Flexographically Printed TiO₂ Thin Films for Electrochemical Label-Free Interleukin-8 Detection

In this work, TiO 2 nanoparticles were printed on top of interdigitated electrodes for the direct non-faradaic detection of interleukin 8. The reported flexographically printed biosensor allows scalable detection of the cytokine at low-cost. Furthermore, non-faradaic impedimetric detection is simple, label-free and enables on-site detection of biomarkers. Physical properties of the printed layers were characterized via surface profilometer and scanning electron microscope. The results show a dense and continuous film of TiO 2 on top of the interdigitated electrodes. X-ray diffraction was also performed to investigate the printed layer and confirmed the passivation of the surface by the printed layer. Chemical analysis was carried out using energy dispersive X-ray and X-ray photoelectron spectroscopy which further confirmed the passivation of interdigitated electrodes surface by TiO 2 . Finally, the printed film was modified with IL-8-antibodies through standard functionalization steps. The biosensors were then used for the direct detection of IL-8-antigens using non-faradaic electrochemical impedance spectroscopy. The biosensors demonstrated sensitivity and LoD of 24.6 nF/log(ng/mL) and 30 pg/mL, respectively, which is comparable to other reported biosensors. The reported technology is promising for low-cost and mass producible sensors in the future for the monitoring of health biomarkers.