Wetting properties of phospholipid-polypeptide monolayers deposited onto polyethylene terephthalate

The paper presents changes in wettability of the unmodified and modified polyethylene terephthalate (PET) surfaces. A low temperature air plasma was used to activate the polymer surface and to change its hydrophilic–hydrophobic properties. Then, using the Langmuir-Blodgett technique, the Langmuir monolayers of 1,2–dipalmitoyl–sn–glycero–3–phosphocholine (DPPC) and cyclosporine A (CsA) with different molar fractions, i.e. χ=0.25, 0.50, 0.75, were deposited onto the activated PET surface. A series of DPPC and CsA monolayers was also transferred onto the PET-supported chitosan layer, previously produced by the dip-coating method. The wetting properties of such modified PET surfaces were then investigated by the contact angle measurements using three test liquids with well known surface tension components. The obtained results show that wettability depends on the composition of the deposited DPPC/CsA layer with or without chitosan. Presence of chitosan makes the DPPC/CsA film surface more polar due to specific organization of molecules that expose their polar heads outside.