This project combines electrokinetic (EK) methods with surface plasmon resonance (SPR) spectroscopy to construct a flexible, modular lab-on-a-chip platform for determination of target biomarkers. Small volume channels are etched into a dielectric substrate where EK methods for concentration and separation (i.e. dielectrophoresis and electrophoretic capture) of target analytes from the other compounds in the biofluids are employed to condition the sample for SPR detection. For example dielectrophoresis and electrophoretic capture will be employed to locally concentrate the target analytes in the microfluidic channel while minimizing the local concentration of interfering proteins. Gold sensing pads can be employed for direct label-free SPR analyses, coated with bioreceptors to increase sensitivity and selectivity, or coated with bioreceptors for the analysis followed by signal amplification with the another antibody to the target biomarker. Methods for signal enhancement such as antibody sandwich assays will be included with the lab-on-a-chip design to achieve a greater degree of sensitivity. This sensor will be applied to detection of biomarkers for myocardial infarction. The proposed platform offers the following attributes beneficial to any bioassay: """""""" The modular, 'chip'based sensing platform can separate, concentrate, and quantify multiple protein and peptide biomarkers required for a panel assay. """""""" Electrokinetic methods and SPR detection with sandwich assays are both appropriate for analyzing physiological levels of proteins and peptides. """""""" The system is ideally suited for small volume analyses. EP and DEP work best in small channels approximately 10 to 100 microns in diameter. SPR is sensitive to refractive index changes within 200 nm of the gold sensing pads. """""""" EK can rapidly separate and concentrate analytes from complex mixtures based on electrophoretic mobility. High resolution separations are possible and 1000-fold preconcentration can be achieved with dielectrophoresis or addressable electrophoretic capture.
We expect that the sensor system developed here will enable more timely diagnoses of MI and stroke type;the low cost and fieldability of the sensor system will enable first responders to achieve a more definitive diagnosis prior to arrival in the emergency room. Likewise, rural and poor clinics can better triage patients, minimizing the burden of sending many urgent care cases to larger hospitals for tests. If the ability to prognosticate wound healing is realized, the efficacy of treatment and the seriousness of injury (i.e. for diabetics or burn patients) can be determined at an earlier date. This would allow doctors to optimize treatment for each particular patient.
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