On the interaction of alginate-based core-shell nanocarriers with keratinocytes in vitro

• Alginate-based nanocarriers (ANC) were characterized as core-shell structures by cryo TEM.
• ANC present hydrodynamic diameter around 230 nm with a monodisperse tendency.
• ANC penetrate into keratinocytes by endocytosis involving the route of caveolae.
• ANC show no toxicity on keratinocytes after 72 h of contact up to 1.5 g/L.
• ANC drug delivery skills to keratinocytes were demonstrated by FRET-based methods.

Calcium alginate nanocarriers (CaANCs) were developed as a potential tool for delivery of hydrophobic active molecules such as pharmaceutical and cosmetic active ingredients. In this study, we focused on interactions between CaANCs and keratinocytes in culture and examined toxicity, internalization and drug release. Prior to cellular interactions, cryogenic transmission electron microscopy images showed that CaANCs appear as regular, spherical and dense particles, giving evidence of the surface gelation of CaANCs. Their size, around 200 nm, was stable under tested conditions (temperature, culture media, presence of serum and presence of encapsulated dye), and their toxicity on keratinocytes was very low. Flow cytometry assays showed that CaANCs are internalized into keratinocytes by endocytosis with a predominant implication of the caveolae-mediated route. Förster resonance energy transfer (FRET) demonstrated that after a 2 h contact, the release of CaANC contents in the cytoplasm of keratinocytes was almost complete. The endocytosis of CaANCs by a lysosome-free pathway, and the rapid release of their contents inside keratinocytes, will allow vectorized molecules to fully exhibit their pharmacological or cosmetic activity.

Core shell alginate-based nanocapsules (CaANC) internalized in keratinocytes.Figure optionsDownload as PowerPoint slide