Characterisation and application of electrodes with hydrogenated titania nanotubes modified with M13 bacteriophage

M13 bacteriophages (in short, phages) have an intrinsic ability to infect Escherichia coli bacteria but can be engineered to exhibit specific peptides on their surface which enables them to selectively bind to diverse targets. Therefore, such phages can be used as a sensing element in a biosensor. Consequently, our aim is to assess the effectiveness of sponge-like, laterally spaced, hydrogenated titania nanotubes (S-TiO2-NTs) as an immobilisation scaffold for M13 phages in electrochemical systems. The electrodes used in this study were fabricated via anodisation and calcination in a hydrogen atmosphere. Electrochemical methods were used to study the capacitive and faradaic currents of the S-TiO2-NTs electrodes in varying concentrations of M13 phage lysate immobilised through physisorption. Moreover, measurements over 8 days, at 37°C and in human serum, were performed to evaluate the stability of the phage-modified electrodes. The obtained results demonstrated that the phages were successfully adsorbed on the electrode surface, which was also confirmed by scanning electron microscopy. Furthermore, the S-TiO2-NTs with wild-type M13 phage were used to detect E. coli bacteria. The limit of detection (LOD) for the electrode was LOD = 3 cells/ml, and the linear range was 10-104 cells/ml. The results demonstrate that S-TiO2-NTs electrodes are promising immobilisation platforms for M13 phages and could be utilised to fabricate phage-based biosensors.