TEM analysis in high magnification was performed to evaluate the uncoated SPION, the PMMA-coated SPIONs and the dispersion of the PEG bis(amine)-grafted nanoparticles. This test was principally aimed to observe the morphology of the grafted nanoparticles. The TEM image in Fig. 1C illustrates a core-shell structure of the grafted SPIONs. The mean diameter of grafted particles and standard deviation using average of 76 particles are 13.6nm (±2.8nm) and naked SPIONs with a roughly spherical shape using average of about 32 particles are 8.5 nm(±2.6nm). Dynamic light scattering (DLS) measurement of the grafted particles diameter in deionized water are considerably larger,as 189
On closer inspection, the TEM results reveal that the PMMA/SPION nanoparticles are effectively embedded in the polymer matrix. The SPION core are surrounded by a layer of materials with a lower contrast, corresponding to the PMMA grafted with PEG bis(amine). This is confirmed by the FTIR technique.