3 µg/mL, which is an order of magnitude more toxic than various zinc and bismuth salts. However, the comparisons are not perfect due to differences in experimental details. We estimate that the upper bound for residual catalyst content in our samples as prepared for the cell culture tests is in the range of 100-150 µg. Thus, given the similar gel fractions for all samples, the differences in cytotoxicity are likely the result of toxicity of residual DBTDL (see also Figure ). In order to assess the potential for oxygen inhibition , we photocured materials in both inert (argon) atmosphere as well as in open air, as may be expected to occur during a surgical procedure. We did not observe any effect of the atmosphere present during photocuring, indicating that the effect of oxygen inhibition is relatively modest. Likewise, FTIR analysis of all of the materials confirms the complete purification of residual HEMA (Figure ), which has a reported IC50 of approx. 1.3 mg/mL . We conclude that all of the obtained materials using non-organotin catalysts can be considered well-suited for photocuring in situ without specialized oxygen-free conditions. At the same time, this study and the cell culture experiments were intended to serve as a proof-of-concept and screening; additional animal studies will be needed to address in vivo outcomes such as inflammatory response and fibrosis.