|M.Sc Student||Krepker Maksym|
|Subject||Development and Characterization of Optical Biosensors for|
Detection of Organophosphorus-Containing
|Department||Department of Biotechnology and Food Engineering||Supervisor||Professor Ester H. Segal|
|Full Thesis text|
The rapid detection of organophosphate (OPs) neurotoxins in the environment has become increasingly important for both homeland security and health protection due to their extreme toxicity. Our research is designed to answer this important challenge. We develop a new class of hybrid nanomaterials that can be employed as label-free optical biosensors for the rapid detection of OPs. We immobilize the enzyme organophosphorus hydrolase (OPH) upon the walls of the nanostructured porous silica (PSiO₂) and selectively synthesize poly(2-[dimethylamino]ethyl methacrylate) hydrogel in situ within the mesopores of the PSiO2 host above the immobilized OPH. The resulting nanostructured composite material combines an oxidized PSi optical nanostructure i.e., a Fabry-Pérot thin film, used as the optical transducer element, the pH-responsive hydrogel and the enzyme OPH, capable of hydrolysing organophosphates, releasing protons as hydrolysis products and, thus, lowering pH. The functional basis of the biosensor is a pH-triggered volume change of the hydrogel induced by the hydrolysis products of the OP compound. The swelling of the hydrogel is optically monitored using reflective interferometric Fourier transform spectroscopy (RIFTS), when swelling kinetics is found to correlate with the initial concentration of the model organophosphate, methyl paraoxon, that was present in the analyzed solution. The current sensitivity of the biosensor is as low as 40 μM with a typical response time is tens of minutes.