Liquid Crystal Microcavity Biosensors for Real-Time Liver Injury Monitoring via Whispering Gallery Mode Laser.

Real-time monitoring of liver injury is essential for preserving physiological health. Alanine aminotransferase (ALT) detection is widely regarded as a fundamental approach for the early diagnosis of liver injury. However, existing detection methods often suffer from complex operation, high costs, and limited sensitivity. Here, we introduce a real-time biosensor based on functionalized liquid crystal microcavities with whispering gallery mode (WGM) laser for rapid and sensitive ALT detection. The microcavity functionalized with stearic acid exhibits distinct optical responses to ALT-catalyzed enzymatic reactions across varying concentrations. The high-quality factor of the microcavity obviously enhances its biosensing performance. Simulations reveal variations in the electric field behavior of WGM lasing as the liquid crystal microcavity transitions between radial and bipolar configurations. Further analysis was conducted using experimental WGM spectra and corresponding polarized optical microscopy images. Experimental results demonstrate a strong linear correlation between ALT concentration and reaction time within the range of 0 to 240 U/l. This biosensor exhibits a sensitivity of 0.67 s/(U/l), indicating its potential as a promising approach for early liver injury assays. In addition to in vitro verification, in vivo validation using mouse serum samples further confirms its practical applicability, yielding results consistent with those tested by using commercial assay kits. This method offers a simple, cost-effective, and efficient detection of ALT, underscoring the potential of liquid crystal microcavities for biosensing in liver injury monitoring.