Development of Gelatin-Alginate-TiO2-SOD Biosensor for the Detection of Superoxide Radicals

In this work, a biosensor that uses gelatin and alginate hydrogels in addition to titanium dioxide (TiO 2 ) nanoparticles (NPs) as sensor matrix was developed in order to detect superoxide radicals (O2 •- ), which play role in carcinogenesis when present in excess levels. Parameters affecting the performance of the biosensor such as amount of gelatin-alginate ratio, amount of TiO 2 NPs, concentration of SOD enzymes and glutaraldehyde cross-linker were investigated. Electrochemical Impedance Spectroscopy (EIS) and chronoamperometry were used as electrochemical technique for the development of biosensor as well as characterisation steps. The developed biosensor exhibited two linear ranges between 0.0009 mM – 0.125 mM and 0.25 mM – 2 mM which were utilized as calibration curves. Detection limit of the biosensor was found 0.9 μM, which was at appropriate level for the detection of O2 •- in tumour samples. Finally, the constructed biosensor showed significant analytical performance such as high selection for O2 •- , low detection limit, and long-term stability.