Design of a nanocarrier with regulated drug release ability utilizing a reversible conformational transition of a peptide, responsive to slight changes in pH.

We investigated the drug releasing behavior of a novel nanocarrier system, utilizing a peptide to act as a nanogate to the mesopore, on a mesoporous silica nanoparticle. The surface peptide on mesoporous silica displayed pH-dependant mesopore cap-uncap switching behavior, enabled by the reversible β-sheet-to-random coil conformational transition resulting from slight pH changes between 8.0 and 6.0. The peptide adopted a β-sheet structure under weakly basic conditions (pH 8.0) and a random coil conformation under weakly acidic conditions (pH 6.0). We demonstrated the pH-dependant regulation of the material's drug release property by the reversible conformational transition of the surface peptide. Under basic pH conditions, the drug release from the nanocarrier was significantly inhibited. However, under acidic pH conditions, the drug in the mesopore was gradually released.