Micro protein patterning using a lift-off process with fluorocarbon thin film

Abstract

This paper discusses micro protein patterning using fluorocarbon (FC) thin films patterned by a lift-off process to prevent the nonspecific binding of protein. 3M’s Fluorad™ and Asahi Glass’s CYTOP™ were evaluated in FC film patterning using the lift-off process. Surface characterization of patterned FC films was performed for various static and dynamic contact angles, surface energy, roughness, surface morphology, and fluorescence intensity after each step of the lift-off process and surface modification for protein patterning. The CYTOP™ films were found to have better biochemical resistance than the Fluorad™ films for surface characterization. The CYTOP™ films preserved the surface properties, demonstrating a narrow variation of static and dynamic contact angles, contact angle hysteresis, and surface roughness in repeated surface modifications for the protein patterning over 17 h. In a nonspecific binding test of BSA, it was found that the nonspecific binding on the CYTOP™ film appeared considerably above 2 μg/ml from the surface characterization. We fabricated 100 μm diameter circular silicon nitride (SiN) patterns with the CYTOP™ film background. FITC-labeled BSA was patterned on the silicon nitride surface after chemical oxidation for SiOH group activation, silanization, and aldehyde treatment.