Micropatterned, self-assembled monolayers for fabrication of transfected cell microarrays

The aim of this study was to develop the cell microarray that allows efficient transfer of multiple genes into mammalian cells cultured on the microarray in a high-throughput fashion. A microarray was fabricated using a gold-coated glass plate having a micropatterned, self-assembled monolayer of alkanethiols carrying ionic and nonionic terminal groups. Plasmid DNA and a cationic lipid were loaded by alternate electrostatic adsorption to the microspots to obtain a plasmid DNA microarray. The loading and the release of lipid-DNA complex were studied by, respectively, the fluorescence staining of DNA and the imaging of the microarray with a surface plasmon resonance (SPR) apparatus. The transfection efficiency was evaluated by directly plating and culturing human embryonic kidney cells onto the microarray. The results demonstrated that cells which adhered to the DNA-loaded spots were transfected to express the encoded model proteins for several days. The chemistry of the monolayers and the number of alternate adsorption cycles had large effects on the efficiency of transfection. This may be explained from the availability of the lipid-DNA complex to the cells directly contacted. We conclude that the micropatterned, self-assembled monolayers greatly facilitate regionally defined loading of DNAs and expression of the encoded protein in mammalian cells.