Numerous requirements were imposed on the development of the “LabBag®”, which initially had to be resolved on the material side. Examples include durability over a wide temperature range as well as transparency and processability. Following the selection of suitable polymer films, appropriate layer systems then had to be identified which would allow the formation of droplets on the surface.
Following the selection of suitable materials, hydrophilic and repellent superhydrophobic coatings were applied by means of an atmospheric pressure plasma process. This coating pattern enables the formation of defined droplets by simply shaking the bags. In these “hanging drops”, the stem cells develop into three-dimensional cell aggregates, which can then be differentiated into specific cells.
Coating the inside of the bag using the atmospheric pressure plasma process is a “dry” process, i.e. there is no need to use any solvents whatsoever. This is a major advantage, as residues of the solvent might possibly damage the cells. In addition, the desired layer properties can be set via the utilized process gases and layer patterns, resulting in an optimized surface for the formation of the hanging drops. Further advantages of the LabBag® are lower personnel and material costs, a high cell yield and process reliability, easy adjustment of the droplet volume and, consequently, the aggregate sizes through variation of the deposited spot diameters on the bag surface, and cryopreservation of the cells in the LabBag®.