Synthesis of a sorbent via molecular imprinting onto magnetic-monodisperse-porous silica microspheres and its usage in selective biomolecule isolation

In the scope of the thesis, monodisperse-porous silica microspheres used as support material for selective sorbent synthesis for biomolecule isolation by molecular imprinting were synthesized by multi-step hydrolysis / condensation method. For the magnetic form, iron oxide nanoparticles were immobilized in silica microspheres. Subsequently, folic acid (FA) was imprinted molecularly on the microspheres in both forms. After molecular imprinting, the sorbent was washed away and the imprinted target molecule was removed from the structure and the selective adsorption behavior of the obtained sorbent to target molecule (FA) was studied in a batch and continuous system. Equilibrium adsorption capacity values (Q) were found and imprinting factors (IF) were determined by scanning sorbent concentration and target molecule concentration with molecularly imprinted microspheres (MMIP and MIP) and unimprinted microspheres (MNIP and NIP) in magnetic and non-magnetic form in the batch system. At optimal sorbent concentration, the Q values for MIP and NIP were 30.88 mg FA/g microspheres and 7.57mg FA/g microspheres, respectively, and the IF value was 4.08. For MMIP and MNIP, the Q values were determined as 48.19mg FA/g microspheres and 17.57mg FA/g microspheres, so the IF value was 2.74. The selectivity test showed that folic acid had a higher IF value in the batch adsorption system than molecules of similar structure. It has been shown that MIP and MMIP sorbents can be used in a reusable form in a batch system. The size distribution and surface morphologies of the microspheres were determined by scanning electron microscopy (SEM) images and the presence of the polymeric structure on the microspheres after molecular imprinting was determined by images obtained from the transmission electron microscope (TEM). Pore size and specific surface areas were determined by nitrogen adsorption / desorption method (BET) and the magnetic behaviors of microspheres in magnetic form were determined by vibrating sample magnetometer (VSM). When the adsorption behavior of the continuous system was examined, it was observed that the microcolumns containing MIP and NIP reached saturation in 6 and 3 minutes, respectively. Reusability testing for the continuous system revealed that the microcolumn can be reused for 4 cycles. These results demonstrate that both the batch and the continuous system are suitable for folic acid isolation and FA assay is successful with molecular imprinting. Keywords: Monodisperse-porous silica, magnetic microspheres, molecular imprinting, sorbent, adsorption, folic acid.