Microfluidic production of protein loaded chimeric stealth liposomes

The addition of polyethylene glycol (PEG) on the surface of liposomes increases their circulation time when administered intravenously. However, the inclusion of PEG using PEGylated phospholipids could result in a possible micelles formation. The development of chimeric systems mixing synthetic biocompatible and biodegradable PEG-containing copolymers with lipids is a strategy to obtain as well PEGylated liposomes. Microfluidics is an innovative manufacturing technology easy to scale up that presents high reproducibility, low batch-to-batch variation, and better control over particles characteristics. Taking advantage of this technique, in this research work, chimeric stealth liposomes were produced mixing five different synthesized methoxy-poly(ethylene glycol)-block-poly(δ-decalactone) (mPEG-PDL, varying in polymer length) with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and cholesterol. The obtained chimeric formulations were around 150 nm in size with a narrow distribution and an almost neutral surface charge. Ovalbumin (OVA) was used as a model protein to evaluate the loading potential reaching an encapsulation efficiency of 41 ± 4%. The prepared systems showed no cytotoxicity in vitro on THP-1 cell with an uptake up to 89 ± 4% after 3 h. Finally, protein integrity after encapsulation was confirmed with DQ-OVA. In this work, we demonstrated that using microfluidics, it is possible to produce stable and highly protein-loaded chimeric stealth liposomes with good physicochemical characteristics, no toxicity, protein integrity, and effective uptake by endocytosis.