title: Interaction of Sodium Hyaluronate with a Biocompatible Cationic Surfactant from Lysine: A Binding Study.
abstract: Mixtures of natural and biodegradable surfactants and ionic polysaccharides have attracted considerable research interest in recent years because they prosper as antimicrobial materials for medical applications. In the present work, interactions between the lysine-derived biocompatible cationic surfactant N(ε)-myristoyl-lysine methyl ester, abbreviated as MKM, and the sodium salt of hyaluronic acid (NaHA) are investigated in aqueous media by potentiometric titrations using the surfactant-sensitive electrode and pyrene-based fluorescence spectroscopy. The critical micelle concentration in pure surfactant solutions and the critical association concentration in the presence of NaHA are determined based on their dependence on the added electrolyte (NaCl) concentration. The equilibrium between the protonated (charged) and deprotonated (neutral) forms of MKM is proposed to explain the anomalous binding isotherms observed in the presence of the polyelectrolyte. The explanation is supported by theoretical model calculations of the mixed-micelle equilibrium and the competitive binding of the two MKM forms to the surface of the electrode membrane. It is suggested that the presence of even small amounts of the deprotonated form can strongly influence the measured electrode response. Such ionic-nonionic surfactant mixtures are a special case of mixed surfactant systems where the amount of the nonionic component cannot be varied independently as was the case for some of the earlier studies.
authors.affiliation: Institute for the Engineering and Design of Materials, University of Maribor , Smetanova 17, 2000 Maribor, Slovenia.
authors.forename: Matej
authors.initials: M
authors.lastname: Bračič
authors.affiliation: Department of Pharmacy, Biomedical Centre, Uppsala University , SE-75123 Uppsala, Sweden.
authors.forename: Per
authors.initials: P
authors.lastname: Hansson
authors.affiliation: Department of Chemical and Surfactant Technology, Instituto de Química Avanzada de Cataluña, CSIC , Jordi Girona 18-26, 08034 Barcelona, Spain.
authors.forename: Lourdes
authors.initials: L
authors.lastname: Pérez
authors.affiliation: Institute for the Engineering and Design of Materials, University of Maribor , Smetanova 17, 2000 Maribor, Slovenia.
authors.forename: Lidija F
authors.initials: LF
authors.lastname: Zemljič
authors.affiliation: Department of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana , Večna pot 113, 1000 Ljubljana, Slovenia.
authors.forename: Ksenija
authors.initials: K
authors.lastname: Kogej
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry*; D002412:Cations; D006820:Hyaluronic Acid / Q000737:chemistry*; D008239:Lysine / Q000737:chemistry*; D008962:Models, Theoretical; D013050:Spectrometry, Fluorescence; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D001672:Biocompatible Materials; D002412:Cations; D013501:Surface-Active Agents; D006820:Hyaluronic Acid; D008239:Lysine