Material surface engineering for multiplex cell culture in microwell

In this study, we develop a new concept for multiplexed and localized cell co-culture. This cell chip consists of a polystyrene spin-coated solid support bearing gold-bottomed microwells. The cell-chip support is fabricated as follows: (i) electrosputtering of a thin layer of gold (40 nm) onto a polycarbonate substrate, (ii) spin coating of a polystyrene thin film (500 ± 50 nm) over the gold layer, followed by (iii) polystyrene etching through the spotting of toluene nanovolume (300–900 pL). In each gold-bottomed microwell, a small population of adherent cells (approx. 100 cells) can be cultured. In this miniaturized system, different cell lines can be co-cultured on a 1-cm2 surface, opening the way to multiplexed cell-chip development. In order to keep the cells in a properly hydrated environment and to physically retain them before they adhere, a biocompatible alginate polymer was used during the robotized micropipetting. This approach allows for the encapsulation of the cell in a very small volume (50 nL), directly in the microwells. After 24 h of culture, the cells adhered on the gold bottom of the microwells, and the alginate matrix was removed by addition of calcium-free culture medium. Multiplex culture of cells was obtained using in situ produced microwells and encapsulated cells. The microwells are produced by organic solvent etching (nanovolume spotting) of a spin-coated polystyrene thin film, and the living multiple cell line deposition is obtained using on-site encapsulation in an alginate bead.