A Simple, Reproducible Approach to the Preparation of Surface-Chemical Gradients.

Author(s): Morgenthaler, Sara, Seunghwan Lee, Stefan Zürcher, Nicholas D. Spencer

Journal: Langmuir (2003) 19(25): 10459-10462.

Abstract:
We demonstrate a very simple and reproducible preparative approach for the fabrication of surface-chemical gradients.Asurface concentration gradient of adsorbed methyl- or hydroxyl-terminated thiolates was achieved upon gradually immersing a gold-coated substrate into a very dilute thiol solution (0.0033 mM) by means of a linear-motion drive. Subsequent immersion of the substrate into the complementary thiol solution provided a hydrophobicity gradient with a large range (50° of the water-contact angle) and over a significant distance (35 mm). The self-assembled monolayer gradient produced in this way also displayed a high packing density, as demonstrated by dynamic contact-angle and X-ray photoelectron spectroscopy measurements.