米基底,该实验所制备的新型膜状金纳米基底增强效果更佳、灵敏度和准确度更高,具有很大的应用前景。     

干净、均一的表面增强拉曼基底的制备和表征

采用盐酸羟胺种子生长法制备60 nm左右的粒径均一的金纳米粒子, 通过在ITO上修饰3-氨基丙基-三甲氧基硅烷(APTMS)对金纳米粒子进行组装, 得到组装密度较高、均一的表面增强拉曼光谱(SERS)基底; 采用等离子体清洗再用醋酸溶液浸泡除去氧化层的方法, 可获得干净的SERS基底, 这种方法与其它基底除杂方法相比更为简单、操作性强且信号只衰减了20%。     

金纳米粒子的电化学合成及光谱表征

采用电化学方法合成各种形状的金纳米粒子,生成的金纳米粒子形貌与施加电流有关,通过匀速递增电流电解的方法,可制备得到哑铃形,球形以及棒状金纳米粒子,采用恒电流电解方法主要获得球形及哑铃形纳米粒子。利用透射电镜、紫外-可见光谱及拉曼光谱对金纳米粒子进行相关表征。紫外-可见光谱研究发现金纳米棒出现位于近红外区间的吸收峰(985 nm),由此推测棒的长径比约为6。以结晶紫为探针分子,研究了金纳米粒子的表面增强拉曼光谱(SERS)效应,并分析得出其平躺的吸附模式。根据形貌表征的结果推断了纳米粒子的生长机理。     

Colour tunability in a bimodal fluorescent hybrid nanostructure UCNPs@AuNPs@QDs

In the present work, lysine modified NaY_0.78Er_0.02Yb_0.2F₄ upconversion nanoparticles (UCNPs, positively charged) and lysine modified ZnSe:Mn²⁺ quantum dots (QDs, positively charged) are attached onto the surface of citrate reduced gold nanoparticles (AuNPs, negatively charged). The gold nanoparticles not only entangle the QDs and the UCNPs, through electrostatic interaction, but also tune the optical properties of UCNPs through the effect of surface plasmon resonance. The hybrid nanostructure gives green emission both through photoluminescence (under UV excitation) and through photon upconversion (under IR light excitation) process. The colour tuning is observed through variation in the size of QDs and through plasmonic effect of gold nanoparticles. In both the cases, the colour of emission gradually changes from green to red. The colour tunability and bi-modal photon conversion property of this material could be useful for its application in the field of bio-imaging and solar energy harvesting.     

Charge‐dependent adsorption of rhodamine 6G on gold nanoparticle surfaces: fluorescence and Raman study

We study the adsorption behaviors of rhodamine dyes on gold nanoparticles (Au NPs) depending on their surface charges. Rhodamine 6G (Rh6G) dye is tested comparatively for positively and negatively charged Au NPs prepared by the reduction of chitosan and citric acid, respectively. The adsorption of Rh6G is found to be weaker on the positively charged Au NPs, whereas more substantial aggregation is found on negatively charged Au NPs. An increase in the concentration of Au NPs enhances the surface‐enhanced Raman scattering (SERS) intensities only for the Au(−) NPs, whereas the Au(+) NPs do not exhibit any strong SERS signals. Our findings suggest that SERS and reciprocal fluorescence measurements of Rh6G can be used to estimate the surface charges and atomic percentages of Au NPs less than ∼5 ppm. Copyright © 2011 John Wiley & Sons, Ltd.     

Two-dimensional nanopatterning by PDMS relief structures of polymeric colloidal crystals

A new constructive method of fabricating a nanoparticle self-assembly on the patterned surface of a poly(dimethylsiloxane) (PDMS) relief nanostructure was demonstrated. Patterned PDMS templates with close-packed microwells were fabricated by molding against a self-assembled monolayer of polystyrene spheres. Alkanethiol-functionalized gold nanoparticles with an average particle size of 2.5 nm were selectively deposited onto a hydrophobic self-assembled monolayer printed on the substrate by the micro-contact printing (μCP) of the prepared PDMS microwell, in which the patterned gold nanoparticles consisted of close-packed hexagons with an average diameter of 370 nm. In addition, two-dimensional colloidal crystals derived from PMMA microspheres with a diameter of 380 nm and a negative surface charge were successfully formed on the hemispherical microwells by electrostatic force using positively charged PAH-coated PDMS as a template to produce multidimensional nanostructures.     

Stable multilayer thin films composed of gold nanoparticles and lysozyme

It needs appropriately attractive forces to construct multilayer thin films by layer-by-layer (LBL) assembly technique. It is feasible to prepare multilayer thin films on glass slides with negatively charged gold nanoparticles and positively charged lysozyme through the electrostatic LBL assembly technique. The gold nanoparticles/lysozyme multilayer thin films are highly stable; immersion in 0.1 M HCl, NaOH, and surfactant sodium dodecyl sulfate aqueous solutions cannot destroy the films. The highly stable gold nanoparticles/lysozyme multilayer thin films have potential application in long-term antibacterial coating.     

Trapping and release of citrate-capped gold nanoparticles

An electrical method to trap and release charged gold nanoparticles onto and from the surface of gold electrodes modified by an alkanethiol self-assembled monolayer (SAM) is presented. To form electrodes coated with gold nanoparticles (GNPs), amine-terminated SAMs on gold electrodes were immersed in a solution of negatively charged citrate-capped GNPs. Accumulation of GNPs on the electrode surface was monitored by a decrease in the impedance of the SAM-modified electrode and by an increase in the electrochemical activity at the electrode as shown through cyclic voltammetry (CV). Electrostatic interactions between the GNPs and the amine-terminated SAM trap the GNPs on the electrode surface. Application of a subsequent negative bias to the electrode initiated a partial release of the GNPs from the electrode surface. Impedance spectroscopy, cyclic voltammetry, ultraviolet-visible (UV-Vis) spectroscopy and atomic force microscopy (AFM) were used to monitor and confirm the attraction of GNPs to and release from the aminealkanethiolated gold electrodes. This work describes a method of trapping and release for citrate-capped GNPs that could be used for on-demand nanoparticle delivery applications such as in assessing and modeling nanoparticle toxicology, as well as for monitoring the functionalization of gold nanoparticles.     

荧光/表面增强拉曼散射双模式纳米光学探针的构建及性能研究

提出一种新型的荧光及表面增强拉曼散射（SERS）双模式光学纳米探针。首先,通过再沉淀-包覆法合成二氧化硅包覆香豆素6的纳米颗粒,再在二氧化硅表面静电吸附多聚赖氨酸分子形成包覆层,随后通过原位还原的方法在多聚赖氨酸壳层复合银纳米颗粒,最后在银纳米颗粒表面吸附拉曼分子即形成双模式纳米探针。该探针通过二氧化硅包覆的荧光分子产生荧光信号,以多聚赖氨酸表面的银纳米颗粒作为SERS增强基底,利用拉曼分子获得SERS信号,实现了荧光及SERS双模式成像。荧光与表面增强拉曼散射相结合的双模式分析技术可同时发挥二者的优点,提高成像的分辨率和灵敏度,在生物医学领域具有重要的应用价值。     

Annealing of magnetic nanoparticles for their encapsulation into microcarriers guided by vascular magnetic resonance navigation

Cellular uptake, cytotoxicity, and mechanisms of cytotoxicity of the positively charged Au nanoparticles (NPs) were examined in A549 cells, which are one of the most characterized pulmonary cellular systems. Positively charged Au NPs were prepared by chemical reduction using chitosan. The dimension and surface charge of Au NPs were examined by transmission electron microscopy (TEM), dynamic light scattering, and zeta potential measurements. The uptake of Au NPs into A549 cells was also monitored using TEM and dark-field microscopy (DFM) and z-stack confocal microRaman spectroscopy. DFM live cell imaging was also performed to monitor the entry of chitosan Au NPs in real time. The cytotoxic assay, using both methylthiazol tetrazolium and lactate dehydrogenase assays revealed that positively charged Au NPs decreased cell viability. Flow cytometry, DNA fragmentation, real-time PCR, and western blot analysis suggest that positively charged chitosan Au NPs provoke cell damage through both apoptotic and necrotic pathways.     

SERS标记免疫金溶胶的影响因素研究

将表面增强拉曼光谱(SIERS)的高度灵敏性应用于标记免疫检测,具有很大的意义。在“固相抗体-待测抗原-标记抗体”夹心复合物体系中,以(SERS)标记的金溶胶与抗体结合,制备标记抗体。以芳香族化合物苯硫酚为标记分子,与一定大小粒径的金纳米粒子形成S-Au键,生成带有SERS信号的标记金溶胶。表面带负电荷的标记金溶胶与带有正电荷基团的抗体形成牢固的标记免疫金溶胶。从金纳米粒子粒径的选择、在金溶胶中加入苯硫酚的量及反应时间、抗体对标记金溶胶标记分子的SERS信号的影响进行了研究。     

Surface modification of gold nanorods using layer-by-layer technique for cellular uptake

Gold nanorods (NRs), rod-shaped gold nanoparticles, were modified with bovine serum albumin (BSA) and polyethylenimine (PEI) using layer-by-layer technique. From absorption spectroscopy and zeta potential measurements, it was obvious that NRs were wrapped with these polymers without aggregation of NRs. Following BSA modification, the surface-modified NRs (BSA-NRs) were well-dispersed without aggregation in biochemical conditions, verified from absorption spectroscopy. Further modification with PEI provided positively charged NRs (PEI-NRs). A transmission electron microscopy image of PEI-NRs revealed that the surface modification did not affect changing the shape of the initial NRs. In addition, the PEI-NRs retained the colloidal stability of BSA-NRs in biochemical conditions. We have evaluated that transfection activity of PEI-NRs with HeLa cells. From results of gene expression experiments, it was obvious that the stabilization of NRs by BSA and further modification with PEI realized transfection using NRs into cultured cells. Moreover, the cellular uptake of NRs enabled cellular imaging using light scattering from the NRs.     

Rhodamine B-Coated Gold Nanoparticles as Effective “Turn-on” Fluorescent Sensors for Detection of Zinc II Ions in Water

We designed a fluorescence resonance energy transfer system consisting of fluorophore Rhodamine B and gold nanoparticles for sensing of zinc ions in aqueous solution. The electrostatic attraction between positively charged N-atoms in Rhodamine molecules and negatively charged citrate corona of gold nanoparticles led to substantial fluorescence quenching. However, the quenching is switched off in the presence of zinc ions and therefore the system can be used as an effective “turn-on” fluorescence sensor. UV-Vis absorption, fluorescence spectroscopy, and transmission electron microscopy were used for sensor evaluation. The approach of “turn-on” fluorescence has real potential for sensing metallic ions in water.