【作者】 宫晓群；

【导师】 常津；

【作者基本信息】 天津大学 ， 材料学， 2013， 博士

【摘要】 目前，基于量子点的荧光成像和荧光检测已经得到广泛的发展，特别是其在疾病早期、高灵敏、特异性诊断的应用加速了量子点的研究进展。本文主要是在油溶性CdSe量子点的基础上，对其原料配比、反应条件等影响因素进行了探讨，并进一步研究了量子点水溶性改性和复合磁性纳米粒子的方法，最后作为荧光探针应用于微流控液相生物芯片。首先，我们采用高温油相法制备了性能优良的CdSe量子点，该油溶性量子点具有较好的分散性，且粒径可控、均匀，结晶度较高；其发射峰高斯对称，半峰宽可以较好地控制在30nm以内；通过各条件地调控，量子产率（QY）有较大的提高。实验中，我们分别探讨了Cd前体与Se前体的配比，反应温度，反应时间，壳层材料及结构对量子点荧光性能的影响。发现Cd与Se前体的摩尔配比为1:6时，制备的量子点具有最佳的荧光性能；通过调整反应温度和反应时间，可制备不同波长的量子点，且在一定范围内，温度的升高有助于量子点荧光性能的提高。在制备核壳结构的量子点时发现，无机壳层的包覆有助于量子点荧光性能的提高，而合金壳层的包覆即可有效地提高量子产率，又可抑制量子点半峰宽过度增长。其次，为了将量子点应用到生物检测领域，我们对量子点进行了水溶性改性，分别采用了高分子包裹法和配体交换法。前者，我们通过疏水作用力将聚(苯乙烯-co-马来酸酐)包覆在量子点表面（QDs@PSMA），利用开环法将量子点转移到水相，并同时将量子点表面类PEG化。实验表明改性后的量子点具有较好的水溶性和较低的蛋白吸附性，在荧光免疫检测中，显示了较好的特异性；后者，我们应用自主设计合成的巯基乙胺接枝聚γ谷氨酸(PGA-g-MEA)，PGA-g-MEA链上的多个巯基取代了量子点表面的有机配体，将量子点转移到水相中去，改性后的量子点具有较小的粒径，约10nm，且显示了较高的pH和温度稳定性。再次，我们将量子点与磁性纳米粒子进行复合，制备了双功能的磁性荧光纳米粒子。同样是基于简单的开环法，利用Fe3O4@SiO2表面的氨基开环QDs@PSMA表面的马来酸酐，并同时表面类PEG化。实验发现，该种方法制备的磁性荧光纳米粒子的荧光强度远高于二氧化硅共包裹法制备的纳米粒子，且在不同pH溶液和温度条件下展现出较好的胶体和荧光稳定性，同时该磁性荧光纳米粒子也显示了低的细胞毒性和低非特异吸附性，为其进一步的生物应用奠定了基础。最后，我们初步构建了基于量子点荧光探针的微流控液相生物芯片检测系统，主要包括四部分，即基于量子点荧光探针和量子点荧光编码微球的夹心反应检测系统；通过聚焦，促使编码微球快速、单列通过检测区域的微流控芯片；可以实时读取编码微球信息的检测系统；以及信息处理系统。在微流控检测系统构建的基础上，初步实现了编码微球的实时解码和夹心免疫信息的解读，为以后进一步的高通量检测奠定了坚实的基础。更多还原

【Abstract】 Now, there is great development in bioimaging and biodetection based onquantum dots(QDs) probes, and their potential application in the early sensitive andspecific diagnosis of disease has promoted the research of QDs. In this paper, wefirstly studied the different influence on the fluorescence properties of CdSe QDs,then two methods to prepare water-soluble QDs were investigated, as well as thepreparation of magnetic fluorescent nanocomposites. Finally, the QDs probes wereapplied in microfluidic biochip assays.Firstly, we prepared high crystallization and monodispersion CdSe QDs bycolloid chemistry method. The emission spectra of CdSe QDs were Gaussiansymmetric with full width at half maximum (FWHM) less than30nm. During thepreparation, the influences of the ratio of Cd and Se precursors, reactive temperature,reactive time and the materials of shell on the fluorescence properties of QDs wereinvestigated. The results indicated that when the ratio of Cd and Se precursors was1:6，we could get the highest quality QDs; As the reactive temperature or timeincreased, the absorption and emission peak of QDs were obviously red shifted.Significantly, the reactive temperature had a great influence on the quantum yield(QY) of QDs. As for the core/shell QDs, there was a marked increase in the QY with anarrow FWHM after CdSe QDs coated with inorganic shells.Secondly, in order to apply the QDs in biodetection, the oil-soluble CdSe QDsneed be transferred into aqueous phase. Two methods were employed to modify theQDs, those were polymer encapsulation method and ligand exchange method. In thefirst method, the poly(styrene-co-maleic anhydride) terminated with cumene (PSMA)was introduced to coat the oil-soluble QDs by the hydrophobic interaction, then theQDs@PSMA were transferred into aqueous phase by a ring-opening reaction andfunctionalized with Jeffamine M-1000polyetheramine (M1000). The water-solubleQDs@PSMA showed a good fluorescence and colloid stability in different pHsolution and a low protein absorption in PBS solution with10%fetal bovine serum(FBS). In addition, it also exhibited a high specificity in fluoimmunoassay. In the second method, a kind of self-synthesized multidentate polymer PGA-g-MEA wasapplied to transfer the oil-soluble QDs into aqueous phase by ligand exchange. TheQDs@PGA-g-MEA had a quite small size about10nm, and showed a high stabilityin pH2-13aqueous solution as well as in different temperature.Thirdly, the magnetic and fluorescent bifunctional nanocomposites (MNQDNCs)were prepared by a ring-opening reaction to conjugate QDs and magneticnanoparticles (MNs). And meanwhile, the MNQDNCs were functionalized withM1000by the same ring-opening reaction. The nanocomposites exhibited a highcolloidal and photochemical stability over a wide pH range (pH2-13), a low proteinadsorption in PBS with10%FBS at37°C, and showed a low nonspecific bindingincubated with Hela cells. Sandwich fluoroimmunoassay and magnetic targetingresults indicated that the nanocomposites can be successfully applied in a variety ofdiagnosis, bioimaging and delivery applications.Finally, we initially constructed microfluidic biochip detection system basedon quantum dots fluorescent probes. The system mainly included four parts, whichwere as follows:1) the sandwich reaction detection system based on quantum dotsprobes and quantum dots coded microspheres；2) the microfluidic biochip allowingencoded microspheres to pass through the interrogation region quickly in single row；3) the detection system which can read the coded microspheres signal in real time;4)information processing systems. Based on the microfluidic biochip arrays system, thereal-time decoding of encoded microspheres and sandwich immunoassay informationwere realized now. The work has laid a solid foundation for the future furtherhigh-throughput detection.更多还原