ESMN embryoid body encapsulated in the 6.3 wt % 8-NBA:4-DBCO hydrogel immediately after encapsulation and erosion of channels (left) and 48 h after. Axons extend into channels that have been exposed to sufficient light to erode the material. Channels represent varying erosion where the exposure time was held constant at 3.16 μs and the power was varied from 15 to 110 mW/μm3. These powers correspond to a tc from 815 to 0.90 μs, based on a δϕ value of 0.20 GM. Channels marked with an asterisks were exposed to light under conditions that do not theoretically lead to complete gel erosion, which is theoretically crossed at <63 mW/μm3 and the ray at 3 o’clock. In all of these conditions, axon growth is not observed. Because axons extend through channels exposed to 39 mW/μm3, it is likely the quantum efficiency, δϕ, of the nitrobenzyl linker under study is actually higher than the previously reported value of a similar compound.(44) Scale bar is 100 μm.