Enzymes Adsorbed on Carbon Nanotubes

University Of Texas San Antonio, San Antonio TX

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Abstract

DESCRIPTION (provided by applicant): The goal of this project is to increase the number of underrepresented minorities participating in biomedical and behavioral research. In that regard, this project will focus on the development of new biosensors based on enzymes adsorbed on carbon nanotubes, and then demonstrate the capabilities of such biosensors by integrating them in capillary electrophoresis microchips. Carbon nanotubes (CNT) display excellent qualities toward electrochemical biosensors. CNT are biocompatible, are stable over a large range of potentials, demonstrate catalytic activities toward many electrochemical reactions, and provide a significant increase in electrode area. Although considerable progress has been made by encapsulating or cross-linking enzymes, the analytical performance of CNT-biosensors still suffers from some fundamental deficiencies such as slow response (>10 sec) and limited sensitivity (~micro-M). The proposed biosensors will have larger and faster response than standard biosensors and will combine the selectivity of enzymes, the catalytic activity and conductivity of carbon nanotubes with the sample handling capabilities and separation means of capillary electrophoresis microchips. The hypothesis of this project is that experimental conditions can be rationally selected to maximize the adsorption of enzymes to carbon nanotubes, while preserving the enzymatic activity. Since the conditions used for the adsorption have a central effect on the enzymatic conformation and activity, we will first investigate how different enzymes interact with carbon nanotubes. By analyzing the adsorption kinetics under different conditions we will establish a rational link between enzyme properties and adsorption conditions. Then, we will demonstrate the advantages of coupling these biosensors to a capillary electrophoresis microchip. We expect to avoid harsh binding conditions (enzyme-electrode), minimize the response time, maximize the signal magnitude, and decrease the peak tailing associated with membranes (applied to trap the enzyme). Since the proposed sensor will be integrated with a capillary electrophoresis microchip, operations such as sample pretreatment, injection, and separation can be included and automated. We will study how enzymes interact with carbon nanotubes. Then, we will apply that information to develop sensors to monitor important molecules and diagnose diseases.