A Biochemical Sensing Platform Based on Functionalized Liquid Crystal Whispering Gallery Mode Microcavities for Liver Biomarker Detection

Real-time, label-free, and highly sensitive biochemical sensing is essential for early clinical diagnostics. Many conventional assays, such as colorimetry, fluorescence, and electrochemistry, are often limited by low sensitivity, complex procedures, and slow response times. Here, we proposed a whispering gallery mode (WGM) biosensing system based on stearic-acid-functionalized liquid crystal (LC) microcavities for biochemical detection. Amphiphilic stearic acid functionalizes the LC microcavity interface, enabling the pH-responsive reorientation of LC molecules. This changes the refractive index profile within the microcavity, resulting in obvious shifts in the WGM lasing spectra. Dynamic variations in molecular orientation within the LC microcavity were monitored using polarized optical microscopy and spectral analysis. Furthermore, this system allows for the highly sensitive detection of alanine aminotransferase and aspartate aminotransferase. Both liver biomarkers were detected in the range of 0.03–0.10U/mL, exhibiting a linear relationship with their respective enzymatic reaction times. WGM spectral wavelength shifts recorded at defined time points (60, 90, and 120 s) enable rapid estimation of enzyme concentrations, allowing preliminary quantification. This approach enables simplified operation, short response time, and label-free detection for early liver injury diagnostics, which offers a potential biochemical sensor for evaluating drug-induced liver injury and monitoring point-of-care liver function.