טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentParahovnik Lora
SubjectWhole-Cell Imprinting in Sol-Gel Materials (Macromolecular
Fingerprinting) for Rapid Bacterial Recognition in
Water Samples via Quartz Crystal
Microbalance (QCM) Detection
DepartmentDepartment of Civil and Environmental Engineering
Supervisor Professor Robert Armon


Abstract

Detecting cells and microorganisms in different matrices is becoming an increasingly important task in a variety of fields. Well established chemical and biological detection methods are highly suitable for this task and yield the desired detection limits, but the analysis time interval is usually time consuming for rapid real-time determinations. For this purpose, there is an emerging need to develop fast and sensitive method for specific identification of bacteria in liquid environments.

Sol-gel derived thin films molecularly imprinted with different bacterial cells previously showed to be an easy and selective method for specific bacterial recognition from water samples. An important feature of the imprinting process is the molecular fingerprints left by these microorganisms alongside morphology, into imprinted film cavities that are complementary to the template molecule in size, shape, and functionality. The resulting imprinted film cavities can then “remember” (i.e., selectively bind) the template bacteria. 

In the proposed research, a method for rapid and selective bacterial recognition will be developed by quartz crystal microbalance (QCM) based biosensor. QCM probes will be coated with sol-gel derived thin films and modified with a surface-imprinting process using different whole bacterial cells such as: Staphylococcus epidermidis, Deinococcus radiodurans, E.coli, Pseudomonas aeruginosa, and Flavobacterium breve.

This work presents a multidisciplinary approach towards achieving a highly sensitive QCM based biosensor. It was demonstrated that TEOS imprinted films on surface showed a high selectivity towards the experimental template bacteria along the adsorption process from water. The high affinity of imprinted sol-gel films toward planktonic cells was determined by cavity morphology and biological residuals entrapped inside the cavity. According to proteomic analysis of imprinted samples, some of the known cell surface proteins were detected inside the imprinted sol-gel cavities.

Furthermore, the sensitivity of present QCM imprinted probes is ~ 10 CFU/ml, which is a significant 100-fold improvement in the detection limit comparatively to QCM based biosensors for whole cells detection. This fact allows this method to be a promising technique for selective detection and quantification of bacteria present in liquids.