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.

Recent Advances in Ocular Drug Delivery Systems

“…Soft contact lens-based DDSs have been investigated by several approaches: (1) Soak and absorption of drug solution [86]; (2) piggyback contact lens combined with a drug plate or drug solution [87]; (3) surface-modification to immobilize drugs on the surface of contact lenses [88]; (4) incorporation of drugs in a colloidal structure dispersed in the lens [89]; (5) ion ligand-containing polymeric hydrogel [90]; and (6) molecularly imprinting of drugs [91,92].…”

Antibacterial Activity of Contact Lenses Bearing Surface-Immobilized Layers of Intact Liposomes Loaded With Levofloxacin

“…42 Briefly, each contact lens was sonicated in 4 mL of anhydrous acetonitrile for 15 min to remove any trace of contaminants. Each contact lens was then immersed in 3 mL of a DSC solution for 1 h under vigorous shaking.…”

“…[40][41][42] The objectives of the present study were to investigate the antibacterial activity of contact lenses bearing surface-immobilized layers of intact liposomes loaded with levofloxacin. Levofloxacin was chosen as a model drug for its broad antibacterial spectrum against both Grampositive and Gram-negative bacteria 43 and its commercial availability in a relatively pure form (and without additives) without any commercial constraint.…”

About the effect of eye blinking on drug release from pHEMA-based hydrogels: anin vitrostudy

“…Different strategies to load the hydrogels with drugs were attempted, e.g. the direct incorporation of the drugs into the monomer mixture before the polymerization step [17,18], the incorporation or surface immobilization of drug-loaded nanostructures (like nanoparticles and liposomes) in the hydrogels' matrix [1,[19][20][21][22] or the use of supercritical fluids to enhance drug loading efficiency [23,24]. However, soaking the lenses in drug solutions still remains the most simple and inexpensive method of loading, besides presenting fewer risks to the integrity of the drug molecules and lenses materials.…”