Hi there, I am trying to coat a 96-well round bottom plate with poly-HEMA as part of my spheroid assay protocol. I dissolved 20 mg/ml of poly-HEMA in 95% ethanol and added 100 microliters of this suspension to each well.

The protocol I am following recommends to leave the plate to sit in the tissue culture hood (sterile) at room temperature for 24 hours or in the 37 degree celsius incubator for 24-72 hours with the lid ajar.

When I tried this, the outside wells had dried up to the point where we could see white powder residue at the bottom of the well. The inner-most wells were still in solution and had not dried.

I threw this plate out and tried again, this time with the lid on during the drying time, as opposed to ajar. It has been 3 days and we still do not see any drying occuring.

What does the polyHEMA-coated wells look like when optimally dry? How do you know when the polyHEMA has dried and the plate is ready for cell-seeding? How do you dry the plate so that all wells are drying at a constant rate?

Thank you in advance!