title: Parallel Control over Surface Charge and Wettability Using Polyelectrolyte Architecture: Effect on Protein Adsorption and Cell Adhesion.
abstract: Surface charge and wettability, the two prominent physical factors governing protein adsorption and cell adhesion, have been extensively investigated in the literature. However, a comparison between these driving forces in terms of their independent and cooperative effects in affecting adhesion is rarely explored on a systematic and quantitative level. Herein, we formulate a protocol that features two-dimensional control over both surface charge and wettability with limited cross-parameter influence. This strategy is implemented by controlling both the polyion charge density in the layer-by-layer (LbL) assembly process and the polyion side-chain chemical structures. The 2D property matrix spans surface isoelectric points ranging from 5 to 9 and water contact angles from 35 to 70°, with other interferential factors (e.g., roughness) eliminated. The interplay between these two surface variables influences protein (bovine serum albumin, lysozyme) adsorption and 3T3 fibroblast cell adhesion. For proteins, we observe the presence of thresholds for surface wettability and electrostatic driving forces necessary to affect adhesion. Beyond these thresholds, the individual effects of electrostatic forces and wettability are observed. For fibroblast, both surface charge and wettability have an effect on its adhesion. The combined effects of positive charge and hydrophilicity lead to the highest cell adhesion, whereas negative charge and hydrophobicity lead to the lowest cell adhesion. Our design strategy can potentially form the basis for studying the distinct behaviors of electrostatic force or wettability driven interfacial phenomena and serve as a reference in future studies assessing protein adsorption and cell adhesion to surfaces with known charge and wettability within the property range studied here.
authors.affiliation: NUS Graduate School for Integrative Science and Engineering, National University of Singapore , Kent Ridge, Singapore 117576.
authors.forename: Shanshan
authors.initials: S
authors.lastname: Guo
authors.affiliation: Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research , 2 Fusionopolis Way, Singapore 138634.|Department of Environmental Science, Zhejiang University , Hangzhou, China 310058.
authors.forename: Xiaoying
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Department of Chemical & Biomolecular Engineering, National University of Singapore , Kent Ridge, Singapore 119260.
authors.forename: Min
authors.initials: M
authors.lastname: Li
authors.affiliation: Department of Chemical & Biomolecular Engineering, National University of Singapore , Kent Ridge, Singapore 119260.
authors.forename: Liya
authors.initials: L
authors.lastname: Shi
authors.affiliation: Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research , 2 Fusionopolis Way, Singapore 138634.
authors.forename: June Lay Ting
authors.initials: JL
authors.lastname: Ong
authors.affiliation: Laboratory of Technological Processes, Faculty of Chemistry, Warsaw University of Technology , Noakowskiego 3, 00-664 Warsaw, Poland.
authors.forename: Dominik
authors.initials: D
authors.lastname: Jańczewski
authors.affiliation: NUS Graduate School for Integrative Science and Engineering, National University of Singapore , Kent Ridge, Singapore 117576.|Department of Chemical & Biomolecular Engineering, National University of Singapore , Kent Ridge, Singapore 119260.
authors.forename: Koon Gee
authors.initials: KG
authors.lastname: Neoh
mesh_terms: D000327:Adsorption; D002448:Cell Adhesion; D000071228:Polyelectrolytes / Q000737:chemistry*; D013499:Surface Properties; D017155:Wettability
chemical_list: D000071228:Polyelectrolytes
keywords: cell adhesion; layer-by-layer assembly; polyelectrolyte multilayer; protein adsorption; surface charge; surface wettability