title: Effect of plasma treatment on the performance of two drug-loaded hydrogel formulations for therapeutic contact lenses.
abstract: Although the plasma technology has long been applied to treat contact lenses, the effect of this treatment on the performance of drug-loaded contact lenses is still unclear. The objective of this work is to study the effect of nitrogen plasma treatment on two drug-loaded polymeric formulations which previously demonstrated to be suitable for therapeutic contact lenses: a poly-hydroxyethylmethacrylate (pHEMA) based hydrogel loaded with levofloxacin and a silicone-based hydrogel loaded with chlorhexidine. Modifications of the surface and the optical properties, and alterations in the drug release profiles and possible losses of the antimicrobial activities of the drugs induced by the plasma treatment were assessed. The results showed that, depending on the system and on the processing conditions, the plasma treatment may be beneficial for increasing wettability and refractive index, without degrading the lens surface. From the point of view of drug delivery, plasma irradiation at moderate power (200 W) decreased the initial release rate and the amount of released drug, maintaining the drug activity. For lower (100 W) and higher powers (300 W), almost no effect was detected because the treatment was, respectively, too soft and too aggressive for the lens materials.
authors.affiliation: Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001, Lisboa, Portugal.
authors.forename: Patrizia
authors.initials: P
authors.lastname: Paradiso
authors.affiliation: INESC Microsistemas e Nanotecnologias and IN-Institute of Nanoscience and Nanotechnology, Rua Alves Redol, 9, 1000-029, Lisbon, Portugal.
authors.forename: Virginia
authors.initials: V
authors.lastname: Chu
authors.affiliation: Chemical Engineering Department and ICEMS, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001, Lisboa, Portugal.
authors.forename: Luís
authors.initials: L
authors.lastname: Santos
authors.affiliation: Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001, Lisboa, Portugal.|CIIEM, Instituto Superior de Ciências da Saúde Egas Moniz, Campus Universitário, Quinta da Granja, Monte de Caparica, 2829-511, Caparica, Portugal.
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: Serro
authors.affiliation: Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001, Lisboa, Portugal.|Bioengineering Department, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001, Lisboa, Portugal.
authors.forename: Rogério
authors.initials: R
authors.lastname: Colaço
authors.affiliation: Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001, Lisboa, Portugal.
authors.forename: Benilde
authors.initials: B
authors.lastname: Saramago
mesh_terms: D002710:Chlorhexidine / Q000737:chemistry*; D003263:Contact Lenses, Hydrophilic / Q000382:microbiology*; D006801:Humans; D020100:Hydrogels / Q000737:chemistry; D064704:Levofloxacin / Q000737:chemistry*; D058626:Plasma Gases; D011102:Polyhydroxyethyl Methacrylate / Q000737:chemistry; D011550:Pseudomonas aeruginosa / Q000254:growth & development*; D012828:Silicones / Q000737:chemistry; D013211:Staphylococcus aureus / Q000254:growth & development*; D017155:Wettability
chemical_list: D020100:Hydrogels; D058626:Plasma Gases; D012828:Silicones; D011102:Polyhydroxyethyl Methacrylate; D064704:Levofloxacin; D002710:Chlorhexidine
keywords: contact lens materials; drug release; pHEMA; plasma treatment; silicone