The concentration ratio of glycated to non-glycated forms of various blood proteins can be used as a diagnostic
measure in diabetes to determine a history of glycemic compliance. Depending on a protein’s half-life in blood,
compliance can be assessed from a few days to several months in the past, which can then be used to provide additional
therapeutic guidance. Current glycated protein detection methods are limited in their ability to measure multiple proteins,
and are susceptible to interference from other blood pathologies. In this study, we developed and characterized DNA
aptamers for use in Surface Plasmon Resonance (SPR) sensors to assess the blood protein hemoglobin. The aptamers
were developed by way of a modified Systematic Evolution of Ligands by Exponential Enrichment (SELEX) process
which selects DNA sequences that have a high binding affinity to a specific protein. DNA products resulting from this
process are sequenced and identified aptamers are then synthesized. The SELEX process was performed to produce
aptamers for a glycated form of hemoglobin. Equilibrium dissociation constants for the binding of the identified aptamer
to glycated hemoglobin, hemoglobin, and fibrinogen were calculated from fitted Langmuir isotherms obtained through
SPR. These constants were determined to be 94 nM, 147 nM, and 244 nM respectively. This aptamer can potentially be
used to create a SPR aptamer based biosensor for detection of glycated hemoglobin, a technology that has the potential to
deliver low-cost and immediate glycemic compliance assessment in either a clinical or home setting.
Molecularly imprinted polymer (MIP) thin films and surface plasmon resonance (SPR) sensing technologies were
combined to develop a novel sensing platform for monitoring real-time theophylline concentration, which is a compound
of interest in environmental monitoring and a molecular probe for phenotyping certain cytochrome P450 enzymes. The
MIPs hydrogel is easy to synthesize and provides shape-selective recognition with high affinity to specific target
molecules. Different polymerization formulas were tested and optimized. The influence of the monomer sensitive factors
were addressed by SPR. SPR is an evanescent wave optics based sensing technique that is suitable for real-time and label
free sensing purposes. Gold nanorods (Au NRs) were uniformly immobilized onto a SPR sensing surface for the
construction of a fiber optics based prism-free localized SPR (LSPR) measurement. This technique can be also applied to
assess the activities of other small organic molecules by adjusting the polymerization formula, thus, this approach also
has many other potential applications.
The peak extinction wavelength of the nano-size noble metal localized surface plasmon resonance (LSPR) spectrum is
unexpectedly sensitive to nanoparticle size, shape, and local external dielectric environment. This sensitivity to the
environment has enabled the development of a new class of nanoscale affinity biosensors. Aptamer (single strand DNA)
based gold nanorods (Au NRs) and magnetic beads (MBs) combined LSPR biosensor has been developed for the rapid
and label-free detection of glycated proteins in small solution volumes. An aptamer self-assembly monolayer (SAM)
functionalized surface plasmon resonance sensor has also been developed for comparison purposes. For demoonstration
purposes, albumin and thrombin are used initially as the target proteins. The ability to monitor such molecules in the
body could facilitate the diagnosis and treatment of diabetic patients.
The objective of this study was to develop rapid, inexpensive, and easily applied in vivo phenotyping strategies for
characterizing drug-metabolizing phenotypes with reference to the cytochrome P450 (CYP) enzymes in biological
fluids. Therefore, the accurate detection of low concentration of theophylline, which can be used as a probe for
cytochrome P450 (CYP450) enzymes (e.g. CYP1A2) activity, could benefit drug-metabolizing studies. In this study, a
portable, specific, and sensitive functionalized surface plasmon resonance (SPR) sensor using polyacrylamide
molecularly imprinted polymers (MIPs) as the highly specific selector is developed for the detection of low
concentration theophylline in the presence of other confounding components, such as, caffeine which has a very similar
chemical structure.
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