硫醇衍生化的纳米金与癌胚抗原相互作用的光学分析

Optical Analysis of the Interaction of Mercaptan Derivatives of Nanogold Particles with Carcinoembryonic Antigen

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。

Gold nanoparticles（AuNPs）have been the subject of intense research for use in biomedicine over the past couple of decades.AuNPs,also referred to as colloidal gold,possess some astounding optical and physical properties that have earned them a prime spot among the new promising tools for medical applications.Today,AuNPs are offered to provide the clinical laboratory with more sensitive,faster,and simpler assays,which are also cost-effective.AuNPs can be used to develop point-ofcare tests and novel testing strategies such as in drug targeting,disease detection,molecular recognition,and biological labels.The typical structure of AuNPs is spherical nano-sized gold particles,but they can also be composed of a thin gold shell surrounding a dielectric core,such as silica（gold nanoshells）.their size range from 0.8to 250 nm and are characterized by high absorption coefficients.AuNPs have some unique optical properties,such as enhanced absorption and scattering,where the absorption cross-section of AuNPs is 4~5orders of magnitude greater than that of rhodamine 6G.When AuNPs aggregate,interaction of locally adjacent AuNPs（plasmon-plasmon interaction）shifts their color to blue.Thus,the binding of AuNP-labeled entities to their respective target would lead to aggregation of the nanoparticles and a detectable shift in the optical signal.The strong absorption of AuNPs can also be used in colorimetric detection of analytes by measuring changes in the refractive index of the AuNP＇s environment caused by adsorption of the target analytes.However,a large number of surface atoms of nanoparticles have huge surplus bonding ability,because of surface effect of gold nanoparticles,result in reuniting and sinking among the nanoparticles which make them unstable.In order to detect traces of carcinoembryonic antigen,one of the tumor targets,a new kind of gold nanoparticle with hyperchormic effect and fluorescence sensitization effect material needs to be prepared.In this paper,novel mercaptan derivative of nanogold particles are prepared and studied using transmission electron microscopy（TEM）,ultraviolet-visible absorption spectra（UV-Vis）,fluorescence emission（FE）spectrum and infrared spectrum（IR）methods.The UVVis and FE results show the presence of new ligands mercaptan,more electrons from the orbit of ligand which can excite to the central ion related orbits and increase fluorescence of gold.Fluorescence sensitization effect was observed when mercaptan derivatives of nanogold interacted with carcinoembryonic antigen（CEA）and no fluorescence sensitization effect was found when nanogold interacted with carcinoembryonic antigen（CEA）.The study of CEA hyperchromic mechanism of mercaptan derivatives nanogold and the CEA by the method of infrared spectrum,shows that the randomized OH bonds in the Au-protein interaction,showed more on the outside of the plane of bending vibration after the interaction with the mercaptan derivative nanogold,making the energy transfer from mercaptan derivatives nanogold to protein easy;leading to its fluorescence sensitization effect.