Fig. 1

Schematic representing the synthesis route of IONPs via a co-precipitation and b thermal decomposition. c–f TEM images and g size/PDI, vs SNPs synthesis reaction times (RT = room temperature, Rxn = reaction). h, i FTIR spectra showing the development of SNPs with the decomposition of iron oleate. TEM images and size distribution histograms of the finally obtained IONPs j SNPs, k Mag and l CNPs