I have tried but didn't get it to work. I think it's (even) more sensitive to oxygen inhibition than Irgacure 2959. I saw it used in a publication for 2PP on a non-aqueous system that was first purged with nitrogen.

You may have better luck if you use an amine coinitiator. For reference check this paper:  http://pubs.acs.org/doi/pdf/10.1021/ma001649r

Riboflavin cannot linking with gelatin. This polysaccharide does contain reactive group to react with riboflavin. in the gound or the excited states.