Poly-β-cyclodextrin strengthen PrO porous oxidase mimic for dual-channel visual recognition of bioactive cysteine and Fe.

To conveniently monitor bioactive cysteine (Cys) and Fe in practice, a kind of poly-β-cyclodextrin strengthen praseodymium oxide (PrO) porous oxidase mimic (p-β-CD@PrO) was constructed by virtue of the strong coordination between nano PrO and poly-β-cyclodextrin substrate. After its microstructure and physicochemical property were characterized in detail, it was noted that porous p-β-CD@PrO 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@PrO-TMB and Fe alter the one at 729 nm of p-β-CD@PrO-ABTS with visual color changes. Under the optimized conditions, the proposed p-β-CD@PrO-TMB and p-β-CD@PrO-ABTS systems were successfully applied for dual-channel monitoring of Cys in Cys capsules and fetal bovine serum and Fe in agricultural products with quite low detection limits, i.e., 7.8×10 mol·L for Cys and 6.93×10 mol·L (S/N=3) for Fe, respectively. The synergetic-enhancement detection mechanisms to Cys and Fe were also proposed.