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.

Addresses:
Campbell CT, Univ Washington, Dept Chem, Box 351700, Seattle, WA 98195 USA.
Univ Washington, Dept Chem, Seattle, WA 98195 USA.
Univ Washington, Dept Bioengn, Seattle, WA 98195 USA.
Univ Washington, Dept Chem Engn, Seattle, WA 98195 USA.

Publisher:
AMER CHEMICAL SOC, WASHINGTON

IDS Number:
285XA

ISSN:
0743-7463