pH-Responsive giant polymeric vesicles prepared via polydimethylsiloxane (PDMS) microfluidics
In the journal Polymer Chemistry were published the results of a team of researchers from the Department of Supramolecular Polymer Systems and their German colleagues, who developed pH-responsive giant polymer vesicles.
“We developed extremely size-uniform cell-mimicking pH-responsive giant polymer vesicles by water-in-oil-in-water (W/O/W) method using PDMS-based microfluidic device,” says Vladimir Sincari from the Department of Supramolecular Polymer Systems (IMC CAS). The pH-responsive polymer poly(ethylene-oxide)-b-poly[2-(diisopropylamino)ethyl methacrylate] was synthesized by reversible addition–fragmentation chain-transfer (RAFT) polymerization and was used in a combination with poly(ethylene oxide)-b-poly(1,2-butadiene) for the production of the giant vesicles. With flow-focusing poly(dimethylsiloxane) (PDMS)-based microfluidic device it was possible to produce highly monodisperse and stable giant vesicles with excellent size control. Confocal laser scanning microscopy was used to evaluate the pH-responsiveness of the giant vesicles. The giant vesicles were loaded with Nile red as a hydrophobic dye into the polymeric membrane and simultaneously with calcein as hydrophilic dye into the aqueous core and the vesicles were tested under the relevant simulated physiological conditions. When the pH was less than the pKa of pH responsive polymer, the polymer block protonates and becomes hydrophilic, inducing water swelling in the polymeric bilayer. This swelling subsequently reduces hydrophobicity of the bilayer membrane to the point where the membrane can no longer maintain its integrity and the giant polymeric vesicles are disrupted. “The results demonstrated the clear dependence of giant vesicles disruption and calcein release on pH. To the best of our knowledge, the spatiotemporal pH-triggered controlled release of a hydrophilic probe in a pH-responsive giant polymeric vesicle was demonstrated for the first time. Finally, the in vitro cytotoxicity of the giant particles in rat mesenchymal stem cells showed excellent biocompatibility, demonstrating the capabilities of pH-responsive giant polymersomes as biomimetic systems for drug delivery, microreactors and artificial stimuli-responsive cell mimics,” adds Vladimir Sincari.