CO₂-switchable oligoamine patches based on amino acids and their use to build polyelectrolyte containers with intelligent gating

The synthesis of well-defined, homodisperse oligoamine structures based on natural basic amino acids, so-called oligoamine “patches”, is presented. They contain an intermediary number of cationic groups (exactly 11 amine groups) to allow sufficiently strong, but reversible, binding to anionic surfaces and polymers and are shown to be non-cytotoxic. Their overall charge can be switched in the ordinary pH range (5.5–7.5) between cationic and anionic by CO₂ complexation and carbamate formation. This process turned out to be completely reversible, i.e. it can be used for the chemical “gating” of structures. Polyelectrolyte containers built with these patches as structural interlayers showed overall stability of the architecture, but a reversible gating of the permeation towards large water-soluble polymer species when contacted with CO₂, as exemplified with a model dextrane.