Micro-sized "pelmeni" - A universal microencapsulation approach overview

Microcapsules of customized shapes offer significant advantages over spherical ones, including enhanced internalization by host cells, improved flow characteristics, and higher packing capacity. In our work, we propose a method for defined-shape polymer capsules fabrication inspired by a traditional “pelmeni” (dumplings) making process. The proposed method is based on soft lithography technique. Two different approaches were demonstrated resulting in polyelectrolyte multilayer and poly(lactic acid) (PLA) capsules both showing monodisperse size and shape distribution with about 7 μm long torpedo-like shape. The PLA capsules are described in terms of their morphology, loading of model cargo molecules, cell cytotoxicity and cell uptake. Carboxyfluorescein, FeCl2 ground crystals and Fe3O4 nanopowder were used as model cargoes for microcapsules. Capsules demonstrate core-shell structure, high loading capacity, hydrophilic molecules retention and internalization by cells without causing toxic effects. The loading efficiency of model cargo in PLA capsules was more than 80 wt%, resulting in about 40 pg of carboxyfluorescein inside each capsule. Proposed method allows unique advantages compared with alternative microencapsulation techniques, such as precise control over capsules' geometry, flexibility for the choice of active cargoes, regardless of their solubility and molecular weight and potential for triggered release mechanism.