Developing Complex Patterns on Surface

Researchers at Worcester Polytechnic Institute, Worcester, Massachusetts have recently published an interesting report in Langmuir. They have develop a method for developing complex nanopatterns on surfaces by combining self-assembly, photolabile protecting groups, and multilayered films. An o-nitrobenzyl protecting group has been incorporated into molecular level films utilizing thiol-gold interactions. When the o-nitrobenzyl group is cleaved by ultraviolet light, a carboxylic acid terminated layer remains on the surface and is available for activation and further functionalization through amide bond formation. Using this method, multilayered films have been constructed and characterized by contact angle goniometry, cyclic voltammetry, grazing incidence infrared spectroscopy, and X-ray photoelectron spectroscopy measurements. Complex surface patterns can be achieved by creating a surface array using a photomask and then further fictionalizing the irradiated area through covalent coupling. Fluorophores were attached to the deprotected regions, providing visual evidence of surface patterning using fluorescence microscopy. Their approach is universal to bind moieties containing free amine groups at defined regions across a surface, allowing for the development of films with complex chemical and physicochemical properties.

Figure. Fluorescence microscopy images of surfaces patterned with 100 μm squares (top) and 100 μm lines separated by 150 μm spaces (bottom), images on the left are of rhodamine 110 (green) and images on the right are cresyl violet 670 (red). Inset: reduced scale images of the photomasks used to pattern the surfaces.