Preparation And Characterization Of Magnetic Nanoparticles And Composite Molecular Imprinted Polymers

Molecular imprinting technology completes the specificity of enrichment andseparation of target molecules, and has been widely applied in trace detection ofharmful substances and active ingredient extraction. This paper combined theproperties of photonic crystal and magnetic ferroferric oxide with the basis ofmolecular imprinted technology respectively, and the main content of this paper is asfollows:⑴The Fe3O4nanoparticles were synthesized by alkaline co-precipitationmethod with the diameter of10~20nm, and modified with PEG, OA or TEOS. Byinvestigating the effect of different molecular weight and concentration of PEG on thestability of the magnetic liquids, PEG-4000with15%(wt%) was the most stableliquid. According to the dosage and dropping speed of OA, adding3~10‰(V%) ofOA dropwise could obtain good monodispersity Fe3O4particles. Changing theamount of TEOS and found SiO2-Fe3O4magnetic would reduce by increasing TEOS.Characterizations of the samples were carried out by FT-IR, XRD, VSM and TEM,and the results showed that PEG-Fe3O4had outstanding magnetic properties andOA-Fe3O4had optimal monodispersity, moreover, the stability of SiO2-Fe3O4was thebest. we can choose a proper way of modification on the basis of materialperformance in subsequent applications.⑵RES molecular imprinted photonic hydrogel (MIPH) was synthesized usingphotonic crystal as the template, RES as the template molecule, MAA as thefunctional monomer, EGDMA as the cross-linker and AIBN as the initiator. Themorphology characterization of photonic crystal and MIPH was studied by scanningelectron microscope (SEM). The results showed that photonic crystal was formed byordered silica developing into six party accumulation structures, and the3-Dinterconnected macroporous structure was shaped in MIPH. The Bragg diffraction ofphotonic crystal and MIPH was investigated by ultraviolet spectrophotometer, and theMIPH after eluting RES was responsive to RES within3minutes, the Bragg diffraction peak shifted from440to463nm with the concentration of RES increasingfrom10-9to10-5mol/L. However nonmolecular imprinted photonic hydrogel (NIPH)had little response to RES. Due to high sensitivity and specificity, quick response andeasy operation, the application of MIPH in food detection area was promising.⑶The Fe3O4nanoparticles was coated by SiO2layer with the surfacemodification of MPS to form end vinyl bonds that provided reaction sites to inducethe occurrence of imprinted polymerization on the surface of Fe3O4@SiO2@MPS. Anovel water-compatible magnetic molecularly imprinted polymers (M-MIPs), forselectively adsorbing and separating vanillin from aqueous solution, was prepared inmethanol-water system. Characterizations of M-MIPs were carried out by X-raydiffraction (XRD), Fourier transform spectrometer (FT-IR), Thermogravimetricanalyzer (TGA), Vibrating specimen magnetometer (VSM) and Scanning electronmicroscopy (SEM). Results indicated that a core-shell structure of M-MIPs wasobtained by coating a layer of silica and MIPs on the surface of Fe3O4. The obtainedM-MIPs possessed a loose and porous structure, and it could be separated fromsolution quickly with an external magnetic field. The adsorption experiments showedthat the binding capacity of M-MIPs was much higher than that of superparamagneticnon-molecularly imprinted polymers (M-NIPs). Meanwhile, the adsorption couldreach equilibrium within100min, with apparent maximum adsorption quantity(Qmax) and dissociation constant (Kd) were64.12μmol/g and58.82μmol/L,respectively, indicating the M-MIPs possessed an high adsorption capacity andaffinity for vanillin. Additionally, the Scatchard analysis revealed that homogeneousbinding sites were formed in the M-MIPs.