Colorimetric discrimination of penicillamine enantiomers with a core-shell structured mesoporous chiral SiO₂@MnO₂...

Using L-tartaric acid (L-TA) as the chiral agent, mesoporous chiral SiO₂ (MCS) synthesized by the template method is in situ grown on the surface of MnO₂ to form a core-shell structure. Due to the higher affinity of L-TA for L-penicillamine (L-Pen), more L-Pen can be immobilized onto the MCS shell, while D-Pen can easily access the MnO₂ core through the mesoporous channels of MCS. Since MnO₂ can be decomposed by Pen, the oxidase-like activity of the MnO₂ nanozyme is significantly degraded in the case of D-Pen. However, the oxidase-like activity of the MnO₂ nanozyme can be well retained in the case of L-Pen, which can catalyze oxygen reduction to reactive oxygen species for the oxidation of colorless o-phenylenediamine to yellow 2,3-diaminophenazine. Therefore, the colorimetric discrimination of Pen enantiomers with the core-shell structured MCS@MnO₂ can be conveniently achieved.