Target Recognition-Triggered Peroxidase-Mimicking Activity Depression in Homochiral Nanochannels for Identifying Cystine Enantiomers

Abstract

Enantioselective identification of chiral molecules is of paramount importance in medical science, biochemistry, and pharmaceutics owing to the configuration-dependent activities of enantiomers. However, the identical physicochemical properties of enantiomers remain challenging in chiral sensing. In this study, inspired by the peroxidase-mimicking activity of Fe(III)-based nanomaterials, an enantioselective artificial architecture is constructed on TiO 2 nanochannels. Homochiral Ti-based metal–organic frameworks (MOFs) use a 2,2′-bipyridine-5,5′-dicarboxylic acid ligand as the artificial enzyme skeleton, Fe(III) as peroxidase-mimicking centers, and l -tartaric acid (TA) as a chiral recognition selector. Using l -/ d -cystine as model enantiomers, the chiral moieties of l -TA on Ti-MOFs allow stereoselective recognition of guest molecules through hydrogen bonds formed between chiral cystine and the host. In a tris(2-carboxyethyl)phosphine hydrochloride-containing environment, the disulfide bonds in cystine molecules are further cleaved, and the HS-tails react with Fe(III) active sites, causing the loss of peroxidase-like performance of nanochannels. Benefitting from the nanochannel architecture’s current–potential ( I – V ) properties, the selective recognition of cystine enantiomers is directly monitored through the peroxidase-like activity change-induced ionic current signatures. This study provides a new and universal strategy for distinguishing disulfide- and thiol-containing chiral molecules.

Topics & Concepts