Functional Magnetic Nanoparticles for Highly Efficient Cholesterol Removal

In this study, magnetic nanoparticles functionalized with carboxylated β-cyclodextrin (CM-β-CD; referred to Fe₃ O₄ @CM-β-CD) were synthesized and used for the efficient removal of cholesterol from milk and egg yolk via host-guest interactions. The results of Fourier-transform infrared, X-ray photoelectron spectroscopy, and thermogravimetric analysis indicated that the CM-β-CD was successfully conjugated to the surface of Fe₃ O₄ , and the amount of CM-β-CD attached on Fe₃ O₄ @CM-β-CD was determined to be 9.164%. The X-ray diffraction and transmission electron microscopy data revealed that the process of CM-β-CD coating did not result in a phase change of the Fe₃ O₄ , and the Fe₃ O₄ @CM-β-CD nanoparticles were determined to have an average size of about 15 nm. The results of isotherm adsorption and kinetic properties indicated that CM-β-CD functionalization increased the cholesterol removal efficiency, and the characteristics of cholesterol adsorption on Fe₃ O₄ @CM-β-CD were fitted well with the Langmuir adsorption model and Lagergren pseudo-1st-order kinetic models. Furthermore, compared with the Fe₃ O₄ nanoparticles, the functionalized Fe₃ O₄ @CM-β-CD nanoparticles exhibited greater cholesterol removal efficiency, and saponification of the milk and egg yolk was found to be beneficial for the cholesterol removal; using the Fe₃ O₄ @CM-β-CD nanoparticles, 98.8% and 94.6% of the cholesterol was extracted in 1 h from saponified milk and egg yolk, respectively, and the Fe₃ O₄ @CM-β-CD nanoparticles still displayed efficient cholesterol removal after 6 reuses.