Simultaneous optical and electrochemical biofilm analysisFilipović, Filip (Avtor) Mandić Mulec, Ines (Mentor) Richter Dahlfors , Agneta (Komentor) biofilmelectrochemical detectionoptical detectionoptotracersMicroorganisms live most of their life as biofilms encapsulated in a matrix. This lifestyle allows for prolonged survival in many environments and affects their importance in microbe-related diseases, as they can form on a variety of surfaces, including living tissue, implanted medical devices, etc. Therefore, the development and improvement of detection and monitoring methods is an important problem in microbiology. Electrochemical techniques have generally not been used for direct detection of bacteria and real-time monitoring has been limited to mostly well-characterized electroactive bacteria, with well-defined redox active metabolites. In this thesis we succeeded in monitoring bacterial growth of Salmonella Enteritidis in real time using organic electrochemical transistors, although we were unable to distinguish between biofilm-forming and non-forming strains. In addition, we were able to detect bacteria up to 10⁵ CFU/mL using this method. This new method was comparable to the classical measurement of optical density (e.g., A₆₀₀). We then focused our research on developing a method based on the detection of extracellular matrix components of biofims. To study these, various ligands are used, however, most of them are either toxic and/or non-specific, creating a need for novel ligands. In this thesis we used a series of organic fluorophores called optotracers, which allow real-time visualization of ECM components. Since optotracers have a very similar structure to PEDOT:PSS, we were able to successfully create a hybrid material from both components. This was done without the need for chemical linkage and did not affect the conductivity of the surfaces coated with the hybrid material. After the biofilm formation on the optotracer-functionalized PEDOT:PSS surfaces, the optotracers were extracted from the PEDOT:PSS and successfully bound to the ECM components. These surfaces were then used to enable successive electrochemical and optical detection, although simultaneous detection was not technically feasible in this case.[F. Filipović]20222022-04-06 07:15:02Magistrsko delo/naloga135986sl