Universal Integration of Liquid Crystals with Inorganic Inverse Opals: Robust and Customizable Regulation for Optical Sensing

Liquid crystal (LC)-based biosensors are attractive for translating subtle molecular interactions into optical signals, but their practical application is hindered by inherent fragility and limited LC regulation principles. Here, we report a universal strategy to construct robust and customizable sensing platforms by integrating nematic LCs into inorganic inverse opals (IO). This approach represents a paradigm shift from using substrates as passive supports to actively engineering them as regulators of the LC orientation. The resulting LC-infiltrated photonic crystal composites exhibit precisely tunable macroscopic optical responses governed by substrate-guided LC reorientation. Using IO-TiO₂ as a model, we establish a unique LC regulation mechanism by exploiting its structural and chemical properties. This mechanism was further elucidated through multiscale computational and experimental investigations. As a proof-of-concept, a one-step and reliable biosensor for reflective spectral detection of tetracycline (a common antibiotic pollutant) is constructed, achieving a linear range of 1 nM to 50 μM and a detection limit of 0.10 nM. Notably, the IO-TiO₂ substrate contributes to enhanced sensor durability and regenerability, evidenced by consistent performance over eight regeneration cycles (relative standard deviation, RSD = 3.06%). These results validate the practical potential of this biosensor, thereby confirming the design flexibility and broad applicability of our strategy. Overall, the integration offers a promising pathway for designing robust LC-responsive systems, with significant potential for advancing compact and customized optoelectronic sensors.