Date of Award

Spring 2004

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biomedical Engineering

First Advisor

Michael J. McShane

Abstract

Currently, there is no means by which rapidly fluctuating glucose and lactate levels can be monitored simultaneously. This dissertation demonstrates that by combining the broad-band versatility of fluorescence spectroscopy with nanoassembly methods, it is possible to construct micro- and nanoscale sensors with precise composition and short diffusion length constant. The work is significant because of its potential as a platform for discovery of basic normal physiological processes that have previously been hidden from researchers' views, more detailed studies of responses to drugs or other stimuli, and even clinical monitoring. The main goal of this work was to develop novel methods that enable the simultaneous study of glucose and lactate transients in the brain extracellular fluid. It is shown that on-line monitoring of glucose concentration can be accomplished using optical probes with nanoassembled analyte specific enzymes combined with fluorescent indicators. A model for fabrication was developed to predict the fluorescence spectrum for a given film architecture. A model for the coupled reaction-diffusion was developed to predict the oxygen concentration in the sensing region of the films as a function of glucose concentration. A model was developed to predict the resulting fluorescence spectrum for the infusion of nanoparticles of a given film architecture. Oxygen sensors were fabricated on quartz slides, optical fibers and nanoparticles. A protocol in vitro and in vivo sensor delivery was developed and the delivery are nanoparticle sensors to the dentate gyrus of the hippocampus was confirmed by real-time fluorescence monitoring of the infusion and fluorescence confocal imaging of sectioned rat brain tissue. The accuracy of the fiber probes was shown to be 0.5% for 0 to 100% oxygen. The fiber probes were further developed in to a glucose probe with the addition of GOx films and a coating of 100 μm PDMS coating, which served as a transport barrier to oxygen. The accuracy of the glucose probe was approximately 21% for 0 to 60 mg/dL glucose.

Download

Share

COinS