Synthesis of zwitterionic polyelectrolyte nanogels via electrostatic-templated polymerization

Zwitterionic polyelectrolyte nanogels are prospective nanocarriers due to their soft loading pocket and regulated charges. We here report a facile strategy, namely, electrostatic-templated polymerization (ETP) for synthesizing zwitterionic nanogels with controlled size and properties. Specifically, with anionic-neutral diblock polymers as the template, zwitterionic monomers such as carboxybetaine methacrylate (CBMA) or carboxybetaine acrylamide (CBAA) are polymerized together with a cross-linker at pH 2 where the monomers exhibit only positive charge due to the protonation of the carboxyl group. The obtained polyelectrolyte complex micelles dissociate upon introducing a concentrated salt. The subsequent separation yields the released template and zwitterionic nanogels with regulated size and swelling ability, achieved by tuning the salt concentration and cross-linker fraction during polymerization. The obtained PCBMA nanogels exhibit charges depending on the pH, which enables not only the selective loading of different dye molecules, but also encapsulation and intracellular delivery of cytochrome c protein. Our study develops a facile and robust way for fabricating zwitterionic nanogels and validates their potential applications as promising nanocarriers for load and delivery of functional charged cargos.

Automated summary

This study presents a facile strategy called electrostatic-templated polymerization (ETP) for synthesizing zwitterionic nanogels with controlled size and properties. By utilizing anionic-neutral diblock polymers as templates, zwitterionic monomers are polymerized together with a cross-linker at pH 2, resulting in the formation of polyelectrolyte complex micelles. These micelles can be dissociated and separated to obtain zwitterionic nanogels with regulated size and swelling ability by adjusting the salt concentration and cross-linker fraction during polymerization. The developed zwitterionic nanogels show potential applications in selective loading and intracellular delivery of charged cargo.