Polyhedral Oligomeric Silsesquioxane Polymer-Caged Silver Nanoparticle as a Smart Colorimetric Probe for the...

The rapid and accurate detection of hydrogen sulfide is of great concern due to its unique role on environmental pollution and signal transmission in physiological systems. Herein, we report a smart colorimetric probe for the selective detection of H₂S. The probe is prepared via a surfactant-free route with cross-linked polyhedral oligomeric silsesquioxane (POSS) polymer cage as capping ligand and reducing agent under microwave irradiation, called poly-POSS-formaldehyde polymer (PPF) cage-AgNPs or PPF-AgNPs for short. The caged silver nanoparticles are well-dispersed with narrow size distribution within 6.0-8.4 nm. Chloride ions and aldehyde groups in PPF make the nucleation and growth of Ag nanoparticles accomplished within a very short time of 1 min. The positively charged PPF-AgNPs exhibit excellent selectivity to H₂S against other anionic species and thiols due to the specific Ag-H₂S interaction, where the favorable protection effect of PPF polymer cage from the nanoparticle aggregation is demonstrated. The colorimetric probe presents a quick response to H₂S (<3 min) and favorable sensitivity within a linear range of 0.7-10 μM along with a detection limit of 0.2 μM. The probe is well demonstrated by analysis of H₂S in various water and biological samples.