Uniform hollow-structured poly(vinyl amine) hydrogel microparticles with controlled mesh property and enhanced cell adhesion

This study introduces a useful approach for fabrication of hollow-structured hydrogel microparticles and for encapsulation of biomacromolecules in the hollow core of the particles. Monodisperse hollow-structured poly(vinyl amine) hydrogel particles were fabricated without using templates that combines the dispersion polymerization and the sequential hydrolysis/crosslinking. The hydrogel shell showed pH-dependent mesh sizes; ∼2 nm at a normal condition (pH 3–12) and ∼11 nm at an expanded condition (pH 2). By taking advantage of pH-responsive mesh property, we demonstrated that dextran macromolecules, whose hydrodynamic radius is between the mesh sizes of the normal and expanded pH conditions, could be encapsulated and stored inside of the shell. Moreover, our hydrogel particles showed strong adhesion to human cells. Some of them were even engulfed by the cell membrane and drawn into the cell even with no aid of site-specific moieties. From these results, it is expected that the hydrogel hollow microcapsules synthesized in this study could be used for delivery of macromolecules into the cells.