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 TiO₂, but not on SiO₂, surfaces. Subsequent adsorption of poly(L-lysine)-g-poly(ethylene glycol) (PLL-g-PEG) rendered the exposed SiO₂ 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 TiO₂ features, arranged within a protein-resistant PLL-g-PEG-modified SiO₂ 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 SiO₂ 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.