MEMS aptamer sensors for detecting plant chemicals

Abstract

<p>In this dissertation, the underlying mechanisms of AAO optical sensor simulation and application are described. AAO based optical biosensors were developed for testing theophylline, silicic acid, and a multiplexed device for detecting multiple plant chemical solutions was designed.</p> <p>Chapter 1 introduces background information about anodic aluminum oxide (AAO), including a basic introduction to the history of AAO development, AAO fabrication, structures, and properties. It also explains the self-ordered nanopore formation mechanism, the optical principles of using Rsoft simulation, and surface functionalization for AAO. Finally, the chapter describes emerging applications in biosensing, bio-detection, and biocompatible interfaces.</p> <p>Chapter 2 introduces AAO as an aptamer-based nanopore thin film sensor for detecting theophylline in a buffer solution and in complex fluids, including plant extracts and serum samples. Experiments revealed that an aptamer-based sensor has good specificity, selectivity, and reasonable reusability with a significantly improved dynamic- detection range. Its low cost and ease of operation make this type of sensor suitable for point-of-care application to monitoring the theophylline level of patients in real time.</p> <p>Chapter 3 introduces a structure-switching aptamer-based nanopore thin-film sensor developed for cost-effective, rapid, sensitive and simple detection of SA in both buffer and plant extracts. A high-affinity SA aptamer was identified by immobilizing the SELEX library rather than SA and screening the library using a structure-switching SELEX approach. This nanosensor also exhibited good selectivity among SA and its common metabolites.</p> <p>Chapter 4 introduces a chip equipped with aptamer-based sensors interfaced with a capillary microfluidic unit suitable for screening and detecting hormones in plant samples. The chip allows samples to be automatically delivered to on-chip sensors without using external pumps, making it suitable for operation in the field or in source- limited settings. Since arrayed sensors can be functionalized with different aptamers specific to different plant hormones, this chip can screen and identify the hormones in unknown samples.</p>