Label-free detection of sialic acid using oxidase-mimicking Co/2Fe MOF via optical behaviour of liquid crystals

초록

Sialic acid (SA) is an essential component of glycoproteins and glycolipids within cellular membranes and plays a pivotal role in various physiological and pathological processes. In this study, we synthesised a metal-organic framework (MOF), Co/2Fe, which was employed for the detection of SA using a stearic acid-doped liquid crystal (LC)-based sensing platform. When applied to SA detection, NANA-aldolase catalyses the conversion of free SA into pyruvate, which is then transformed into H2O2 by the oxidase-mimicking Co/2Fe bimetallic MOF. The substitution of SA with H2O2 induces a pH shift that triggers the deprotonation of stearic acid to stearate, leading to the reorientation of the LC at the aqueous/LC interface. This orientational transition can be observed using a polarised optical microscope. We found that SA can be quantitatively assessed within a linear range of 1.5-400 mu M, with a detection limit of 0.17 mu M. Furthermore, the proposed sensing platform demonstrated high sensitivity and selectivity for the detection of SA in human serum samples. This study highlights the effectiveness of the MOF strategy and introduces a novel approach for SA detection.

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