Photonic Aptasensor Based on the Smart Cholesteric Liquid Crystal Network Structure for Cylindrospermopsin Detection

Solid-state cholesteric liquid crystals (CLC_solid) with one-dimensional photonic structure offer a promising platform for constructing chemical and biological optical sensors, owing to their facile fabrication, signal readout, and sensitive and selective responsiveness to target analytes. In this study, we designed a CLC_solid photonic structure intertwined with an interpenetrating polymeric network (IPN) immobilized with a cylindrospermopsin aptamer (CY9) for the selective detection of the cylindrospermopsin toxin (CYT) in water. Upon exposure to CYT, it induced a blue shift in the color of the IPN_CY9 biosensor chip. This shift occurred because the CY9 aptamer selectively bound to the CYT, reducing the polarity of the IPN hydrogel, leading to water release and shrinkage of the photonic structure. The IPN_CY9 biosensor chips demonstrated the ability to detect CYT within a linear range of 4.2–120 nM, with a limit of detection of 2.55 nM. This innovative biosensor chip not only provides a new strategy for designing targeted toxin biosensors by immobilizing different receptors but also exhibits significant potential for use in portable kits for remote areas.