Fibronectin micropatterns and CYTOOchambers are not toxic in any way for your cells if correct culture conditions are provided. This problem can have various environmental origins:
Please make sure that you followed correctly the procedure to use the CYTOO products, notably regarding the sufficient volume of culture medium.
Contamination by bacteria, yeasts or fungi. Check their presence and decontaminate CYTOOchambers using ethanol 70°. Be sure to work under sterile conditions.
The temperature, moisture or CO2 conditions are not correctly supplied by your incubator.
Cells are not cultured in the correct culture medium. You can also add Hepes buffer pH = 7.4 in the medium for long term experiments on micropatterns.
Cells are cultured with selection pressure antibiotics, which can stress the cells if concentrations are not adjusted.
Cells are stressed because they stayed for a long time in trypsin/EDTA solution before seeding on micropatterns. Try to dilute trypsin/EDTA solution in Hepes containing culture medium to remove your cells from dishes before their seeding on micropatterns.
Cells suffer from freezing and thawing processes. After cell thawing, imperatively culture them during one week in classic conditions before starting experiments on micropatterns.