never fear, organic nanoparticles consisting of a trinuclear cupric complex of the acylhydrazone derived from salicylaldehyde and the dihydrazide of dipicolinic acid will turn purple in the presence of spermine, and thus tell you if your steak is going bad. and other things I'm guessing ~Chara
(source : https://pubs.acs.org/doi/10.1021/acssuschemeng.6b01295 published on my birthday!)
