The Synthesis Of Magnetic Mesoporous Carbons And Preliminary Study On The Adsorption And Release Properties Of Protein Drugs

Magnetic ordered mesoporous carbons （OMCs）, due to their high specific surface area,concentrated pore size distribution, large pore volume and good biocompatibility, haveattracted great technological interest for the application in drug delivery, adsorption andseparation, catalysis and so on. Therefore, the research on the drug absorption and releasebehavior on OMCs has theoretical significance and practical application values. However,during the practical applications, there are still some questions remaining unresolved,（1）the pore size of OMCs is not large enough for macromolecular drug loading,（2） the poortargeting effects limited the targeted application.The present paper presented the systematic synthesis of magnetic OMCs. A series ofFe/OMCs and FeNi/OMCs were synthesized. The magnetic dual-mesoporous carbonspheres with high specific surface area, large pore size and large pore volume were firstsynthesized by a novel one-step method, which simplified synthetic method and improvedthe magnetic targeting. Modification of the magnetic dual-mesoporous carbon spheres werecarried out. The adsorption and release behavior of bovine serum albumin （BSA） andlysozyme on the magnetic dual-mesoporous carbon spheres before and after modificationwere investigated. The following four parts were involved:（1） The synthesis of Fe/OMCs: A series of Fe/OMCs with high specific surface area andlarge pore volumes were synthesized via a simple one-pot method by using F127as astructure-directing agent, Fe（NO₃）₃·9H₂O as magnetic precursor, resorcinol-formaldehyde （RF） as carbon precursor. The resultant materials were characterized by N2sorption, X-raydiffraction （XRD） and physical property measurements system （PPMS）. The experimentalresults showed that with the increasing usage of magnetic precursor, the ordering, thespecific surface area and pore volume of the materials decreased, but the saturationmagnetization increased. The mesoporous carbon exhibited the best ordering, highestspecific surface area and largest pore volume at the molar ratio of Fe（NO₃）₃·9H₂O toresorcinol （Fe/R）0.025:1. But the saturation magnetization intensity became weaker underthe present condition.（2） The synthesis of FeNi/OMCs: Magnetic FeNi/OMCs were synthesized by usingF127as a structure-directing agent, Fe（NO₃）₃·9H₂O and Ni（NO₃）₂·6H₂O as magneticprecursor, RF as carbon precursor. Characterizations were carried out by N2sorption, XRD,transmission electron microscope （TEM）, and PPMS The results showed that the ordering,the specific surface area and pore volume decreased with the increasing content of metalprocursor. But the saturation magnetization showed an increasing tendency. Highly orderedmagnetic FeNi/OMCs with high specific surface area, large pore volumes as well as strongmagnetisms were obtained when the usage of Fe（NO₃）₃·9H₂O and Ni（NO₃）₂·6H₂O were0.3mmol and resorcinol was1.25g.（3） The synthesis and modification of magnetic dual-mesoporous carbon spheres:Magnetic dual-mesoporous carbon spheres were first synthesized by a simple and novelroute, in which Fe（NO₃）₃·9H₂O was used as magnetic precursor, furfuryl alcohol as carbonprecursor, SiO₂nanoparticles（10nm and20nm） as porogen. Characterizations were carriedout by N2sorption, XRD, TEM, SEM and PPMS. The experimental results showed that thesynthesized materials had pore size distributions centered at8nm and23nm, whichindicated a dual-mesoporous structure. Carbon spheres were detected by SEM. And thesaturation magnetization of samples increased with the increasing amount ofFe（NO₃）₃·9H₂O. The specific surface area and pore volume decreased with the decreasingusage of SiO₂nanoparticals. The magnetic dual-mesoporous carbon spheres were modifiedand characterized by infrared spectra. The typical adsorption peak showed that amino functional groups were grafted on the materials.（4） The adsorption and realease of BSA and Lysozyme on magnetic dual-mesoporouscarbon spheres: BSA and Lysozyme were selected as the release protein model. Theadsorption and release behavior of BSA and lysozyme on magnetic dual-mesoporouscarbon spheres before and after modification had been investigated. The results showed thatthe magnetic dual-mesoporous carbon spheres exhibited excellent adsorption and releaseperformance. For the unmodified magnetic dual-mesoporous carbon spheres, the adsorptionamount reached a maximum at pH=10, not at the isoelectric point （pI）. The reason was thatthe isoelectric point of lysozyme shifted from pI for the free lysozyme to lower pH valuesfor the adsorbed lysozyme. Whereas, the modified materials had a larger adsorption amountof lysozyme （730mg/g）. The release rate of lysozyme on the unmodified carbon was45%,slightly larger than that on the modified carbon （43%）. This might be due to functionalgroup grafted on the magnetic dual-mesoporous carbon spheres make the adsorbedlysozyme more consolidate.The adsorption amount of bovine serum albumin on C-1, C-0.5, C-0.2were the largestat pH=5which reached588、528、449mg/g, respectively. The modified carbons had slightlylarger amount of adsorption of BSA （630mg/g）. The release rate of BSA was relativelylower on the modified carbon （47%） than that on the unmodified carbon （51%）. Thepossible reasons were that the H-band consolidated integration between BSA and the aminogroups on the modified magnetic dual-mesoporous carbon spheres. The pore structure ofthe carbon spheres was twisted by the grafted amino group, thus decreasing the release rateof BSA.The release process of lysozyme and bovine serum albumin on magneticdual-mesoporous carbons spheres were fitted by Korsmeyer–Peppas equation （f ktn）.The results showed that with the increase of specific surface area, the release constant kincreased but the release index n decreased. The related parameters were attend.