Micropatterning of perfluoroalkyl self-assembled monolayers for arraying proteins and cells on chips

Organosilane self-assembled monolayers (SAMs) with perfluoroalkyl groups (Rf) on glass surfaces were used for arraying proteins and cells on chips. Quartz crystal microbalance measurements confirmed the inhibition of protein adsorption on Rf-SAM-modified surfaces and showed efficient adsorption on hydroxyl-, carboxyl-, and amino group-modified surfaces. The characteristics of Rf-modified surfaces were evaluated using solvent contact angle measurement and Fourier transform infrared (FTIR) spectroscopy. The Rf surface was highly water- and oil-resistant, as inferred from the contact angles of water, oleic acid, and hexadecane. Specific peaks of IR spectra were detected in the region from 1160 to 1360 cm−1. Etching with dry plasma completely exfoliated the Rf-SAM, exposing the underlying intact glass surface. Modification conditions were optimized using contact angle and FTIR measurements. After dry plasma processing, the contact angles of all solvents became undetectable, and the IR peaks disappeared. Micrometer scale protein and cell patterns can be fabricated using the proposed method. Protein adsorption on micropatterned Rf-SAM-modified chips was evaluated using fluorescence analysis; protein adsorption was easily controlled by patterning Rf-SAM. PC12 and HeLa cells grew well on micropatterned Rf-SAM-modified chips. Micropatterning of Rf-SAM by dry plasma treatment with photolithography is useful for the spatial arrangement of proteins and cells.