【作者】 叶敏；

【导师】 张友玉；

【作者基本信息】 湖南师范大学 ， 分析化学， 2008， 硕士

【摘要】 半导体纳米材料具有独特的光学和电学性质,在过去的几十年中引起了人们的广泛关注。CdS半导体纳米粒子作为一种典型的Ⅱ-Ⅵ族禁带直接半导体纳米材料,与传统的有机染色剂相比,该纳米粒子具有激发光谱宽,发射光谱窄且对称,最大发射波长位置可调,不易光解等特点,因此可以成功地作为荧光探针对细胞和生物样品进行染色,也可用来检测无机离子、生物大分子。本文在文献基础上,水相中合成了高发光、水溶性的CdS纳米粒子,对CdS纳米粒子进行不同官能团的修饰。制备的功能性纳米粒子作为荧光探针定量检测无机离子、DNA及单碱基突变。主要内容如下:（1）综述了半导体量子点的性质、CdS纳米粒子的制备及其在分析科学中的应用。（2）采用水相法合成了粒径均匀、分散性好的CdS纳米粒子,并分别用半胱氨酸和半胱胺对CdS纳米粒子进行修饰。通过优化实验条件,跟踪监测了CdS纳米粒子荧光光谱的变化,探讨了CdS纳米粒子与半胱氨酸、半胱胺之间的相互作用机理,并对其进行表征,研究结果表明,在水相中可以制得稳定且荧光强度较强的CdS纳米溶胶;同时,分别用低浓度的半胱氨酸和半胱胺对其进行修饰,能够得到荧光稳定性较好的功能化CdS纳米粒子。（3）以修饰的纳米粒子为荧光探针,建立了荧光猝灭定量检测锰离子的新方法。考察了多种因素的影响。在最佳实验条件下,测定锰离子的线性区间为0.0534～77.6 mg/L,检出限为0.0168 mg/L。该方法经济、简单、快速、灵敏度高、检出限比较低、检测范围宽,可望用于生物基质样品中微量元素的测定。（4）在水相中合成了半胱氨酸修饰的CdS/ZnS核壳结构纳米探针,并对其进行表征。制得的功能化CdS/ZnS纳米晶近似呈球形,粒径约为20 nm。CdS纳米微粒的表面经ZnS修饰后,表面缺陷减少,其荧光发射峰强度显著增强。利用该探针对DNA进行了定量测定,考察了各种因素的影响,在最佳实验条件下,该方法测出有两个线性区间,分别为:0.0833～3.33μg/mL和3.33～16.7μg/mL,该方法的检出限为2.50×10^-3μg/mL。与其它方法相比,该方法具有简单、经济、快速、灵敏度高、低毒的特点。（5）以已知序列的单核苷酸为对象,磁性纳米颗粒作为压电检测增敏和磁分离材料,以单碱基修饰的CdS纳米粒子作为探针,利用压电与荧光光谱分析,建立一种新型的基于纳米粒子的单核苷酸多态性检测新方法。利用外加磁场的固定过程,成功地提供了一种简便、快捷、廉价的检测装置。加入单核苷酸修饰的CdS纳米粒子后,突变体系频率下降,而对应的完全互补目标DNA链,频率下降可以忽略,这一结果由荧光光谱分析后得到进一步的证实。因此,由于其操作简便且成本低,以上方法必将给研究领域和临床基因分析带来福音。更多还原

【Abstract】 Nanostructured semiconductor materials with unique optical and electrical properties have attracted a lot of interests in the last two decades. As a direct bandgap II-VI semiconductor, CdS nanoparticles have been paid more attentions for their excellent optical properties. Compared to the conventional organic dyes, CdS nanoparticles appear to be less susceptible to photobleaching with much narrower emission spectra and tunable maximum emission wavelength, which have been successfully used as fluorescent probe for the imaging of biological samples and cells. And the CdS nanoparticles become very sensitive to their local environment, and detections of some inorganic ions, proteins, DNA conformations were thus developed based on this property.On the basis of related literatures, the synthesization of highly luminescent water-soluble CdS nanoparticles was studied. We modified the CdS nanoparticles to be fluorescent probes to detect inorganic ion, DNA and single-base mutations. The main work in this thesis is as follows:（1） Reviews were given firstly on the properties, synthetic methods and applications of CdS nanoparticles.（2） CdS nanoparticles were synthesized by the aqueous solution method. The nanoparticles were of uniformity in size and good dispersancy. CdS nanoparticles were modified with cysteine and cysteamine, respectively. The factors those influencing the CdS nanoparticle fluorescence were tracked and inspected. The interaction mechanism between CdS nanoparticles with cysteine and cysteamine were also discussed. Then characterize the samples. The experimental results showed that CdS nanoparticles were stable and of strong fluorescence intensity in aqueous solution. Furthermore, functionalized CdS nanoparticles with good fluorescence stabilities were obtained under the modification with low concentration of cysteine or cysteamine.（3） A new approach was proposed for the sensitive determination of manganese ions with nanoparticles-modified fluorescence probes. Different influencing factors were studied. Under the optimum conditions, the response is linearly proportional to the concentration of manganese （II） ion in the range from 0.0534 mg/L to 77.6 mg/L. The limit of detection is 0.0168 mg/L for.manganese （II） ion. And it was proved to be a low-cost, simple, rapid, sensitive, low-limit method. Functionalized nanoparticles are hopeful to be used as fluorescence probes in detecting trace elements in biological samples.（4） The CdS/ZnS core-shell structure nanoparticles were synthesized in hydrotropic solution and characterized. The shape of CdS/ZnS core-shell particle approximated to a ball with an average diameter of 20 nm. The fluorescence intensity of the band-side emission of the CdS/ZnS was strengthened, and the surface state emission was weakened. Quantitative determination of DNA by functionalized CdS/ZnS core-shell nanofluorescence probe. Various Factors were assessed and the suitable conditions were optimized for the assay of DNA. Linear relationship was found between the quenched fluorescence intensity and the concentration of DNA in the range of 0.0833～3.33μg/mL and 3.33～16.7μg/mL with the limit of detection of 2.50×10^-3μg/mL. The method is also simple, cheap, rapid, sensitive and low toxicity.（5） A novel detection method for single nucleotide polymorphisms （SNPs） based on magnetic nanoparticle and CdS nanoparticle probes has been proposed in this work using fluorescence spectrometry and piezoelectric sensing. Magnetic nanoparticles were used to realize the isolation, separation and purification of DNA probes. Single nucleotide-coded CdS nanoparticles were synthesized and characterized. Magnetic nanoparticles coated by DNA strand with point mutation was immobilized onto the electrode surface with a magnet, ant then the CdS nanoparticle probes was utilized to search the mutation point via base-pairing. The hybridization of DNA with CdS nanoparticle probes caused changes of crystal frequency, whereas nearly no frequency changes for the complementary target could be recorded. Point mutation or single-base mismatch discrimination could be achieved successfully, and then each sample can be simultaneously identified by CdS fluorescent probes. Owing to its easy operation and cost-effectiveness, it was expected that the proposed procedure might hold great promise in both research-based and clinical genetic assays.更多还原