For the first time, we demonstrate that a chaperonin protein lattice can be used as a template to assemble nanocrystal arrays for flash memory fabrication. This provides a brand new approach that can incorporate different types of nanocrystals from a colloidal suspension for flash memory fabrication. Lead selenide (PbSe) and cobalt (Co) nanocrystal assemblies achieved through this method have a high density of 9.5 times1011/cm2 and 1.6 times 1012 /cm2, respectively, as well as very good distribution uniformity. Devices exhibit promising flash memory functions, with a flat band shift of 0.5V under 8V operation, endurance >105 cycles and retention time >104 seconds