Metallothioneins (MTs) are important biomarkers for the early diagnosis of heavy metal poisoning and malignancies. Convenient and cost-effective approaches for the rapid detection of MTs are therefore highly desirable for clinical monitoring. Herein, by taking advantage of the enzyme-mimetic activity of nanoparticles and protein corona-based recognition, insufficient polyhedral oligomeric silsesquioxane (POSS) polymer-caged gold nanoparticles (denoted as PP−AuNPs) are developed for the sensitive colorimetric analysis of MTs. In the presence of MTs, the catalytic reduction of yellow 4-nitrophenol to colorless 4-aminophenol is inhibited due to masking of the exposed PP−AuNPs catalytic surface with MTs corona. MTs are quantified by the presented color contrast with a superior sensitivity up to a 1.5 nM detection limit. Most importantly, the heavy metal ion-and aptamer-free PP−AuNPs platform exhibits excellent selectivity toward MTs over various ions, neutral biomolecules, and protein species, and successful applications are demonstrated by the detection of MTs in complex biological samples.

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The combination of salt-templated thermal polymerization with arginine functionalization produces a porous POSS framework, which facilitates discrimination of phosphoproteins and glycoproteins.