Atmospheric pressure cold plasma versus wet-chemical surface treatments for carboxyl functionalization of polylactic acid: A first step toward covalent immobilization of bioactive molecules.

Affiliation

Laboratoire d'Ingénierie de Surface, Centre de Recherche sur les Matériaux Avancés, Département de génie des mines, de la métallurgie et des matériaux, Université Laval, 1065, avenue de la Médecine, Québec City, G1V 0A6, Canada; Axe Médecine Régénératrice, Centre de recherche du CHU de Québec, Hôpital St. François d'Assise, 10, rue de l'Espinay, Québec city, G1L 3L5, Canada. Electronic address: [Email]

Abstract

The use of polylactic acid (PLA) has attracted growing interest, particularly in recent years, for biomedical applications because of its mechanical properties, biocompatibility, and biodegradability. Despite this, features such as surface hydrophobicity and the absence of suitable functional groups for covalent immobilization of bioactive molecules, make it challenging to endow PLA-based medical devices with additional features and thus broaden their range of applicability. In the present study, we demonstrate the suitability of atmospheric pressure dielectric barrier discharges operating in the Townsend regime as a promising alternative to other surface treatments, such as diazonium and alkali hydrolytic treatments, for carboxyl functionalization of PLA. Chemical changes in PLA surfaces are evaluated by contact angle measurements and by X-ray photoelectron spectroscopy while physical changes are investigated by scanning electron microscopy and atomic force microscopy. The amount of carboxyl groups generated on PLA surfaces is assessed by toluidine blue O assay and substantiated by grafting, through carboxyl groups, a fluorescent probe containing amino functionalities. All of the surface treatments have proven to be very effective in generating carboxylic groups on the PLA surface. Nevertheless, plasma treatment is shown to not degrade the PLA surface, in sharp contrast with diazonium and alkali hydrolytic treatments.

Keywords

Covalent immobilization,Dielectric barrier discharge,Polylactic acid,Surface characterization,Surface functionalization,

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