Preparation of Isorhamnetin Molecularly Imprinted Polymer Microspheres by Modified Precipitation Polymerization

Novel molecularly imprinted polymer (MIP) microspheres for isorhamnetin was prepared for the first time by modified precipitation polymerization using dimethylsulfoxide (DMSO) as co-solvent, divinylbenzene (DVB) as cross-linker, acetonitrile (ACN) as polymerization solvent, and 4-vinylpyridine (4-VP) as functional monomer, respectively. The optimal polymerization conditions were obtained by experimental investigation, which shown as follows: 1 mL DMSO as co-solvent, the concentration of co-monomers was 4% (W/V), and the ratio of 4-VP/DVB was 1:4 (molar ratio). The optimal MIP showed the uniform microspheres, and the diameter of MIP microspheres was mainly 2–3 um. Comparing the characters of the microspheres, the template molecule was only to form imprinted sites, and exert little influence on MIP microspheres’ properties. MIP microspheres with excellent adsorption capacity showed high selectivity to isorhamnetin, the concentrated adsorption capacity of MIP microspheres was 4.54 mg·g−1, achieving the equilibrium in 1 h. And the MIP microspheres adsorption mechanism were primarily chemical single layer adsorption. With quercetin (i.e. structure similar compound) as interfering substance, up to 3.14 of separation factor was obtained. Overall, the MIP microspheres are promising for the purification and separation of isorhamnetin.