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New Faculty Member John Brennan The research of our newest faculty member The Brennan group is developing optical fiber-based biosensors for environmental and biomedical monitoring, with high sensitivity and fast response times, for use in harsh environments without degradation of encapsulated proteins. These goals require (1) the design and optimization of fiber-optic technology to permit excitation and monitoring of encapsulated proteins, (2) the development of an associated spectroscopic assay, and (3) the immobilization of the appropriate chemistry onto the fiber-based instrument. A schematic of a fiber-optic fluorescence instrument developed in the Brennan group is shown below. Immobilization of biological compounds on optical fibers requires the development of new biomaterials prepared from silane-based precursors by the sol-gel route. The goal is to prepare optically transparent biomaterials with good durability which can withstand repeated dehydration-rehydration cycles. Preparations most favorable to protein encapsulation include low temperature processing and minimal use of non-aqueous cosolvents. Biologically interesting fluorescent molecules currently being studied include nitrobenzoxadiazole (NBD), which is used to label proteins. This probe undergoes both excited state charge-transfer and self-quenching processes when present within proteins. By modifying the probe concentration and environment, contributions from both processes to the total fluorescent signal can be uniquely identified and used to better understand the relationship between NBD emission and protein structure. Another probe currently under investigation is 7-azatryptophan (7AW). This probe is a tryptophan analog which has been incorporated into the amino acid sequence of peptides and proteins. The photophysical behaviour of 7AW is far more complicated than is observed for tryptophan, and this results in 7AW being far more sensitive to changes in local environment. Here, time-resolved and steady-state fluorescence methods are being used to examine 7AW photophysics.
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is concerned with the development of biosensor
technology. The encapsulation of proteins into sol-gel derived glass matrices is
investigated for this purpose. In these studies, an understanding of how the encapsulation
of enzymes, antibodies and other ligand binding proteins in sol-gel derived glass matrices
affects both the initial and long-term stability of these biomolecules is essential.
Steady-state and time-resolved fluorescence measurements are used to probe the protein
structure and dynamics, while fluorescence-based assays are done to examine activity (for
enzymes) and binding affinity (for antibodies). 