Cross-linked polypeptide-based gel particles by emulsion for efficient protein encapsulation

- Polypeptide-based gel particles with tunable size and solution property were prepared by emulsion.
- They exhibited excellent colloidal stability and biocompatibility.
- Protein can be encapsulated at high efficiency and still retain its bioactivity.
- Versatile gel particles comprising various type of polymers can be prepared via this approach.

We report the preparation of cross-linked poly(l-lysine) (PLL), polyethylene glycol-block-poly(l-lysine) (PEG-b-PLL), and poly(l-lysine)-block-polysarcosine (PLL-b-PSar) gel particles with size ranged between 100 and 250 nm by emulsion and their evaluation as carriers/encapsulants for protein encapsulation/delivery. Their size and solution property were depended upon polymer molecular weight, composition, and cross-linking degree. These gel particles exhibited not only excellent colloidal stability at a wide range of solution pH but also enhanced biocompatibility due to the incorporation of neutral polymer segments and genipin cross-link. We also showed that a variety of protein can be efficiently encapsulated in gel particles and the encapsulated protein still exhibited bioactivity. The in vitro protein release study showed that reduction-responsive gel particles can be prepared by incorporating disulfide bond in gel network. This study demonstrated that versatile gel particles comprising various types of polymers can be prepared and are potentially useful as protein carriers and encapsulants.

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