title: Fabrication and characterization of contact lenses bearing surface-immobilized layers of intact liposomes.
abstract: Intact liposomes were immobilized onto soft contact lenses. In the first step, polyethylenimine was covalently bounded onto the hydroxyl groups available on the surface of a commercial contact lens (Hioxifilcon B). Then, NHS-PEG-biotin molecules were bounded onto the surface amine groups by carbodiimide chemistry. NeutrAvidin were bounded onto the PEG-biotin layer. Liposomes containing PEG-biotinylated lipids were docked onto the surface-immobilized NeutrAvidin. Consecutive addition of further NeutrAvidin and liposome layers enabled fabrication of multilayers. Multilayers of liposomes were also produced by exposing contact lenses coated with NeutrAvidin to liposome aggregates produced by the addition of free biotin in solution. XPS revealed the immobilization of the different layers. By blocking with excess biotin surface-immobilized NeutrAvidin on contact lenses bearing PEG-biotin layers produced under cloud point conditions, ELISA showed that the docking of NeutrAvidin was dependent on biotin-NeutrAvidin affinity binding, with little evidence for nonspecific physisorption; however, it was not possible to differentiate specific versus nonspecific binding of NeutrAvidin attached onto PEG-biotin layers grafted without cloud point conditions. AFM imaging revealed liposome sizes of 106 and 155 nm for layers of liposomes produced (i) by the consecutive addition of further NeutrAvidin and liposomes and (ii) by the exposure of NeutrAvidin-coated contact lenses to liposome aggregates, respectively. The release kinetics of a fluorescent dye demonstrated that intact liposomes had been immobilized onto contact lens surfaces. The stability of surface-immobilized liposomes onto contact lens surfaces showed temperature dependence. Surface-bound liposomes can be stored up to 1 month at 4 degrees C with little release of their content.
authors.affiliation: Laboratoire de Bioingénierie et de Biophysique de l'Université de Sherbrooke, Department of Chemical Engineering, Université de Sherbrooke, 2500, Blvd de l'Université, Sherbrooke, Québec, Canada J1K 2R1.
authors.forename: Anne
authors.initials: A
authors.lastname: Danion
authors.forename: Heïdi
authors.initials: H
authors.lastname: Brochu
authors.forename: Yves
authors.initials: Y
authors.lastname: Martin
authors.forename: Patrick
authors.initials: P
authors.lastname: Vermette
mesh_terms: D001360:Avidin / Q000737:chemistry; D001710:Biotin / Q000737:chemistry; D020099:Coated Materials, Biocompatible / Q000737:chemistry; D003263:Contact Lenses, Hydrophilic; D016503:Drug Delivery Systems; D005452:Fluoresceins / Q000008:administration & dosage / Q000493:pharmacokinetics; D005456:Fluorescent Dyes / Q000008:administration & dosage / Q000493:pharmacokinetics; D006801:Humans; D066298:In Vitro Techniques; D008081:Liposomes / Q000737:chemistry; D008422:Materials Testing; D018625:Microscopy, Atomic Force; D009883:Ophthalmic Solutions / Q000008:administration & dosage; D011108:Polymers / Q000737:chemistry; D013057:Spectrum Analysis; D014965:X-Rays
chemical_list: D020099:Coated Materials, Biocompatible; D005452:Fluoresceins; D005456:Fluorescent Dyes; D008081:Liposomes; D009883:Ophthalmic Solutions; D011108:Polymers; C093483:neutravidin; D001360:Avidin; C024098:6-carboxyfluorescein; D001710:Biotin