Methods for integrating enzyme systems with
electrochemical reactions having applications to diagnostic
sensing are described. Diagnostic tests that include
biological molecules can be classified as biosensors.
Existing testing methods often require trained technicians
to perform, and laboratory settings with complex
infrastructure. The theme of this dissertation is the
development of methods that are faster, easier to use, and
more applicable for non-laboratory environments. These goals
are accomplished in systems using enzymatic catalysis and
galvanic processes.
Two biosensors with specific model pathologies have
been designed and demonstrated in this study. The first
assay senses a DNA fragment representing the Epstein Barr
virus and uses enzyme-mediated Ag deposition over a
v
microfabricated chip. The chip contains a specially designed
pair of electrodes in an interdigitated array (IDA).
Detection is signaled by a change in the resistance between
the two electrodes.
The second biosensor discussed in this study is
targeted towards the digestive enzyme trypsin. It is selfpowered
due to its construction within an open-circuit
galvanic cell. In this system, a small volume of blood serum
is introduced onto the device over barriers made of protein
and Al that block the anode from solution. In the presence
of trypsin, the protein gel is rendered more permeable to
sodium hydroxide. Adding hydroxide initiates the dissolution
of the Al layer, closing the cell circuit and illuminating a
light-emitting diode (LED). A relationship was observed
between LED illumination time and trypsin concentration.
Biosensors that utilize enzymes to generate or amplify
a detectable signal are widely used, and the final project
of this study uses a nanoparticle based approach to protect
the catalytic activity of alkaline phosphatase (AlkP) from
hostile chemicals. By incubating Au colloid with AlkP
overnight and adding Ag+, core@shell nanoparticles of
Au@Ag2O can be isolated that show AlkP activity. The
resulting enzyme-metal composite material was analytically
characterized and demonstrated greater activity in the
presence of organic inhibitors relative to either wild type
vi
or Au colloid-associated AlkP without the Ag2O shell. The
stabilization procedure is complete in one day using a onepot
synthesis. This method may provide opportunities to
carry out biosensing chemistry in previously incompatible
chemical environments. / text
| Identifer | oai:union.ndltd.org:UTEXAS/oai:repositories.lib.utexas.edu:2152/ETD-UT-2011-08-3847 |
| Date | 03 January 2013 |
| Creators | Zaccheo, Brian Andrew |
| Source Sets | University of Texas |
| Language | English |
| Detected Language | English |
| Type | thesis |
| Format | application/pdf |
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