BME PhD Dissertation Defense - George Daaboul

10:30 am on Monday, April 8, 2013
8 Saint Mary's St, Room PHO339
Committee Members:
M. Selim nl, Ph.D. (ECE/BME, Advisor)
Bennett B Goldberg, Ph.D. (Physics/BME)
John H. Connor, Ph.D. (Microbiology, BU School of Medicine)
Catherine Klapperich, Ph.D. (BME)
Charles Delisi, Ph.D. (BME, Chair)
Emre zkumur, Ph.D.

Title: "Interferometric Biosensing Platform for Multiplexed Digital Detection of Viral pathogens and Biomarkers"

Abstract: Label-free optical biosensors have been established as proven tools for monitoring specific biomolecular interactions. However, compact and robust embodiments of such instruments have yet to be introduced in order to provide sensitive, quantitative, and high-throughput biosensing for low-cost research and clinical applications. Here we present the interferometric reflectance imaging sensor (IRIS) using an inexpensive and durable multi-color LED illumination source. IRIS monitors biomolecular interaction through measurement of biomass addition to the sensor's surface. We demonstrate the capability of this system to dynamically monitor antigen–antibody interactions with a noise floor of 5.2 pg/mm2 and DNA single mismatch detection under isothermal melting conditions in an array format.
Ensemble detection of binding events did not provide the sensitivity needed for detection of infectious disease and clinical biomarkers at clinically relevant concentrations. Therefore, a new approach was adapted to the LED IRIS platform that allowed the detection and identification of individual nanoparticles on the sensor's surface. The new detection method was termed single particle IRIS (SP-IRIS). We developed two detection modalities for SP-IRIS. First, we developed an assay for label-free virus detection. We verified that SP-IRIS can accurately size viral particles. Then we demonstrated that single nanoparticle counting and sizing methodology on SP-IRIS leads to a specific and sensitive virus sensor that can be multiplexed. Finally we developed an assay for the detection of Ebola and Marburg. The assay was tested using vesicular stomatitis virus (VSV) pseudotypes. A detection limit of 5 x 103 PFU/ml was demonstrated for both Ebola and Marburg using the VSV pseudotypes. The second modality of SP-IRIS we developed single molecule counting of biomarkers utilizing a sandwich assay with a detection probe labeled with a gold nanoparticle. We demonstrated the use on single molecule counting in a nucleic acid assay for melanoma biomarker detection. We showed that a single molecule counting assay can lead to detection limits in the aM range. The improved sensitivity of IRIS utilizing single nanoparticle detection will allow the utilization of a simple and low-cost technology for rapid virus detection and multiplexed molecular screening for clinical applications.