Stable liquid crystal-infiltrated photonic crystal sensing film for facile detection of streptomycin

Abstract

Liquid crystal (LC) biosensors have attracted interest due to their simplicity and ability to visualize results. However, their inherent instability including the fluidity of LCs and the complexity of operation, limits their potential as reliable and user-friendly detection tools. To enhance their practical applicability, a stable and facile LC-infiltrated photonic crystal (LCP) sensing film is developed through optimization of film substrate preparation and investigation of the response mechanism. The reflection peak of the LCP film, which is modulated by changes in LC orientation within the film, can be recorded using a fiber-optic spectrometer or observed visually. Molecular dynamics simulations, integrated with experimental data, were employed to improve LC induction efficiency and increase signal strength. This approach inherently improves the stability and sensitivity of LC biosensors, expanding their potential for use in compact devices. A triple-helix molecular conformational switch is introduced to establish a versatile and specific detection platform. When streptomycin was chosen as a model analyte, the LCP film exhibited a linear range from 5 nM to 10 μM, with a detection limit of 0.40 nM and a relative standard deviation of 2.19%, indicating high precision and reliability. Its practical application was further confirmed with food samples, highlighting its potential for at-home testing of antibiotic residues.