Nanocomposite based biosensors for physiological sensing
Abstract
Electrochemical biosensors transform biological information into measurable electrical signals. A typical biosensor consists of three elements: analyte, biorecognition element and transduction element. The development of biosensors for the quantitative determination of biological molecules has been an attractive and active research field. This dissertation focuses on the 2 major fields of biosensor research: biosensor enhancement and physiological sensing. For biosensor enhancement, a study was carried out to compare different enzyme immobilization approaches combined with nanomaterials. Appropriate enzyme immobilization approaches enhanced biosensor performance by preserving enzyme activities and increasing the enzyme loading, while the incorporation of nanomaterials in biosensor construction further improved the sensitivity. A comparison protocol using current density was proposed, which standardized the comparison of biosensors based on different electrodes and nanomaterials. The protocol could also be used to study the impacts of variables which were inherent in each fabrication scheme (e.g., the amount of enzymes and the type of nanomaterials) by evaluating the integrative effects of these variables on biosensing, which would lead to optimized biosensor designs. Subsequently, novel nanocomposites incorporating carbon nanotube, graphene and Pt black that significantly increased the effective surface area and the electrocatalytic activities were developed. Glucose, ethanol and ATP biosensors based on the nanocomposites were constructed and exhibited enhanced performance, demonstrating that the nanocomposites possessed great potential as excellent platforms for versatile biosensing applications. For physiological sensing, microbiosensors based on nanocomposites were operated in the self-referencing (SR) modality. SR is a real-time and non-invasive microbiosensor technique based on Fick's first law of diffusion, which converts static concentration biosensors into dynamic biophysical flux biosensors, and eliminates noise by phase discrimination. SR microbiosensors were used to study physiological glucose metabolism and ATP release. Studies based on the physiological biosensors have provided important insights into diabetes, cancer, microbial biofilms, neurotransmission and wound healing.
Degree
Ph.D.
Advisors
Porterfield, Purdue University.
Subject Area
Biomedical engineering
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