A universal and label-free sensor system based on aptamers and porous Silicon

快速、灵敏和选择性地检测各种分析物是质量保证、环境监测和生产过程以及诊断中的关键步骤。生物传感器可以满足这些要求。本研究项目的目的是开发和测试一种新型的无标记通用生物传感器系统，该系统基于适体作为识别元件，结合多孔硅支架进行简单的实时传感。虽然适体提供了沿着的特异性以及基于其核酸性质设计新的检测方案的潜力，但多孔硅允许简单和无标记的检测。在第一个项目阶段，适体修饰的多孔硅作为用于较大分析物的通用、灵敏和快速检测平台的适用性（即使在复杂的样品中），如细胞和蛋白质，以及分析小分子的可能性-原则上。对这些系统进行了详细的评估和测试。在该项目的第二阶段，我们的目标-按计划-开发一个多路复用的光学传感器系统的基础上，适配体修饰的多孔硅，同时检测不同的分析物。此外，为了提高系统的灵敏度-特别是对于小分子的检测-计划开发和实施更复杂的信号增强策略。为了实现这一点，我们将遵循两种策略：（i）我们将开发竞争性测定，其中使用与适体靶结合位点互补的寡核苷酸，因此可以与靶竞争。为了进一步增加信号，将用纳米颗粒修饰寡核苷酸。(ii)在第二种信号增强策略中，多孔硅表面将用荧光纳米颗粒修饰，所述荧光纳米颗粒在结合目标分析物时改变其发射，因此允许双峰和更灵敏的检测。此外，为了允许容易和准确的处理，将引入微流体。微阵列技术的实现将实现高度的多重化，促进不同分析物的同时检测。将对这些系统进行第一阶段检测的分析方法检测，但主要关注小分子。作为一种高度相关的小分子，抗生素被选为模型系统，以开发项目第二阶段的信号增强策略和多路复用生物传感器。尽管如此，开发的方法将适用于其他小分子，从而为从环境监测和食品安全到诊断的各种应用提供多功能平台技术。

Rapid, sensitive and selective detection of various analytes is a critical step in quality assurance, environmental monitoring and production processes, as well as in diagnostics. Biosensors can fulfill these requirements. The aim of this research project is the development and testing of a novel label-free universal biosensor system based on aptamers as recognition elements combined with a porous silicon scaffold for simple real-time sensing. While the aptamers provide specificity along with the potential to design novel detection schemes based on their nucleic acid nature, the porous silicon allows for simple and label free detection.Within the first project phase the applicability of aptamer-modified porous silicon as a versatile, sensitive and rapid detection platform for larger analytes (even in complex samples), such as cells and proteins were shown as well as the possibility - in principle - to analyze small molecules. These systems were evaluated and tested in detail. In the second phase of the project we aim – as planned - to develop a multiplexed optical sensor system based on aptamer-modified porous silicon for simultaneous detection of different analytes. Additionally, in order to increase the sensitivity of the system – especially for the detection of small molecules - the development and implementation of more sophisticated signal enhancement strategies is planned. To achieve this, we will follow two strategies: (i) We will develop competitive assays in which oligonucleotides complementary to the aptamers target binding site are used and can therefore compete with the target. To further increase the signal, the oligonucleotides will be modified with nanoparticles. (ii) In the second signal enhancement strategy the porous silicon surface will be modified with fluorescent nanoparticles which are changing their emission upon binding of the target analyte, therefore allowing for bimodal and more sensitive detection. Moreover, to allow easy and accurate handling microfluidics will be introduced. Implementation of microarray technology will enable a high degree of multiplexing, facilitating the simultaneous detection of different analytes. These systems will be tested for the analytical procedures tested in the first phase but main focus will be placed on small molecules. As a highly relevant class of small molecules, antibiotics are chosen as model system to develop signal enhancement strategies and multiplexed biosensors within the second phase of the project. Nonetheless, the developed methods will be applicable to other small molecules, thereby providing a versatile platform technology for various applications ranging from environmental monitoring and food safety to diagnostics.