Abstract:
The research described in this thesis concerns the investigation of technologies for the
molecular engineering of the biosensor interface. Two avenues of investigation have
been explored: the use of polymer matrices to modify the properties and functions of
optical biosensor interfaces and the conjugation of photochromic dyes to protein
systems to achieve photomodulation of protein function for biosensor applications.
A comparison of the industry standard polymer, carboxymethyl dextran (CMD) was
made against carboxymethyl cellulose and mixed systems, including a novel synthetic
polymer, carboxylated polynoxylin. While CMD was found to provide the highest
surface loading of protein, mixed polymers demonstrated the ability to allow
prediction of surface loading, and showed features such as improved resistance to
biological degradation.
A novel method of depositing interfaces was investigated, allied to a study of liquid
handling methods. A system was developed that allowed a printed heterogeneous
array to be produced which showed preferential binding of specific analytes to
defined areas of the sensor, whilst the other printed arrays retaining a high degree of
non-specific interaction.
The use of photochromic dyes to modulate protein function was applied to glucose
oxidase and horseradish peroxidase. From the initial results, a hypothesis regarding
the mechanism of photomodulation and its effect concerning the molecular weight of
the conjugated protein was proposed. This was examined by the photomodulation of
members of the peroxidase super family, antibodies and Fab fragments. From these
results, the hypothesis was proved to be correct but incomplete, and was modified to
include the disruption of the hydration shell around the protein caused by
photochromic switching.
Further research directly related to these experiments, and in novel fields of
investigation have been proposed.