Implantable Fluorogenic\nDNA Biosensor for Stress Detection

Implantable sensors that can monitor analytes related\nto cognitive\nand physiological status have gained significant focus in recent years.\nWe have developed an implantable biosensor to detect dehydroepiandrosterone\nsulfate (DHEA-S), a biomarker related to stress. The biosensor strategy\nwas based on the principle of forced intercalation (FIT) aptamers\ndesigned to detect subtle intramolecular changes during aptamer-target\nbinding events. By incorporating a steroid-specific fluorogenic aptamer\ninto a hydrogel, the sensitivity and biostability of the FIT biosensor\nfiber were improved, which were essential for designing implantable\nsensors to monitor biomarker levels in the living body. The polyethylenimine-based\nhydrogel chosen for this study produced an optically transparent cross-linked\nnetwork with optimal microstructure, physicochemical, and mechanical\nproperties, making it suitable for optical biosensors. The <i>in vitro</i> studies showed that the biosensor fiber was successfully\nactivated in human serum and skin analogue, providing a linear response\nto physiological concentrations of the steroid. We believe that this\ntype of implantable platform can be effective in monitoring more complex\nbiomarkers associated with physiological or psychological health.