Enzyme inhibitor-linked liquid crystal biosensor for monitoring of enrofloxacin in food samples

Document Type

Article

Publication Date

Winter 12-26-2025

Abstract

Enrofloxacin (Enr) is a potent antibiotic that is unapproved for human use due to its potential toxicity, which poses significant health risks. This underscores the importance of monitoring its presence in food samples. We have developed an enzyme inhibitor-linked liquid crystal (EILi-LC) biosensor to detect Enr, utilizing an Enr-conjugated malathion aptamer (EM) in conjunction with acetylcholinesterase (AChE). In the absence of Enr, EM binds to the immobilized Enr antibody in a 96-well plate, capturing malathion. AChE then catalyzes the enzymatic hydrolysis of myristoylcholine (Myr), producing a bright liquid crystal (LC) image observable under a polarized optical microscope (POM). Conversely, in the presence of Enr, a dark LC image is generated due to the formation of a self-assembled monolayer at the aqueous/LC interface by Myr. The EILi-LC biosensor detects Enr by shifting from a bright to a dark image, with a detection range of 2–20 nM and a low detection limit of 1.05 nM (3.77 × 10−4 ng/g). It demonstrates high selectivity for Enr when tested alongside other antibiotics and successfully identifies Enr in samples of pork, fish, and milk. Additionally, we have developed a portable liquid crystal detection device (LCDD) for on-site analysis, which yields results comparable to those obtained from POM. Thus, the EILi-LC biosensor and LCDD provide an effective method for monitoring Enr, making them highly suitable for on-field food and environmental analysis.

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