Bioinspired\nDual Hemin-Bonded G‑Quadruplex\nand Histidine-Functionalized Metal–Organic Framework for Sensitive\nBiosensing

Biomimetic enzymes have emerged as ideal alternatives\nto natural\nenzymes, and there is considerable interest in designing biomimetic\nenzymes with enhanced catalytic performance to address the low activity\nof the current biomimetic enzymes. In this study, we proposed a meaningful\nstrategy for constructing an efficient peroxidase-mimicking catalyst,\ncalled HhG-MOF, by anchoring histidine (H) and dual hemin-G-quadruplex\nDNAzyme (double hemin covalently linked to 3′ and 5′\nterminals of G-quadruplex DNA, short as hG) to a mesoporous metal–organic\nframework (MOF). This design aims to mimic the microenvironment of\nnatural peroxidase. Remarkably, taking a terbium MOF as a typical\nmodel, the initial rate of the resulting catalyst was found to be\n21.1 and 4.3 times higher than that of Hh-MOF and hG-MOF, respectively.\nThe exceptional catalytic properties of HhG-MOF can be attributed\nto its strong affinity for substrates. Based on the inhibitory effect\nof thiocholine (TCh) produced by the reaction between acetylcholinesterase\n(AChE) and acetylthiocholine, a facile, cost-effective, and sensitive\ncolorimetric method was designed based on HhG-MOF for the measurement\nof AChE, a marker of several neurological diseases, and its inhibitor.\nThis allowed a linear response in the 0.002 to 1 U L<sup>–1</sup> range, with a detection limit of 0.001 U L<sup>–1</sup>.\nFurthermore, the prepared sensor demonstrated great selectivity and\nperformed well in real blood samples, suggesting that it holds promise\nfor applications in the clinical field.