I used the MAK143 ROS kit on DIV 21 primary neurons, with kit reagents heated to 37 C, and I saw consistent but bright baseline fluorescence across control neuron networks in four well plates. I cannot upload pictures until the bigger paper is published, but I could see somas, axons and the dense networks of individual spines/dendrites even on low mag (10x) in all neurons. This high base fluorescence might be because neurons have a high metabolism rate relative to other body cells, I haven't tested on other cells yet or with other kits.
Also, I saw the kit was used in this paper:
Misra, Santosh K., et al. "Multi-functionality redefined with colloidal carotene carbon nanoparticles for synchronized chemical imaging, enriched cellular uptake and therapy." Scientific reports 6 (2016): 29299.