Fabrication and Biosensing Application of SiO ₂ –TiO ₂ Hybrid Inverse Opal Fabry-Pérot Layers

In this work, we fabricated uniformly ordered SiO₂-TiO₂ hybrid inverse opal Fabry-Pérot layers based on sol-gel cogrowth strategy and utilized their unique Fabry-Pérot fringes for real-time and dynamic monitoring of lipid degradation processes. By optimizing the concentrations of polystyrene nanospheres, we achieved precise modulation of film thickness, ranging from nanometers to micrometers. The homogeneous SiO₂-TiO₂ hybrid system is formed through the combination of titanium(IV) bis (ammonium lactato) dihydroxide solution and tetraethyl orthosilicate precursors, allowing refractive index (RI) tailoring via SiO₂-TiO₂ ratio regulation. Evaluation using ordered porous layer interferometry (OPLI) platform confirms the optimized films exhibit both high optical interference contrast and RI sensitivity. Building upon this foundation, a lipid interferometric layer is constructed within the inverse opal film and integrated with OPLI system to create a biosensing platform. This system enables real-time monitoring of lipid and lipase digestion processes, with changes in effective optical thickness are calculated from Fabry-Pérot fringe pattern shifts induced by RI variations during digestion. The biosensor demonstrates excellent sensitivity and a wide linear range (5-2000 U/L) for real-time process monitoring, offering new possibilities for studying liquid-phase biomolecular interactions. This integrated platform shows significant potential for applications in clinical diagnostics and pharmaceutical research.