Thin Solid Films, Vol.513, No.1-2, 338-346, 2006
Surface composition gradients of immobilized cell signaling molecules. Epidermal growth factor on gold
Surface composition gradients of the signaling molecule, epidermal growth factor (EGF), have been prepared by an adaptation of the electrochemical gradient technique. EGF is covalently bound to the reactive component, 11-amino-1-undecanethiol (AUT), in a counter-propagating two-component gradient composed of AUT and poly(ethylene glycol) thiol (PEG) using carbodiimide coupling chemistry. Areas of the surface presenting -NH2 termination react with succinimidyl esters of solvent-accessible acidic amino acids in EGF, while non-specific protein adsorption is resisted in the PEG regions. The maximum surface coverage of EGF prepared in this manner was determined by surface plasmon resonance reflectometry (SPR) on spatially uniform films to be 20%