Real-time monitoring of key biomarkers is a critical prerequisite for early disease diagnosis and personalized therapy. Early detection of liver function impairment particularly relies on the measurement of serum alanine aminotransferase (ALT). However, conventional methods, including electrochemical, colorimetric, and fluorescence-based assays, often suffer from operational complexity, high cost, and limited sensitivity, making them inadequate for “rapid, real-time, and low-cost” detection needs in clinical intraoperative monitoring or home-based health management. Therefore, the development of a novel, convenient, and highly sensitive ALT detection strategy holds significant clinical value and application potential.

Recently, the research team led by Prof. Hanyang Li at Harbin Engineering University has integrated functionalized liquid crystal (LC) microcavities with whispering-gallery-mode (WGM) laser technology to establish a novel real-time biosensing platform (Figure 1), enabling highly sensitive detection of ALT.

Construction of Functionalized LC Microcavity Sensor
The team introduced stearic acid as a functional molecule within the LC microcavities. Leveraging its pH-responsive properties, the system can generate a pronounced optical response to pH variations induced by the ALT-catalyzed enzymatic reaction. These pH changes alter interfacial anchoring conditions, driving reversible transitions of LC molecules between radial and bipolar configurations. The resulting molecular orientation changes directly modulate the effective refractive index of the microcavity, thereby inducing a measurable redshift in the WGM laser resonance wavelength. This mechanism allows for real-time, label-free optical sensing of ALT enzymatic activity.

In Vitro and In Vivo ALT Detection
The normal reference range for ALT is typically 0–40 U/L, with critical thresholds at 40, 80, and 200 U/L being particularly relevant for early liver injury diagnosis. Experimental results demonstrated a highly linear correlation between ALT concentration (0–240 U/L) and reaction completion time, achieving a sensitivity of 0.67 s/(U/L). Based on both the reaction completion time and spectral peak dynamics, the platform enables graded evaluation of mild (40–80 U/L), moderate (80–200 U/L), and severe (>200 U/L) liver injury, providing a quantitative framework for more refined liver function assessment.

To further validate the clinical applicability of the proposed ALT biosensing approach, in vivo tests were conducted using mouse serum. The results showed excellent agreement with commercial ALT assay kits, further demonstrating the platform’s practicality and potential for clinical translation.

The complete study is accessible via DOI: 10.34133/research.0824