Our experimental approach is summarized in Figure . Briefly, fluorescence profiles were derived for lettuce, spinach, chicken, and beef products through evaluation at four wavelengths commonly employed within fluorescence biosensing (Figure ). Fluorescence was also assessed over time to account for changes that occurred over the food products' lifespans. Fluorophore visibility against target food backgrounds was evaluated using contact-printed oligonucleotides labelled with fluorophores corresponding to each of the four selected wavelengths (Figure ). Contact printed fNAPs were similarly immobilized onto food packaging, where they demonstrated both cleavage functionality and visibility with underlying food samples (Figure ).