The objective of this research is to increase the sensitivity of label-free biomolecular detectors to levels achieved by label-based detectors (e.g. fluorescence) that are sensitive but time-consuming and costly. A method that improves sensitivity without modification of sensor structure or operation principle is highly desirable. The approach is to incorporate activated receptor molecules into biosensors. Single-stranded DNA or RNA-based molecules, namely aptazymes that perform enzyme activity upon binding to small targets will be used as receptor molecules. Accordingly, biosensors will detect the activity of relatively large aptazymes as opposed to directly detecting the binding of small target molecules. Since the activity will be triggered by small target molecules, they will be indirectly detected with greatly amplified sensitivity. The efficacy of the technique will be demonstrated on the surfaces of a few model label-free detection systems (both commercial and nanomechanical sensors built in-house) whereby small molecules whose direct binding would reveal signals too small to detect will be indirectly detected via aptazyme activity. All experimental work will be undertaken by Purdue. The aptazyme synthesis will be performed at the University of Texas at Austin.
This research project intends to make a broad impact on high-throughput detection of biomolecules such as DNA, RNA, proteins and small molecules whose sensitive detection is of top importance for early diagnosis of many cancers that take 500,000 American lives every year. The findings of this project will be a significant step towards the development of fast, low-cost and high-resolution biomolecular detectors and towards the understanding of biomolecular interactions on solid surfaces. This project will also have significant educational contributions by setting an interdisciplinary stage where engineering students and chemists can interact and learn from each other. A part of the project will also be linked to a graduate level laboratory course.
