title: Quantitative Nanomechanical Properties of Multilayer Films Made of Polysaccharides through Spray Assisted Layer-by-Layer Assembly.
abstract: Nanomechanical properties of alginate/chitosan (Alg/Chi) multilayer films, obtained through spray assisted layer-by-layer assembly, were studied by means of PeakForce quantitative nanomechanical mapping atomic force microscopy (PF-QNM AFM). Prepared at two different alginate concentrations (1.0 and 2.5 mg/mL) and a fixed chitosan concentration (1.0 mg/mL), Alg/Chi films have an exponential growth in thickness with a transition to a linear growth toward a plateau by increasing the number of deposited bilayers. Height, elastic modulus, deformation, and adhesion maps were simultaneously recorded depending on the number of deposited bilayers. The elastic modulus of Alg/Chi films was found to be related to the mechanism of growth in contrast to the adhesion and deformation. A comparison of the nanomechanical properties obtained for non-cross-linked and thermally cross-linked Alg/Chi films revealed an increase of the elastic modulus after cross-linking regardless alginate concentration. The incorporation of iron oxide nanoparticles (NPs), during the spray preparation of the films, gave rise to nanocomposite Alg/Chi films with increased elastic moduli with the number of incorporated NPs layers. Deformation maps of the films strongly suggested the presence of empty spaces associated with the method of preparation. Finally, adhesion measurements point out to a significant role of NPs on the increase of the adhesion values found for nanocomposite films.
authors.affiliation: Instituto de Ciencia y Tecnología de Polímeros, ICTP-CSIC , Juan de la Cierva, 3, 28006 Madrid, Spain.
authors.forename: Miryam
authors.initials: M
authors.lastname: Criado
authors.affiliation: Instituto de Química Física Rocasolano, IQFR-CSIC , Serrano 119, 28006 Madrid, Spain.
authors.forename: Esther
authors.initials: E
authors.lastname: Rebollar
authors.affiliation: Instituto de Estructura de la Materia, IEM-CSIC , Serrano 121, 28006 Madrid, Spain.
authors.forename: Aurora
authors.initials: A
authors.lastname: Nogales
authors.affiliation: Instituto de Estructura de la Materia, IEM-CSIC , Serrano 121, 28006 Madrid, Spain.
authors.forename: Tiberio A
authors.initials: TA
authors.lastname: Ezquerra
authors.affiliation: Institut Charles Sadron, Centre National de la Recherche Scientifique, Université de Strasbourg , 23 rue du Loess, 67034 Cedex 2 Strasbourg, France.
authors.forename: Fouzia
authors.initials: F
authors.lastname: Boulmedais
authors.affiliation: Instituto de Ciencia y Tecnología de Polímeros, ICTP-CSIC , Juan de la Cierva, 3, 28006 Madrid, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Mijangos
authors.affiliation: Instituto de Ciencia y Tecnología de Polímeros, ICTP-CSIC , Juan de la Cierva, 3, 28006 Madrid, Spain.
authors.forename: Rebeca
authors.identifier: 0000-0001-7332-0134
authors.initials: R
authors.lastname: Hernández
mesh_terms: D000464:Alginates / Q000737:chemistry*; D048271:Chitosan / Q000737:chemistry*; D055119:Elastic Modulus; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D018625:Microscopy, Atomic Force; D011134:Polysaccharides / Q000737:chemistry*
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; D011134:Polysaccharides; D020723:Glucuronic Acid; D048271:Chitosan