Microfluidics-based self-assembly of peptide-loaded microgels: Effect of three dimensional (3D) printed micromixer design

摘要

In an effort to contribute to research in scalable production systems for polymeric delivery systems loaded with antimicrobial peptides (AMPS), we here investigate effects of hydrodynamic flow conditions on microfluidic particle generation. For this purpose, rapid prototyping using 3D printing was applied to prepare micromixers with three different geometric designs, which were used to prepare Ca2+-crosslinked alginate microgels loaded with the AMP polymyxin B in a continuous process. Based on fluid dynamic simulations, the hydrodynamic flow patterns in the micromixers were designed to be either (i) turbulent with chaotic disruption, (ii) laminar with convective mixing, or (iii) convective with microvortex formation. The physicochemical properties of the microgels prepared with these micromixers were characterized by photon correlation spectroscopy, laser-Doppler micro-electrophoresis, smallangle x-ray scattering, and ellipsometry. The particle size and compactness were found to depend on the micromixer geometry: From such studies, particle size and compactness were found to depend on micromixer geometry, the smallest and most compact particles were obtained by preparation involving microvortex flows, while larger and more diffuse microgels were formed upon laminar mixing. Polymyxin B was found to be localized in the particle interior and to cause particle growth with increasing peptide loading. Ca2+-induced cross-linking of alginate, in turn, results in particle contraction. The peptide encapsulation efficiency was found to be higher than 80% for all investigated micromixer designs; the highest encapsulation efficiency observed for the smallest particles generated by microvortexmediated self-assembly. Ellipsometry results for surface-immobilized microgels, as well as results on peptide encapsulation, demonstrated electrolyte-induced peptide release. Taken together, these findings demonstrate that rapid prototyping of microfluidics using 3D-printed micromixers offer