Selective Molecular Assembly Patterning:  A New Approach to Micro- and Nanochemical Patterning of Surfaces for Biological Applications

A novel patterning technique based on selective self-assembly of alkane phosphates on metal oxide surfaces is presented. Standard photolithography was used to create patterns of titanium dioxide within a matrix of silicon dioxide. Alkane phosphates were found to self-assemble on TiO 2, but not on SiO 2, surfaces. Subsequent adsorption of poly( l -lysine)- g -poly(ethylene glycol) (PLL- g -PEG) rendered the exposed SiO 2 surface resistant to protein adsorption. X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry were employed to monitor the assembly processes. Protein-adsorption studies by means of fluorescence microscopy conclusively established that the resulting surfaces displayed protein-adhesive, alkyl phosphate modified TiO 2 features, arranged within a protein-resistant PLL- g -PEG-modified SiO 2 matrix. Human foreskin fibroblasts, incubated in a serum-containing medium, were found to selectively attach to the protein-adhesive areas, where they developed focal contacts. No interaction of cells with the PLL- g -PEG-coated SiO 2 areas was evident for at least 14 days. This patterning approach, termed selective molecular assembly patterning, is considered to be suitable for reproducible and cost-effective fabrication of biologically relevant chemical patterns over large areas.