Demonstration of multi-analyte patterning using piezoelectric inkjet printing of multiple layers.

Patterning substrates with biological reagents is a critical component of biosensor development. Many applications require multi-analyte patterning capabilities, with a need to deposit several species reproducibly with a high degree of precision. We demonstrate a piezoelectric inkjet printing system that is capable of creating sub-millimeter (down to 150microm) patterns of aqueous and nonaqueous reagents with precise placement for biosensor applications. The size, shape, and density of the patterns may be modified by simple adjustments of the patterning parameters. Using this system, two methods of multi-analyte protein patterning for use in biosensor assays are demonstrated. The first method involves the deposition of multiple proteins directly onto a gold substrate. Specific binding of an antibody to the deposited antigen is demonstrated, although nonspecific adsorption of the antibody may limit the utility of this simple method in quantitative biosensor applications. A second, more sophisticated multi-analyte patterning method involves two sequential patterning steps, consisting of an initial deposition onto gold of a mixed thiol layer to provide oriented binding capabilities in a nonfouling background and a second deposition of multiple biotinylated proteins. Highly specific antibody binding to this patterned multi-analyte surface was demonstrated, with minimal nonspecific adsorption to the surrounding regions. Thus, this method produces high-quality, localized, and customizable sub-millimeter patterns in a nonfouling background for multi-analyte bioassay development.