BME PhD Dissertation Defense - Margo Monroe

10:00 am on Friday, April 5, 2013
12:00 pm on Friday, April 5, 2013
LSEB 103, 24 Cummington Mall
Highly sensitive and multiplexed platforms for allergy diagnostics

Committee Members:
Selim Unlu (ECE/BME)
Catherine Klapperich (BME, Chair)
Muhammad Zaman (BME)
Frederic Little (BU School of Medicine)
Marcella Chiari (Institute of Chemistry of Molecular Recognition, National Research Council of Italy)

Allergy is a disorder of the immune system caused by an immune response to otherwise harmless environmental allergens. Currently 20% of the US population is allergic and 90% of pediatric patients and 60% of adult patients with asthma have allergies. These percentages have increased by 18.5% in the past decade, with predicted similar trends for the future. Here we design sensitive, multiplexed platforms to detect allergen-specific IgE using the Interferometric Reflectance Imaging Sensor (IRIS) for various clinical settings. A microarray platform for allergy diagnosis allows for testing of specific IgE sensitivity to a multitude of allergens, while requiring only small volumes of patient sample. However, microarray technology is limited by i) the variation of probe immobilization, which hinders the ability to make quantitative, assertive, and statistically relevant conclusions necessary in immunodiagnostics and ii) the use of fluorophore labels, which is not suitable for some clinical applications due to the tendency of fluorophores to stick to blood particulates and require daily calibration methods.

First, a highly sensitive, calibrated, and multiplexed platform was engineered to more specifically and rapidly determine allergic sensitization in clinical samples compared to conventional methods. This calibrated fluorescence enhancement (CaFE) method integrates the low magnification modality of IRIS with enhanced fluorescence sensing in order to directly correlate immobilized probe (major allergens) density to allergen-specific IgE in patient serum. However, this platform only operates in processed serum samples, which is not suitable for point of care testing. Thus, an alternative allergy diagnostic platform using a high magnification modality of IRIS was developed to automatically discriminate and size single nanoparticles bound to specific IgE in unprocessed, characterized human blood and serum samples. The high magnification (nanoparticle counting) modality in conjunction with low magnification of IRIS in a combined instrument offers four significant advantages compared to existing sensing technologies: IRIS i) corrects for any variation in probe immobilization, ii) detects proteins from attomolar to nanomolar concentrations in unprocessed biological samples, iii) unambiguously discriminates nanoparticles tags on a robust and physically large sensor area, iv) detects protein targets with conjugated nanoparticle tags (~40nm diameter), which minimally affect assay kinetics compared to conventional microparticle tagging methods, and v) utilizes components that make the instrument inexpensive, robust, and portable. These features make IRIS an ideal candidate for clinical and diagnostic applications, such a POC testing.