Katarzyna Lechowicz
supervisor: Mateusz Ĺmietana
Despite intensive development of various biosensing solution, fast and reliable detection of Borrelia bacteria is challenging. In this work we report for the label-free optical fiber sensor where the measurement can be simultaneously performed in optical and electrochemical domains. The sensor is based on multimode optical fiber, where a short section of the core was coated with indium tin oxide (ITO) thin film using RF magnetron sputtering method. Application of transparent conductive oxide, such as ITO, provides a possibility of double-domain detection where due to the film conductivity, the sensor may be investigated by electrochemical (EC) methods where ITO-coated fiber is used as working electrode (WE), as well as optical methods where lossy-mode resonance (LMR) is investigated. LMR-based sensors are relatively easy to fabricate and are considered as a cheaper alternative for surface plasmon resonance sensors. Detection of Borrelia burgdorferi CB43 has been performed by using bacteria’s surface protein directed antibodies as bioreceptor. As a redox probe for EC measurements 1mM 1,1’-Ferrocendimethanol (0.1M PBS) has been used.In order to provide binding agent between ITO’s surface and the receptor layer,sensors have been chemically functionalized using APTES silanization. Investigated concentrations were in range from 340 ng/mL up to 34 μg/mL. Due to application of double-domain sensing concept, we enhance the sensitivity of the structure and decrease of false results