title: Probing the Surface Hydration of Nonfouling Zwitterionic and PEG Materials in Contact with Proteins.
abstract: Zwitterionic polymers and poly(ethylene glycol) (PEG) have been reported as promising nonfouling materials, and strong surface hydration has been proposed as a significant contributor to the nonfouling mechanism. Better understanding of the similarity and difference between these two types of materials in terms of hydration and protein interaction will benefit the design of new and effective nonfouling materials. In this study, sum frequency generation (SFG) vibrational spectroscopy was applied for in situ and real-time assessment of the surface hydration of the sulfobetaine methacrylate (SBMA) and oligo(ethylene glycol) methacrylate (OEGMA) polymer brushes, denoted as pSBMA and pOEGMA, in contact with proteins. Whereas a majority of strongly hydrogen-bonded water was observed at both pSBMA and pOEGMA surfaces, upon contact with proteins, the surface hydration of pSBMA remained unaffected, but the water ordering at the pOEGMA surface was disturbed. The effects of free sulfobetaine, free PEG chains with two different molecular weights, and PEG coated gold nanoparticles on the surface hydration of proteins were investigated. The results indicated that free sulfobetaine could strengthen the protein hydration layer, but free PEG chains greatly disrupt the protein hydration layer and likely directly interact with the protein molecules. In contrast to free PEG, the PEG chains anchored on the nanoparticles behave similarly to the pOEGMA surface and could induce strong hydrogen bonding of the water molecules at the protein surfaces.
authors.affiliation: †Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States.
authors.forename: Chuan
authors.initials: C
authors.lastname: Leng
authors.affiliation: ‡Department of Chemical Engineering, University of Washington, Seattle, Washington 98195, United States.
authors.forename: Hsiang-Chieh
authors.initials: HC
authors.lastname: Hung
authors.affiliation: †Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States.
authors.forename: Shuwen
authors.initials: S
authors.lastname: Sun
authors.affiliation: §Ian Wark Research Institute, University of South Australia, Mawson Lakes, SA 5095, Australia.
authors.forename: Dayang
authors.initials: D
authors.lastname: Wang
authors.affiliation: ‡Department of Chemical Engineering, University of Washington, Seattle, Washington 98195, United States.
authors.forename: Yuting
authors.initials: Y
authors.lastname: Li
authors.affiliation: ‡Department of Chemical Engineering, University of Washington, Seattle, Washington 98195, United States.
authors.forename: Shaoyi
authors.initials: S
authors.lastname: Jiang
authors.affiliation: †Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States.
authors.forename: Zhan
authors.initials: Z
authors.lastname: Chen
mesh_terms: D000327:Adsorption; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D007477:Ions; D008422:Materials Testing / Q000379:methods; D011092:Polyethylene Glycols / Q000737:chemistry*; D011485:Protein Binding; D011506:Proteins / Q000737:chemistry*; D013057:Spectrum Analysis / Q000379:methods; D014867:Water / Q000737:chemistry*; D017155:Wettability
chemical_list: D020099:Coated Materials, Biocompatible; D007477:Ions; D011506:Proteins; D014867:Water; D011092:Polyethylene Glycols
keywords: gold nanoparticles; hydration; hydrogen bonding; nonfouling materials; poly(ethylene glycol) (PEG); sulfobetaine; sum frequency generation (SFG) vibrational spectroscopy; zwitterionic polymer