Ferrocene-functionalized indium-oxo cluster nanozyme for the detection of hydrogen peroxide and ascorbic acid

Nanozymes are a class of nanomaterials with intrinsic enzyme-like properties, which overcome the limitations of natural enzymes, such as poor stability, high cost, and difficulty in storage, thus achieving rapid development. Herein, the enzyme-like activity of ferrocene-functionalized indium-oxo cluster (TPP⁺)[In₇FcDCA₆(µ₄-O^2-)₃(µ₃-OCH₃)(Cl^-)₃], named [In₇Fc₆], was analyzed. The obtained [In₇Fc₆] cluster has good peroxidase-like activity, which can catalyze the reaction of 3,3',5,5'-tetramethylbenzidine (TMB), o-phenylenediamine (OPD), and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) with H₂O₂. Therefore, based on the peroxidase-like activity of [In₇Fc₆], a colorimetric sensor for the detection of H₂O₂ was developed, which could detect H₂O₂ in the concentration range of 1-170 μM, and the detection limit was 0.24 μM. In addition, we also established a colorimetric sensor for detecting ascorbic acid (AA) in the range of 3-130 μM with a detection limit of 0.81 μM. The practicability of the established colorimetric sensor was also verified in cells and serum. This research opens up new horizons for exploring new application possibilities for clusters in biomolecular detection.