Poly-β-cyclodextrin strengthen Pr₆O₁₁ porous oxidase mimic for dual-channel visual recognition of bioactive cysteine and Fe²⁺

To conveniently monitor bioactive cysteine (Cys) and Fe²⁺ in practice, a kind of poly-β-cyclodextrin strengthen praseodymium oxide (Pr₆O₁₁) porous oxidase mimic (p-β-CD@Pr₆O₁₁) was constructed by virtue of the strong coordination between nano Pr₆O₁₁ and poly-β-cyclodextrin substrate. After its microstructure and physicochemical property were characterized in detail, it was noted that porous p-β-CD@Pr₆O₁₁ exhibited excellent enzyme-like catalytic activity to accelerate the oxidation of 3,3′,5,5,′-tetramethylbanzidine (TMB) and 2,2′-azinobis (3-ethylbenzo-thiazoline-6-sulfonic acid) ammonium salt (ABTS) with significant color-enhancement effect in the air. Based on the signal amplification, trace Cys could exclusively deteriorate the UV-vis absorbance at 653 nm of p-β-CD@Pr₆O₁₁-TMB and Fe²⁺ alter the one at 729 nm of p-β-CD@Pr₆O₁₁-ABTS with visual color changes. Under the optimized conditions, the proposed p-β-CD@Pr₆O₁₁-TMB and p-β-CD@Pr₆O₁₁-ABTS systems were successfully applied for dual-channel monitoring of Cys in Cys capsules and fetal bovine serum and Fe²⁺ in agricultural products with quite low detection limits, i.e., 7.8×10⁻⁹ mol·L⁻¹ for Cys and 6.93×10⁻⁸ mol·L⁻¹ (S/N=3) for Fe²⁺, respectively. The synergetic-enhancement detection mechanisms to Cys and Fe²⁺ were also proposed.