M.Sc Thesis

M.Sc StudentSchwartz Ortal
SubjectMicrofluidic Assay for Continuos Bacteria Detection
Using Antimicrobial Peptides and Isotachophoresis
DepartmentDepartment of Nanoscience and Nanotechnology
Supervisor ASSOCIATE PROF. Moran Bercovici
Full Thesis textFull thesis text - English Version


Pathogen detection is of the utmost importance in the identification, prevention and treatment of health risks associated with bacterial infections. Food analysis, water and environment quality control and clinical diagnosis all require rapid and sensitive diagnostic tools for pathogen detection. In recent years the pathogen detection methods evolved and improved significantly, especially due to implementation of high-end microfluidic techniques, but still the need for continuous, rapid, sensitive and point-of-care detection platform remains unanswered.

In this dissertation we present the development of a novel microfluidic assay for continuous and quantitative detection of bacteria in water. We leverage isotachophoresis (ITP), an electrophoretic focusing technique, to create a stationary high concentration zone of fluorescently-labeled antimicrobial peptides (AMPs) in a microfluidic channel. The tested water sample flows continuously through this high concentration AMPs reaction zone; any bacteria present in the sample is simultaneously labeled by, and separated from, the high concentration AMPs. The labeled bacteria continue into the downstream pure-buffer zone where the fluorescence signal is monitored, providing a direct quantitative measurement of the original bacterial concentration in the sample.

Within the scope of this work we have demonstrated, the assay’s applicability for quantitative detection of E. coli as well as its stability over a 1 hr monitoring time. Furthermore, we have provided a simple yet detailed model for predicting the performance and sensitivity of the assay at different operating conditions.

To conclude, the assay we developed and demonstrated has the potential to enable continuous monitoring of water at the point-of-need, relieving the dependence on clinically-trained personnel, and eliminating the need to transport samples to a centralized lab. It is a one-step method for labeling, separation and detection of bacteria in sample. The use of a microfluidic platform, as well as the significant focusing of labeling probes by ITP, result in significant reduction in the amount of expensive reagents required for detection and enables on-line continuous monitoring which is not possible in other applications. We believe the assay may also be applicable for pathogen detection in food safety and medical diagnostics applications, where rapid pathogen detection is also crucial.