Doctor of Philosophy (PhD)
It is becoming more important to detect ultra-low concentrations of analytes for biomedical, environmental, and national security applications. Equally important is that new methods should be easy to use, inexpensive, portable, and if possible allow detection using the naked eye. Detection of low concentrations of analytes generally cannot be achieved directly, but requires signal amplification by catalysts, macromolecules, metal surfaces or supramolecular aggregates. The rapidly progressing field of macromolecular signal amplification has been advanced using conjugated polymers, chirality in polymers, solvating polymers and polymerization/depolymerization strategies. The use of molecularly imprinted polymers is ideal for creation of novel sensors to meet the demands of bioanalytical fields. Often referred to as plastic antibodies, molecularly imprinted polymers can often approach the activity and specificity of antibodies. Additionally, they are cheap to produce relative to traditional bioassays, exhibit greater stability to pH, heat, enzymatic degradation, and are reusable over long periods of time. The ever expanding field of molecularly imprinted polymers generally focuses of new techniques and materials aimed at increasing the selectivity of artificial binding sites based of improved shape, size, or functional selectivity both as a function of bulk polymer matrix and functional receptor molecules located in the active site. Here, a new type of aptamer-based hydrogel with specific response to target proteins demonstrates an additional category of macromolecular signal amplification. This super-aptamer assembly provides the first example of using protein-specific aptamers to create volume changing hydrogels with amplified response to the target protein. A remarkable aspect of these super-aptamer hydrogels is that volume shrinking is visible to the naked eye down to femtomolar concentrations of protein. This extraordinary macromolecular amplification is attributed to a complex interplay between protein-aptamer crosslinks and the structure of the hydrogel network surrounding it. Additionally, the further investigation of the role played by N, O-bismethacrylethanolamine toward the recognition of a pair of enantiomers was explored. Previous work showed its utility as a one monomer moleculary imprinted polymer material capable of enantiomeric separation. Its further characterization was explored here concerning its ability to be used as a binding receptor in concert with its role in reducing polymer matrix non-selective binding. The deconvolution of this duality could lead to the design of better monomers capable of greater specificity and selectivity in monolithic molecularly imprinted polymers.
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Gariano, Nicholas Alexander, "Super-aptamer bio-imprinted hydrogels : an investigation into the optimization and characterization of cross-linked polymeric materials displaying macromolecular amplified responses" (2013). LSU Doctoral Dissertations. 388.