Published by Microchimica Acta

Volume 191, article number 307, (07 May 2024)

Abstract

An assay that integrates histidine-rich peptides (HisRPs) with high-affinity aptamers was developed enabling the specific and sensitive determination of the target lysozyme. The enzyme-like activity of HisRP is inhibited by its interaction with a target recognized by an aptamer. In the presence of the target, lysozyme molecules progressively assemble on the surface of HisRP in a concentration-dependent manner, resulting in the gradual suppression of enzyme-like activity. This inhibition of HisRP’s enzyme-like activity can be visually observed through color changes in the reaction product or quantified using UV-visible absorption spectroscopy. Under optimal conditions, the proposed colorimetric assay for lysozyme had a detection limit as low as 1 nM and exhibited excellent selectivity against other nonspecific interferents. Furthermore, subsequent research validated the practical applicability of the developed colorimetric approach to saliva samples, indicating that the assay holds significant potential for the detection of lysozymes in samples derived from humans.

A schematic representation of the enzyme mimic-based biosensor for lysozyme detection. Lysozyme-sensing probes including the aptamer-binding region are first attached to HisRPs through electrostatic interaction, forming a sensing probe-HisRP hybrid complex. Then, the aptamers capture the target lysozyme, inhibiting the catalytic signal produced by the oxidation of TMB by H2O2.