催化信标液晶生物传感检测铀的方法学研究

Uranium is a radioactive heavy metal pollutant that exists ubiquitously in the environment. Human beings have a high probability of exposure to uranium, which can cause severe adverse effects to human health. For these reasons, the development of sensitive, accurate, practical detection method of uranium is very important. In our preliminary studies, we found that the liquid crystal (LC) sensors are well suited for accurate on-site and real-time detection of biomolecule. The principles of LC-based biosensors rely on optical, anchoring, and birefringent properties of the LC material. Since the orientation of LC molecules is extraordinarily sensitive to physical and chemical properties of a bounding interface. LC can be used as a molecular amplifier to transduce the presence of binding events on solid surfaces into different optical signals. The acute optical signal changes can reflect a wealth of information on biochemical bounding events. The LC biosensors are sufficiently simple, low cost, and it can even be performed in ambient lighting without the need for electrical power. These advantages make the LC biosensors can even be applied in locations remote from central laboratories, as well as in assays of patterned arrays of species. DNAzymes are DNA fragments which with active catalytic functions can been obtained through in Vitro selection process from a large DNA library, especially in the presence of metal cofactors. Most DNAzymes require metal ion cofactors for structure and function, and many DNAzymes show high metal-binding affinity and specificity. Recognizing the potential of DNAzymes as a new class of molecules specific for a wide range of metal ions, we try to develop highly sensitive and selective signal-enhanced LC biosensing technique for determination of uranium using the DNAzymes into a catalytic beacon method. In this method the substrate strand is elongated on both the 5′and 3′ ends to hybridize with signal enhanced system. Upon addition of uranium, the signal enhanced -labeled fragments released after cleavage are hybridized with the capture DNA probe which fixed on the film.This bounding events can greatly disrupt the uniform LC molecular arrangement, making the optical image of LC cell birefringent as a result. Study on the relationship between the amount of uranium and the changes of optical image signal, we can develop a new method for determination of uranium. This method is of high selectivity and sensitivity, and it can simplify the sample processing steps. With the study on this project, we can provide new research ideas and experimental evidences for the determination of other radioactive metal by LC biosensing techniquwith.

铀是一种具有放射性的重金属污染物，研究铀的灵敏、准确、切实可行的检测新方法对于环境监测、维护人类健康具有重要意义。基于液晶生物传感器简便、易于阵列化、便于实时、原位监测等优势和课题组在液晶生物传感机制、生物大分子检测方面的前期工作，本项目拟采用DNAzyme作为特异性的敏感识别元件，结合信号放大手段，利用液晶生物传感器对偏正光的双折射特性，监测铀催化作用于DNAzyme后，底物链断裂释放，被捕获固定于传感装置表面，导致液晶取向改变引起相关光学信号变化，通过研究铀的量与光学信号之间的关系，建立催化信标液晶生物传感检测铀的新方法。并深入探讨DNAzyme对铀的分子识别和液晶生物传感机制。该法采用DNAzyme，选择性好；结合信号放大技术，灵敏度高；不需繁杂、费时的样品处理步骤。通过本项目的研究，可为深入研究基于功能化核酸的其他放射性核素或金属离子的液晶生物传感分析方法提供科研思路和实验依据。

铀是一种具有放射性的重金属污染物，研究铀的灵敏、准确、切实可行的检测新方法对于环境监测、维护人类健康具有重要意义。本课题将液晶生物传感的先进性与铀酰离子分析检测的必要性相结合，对构建催化信标液晶生物传感检测铀的方法进行研究。.构建液晶生物传感的关键步骤之一为传感基底的构建，我们首先对液晶基底的功能膜的组装进行了研究探讨，采用了两种方法构建液晶传感基底，APTES/DMOAP和TEA/DMOAP，均将其应用于液晶生物传感构建，并发表相应文章于Chemical Communications和Analytical Chemistry上。对比后发现TEA/DMOAP较APTES/DMOAP更为简单，固定效果更好。. 提高检测方法灵敏度的有效手段之一为采用信号放大技术，因此我们还研究了银沉积、纳米金、滚环扩增三种信号放大方法在液晶生物传感中的应用，发现银沉积、纳米金具有良好的信号放大作用，滚环扩增与液晶生物传感相结合的效果不佳。同时发现液晶分子自身具有信号放大的功能。. 在此基础上基于液晶生物传感器简便、便于实时、原位监测的特点采用DNAzyme作为特异性的敏感识别元件，结合结晶分子的信号放大作用，利用液晶生物传感器对偏正光的双折射特性，监测铀催化作用于DNAzyme后，底物链断裂释放，被捕获固定于传感装置表面，导致液晶取向改变引起相关光学信号变化，通过研究铀的量与光学信号之间的关系，建立催化信标液晶生物传感检测铀的新方法，并深入探讨DNAzyme对铀的分子识别和液晶生物传感机制。该法将放射性金属离子的检测转化为核酸生物大分子的检测，显著提高了液晶生物传感的检测灵敏度。将功能核酸引入构建液晶生物传感，基于DNAzyme对铀酰离子的高度特异性，该传感方法选择性好；结合液晶分子的信号放大功能，灵敏度高，该方法对25nM的铀有显著响应；不需繁杂、费时的样品处理步骤。通过本项目的研究，可为深入研究基于功能化核酸的其他放射性核素或金属离子的液晶生物传感分析方法提供科研思路和实验依据。