【作者】 王艳芳；

【导师】 杨文胜；

【作者基本信息】 吉林大学 ， 物理化学， 2017， 硕士

【摘要】 荧光染料发展非常迅速,广泛应用于荧光免疫,荧光探针,细胞染色等。然而其应用往往会受到荧光染料分子发射强度低、稳定性差以及在水中溶解度较低等缺点的制约。近年来,贵金属粒子@二氧化硅核壳型复合材料优良的生物相容性、水溶性以及独特的光学性质,使其在环境监测、生化分析、生物成像及临床诊断等诸多领域展现了广阔的应用前景。研究表明,将染料掺杂到这种核壳型复合材料中时,可以提高激发效率、增强发光。目前,被用于金属增强荧光的金属纳米材料一般为银纳米球、金纳米球以及金纳米棒等等。但是银纳米球的表面易于被氧化、稳定性差,包覆过程不可控等等的性质在一定程度上限制了其应用,而金纳米球的荧光增强作用往往达不到理想的效果,所以具有独特的各向异性的非球形纳米粒子逐渐受到关注。金纳米花粒子是表面为多枝结构,具有较大的比表面积的一种金纳米粒子,相较于球形粒子,拥有着更好的表面增强拉曼散射、催化等性质,并被广泛应用。论文主要研究了金纳米花@二氧化硅-异硫氰酸罗丹明B（Au NF@SiO₂-RBITC）核壳型复合材料的可控制备,系统的考察金纳米花内核、染料浓度以及二氧化硅壳层厚度对粒子荧光性质的影响。以此为基础,建立了一种新型的铜离子荧光检测方法。主要的工作内容包括:1.Au NF@SiO₂-RBITC核壳型复合材料的可控制备及其荧光性质研究。在St?ber体系中,通过调节氨水用量,将金纳米花包覆于二氧化硅壳层中,制备了一系列Au NF@SiO₂复合粒子,其二氧化硅壳层厚度分别为7,12,15,17和22 nm。接下来将染料RBITC与氨基化的硅烷试剂3-氨丙基三乙氧基硅烷（APS）共价偶联,通过APS-RBITC与四乙氧基硅烷（TEOS）进行共水解缩合反应,制备出Au NF@SiO₂-RBITC复合粒子。系统的考察金纳米花内核、染料浓度以及二氧化硅壳层厚度对粒子稳态及瞬态荧光性质的影响。研究发现,在实际掺杂的RBITC浓度为7.25×10-4 mg/m L,二氧化硅壳层厚度为15 nm时,Au NF@SiO₂-RBITC复合粒子显现了最优化的金属增强荧光效应。与相同的条件下无金纳米花内核的SiO₂@SiO₂-RBITC粒子相比,Au NF@SiO₂-RBITC的荧光增强了4倍,染料荧光寿命显著降低。2.Au NF@SiO₂-RBITC复合粒子对铜离子的荧光响应行为研究。选择SiO₂壳层厚度为15 nm的Au NF@SiO₂-RBITC复合粒子研究其对铜离子的荧光响应行为。铜离子与氨水通过配位键结合而形成四氨合铜络离子（[Cu（NH3）4]2+）,其吸收峰位于600 nm,与Au NF@SiO₂-RBITC复合粒子的发射光谱相互重叠。从而淬灭粒子的荧光。研究发现,当Cu²⁺的浓度在8×10-8⁸×10-6 mol/L之间时,荧光强度下降的比例与铜离子浓度呈现线性关系。与传统的无金纳米花内核的SiO₂-RBITC粒子相比,Au NF@SiO₂-RBITC复合粒子对铜离子响应的线性范围和灵敏度均有显著提高。以此为基础,可实现对铜离子的定量检测。更多还原

【Abstract】 Fluorescent nanoparticles（NPs）possess high brightness and improved photostability as compared to conventional fluorescent dyes,they have attracted considerable interest over the past decade as valuable alternative to conventional organic fluorophores in a diversity of applications.Owing to the growing demand for selective chemo-sensors in biology and environmental monitoring,the design of sensing devices based on fluorescent nanoparticles,usable in aqueous medium,is a topic of sustained interest.However,the applications are often limited due to the low fluorescence intensity.Therefore,it is highly needed to enhance the fluorescence intensity of the dyes to improve the sensitivity.Noble metals have been demonstrated to enhance fluorescence of rare-earth ions,organic dyes,and quantum dots using the resonant coupling between the surface plasmon resonance bands of metals and absorption or emission band of fluorescent materials,which is known as metal enhanced fluorescence.However,up until now,there has been no study on the fluorescence enhancement of gold nanoflowers.Core-shell structures have been reported as an effective mean to improve the stability of gold nanoflowers,as well as to provide a spacer to control the distance between metal enhancer and fluorophore for optimized fluorescence efficiency.Inspired by metal enhanced fluorescence,we prepared core-shell（gold nanoflower core-silica shell）composite particles doped with RBITC based on the metal-spacer fluorophore approach,and investigated the fluorescence enhancement property and copper ions detection of Rhodamine B isothiocyanate（RBITC）with the assistance of gold nanoflowers.The article includes two parts:1.Study on the controllable preparation and the fluorescence properties of Au NF@SiO₂-RBITC composite particles.In St?ber system,a series of Au NF@ SiO₂ composite particles were prepared by adjusting the amount of ammonia.As a result,thicknesses of the silica shell were regulated between 7 nm and 22 nm.Then,RBITC were doped into silica shell by covalent coupling with（3-aminopropyl）-triethoxylsilane（APS）.The effect of Au core,the concentrations of RBITC and the thicknesses of silica shell on the fluorescent properties of the composite particles were investigated by steady-state and time-resolved fluorescence measurement.It was found that the Au NF@SiO₂-RBITC composite particles achieved optimized metal-enhanced fluorescence effect when the actual doping concentration of RBITC was 7.25×10-4 mg / m L and the thickness of the silica shell was 15 nm.Compared with SiO₂@SiO₂-RBITC composite particles under the same conditions,the fluorescence intensity of Au NF@SiO₂-RBITC composite particles was enhanced by 4 times and the fluorescence lifetime of the dye was significantly decreased.2.Study on the fluorescence response ability of Au NF@SiO₂-RBITC composite particles to copper ions.The Au NF@SiO₂-RBITC composite particles with silica shell thickness of 15 nm were chosen to study their fluorescence response to copper ions.Ammoniacal copper complex ions（[Cu（NH3）4]2+）were formed by the coordination of copper ions and ammonia.The absorption peak of the complex ions was about 600 nm,which can be overlapped with the emission spectra of Au NF@SiO₂-RBITC composite particles.Since that,the fluorescence of the composite particles were quenched due to energy transfer between the [Cu（NH3）4]2+ and the composite particles.It was found that the ratio of fluorescence intensity decreased linearly when the concentration of copper ions was between 8×10-8⁸×10-6 mol / L.Compared with SiO₂-RBITC particles,the Au NF@SiO₂-RBITC composite particles significantly improved the detection linear range and sensitivity.更多还原