Speaker: Xiangchen Che, ECpE Graduate Student
Advisor: Long Que
Title: Nanostructured aluminum oxide thin film-based fluorescent sensing: Fluorescence enhancement effect and applications
Abstract: The fluorescence technique, which can provide very high sensitivity and large multiplexing capabilities over other detection methods, is one of the most widely utilized techniques for a variety of biosensing and detection. In this seminar, three topics of newly developed anodic aluminim oxide (AAO) based fluorescence technology will be covered: (1) the effects of the nanopore size, porosity and the thickness of the AAO thin film on the fluorescence enhancement will be presented. It has been found that the fluorescence enhancement of the AAO thin film is gap-dependent. These experimentally observed phenomena have been verified qualitatively by simulations using finite element analysis. These results provide a guideline to achieve the optimum fluorescence enhancement of the AAO thin film by modifying its dimensional parameters. (2) A new class of molecular beacon biosensors based on the AAO surface has been developed. AAO surface is used to enhance the fluorescent signals of the fluorophore-labeled hairpin DNA. When a target DNA with a complementary sequence to that of the hairpin DNA is applied on the sensor, the fluorophores are forced to move away from the AAO surface due to the hybridization between the hairpin DNA and the target DNA, resulting in the significant decrease of the fluorescent signals. The observed signal reduction is sufficient to achieve a demonstrated detection limit of 10 nM. The control experiments have also demonstrated that the bioassay used in the experiments has excellent specificity and selectivity, indicating the great promise of this type of sensor for diagnostic applications. (3) A new class of AAO surface enabled fluorescence sensors for monitoring the cell secretion has been developed. Using a sandwich assay, we have successfully detected the purified TGFB1 in buffer solution and the detection limit is 10 ng/ml. In addition, in our preliminary experiments, we have successfully detected the TGFB1 secreted directly by ITAF cells.