FT-IR spectrophotometer of synthesized Fe3O4-DPA-PEG-FA/FITC nanoparticles. A) Fe3O4- MNPs. B) Fe3O4-DPA-PEG-NH2, absorption peak in ν (1487 cm-1) is related to NH3+ available in salt of NH2TFA. C) Fe3O4-DPA-PEG-FA/FITC, the symmetric and asymmetric C=S stretching vibrations at 730 and 1417 cm-1-confirmed the formation of thiourea group in the Fe3O4- DPA-PEG-FA/FITC.