Preparation And Application Of Magnetic Mesoporous Silica Microspheres

Magnetic mesoporous nano-composite material as a new functional materialsare widely used in drug targeting, bioaccumulation and separation, magnetichyperthermia, enzyme immobilization, and other fields. Preparation of magneticmesoporous silica microspheres is undoubtedly one of the hotspots in the field,which not only has the unique biological affinity and low toxicity, but also bothgood magnetic response. Coupled with the huge specific surface area, insubsequent applications, it can effectively increase the chance of contacting withthe reactant microspheres to improve the efficiency of the actual application.Contents of this paper are mainly Mesoporous Silica Microspheres (MSMs),preparation of Magnetic Mesoporous Silica Microspheres (M-MSMs) andadsorption properties of proteins and immobilization aspects of the application:1. Select TEOS as the silicon source, cetyl trimethyl ammonium bromide(CTAB) as a template, ethanol as a co-solvent, the improved Stober method, andfinally the use of ultrasound-assisted extraction removing the template manner,in a simple, green synthesis process for preparing mesoporous silica microsphereswith good monodisperse core-shell structure (MSMs). Transmission electronmicroscopy, scanning electron microscopy and X-ray diffraction and other meansof characterization, the results show: MSMs monodisperse good, not only hasordered mesoporous structure, and the shape of a sphere showing a core-shell;infrared and thermal gravimetric analysis. The results showed that the templatehas been largely removed. The effects of synthesis conditions on the morphologyof microspheres and monodisperse, the results showed that: the content of thetemplate only affects the MSMs microsphere particle size and shell thickness andhas no effect on the pore size, along with the amount of CTAB increases, the sizeof microspheres gradually decreases; decreased with concentrated ammoniasilicon source and amount of the increase or decrease alcohol-water volume ratio,the particle size of the microspheres MSMs first increases, graduallymonodisperse reduction; temperature decreases, longer reaction time increases the particle size of the microspheres, monodisperse getting better.2. Using the two-step method, first to a method for the synthesis of SiO2sol,and then to carbon-coated iron (Fe/C) for the magnetic core, PVP as dispersant,ethanol as the dispersion medium, magnetic successfully prepared mesoporoussilica microspheres (M-MSMs). Characterization results from TEM and SEMimages, mesoporous silica microspheres successfully embedded inside the nuclear.Magnetic microspheres size is about500nm, showing core-shell structure, there isobviously a shell structure, pore-free. However, significant changes in themesoporous showing disorder, which may be due to the magnetic core as a resultof the intervention. The microspheres were studied after glutaraldehyde activationof the adsorption properties of bovine serum albumin (BSA), the results showedthat when the initial concentration of BSA was1.2mg·mL-1, its adsorptioncapacity of116mg·g-1; optimum adsorption pH4.8, optimum adsorption time was1.0h, optimum adsorption temperature is35℃, Further studies have shown thatthe adsorption capacity of BSA microspheres with increasing ionic strength ofNaCl decreased.3. Magnetic mesoporous silica microspheres (M-MSMs) were used toimmobilize for horseradish peroxidase (HRP), using glutaraldehyde cross-linkedadsorption immobilized successfully horseradish peroxidase (MagneticMesoporous Silica Microspheres Immobilized Horseradish peroxidase,M-MSMs-HRP). HRP immobilization conditions discussed, such as: reactiontime, to affect the amount of enzyme, pH and other properties of the immobilizedenzyme activity, the results showed that: the optimal amount of enzyme to0.08mg·mL-1, the best immobilization time was4.0h, the optimum pH is7.5, therelative activity reached a maximum. Freedom horseradish peroxidase andMichaelis constant immobilized horseradish peroxidase were1.5225mM and0.7251mM, M-MSMs-HRP and free HRP immobilized after comparison showsthat after the heat, acidity, has significantly improved storage stability. TheM-MSMs-HRP for the degradation of phenol substances, the results showed that:after the carrier M-MSMs immobilized HRP was significantly higher than for phenol removal of free HRP, strong magnetic response at six times after repeateduse the relative activity of immobilized enzyme was35.71%for phenol removalrate was37.28%, showing that the magnetic mesoporous silica microspheresimmobilized horseradish peroxidase in the degradation of low concentrations ofphenol solution with a certain prospect.