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Size‐Exclusion Effect and Protein Repellency of Concentrated Polymer Brushes Prepared by Surface‐Initiated Living Radical Polymerization
Author(s) -
Yoshikawa Chiaki,
Goto Atsushi,
Ishizuka Norio,
Nakanishi Kazuki,
Kishida Akio,
Tsujii Yoshinobu,
Fukuda Takeshi
Publication year - 2007
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.200750220
Subject(s) - quartz crystal microbalance , atom transfer radical polymerization , adsorption , polymer , polymer brush , protein adsorption , dispersity , chemical engineering , polymerization , materials science , polymer chemistry , methacrylate , chemistry , organic chemistry , composite material , engineering
The adsorption of proteins on poly(2‐hydroxyethyl methacrylate) (PHEMA) brushes was systematically investigated from the viewpoint of the size‐exclusion effect of the concentrated brushes. By use of surface‐initiated atom transfer radical polymerization, well‐defined, concentrated PHEMA brushes were successfully grafted on the inner surface of the silica monolithic column with meso pores of ca. 80 nm as well as a silicon wafer and a quartz crystal microbalance (QCM) chip. By eluting low‐polydispersity pullulans with different molecular weight through the modified monolithic column, the concentrated PHEMA brush was characterized and demonstrated to sharply exclude solute molecules with the critical molecular size (size‐exclusion limit) comparable to the distance between the nearest‐neighboring graft points d . The elution behaviors of proteins with different sizes were studied with this PHEMA‐grafted column: the protein sufficiently larger than the critical size was perfectly excluded from the brush layer and separated only in the size‐exclusion mode by the meso pores without affinity interaction with the brush surface. Then, the irreversible adsorption of proteins on PHEMA brushes was investigated using QCM by varying graft densities ( σ = 0.007, 0.06, and 0.7 chains/nm 2 ) and protein sizes (effective diameter = 2–13 nm). A good correlation between the protein size and the graft density was observed: proteins larger than d caused no significant irreversible adsorption on the PHEMA brushes. Thus, we experimentally substantiated the postulated size‐exclusion effect of the concentrated brushes and confirmed that this effect plays an important role for suppressing protein adsorption.