Hello Marine Lambert

You could probably use the invitro method mentioned in the paper attached.

https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.550.2283&rep=rep1&type=pdf

Best.

Adding sunscreen to the medium would be challenging as you would need to produce a sterile emulsion. The paper Malcolm mentions uses skin equivalent models so the sunscreen can be directly applied to a "dry" surface. If you need to use monolayer cultures (is this an appropriate model?) you could consider applying the sunscreen as an even film (at whatever density you required) to a UV-transmissible plastic lid that would cover your culture plate. This way the sunscreen would not need to be sterile and would better mimic sunscreen use. Just a thought...