Liquid Crystal Sensor Harnessing a Biomimetic Acetylcholinesterase Nanozyme for Detection of Trypsin in Human Serum

Abnormal levels of trypsin in the human body can lead to various diseases, yet conventional detection methods often lack operational simplicity and real-time readout capabilities. This work presents a state-of-the-art metal organic framework (MOF) nanozyme-integrated liquid crystal (LC) sensor (MHN-LC sensor) and demonstrates the detection of trypsin as a proof of the concept. By rational engineering of the MOF-808 framework with Al³⁺ and l-histidine coordination, a novel MOF nanozyme (MHis-NE) exhibiting exceptional acetylcholinesterase (AChE)-mimetic activity is successfully prepared. In the presence of trypsin, the gelatin hydrogel-encapsulated MHis-NE immobilized on the centrifuge tube lid is released into the aqueous solution due to trypsin-triggered gelatin degradation. Subsequently, a surfactant myristoylcholine is catalytically hydrolyzed by released MHis-NE into choline and myristic acid. This enzymatic cascade induces a characteristic LC optical transition from a dark to bright appearance, corresponding to the interfacial LC molecular reorientation from homeotropic to planar alignment. This MHis-NE LC sensor achieves a detection limit of 1.09 × 10^-5 mg/mL for trypsin with a broad detection range from 10^-4 to 1 mg/mL. It also can be applied to trypsin quantification in human serum with superior selectivity against other enzymes as potential interferents. The developed strategy not only advances the nanozyme-mediated signal transduction principle but also significantly expands the potential of various LC sensors.