Synthesis and Characterization of G4@IONPs

G₄@IONPs synthesis and characterization were explained in detail in our previous studies [21 (link),36 (link)]. Briefly, IONPs were synthesized by co-precipitation of 0.84 g of FeSO₄ and 1.22 g of FeCl₃ and then functionalized by PAMAM dendrimers with step by step addition of methyl acrylate and Ethylenediamine (Figure 2a). 50 mL methyl acrylate/methanol solution (20%, v/v) was added to the 10 mL ethanol solution of APTS coated IONPs (5 g/L); after 1h sonication and stirring, 15 mL ethylenediamine/methanol (50%, v/v) was added to the previous solution followed by 3 h sonication at room temperature. Subsequently, methoxypolyethylene glycol (mPEG) molecules (molecular weight = 4000 Da) having three times the mass of the iron were dissolved in ethanol and added to the G₄@IONPs solution before 18 h reflux. Transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy were applied to assess G₄@IONPs size and presence of PAMAM bonds on the IONPs surface, respectively. In addition,, the surface charge of G₄@IONPs was measured using a Zetasizer instrument (Malvern Panalytical, Malvern, UK).