## 3 Results  
### Characterization  
The co-precipitation protocol was used to synthesize iron oxide nanoparticles (Fe\({}_{3}\)O\({}_{4}\)) by mixing two types of iron salts. As shown in Figure 1A, Fe\({}_{3}\)O\({}_{4}\) nanoparticles are nearly spherical with an average particle size of ca. 21 nm. However, Fe\({}_{3}\)O\({}_{4}\) nanoparticles have shown agglomeration as a result of their paramagnetic property. After coating Fe\({}_{3}\)O\({}_{4}\) nanoparticles with mesoporous silica shell using TEOS as silica source and CTAB as directing agent in a basic solution, there was an increase in the particle size from 21 nm to ca. 230 nm, with the shape of semi-sphere-like nanoparticle, as shown in Figure 1B. The presence of Fe\({}_{3}\)O\({}_{4}\) nanoparticles in the core of mesoporous nanomaterials is clearly seen in the TEM image (Figure 1C), indicating successful coating. The average core size was estimated to be 19 nm, which is in agreement with the SEM image of Fe\({}_{3}\)O\({}_{4}\) nanoparticles. Figure 1D,E show SEM and TEM images of magnetic mesoporous silica nanoparticles after polymerization. There is a noticeable increase in the average diameter of Fe\({}_{3}\)O\({}_{4}\)@MSN-PDEAEMA, with ca. 20 nm, compared with none coated nanoparticles. The PDEAEMA brushes showed as a layer surrounding the modified Fe\({}_{3}\)O\({}_{4}\)@MSNs. The XRD patterns of both magnetite nanoparticles (Fe\({}_{3}\)O\({}_{4}\)-NPs) and magnetite-modified silica nanoparticles (Fe\({}_{3}\)O\({}_{4}\)@MSNs) are demonstrated in Figure 2. The characteristic peaks in the spectrum of Fe\({}_{2}\)O\({}_{3}\)-NPs agreed well with the standard cubic phase of magnetite Fe\({}_{3}\)O\({}_{4}\). The observed peaks at 20 values of 30.2\({}^{\circ}\), 35.6\({}^{\circ}\), 43.2\({}^{\circ}\),53.9, 57.3\({}^{\circ}\) and 62.9\({}^{\circ}\), assigned to the lattice planes (220), (311), (400), (422), (511), and (440) (JCPDS 88-0866), respectively. These peaks also appeared in the Fe\({}_{3}\)O\({}_{4}\)@MSNs sample except the peaks at 20 values of 30.2\({}^{\circ}\)and 53.9\({}^{\circ}\), which might be attributed to the presence of an amorphous silica shell. The sharpness and the intensity of most Fe\({}_{3}\)O\({}_{4}\) peaks indicate that the crystalline nature of Fe\({}_{3}\)O\({}_{4}\) was not affected by a mesoporous silica shell. The nitrogen adsorption-desorption isotherms of Fe\({}_{3}\)O\({}_{4}\)-NPs and Fe\({}_{3}\)O\({}_{4}\)@MSNs are shown in Figure 3, and the related parameter results are listed in Table 1. It was observed that Fe\({}_{3}\)O\({}_{4}\)-NPs and Fe\({}_{3}\)O\({}_{4}\)@MSNs exhibited type-IV isotherm, which reveals the material's mesoporous characteristics. However, a variation in the hysteresis Loops was observed for both materials, as Fe\({}_{3}\)O\({}_{4}\)@MSNs showed a typical H1 hysteresis loop, indicating the presence of a narrow range of uniform mesopores where networking effects are minimal, whereas H3 hysteresis loop was obtained for Fe\({}_{3}\)O\({}_{4}\)-NPs indicates the existence of complex pore structure and networking effects are significant. A specific surface area of 568.3 m\({}^{2}\)/g and 61.8 m\({}^{2}\)/g were obtained for Fe\({}_{3}\)O\({}_{4}\)@MSNs and Fe\({}_{3}\)O\({}_{4}\)-NPs, respectively. Fe\({}_{3}\)O\({}_{4}\)@MSNs had well-defined narrow pores size ca.5 nm, whereas Fe\({}_{3}\)O\({}_{4}\)-NPs had a broader pore size distribution of ca 20-50 nm, which could be related to the agglomeration of the magnetite NPs. Figure 1: Microscopic images of the synthesized nanoparticles: (**a**) SEM image of Fe\({}_{3}\)O\({}_{4}\) nanoparticles; (**b**) SEM image of Fe\({}_{3}\)O\({}_{4}\)@MSNs; (**c**) TEM images of Fe\({}_{3}\)O\({}_{4}\)@MSNs; (**d**) SEM image of Fe\({}_{3}\)O\({}_{4}\)@MSN-PDMAEMA; (**e**) TEM images of Fe\({}_{3}\)O\({}_{4}\)@MSN-PDMAEMA. Figure 4 illustrates the FTIR spectra of as made Fe\({}_{3}\)O\({}_{4}\)@MSNs, Fe\({}_{3}\)O\({}_{4}\)@MSNs (without CTAB), Fe\({}_{3}\)O\({}_{4}\)@MSN-Br, and Fe\({}_{3}\)O\({}_{4}\)@MSN-PDEAEMA.