The need for overnight and continuous monitoring of glucose levels in diabetic
patients is profound, especially among juveniles. Implantation of a chemical assay
which responds optically to changes in glucose concentration shows promise as a
technology capable of continuously monitoring blood sugar with little invasion into the
body. Previous fluorescent chemical assays, based on the affinity binding reaction
between Concanavalin A protein and dextran, performed well but suffered from limited
dermal penetration. In this work, a novel replacement for the dextran molecule
(glycosylated dendrimer) was fabricated and tested to determine if it would improve the
overall response of the sensing chemistry to glucose. Experiments were carried out and it
was found that the assayâÂÂs functionality was based on the controlled aggregation of the
Con A protein and the modified dendrimer molecule. This new assay proved to be
specific to glucose, reversible, and independent of fluorophore dye attached to the
protein.
This research was furthered by encapsulation of the new assay into a PEG
hydrogel which showed response to glucose but, due to leeching, did not perform well under repeated exposures. A new method for encapsulation was proposed based on
poration of the hydrogel to create micropores capable of holding the assay chemistry and
allowing it to react to incoming glucose, while the surrounding polymer restricted
leeching. Preliminary results with previous assays proved the potential of a mannitol
based poration procedure, but unforeseen complications in lyophilization of the new
sensor assay restricted its completion. Due to instability of Con A in solution, it was
hypothesized that the immobilization of it onto the surface of an active substrate would
increase its stability overtime as seen in previous works. The immobilization procedure
was performed on Con A for both polystyrene spheres and gold (nanoshells and colloid).
Both results showed an adequate amount of protein on the surface of the particles, but
little binding activity was demonstrated. Overall, the improvements to the sensor
chemistry response were notable and the potential for stabilization and enhancement of
the response through the use of an active substrate is promising.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/4991 |
| Date | 25 April 2007 |
| Creators | Ibey, Bennett Luke |
| Contributors | Cote', Gerard L. |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | 3645862 bytes, electronic, application/pdf, born digital |
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