Surface reactions of 4-aminothiophenol with heterobifunctional crosslinkers bearing both succinimidyl ester and maleimide for biomolecular immobilization.

Surface reactions of 4-aminothiophenol (4-ATP) with a series of heterogeneous crosslinkers containing both maleimide and succinimidyl ester groups were investigated with infrared reflection absorption spectroscopy (IRRAS) and X-ray photoelectron spectroscopy (XPS). Two types of surface reactions exist: (1) for most crosslinkers, a dominant reaction of amine and succinimidyl ester gave homogeneous maleimide-pendant surfaces; (2) for other crosslinkers, a side reaction between amine and maleimide, accompanying the main reaction, yielded heterogeneous surfaces with two linking groups, maleimide and succinimidyl ester. A typical example for the second case is the reaction of surface amines with N-succinimidyl-6-maleimidylhexanoate (SMH). Finally, a peptide, H-Gly-Arg-Gly-Asp-Ser-Pro-Cys-OH (GRGDSPC), was immobilized on the SMH-derived surface as a bridging structure through two linkages, cysteine thioether and glycine amide.