dc.description.abstract | Biomacromolecules, mainly nucleic acids and proteins, are involved in
every cellular process and therefore their aberrant level or function is linked with
most of the diseases. Controlling these macromolecules using light can therefore
be immediately applied towards a range of biomedical fields including
bioengineering, biotechnology, biochemistry, medicinal chemistry, diagnostics,
therapeutics, and so on.
In this dissertation, multiple approaches to create the photoactivable
macromolecules and their applications in biomedical field are discussed. In the
first part of this dissertation, optimization of light activated RNA interference
(LARI), a technique developed earlier in our lab, is discussed. By modifying
nucleic acid with various new photolabile groups, RNA interference (RNAi) was
brought under the control of light. Using these novel caged macromolecules,
gene expression was patterned in cell monolayers, demonstrating the potential of
LARI in controlling the spacing, timing and extent of gene expression.
In second part of the dissertation, insulin, a protein, was modified with
new photolabile groups and then crosslinked to a solid matrix to create an
insoluble photoactivable depot (PAD). Insulin with various degrees of
photolabile modifications were purified and studied for their photokinetics. Furthermore, using this new approach, the release of protein from a matrix
system was precisely controlled using light. This new photoactivable insulin
depot could load several weeks worth of insulin in the volume of a single
injection. Therefore, this could potentially solve the problem of multiple insulin
injections, administered by millions of diabetics everyday. Furthermore, the
amount of insulin released from the depot can be tightly controlled using light.
In future, this technique can potentially be coupled with non-invasive
continuous glucose monitoring devices for automatic detection and control of
blood sugar level in patients. Finally, this PAD approach could be applied to
other macromolecules, hormones and drugs.
Furthermore, we utilized a universal photolabile crosslinking reagent,
developed for insulin, for site-specific end labeling of different types of nucleic
acids with these groups. Using these groups, we can temporarily attach other
molecules like fluorophore, intercalator, drugs, proteins, etc. on to nucleic acids.
Finally, these groups can be photocleaved to regenerate the native nucleic acids. | eng |