Creation of a mixed poly(ethylene glycol) tethered-chain surface for preventing the nonspecific adsorption of proteins and peptides

Abstract

Using a heterotelechelic poly(ethylene glycol) (PEG) possessing a mercapto group at one end and an acetal group at the other end (acetal-PEG-SH), the authors constructed a reactive PEG tethered-chain surface on a surface plasmon sensor (SPR) gold chip for biosensing with high sensitivity. Nonspecific bovine serum albumin adsorption on the PEG tethered-chain surface was significantly influenced by the density of the PEG chain, and was almost completely suppressed by increasing the PEG density through the repetitive treatment of the chip surface with acetal-PEG-SH. The PEG density was increased even more by adding an underbrushed layer made of shorter-PEG-SH-chain molecules (2 kDa, hereafter 2k) to the surface made of longer-PEG-SH-chain molecules (5 kDa, hereafter 5k). SPR measurement then gave an estimate of the adsorption of a series of proteins with varying sizes and isoelectric points on the PEG chain surface having an underbrushed layer (PEG5k/2k surface). As compared to other SPR surfaces, viz., a commercial carboxymethyl dextran and conventional PEG5k tethered-chain surface without an underbrushed layer, the mixed PEG5k/2k surface showed almost complete inhibition of the nonspecific adsorption not only of high-molecular-weight proteins but also of low-molecular-weight peptides.

Surface-immobilised antimicrobial peptoids

“…In order to create surfaces with both active antibacterial and passive antifouling properties, we modified surfaces with PMP1-AMP or PMP1-C first and then backfilled with the shorter PMP1 10 . Modifying surfaces with a two-step approach involving grafting of a longer polymer followed by backfilling with a shorter one, has been shown to be an effective strategy for enhancing antifouling performance of polymer brushes (Fang et al, 2005;Satomi et al, 2007;Uchida et al, 2007). In the present case, backfilling with PMP1 10 should facilitate extension of the active AMP moiety away from the surface for interaction with bacteria that encounter the modified surface.…”

Construction of a densely poly(ethylene glycol)-chain-tethered surface and its performance

“…Nonspecifically adsorbed mass on PEG surfaces and on CM surfaces was calculated by using 1 RU (unit in BiaCore Instrument) as 0.088 ng cm À2 and as 0.18 ng cm À2 . This figure is reproduced from the study by Katsumi et al, 45 by courtesy of the publishers, Elsevier, Amsterdam, The Netherlands.…”

“…Figure 3 shows the protein adsorption character of a surface plasmon resonance (SPR) sensor chip coated with sulfanyl-ended PEG (SH-PEG) tethered chains as a function of protein sizes. 45 The mixed-PEG chain tethered on a gold surface was created by the successive immobilization of SH-PEG (5 kDa) followed by SH-PEG (2 kDa). 13 When dextran gel was used as a control, nonspecific adsorption was prevented to some extent when using high-molecular-weight protein.…”

Mixed poly (ethylene glycol) and oligo (ethylene glycol) layers on gold as nonfouling surfaces created by backfilling

“…The grafting from technique generally gives higher graft density since the limiting factor is diffusion of monomer onto the reactive ends of growing chains, whereas in the case of the grafting to technique the limitation is diffusion of entire polymer chains to the reactive substrate. 10 Several strategies such as cloud point grafting, 11 grafting in homopolymer solutions, 12 grafting from polymeric melts, 13 and underbrush formation by backfilling with shorter molecules 14 have been used to increase the graft density for grafting to techniques. The backfilling approach, unlike the other three strategies that depend on minimization of excluded volume interactions, is a simple method wherein the interchain spaces present in layers of high M W PEG chains are filled with shorter PEG chains that can diffuse to the surface.…”