基于半导体纳米复合物的光电化学microRNA传感

发布时间：2018-07-20 09:01

【摘要】：MicroRNAs(miRNAs)为一系列短的内生非编码RNAs,在细胞的分化和增殖、肿瘤转移、病毒复制及神经退化过程中,扮演了重要的角色。因此,急需发展一种快速、简便、高灵敏性及高选择性定量检测miRNAs的方法。光电化学法是一种新兴的生物分析技术,在最近几年得到了广泛的关注。由于其激发光源和检测信号系统是完全分离的,使得检测时的背景信号较弱,从而提高了检测的灵敏度。此外,光电化学检测技术比传统的光化学和电化学检测法更快速、方便,选择性和精确度更高。本论文基于半导体纳米复合物,运用光电化学检测技术测定miRNAs,开展了以下两个方面的工作:1基于DNA-CdS量子点(QDs)敏化的羧酸化单壁碳纳米管(SWCNTs-COOH),我们设计出一种通用的光电化学生物传感平台。探针DNA-CdS QDs通过一步法合成获得,这比先前报道的合成方法更简便,DNA标记的CdS QDs通过π-π堆积效应结合到SWCNTs-COOH上形成具有光电化学活性的半导体纳米复合物。此纳米复合物展示出高的光电转换效率和良好的稳定性。MiRNAs为一类内生的非编码RNAs,在不同的生物学过程中扮演着重要的角色。以miRNA-7f作为模型,由于目标miRNA与探针DNA杂交,使得量子点修饰的DNA从SWCNTs-COOH表面脱离,基于此我们构建了一种新颖的信号减弱型的光电化学生物传感器,可以直接检测miRNA。我们提出的直接检测miRNA的方法相对于间接法来说检测的花费更低、更方便、更省时。在405 nm的可见光照射和较低的电位(-0.05 V)下,结合循环酶放大效应,该光电化学生物传感器检测miRNA-7f展现出宽的检测范围(50 fM-100 pM)和低的检测限(34 fM)。这种具有高灵敏度及高选择性的新颖的直接检测miRNAs的光电化学法有望应用于临床上miRNA的化验。2 Au纳米粒子通过酰胺键与ZnSe-COOH纳米晶组装制得了具有良好光电化学活性的半导体纳米复合物。Au纳米粒子产生热电子进入ZnSe-COOH纳米晶中,发生局域表面等离子体共振,产生了显著增强的光电流,从而极大的提高了光电化学生物传感器检测的灵敏度。基于该纳米复合物,我们发展了一种新颖的光电化学生物传感器平台。p19蛋白质与21-23碱基对(bp)双链RNA(dsRNA)有着高的特异性和亲和性,结合到dsRNA上的p19蛋白质能有效的阻碍电子供体向电极表面传输电子,得到一个减弱的光电流信号。以miRNA-122a为目标物,它能与探针RNA杂交形成21个bp的dsRNA,以此设计出一种高灵敏度的直接检测miRNA的光电化学生物传感器。该光电化学传感器对miRNA-122a检测的线性范围为350 fM至5 nM,检测限低至153 fM。此外该,传感器还表现出一系列其它优良的性能如易组装、响应迅速、灵敏度高、特异性好。把Au纳米粒子修饰到水溶性的ZnSe-COOH纳米晶上产生表面等离子体共振以此来提高光电化学检测的灵敏度,促进了光电化学生物传感的发展,拓宽了半导体纳米复合物的应用,具有广阔的前景。
[Abstract]:MicroRNAs (miRNAs), a series of short endogenous non-coding RNAss, play an important role in cell differentiation and proliferation, tumor metastasis, viral replication and neurodegeneration. Therefore, it is urgent to develop a rapid, simple, sensitive and selective method for quantitative detection of miRNAs. Photochemistry is a new biological analysis technology, which has been paid more and more attention in recent years. Because the excitation light source is completely separated from the detection signal system, the background signal is weak and the sensitivity of detection is improved. In addition, photochemical detection technology is faster, more convenient, more selective and more accurate than traditional photochemical and electrochemical methods. This thesis is based on semiconductor nanocomposites. In order to determine miRNAss by photochemical detection technique, we have carried out the following two aspects: 1: 1 carboxylic single-walled carbon nanotubes (SWCNTs-COOH) sensitized by DNA-CdS quantum dots (QDs). We have designed a universal photochemical biosensor platform. The probe DNA-CdS QDs were synthesized by one-step method, which is simpler than the previously reported synthesis method. The DNA-labeled CDs QDs are bonded to SWCNTs-COOH by 蟺-蟺 stacking effect to form photochemically active semiconductor nanocomposites. This nanocomposite shows high photovoltaic conversion efficiency and good stability. MiRNAs are an endogenous non-coding RNAs.MiRNAs play an important role in different biological processes. Using miRNA-7f as a model, because the target miRNA is hybridized with probe DNA, quantum dot modified DNA is separated from SWCNTs-COOH surface. Based on this, a novel signal weakening photochemical biosensor is constructed, which can be used to detect miRNA directly. Our method for direct detection of miRNA is less expensive, more convenient and less time consuming than indirect method. Under 405nm visible light irradiation and low potential (-0.05 V), the photochemical biosensor showed a wide detection range (50fM-100pM) and a low detection limit (34fM) combined with cyclic enzyme amplification. This novel photochemical method with high sensitivity and selectivity for direct detection of miRNAs is expected to be used in clinical miRNA assay. 2.Au nanoparticles are assembled with ZnSe-COOH nanocrystals by amide bond to obtain good photochemical activity. The semiconductor nanocomposite. Au nanoparticles produce hot electrons into ZnSe-COOH nanocrystals. Local surface plasmon resonance (SPR) produces a significantly enhanced photocurrent, which greatly improves the detection sensitivity of photochemical biosensor. Based on the nanocomposites, we have developed a novel photoelectrochemical biosensor platform. P19 protein and 21-23 base pair (bp) double-stranded RNA (dsRNA) have high specificity and affinity. The p19 protein binding to dsRNA can effectively block the electron donor from transporting electrons to the electrode surface and obtain a weakened photocurrent signal. With miRNA-122a as the target, it can be hybridized with probe RNA to form 21 BP dsRNAs. A highly sensitive photochemical biosensor for direct detection of miRNA was designed. The linear range of the photochemical sensor for miRNA-122a is from 350 FM to 5 nm, and the detection limit is as low as 153 FM. In addition, the sensor also shows a series of other excellent properties such as easy assembly, rapid response, high sensitivity and good specificity. Surface plasmon resonance (SPR) was generated by modifying au nanoparticles onto water-soluble ZnSe-COOH nanocrystals to improve the sensitivity of photochemical detection, promote the development of photochemical biosensors, and broaden the application of semiconductor nanocomposites. There is a bright future.
【学位授予单位】：南京师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1;O657

【相似文献】