Attachment of Functionalized Poly(ethylene glycol) Films to Gold Surfaces

Abstract

The attachment of linear poly(ethylene glycol) (PEG) molecules (MW = 2000−5000) to gold surfaces via orthopyridyl−disulfide (OPSS) terminal groups has been studied with X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (TOF−SIMS), and surface plasmon resonance (SPR). The molecules examined included a PEG molecule terminated with a methoxy group and derivatized with an OPSS group at the other end (M-PEG-OPSS), a PEG molecule derivatized with OPSS at both ends (PEG-(OPSS)2), and a PEG derivatized with an N-hydroxysuccinimide group at one end and an OPSS group at the other (NHS-PEG-OPSS). Exposure of gold to aqueous solutions of these resulted in immobilization via gold−thiolate bonds from the OPSS disulfide groups. The resulting mixed PEG−/OPS− thiolate monolayers were not always in 1:1 ratio. Most of the PEG-(OPSS)2 molecules formed gold−thiolate bonds at both ends, but some left a free, intact OPSS group. For biosensor applications, this or the free NHS groups in the NHS-PEG-OPSS films can be used to immobilize biomolecules with accessible cysteines or lysines via formation of disulfide bonds or amide bonds, respectively. The PEG films formed by M-PEG-OPSS and PEG-(OPSS)2 resist the adsorption of albumin.

Versatile microsphere attachment of GFP-labeled motors and other tagged proteins with preserved functionality

“…In addition, to prevent microsphere aggregation, we simultaneously cover the microspheres with a dense monolayer of covalently-attached PEG molecules, which do not have any further reactive groups at the free end. PEGylation is widely used to efficiently passivate microspheres for in vivo [11][12][13][14] and in vitro [15][16][17][18] experiments and for different kinds of surfaces [19][20][21]. Also, there are other protocols that use PEG for functionalization [22,23].…”

Polymer Loops vs. Brushes on Surfaces: Adsorption, Kinetics, and Viscoelastic Behavior of α,ω‐Thiol Telechelics on Gold

“…While other groups have considered systems involving multiply-bound polymer chains, [21,22,26] a clear method for the fabrication of such surfaces continues to be obscure due to the lack of insight into the adsorption and assembly process of such materials. Further, there have been no systematic studies to explore the structure-property relationships of surfaces covered by polymer loops.…”

A novel PEG coating immobilized onto capillary through polydopamine coating for separation of proteins in CE

“…3C, PEG immobilization on polydopamine-modified raw materials of capillaries altered the surface chemical composition as evidenced by the decreasing signal in the nitrogen peak (399.9 eV) and Si (154 eV for Si2s and 103 eV for Si2p) and the increasing signal in the oxygen peak (532.5 eV). Moreover, the XPS C1s spectra of unmodified materials, polydopamine-coated raw materials, and polydopamine-graft-PEG-coated raw materials (data not shown) revealed a significant increase in the ether (c-o) peak at 285.9 eV, which had an appearance that was typical of a surface-bound PEG polymer [41,42].…”