Polyion complex micelles formed by azobenzene-based polymer with multi-responsive properties

Compared with the single polymer micelle system, the polyion complex micellar system is consisted of two or more polymers with different composition, which has more flexible structural adjustment and better performance, making them widely used in drug control release. In this work, two azobenzene-based amphiphilic copolymers P (MMA-co-PEGMA-co-NIPAM-co-HAZOMA) with ionized carboxyl and P (MMA-co-PEGMA-co-NIPAM-co-NNAZOMA) with protonated tertiary amine group were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. We studied self-assembled behavior of polymers and multi-component polymers, including their multiple responsiveness and the encapsulation, controlled release properties of polyion complex micelle. Light, pH, temperature, and reduction responsiveness of three micelles were investigated by UV-vis spectroscopy, transmission electron microscope (TEM), and dynamic light scattering. Compared to RCP 1, and RCP 2, RCP 1/RCP 2 micelle can release Nile red in both acidic and alkaline environment. When temperature reached critical solution temperature, RCP 1/RCP 2 micelle would release Nile red faster. Polyion complex micelle had better release performance compared to single micelles at the same environment, and could release in a wider range pH, making it had more potential applications in biological science field.

Automated summary

In this study, two azobenzene-based amphiphilic copolymers were synthesized by RAFT polymerization, and their self-assembled behavior as well as encapsulation and controlled release properties of polyion complex micelle were investigated. The responsiveness to light, pH, temperature, and reduction of the micelles were tested, and it was found that the polyion complex micelle had better release performance compared to single micelles in the same environment and could release in a wider range of pH levels.