Preparation Of Magnetic Cellulose Tris-(4-methylbenzoate) Enantioselective Adsorption Materials

Many biologically and pharmacologically interesting compounds are chiral but their physiological properties are significantly different between enantiomers, hence to get optically pure enantiomer is of great importance for further study. Up to now, various approaches have been developed for chiral analyses and separation, including gas chromatography, capillary electrophoresis, high-performance liquid chromatography(HPLC), and solid phase extraction(SPE), et al. However, the available methods are still lag far behind the need. Nowadays, magnetic microspheres are of great interest because of their inherent properties such as large surface area, low cytotoxicity, and fast response under applied external magnetic field. Various chiral selectors have been immobilized on Fe3O4 microspheres, such as human serum albumin, bovine serum albumin, cyclodextrins, cellulose derivatives, and successfully applied into chiral separation. In this work, chrial selector, cellulose derivatives and Fe3O4 microspheres were prepared to be composite materials, and their chiral recognition abilities were investigated.(1) Cellulose tris-(4-methylbenzoate) modified magnetic microspheres for enantioselective absorption of racemic drugsCellulose tris-(4-methylbenzoate)(CTMB) coated magnetic microspheres was prepared and characterized by fourier transform-infrared spectra, thermogravimetric analysis, transmission electron microscopy. S-ibuprofen was taken as a model to investigate the adsorption capacities and recycling performance of Fe3O4@CTMB. It revealed the adsorption of S-ibuprofen on Fe3O4@CTMB obeyed the Langmuir adsorption isotherm and the maximum adsorption amount is 2.20 mg/g. The results of high performance liquid chromatography demonstrated that the as-prepared absorbents can selectively adsorbed S-ibuprofen of racemic ibuprofen and R-nimodipine of racemic nimodipine. It indicated that the as-prepared CTMB coated magnetic microspheres showed enantioselectivity and can be used for further chiral separations of different kinds of racemates.(2) Electrospinning of magnetic CTMB microparticles for enantioselective absorption of racemic drugElectrospinning was introduced to prepare magnetic enantioselective materials for the first time. Firstly, the electrospinning parameters were optimized. Then, Transmission electron microscopy, Scanning electron microscopy, Fourier transform infrared spectroscopy, Thermogravimetric analysis, X-ray diffractometer were used to characterize the cellulose tris-(4-methylbenzoate) magnetic materials, and the results showed that Fe3O4@cellulose tris-(4-methylbenzoate) were microparticles and with high magnetic sensitivity. The results of separation racemic ibuprofen indicated E-Fe3O4@cellulose tris-(4-methylbenzoate) could be novel materials for chiral separation. Most importantly, this work provided an efficient and economical procedure to prepare magnetic enantioselective materials with selectivity and reproducibility.(3) Electrospinning of magnetic cellulose diacetate microparticlesA cellulose derivative, cellulose diacetate(CDA) was choosen as chiral selector for first time. And electrospinning technique was also be used to prepare CDA and Fe3O4 composite materials. A series of characterization was carried out: The FT-IR spectra showed the successfully preparation of E-Fe3O4@CDA; the TEM showed the E-Fe3O4@CDA were microparticles with a uniform size; it can be separated completely in 30 s under an externally applied magnetic field indicates a good magnetic ability. Racemic ibuprofen was as model to study the chiral separation ability of E-Fe3O4@CDA. Above results demonstrated that electropinning is one universal method to prepare magnetic enantioselective materials.