Self assembled DC sputtered nanostructured rutile TiO₂ platform for bisphenol A detection

A novel biosensor platform comprising of the functionalized sputtered rutile nanostructured titanium dioxide (nTiO2) for rapid detection of estrogenic substance (bisphenol A) has been proposed. The direct current (DC) sputtering of titanium (Ti) on glass substrate has been converted to ordered nanostructured TiO2 film via oxidation. The nanostructured TiO2 surface was functionalized with self-assembled monolayer (SAM) of 3-aminopropyltriethoxysilane (APTES) and glutaraldehyde. The enzyme molecule, tyrosinase (Tyrs) has been covalently immobilized on the surface of APTES modified nanostructured TiO2 film. To investigate the crystalline structure and surface morphology of functionalized nTiO2/Ti electrode, the X-ray diffraction, scanning electron microscopy, atomic force microscopy and Fourier transform infrared spectroscopy have been carried out. This impedimetric biosensor exhibits a comparable sensitivity (361.9 kΩ/µM) in a wide range of detection (0.01-1.0 µM) and a response time of 250 s for bisphenol A (BPA) monitoring. This novel manufacturing process for nTiO2 film is cheap, practical and safer for functionalization with SAM and glutaraldehyde to improve the biosensor efficacy. The strong protein absorption capability of the nTiO2 surface demonstrates an excellent electrochemical biosensor and could be useful for the detection of other phenolic compounds.