Facile preparation of pH-responsive gelatin-based core-shell polymeric nanoparticles at high concentrations via template polymerization

Adopting gelatin as template macromolecules and acrylic acid (AA) as monomers, core-shell polymeric nanoparticles at a concentration of 30 mg/mL was successfully prepared via template polymerization, in which polymerization of the monomer and self-assembly between the polymer and the template take place simultaneously. The self-assembly was driven by specific interactions between gelatin and PAA produced in-situ, leading to nanoparticles with insoluble inter-polymer complexes of PAA and gelatin as the core and soluble gelatin as the shell. DLS and electrophoretic light scattering techniques were used to monitor the in-situ polymerization process, which indicated a size shrinkage and a surface charge decrease of the nanoparticles. The structure and morphology of the nanoparticles were characterized by FT-IR, TEM and SFM. The structure stability of the nanoparticles was improved by selectively crosslinking gelatin with glutaraldehyde. The nanoparticles also exhibit excellent pH-response: when pH changed from acid to base, the particles' volume expanded more than 80 times.