Microcasting with agarose gel via degassed polydimethylsiloxane molds for repellency-guided cell patterning†
Hydrogel patterning methods are widely used for cell patterning because they offer better long-term stability than protein patterning methods such as micro-contact printing, but conventional hydrogel patterning methods require special apparatuses such as a laser or an electron beam lithography system or they have complicated chemical operations which prevent their practical use in biological laboratories. A simple method was developed to cast a hydrogel solution without external power sources using a polydimethylsiloxane (PDMS) mold with micro-channels. This study employed “the accumulation of vacuum pressure” in a degassed lump of PDMS as a driving force for introducing agarose solution into the micro-channels. Sufficient vacuum pressure could be accumulated within 1 h in the PDMS elastomer that was acting as a vacuum tank, and 2 w/v% agarose solution could be aspirated into the micro-channels with widths from 100 to 2000 μm and a height of 19 μm, fully filling them. After the gelation and dehydration of agarose solution in the micro-channels, the patterns of agarose gel on the channels were successfully cast with a 90%-width accuracy. By using the repellency of agarose gel toward cell adhesion, patterned cultures of myoblasts and cortical neurons were successfully prepared. This technique is expected to be useful in repellency-guided cell patterning for various types of cells, with applications to cell–cell interactions and axon guidance.