title: Factors Affecting Peptide Interactions with Surface-Bound Microgels.
abstract: Effects of electrostatics and peptide size on peptide interactions with surface-bound microgels were investigated with ellipsometry, confocal microscopy, and atomic force microscopy (AFM). Results show that binding of cationic poly-L-lysine (pLys) to anionic, covalently immobilized, poly(ethyl acrylate-co-methacrylic acid) microgels increased with increasing peptide net charge and microgel charge density. Furthermore, peptide release was facilitated by decreasing either microgel or peptide charge density. Analogously, increasing ionic strength facilitated peptide release for short peptides. As a result of peptide binding, the surface-bound microgels displayed pronounced deswelling and increased mechanical rigidity, the latter quantified by quantitative nanomechanical mapping. While short pLys was found to penetrate the entire microgel network and to result in almost complete charge neutralization, larger peptides were partially excluded from the microgel network, forming an outer peptide layer on the microgels. As a result of this difference, microgel flattening was more influenced by the lower Mw peptide than the higher. Peptide-induced deswelling was found to be lower for higher Mw pLys, the latter effect not observed for the corresponding microgels in the dispersed state. While the effects of electrostatics on peptide loading and release were similar to those observed for dispersed microgels, there were thus considerable effects of the underlying surface on peptide-induced microgel deswelling, which need to be considered in the design of surface-bound microgels as carriers of peptide loads, for example, in drug delivery or in functionalized biomaterials.
authors.affiliation: Department of Pharmacy, Uppsala University , P.O. Box 580, SE-752 32 Uppsala, Sweden.
authors.forename: Lina
authors.initials: L
authors.lastname: Nyström
authors.affiliation: Department of Pharmacy, Uppsala University , P.O. Box 580, SE-752 32 Uppsala, Sweden.
authors.forename: Randi
authors.initials: R
authors.lastname: Nordström
authors.affiliation: School of Materials, The University of Manchester , MSS Tower, Manchester, M13 9PL, United Kingdom.
authors.forename: Jane
authors.initials: J
authors.lastname: Bramhill
authors.affiliation: School of Materials, The University of Manchester , MSS Tower, Manchester, M13 9PL, United Kingdom.
authors.forename: Brian R
authors.initials: BR
authors.lastname: Saunders
authors.affiliation: Department of Surface and Corrosion Science, School of Chemical Science and Engineering, KTH Royal Institute of Technology , SE-100 44 Stockholm, Sweden.|Institute for Advanced Studies, IMDEA Nanoscience , 28049 Madrid, Spain.
authors.forename: Rubén
authors.initials: R
authors.lastname: Álvarez-Asencio
authors.affiliation: Department of Surface and Corrosion Science, School of Chemical Science and Engineering, KTH Royal Institute of Technology , SE-100 44 Stockholm, Sweden.|SP Technical Research Institute of Sweden , SP Chemistry, Materials and Surfaces, SE-114 86 Stockholm, Sweden.
authors.forename: Mark W
authors.initials: MW
authors.lastname: Rutland
authors.affiliation: Department of Pharmacy, Uppsala University , P.O. Box 580, SE-752 32 Uppsala, Sweden.
authors.forename: Martin
authors.initials: M
authors.lastname: Malmsten
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D004337:Drug Carriers / Q000737:chemistry*; D005782:Gels; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D009994:Osmolar Concentration; D011107:Polylysine / Q000737:chemistry; D011485:Protein Binding; D013499:Surface Properties
chemical_list: D000180:Acrylic Resins; D004337:Drug Carriers; D005782:Gels; C478961:poly(ethylacrylate); D011107:Polylysine