In vitro interaction of polyelectrolyte nanocapsules with model cells.

The nanocapsules based on a liquid core with polyelectrolyte shells prepared by the technique of sequential adsorption of polyelectrolytes (LbL) were investigated to verify capsules bioacceptance. Using AOT (docusate sodium salt) as emulsifier, we obtained liquid cores, stabilized by the interfacial complex AOT/PLL (poly-l-lysine hydrobromide). These liquid cores were encapsulated by sequential adsorption of polyelectrolytes using biocompatible polyanion PGA (poly-l-glutamic acid sodium salt) and biocompatible polycation PLL. The average size of the formed capsules was 60-80 nm. The influence of a number of polyelectrolytes layer in the shell (thickness of polyelectrolytes shell), surface charge, and capsule doses on cell viability was studied in a cellular coculture assay. In order to improve nanocapsules biocompatibility, the PEG-ylated external layers were prepared using PGA-g-PEG (PGA grafted by PEG poly(ethylene glycol)). For the most toxic nanocapsules (with only one polycation layer) about 90% of cells could survive when the concentration of nanocapsules was below 0.2 × 10(6) per one cell. That suggests that they use as a delivery vehicles is quite safe for living cells. Analysis of internalization of AOT(PLL/PGA)4-g-PEG in HEK 293 cells indicates that tested nanocapsules can easily penetrate cells membrane.