Successful mammalian cell adhesion is an important aspect of cell life cycle, proliferation, and signalling. In laboratories, researchers mostly use dishes which usually are pre-treated by suppliers for an enhanced adhesion of cells. There is a lot known about cell adhesion [1], however, some experiments require for the cells to grow on unconventional special surfaces. When using a specific substrate or surface for cell adhesion, it is necessary to experimentally find out which conditions would ensure a sufficient adhesion of a certain cell line. In our example, we are using polycarbonate membrane, which will be implemented into a microfluidics chip for electroporation of adherent cells and plasmid DNA inside of it.
Our objective is to prepare polycarbonate membrane by modifying it to facilitate adhesion of mammalian cells on it. Polycarbonate membrane is available commercially in different thicknesses and containing pores in different sizes. Oxygen plasma is known to increase the number of oxygen-containing groups, such as peroxide, hydroxyl, carboxyl groups on a substrate or surface, which makes the surface even more hydrophilic and ensures attachment of adhesion molecules [2]. We have tested an influence of oxygen plasma treatment for cell adhesion after membrane was also coated with poly-D-lysine. The results showed that only one fifth of cells attach to polycarbonate membrane without oxygen plasma treatment, meanwhile, more than 90 per cent of cells adhered on membrane with oxygen plasma treatment.
Next, we have tested the influence of other adhesion molecules - type I collagen and fibronectin for cell adhesion on polycarbonate membrane pre-treated with oxygen plasma. Our results showed that there is no significant difference in numbers of adherent cells between different adhesion molecules used; the mammalian cells easily attach to polycarbonate membrane which was coated with poly-D-lysine and any adhesion molecule (or their combinations) mentioned above. With the indication of our results, we conclude, that oxygen plasma treatment is a necessary step to induce cell adhesion on polycarbonate membrane; also, coating polycarbonate membrane with any adhesion molecules (fibronectin, collagen I and poly-D-lysine) is sufficient for achieving a required level of cell adhesion on polycarbonate membrane.