Aqueous micro-contact printing of cell-adhesive biomolecules for patterning neuronal cell cultures

Abstract

Micro-contact printing (mu CP) technique has been widely used for generating micro-scale patterns of biomolecules for patterning live cells. The contact-printing process is carried out in air, while most of the biomolecules including proteins and antibodies should be handled in a solution to preserve their bioactivity. Here we attempted to print biomolecules under aqueous conditions by modifying certain steps that are known to be critical for the bioactivity. The proposed contact-printing process is as follows: After inking the stamp with biomolecule in a solution, the stamp was rinsed in ultra-sonication bath to remove excessive inked biomolecules on the stamp and the following contact-printing process ('stamping') was carried out in a buffered solution. By this way, inked biomolecules were consistently handled under a well-defined aqueous condition. Results showed that high-resolution micropatterns of biomolecules can be printed under the aqueous condition (aqueous micro-contact printing, aq-mu CP) and it was readily applicable for patterning neuronal cell cultures. Using the modified process, we were able to print widely separated patterns (2 mu m-wide lines with 400 mu m spacing), which was not achievable with conventional mu CP. Extracellular matrix proteins (laminin and fibronectin) were readily printed in a few micrometer scale patterns and their biological activities were confirmed by immunoassays and neuronal cell cultures. We also demonstrated that pH sensitive surface biofunctionalization scheme can be implemented with the proposed aq-mu CP for patterning neuronal cell cultures. The aq-mu CP improves the existing surface patterning strategy by extending printable patterns and proteins for neuronal cell chip design.