Preparation Of Magnetic Core-Shell Polymer Microspheres And Their Application In Protein Screening

Nanoparticles are easy to agglomerate and toxic to organisms.Its application in the fields of biology and medicine is limited.Core-shell microspheres are prepared through structural tuning at the atomic and molecular levels.The excellent performance of core-shell microspheres comes from both nuclear and shell materials.It provides new ideas for exploring fields such as biomedicine,energy storage devices,and active catalysis.The P(St-MAA)and P(St-MAA-NH2)copolymer microspheres were prepared by dispersion polymerization method.The Fe3O4 nanoparticles on the surface of microspheres were generated by chemical precipitation.The research investigated the effects of different factors on the functional groups,particle size,and dispersion coefficient of copolymer microspheres.The effects of particle size and functional groups,concentration of iron salt(FeSO4·7H2O)and concentration of dispersant(PVP)on the morphology,functional groups,and magnetic properties of core-shell microspheres were studied.The magnetic copolymer microspheres P(St-MAA)@Fe3O4 and P(St-MAA-NH2)@Fe3O4 were applied for magnetic separation detection.Bovine serum protein(BSA),bovine hemoglobin(BHB),and BSA-BHB solution were used as the model environments for the protein separation research.The adsorption,separation and selective properties of the core-shell microspheres modified with different functional groups for the proteins were studied.The main research content includes the following aspects:(1)Styrene(St),Methacrylic acid(MAA)and acrylamide(AM)were the monomers.Polyvinylpyrrolidone(PVP)was the dispersant.Methanol/ethanol/water(MeOH/EtOH/H2O)was the dispersion medium.Azodiisobutyronitrile/benzoyl peroxide(ABIN/BPO)was the initiator.The P(St-MAA)copolymer microspheres with different particle sizes were prepared by dispersion polymerization method.The process technology for controlling and adjusting the particle size of microspheres had been mainly studied.The results of independent research on each variable indicate that the dosage of monomers and initiators has a significant impact on the particle size of microspheres.The particle size of microspheres ranges from 142 nm to 325 nm with an increase in monomer dosage.The average particle size of microspheres increases from 167 nm to 307 nm with the increase of initiator dosage;The polarity of monomers can cause small changes in the particle size of microspheres.The particle size of P(St-MAA-NH2)microspheres ranges from 142 nm to 183 nm.Fine adjustment of microsphere particle size can be achieved by adjusting the stirring speed and dispersion medium ratio.The half-life of the initiator,shear force,and polarity of the dispersion medium have a significant impact on the monodispersity of the microspheres.The monodispersibility of the series of microspheres prepared in this article are good.(2)The P(St-MAA)@Fe3O4 core-shell microspheres was composed of the P(St-MAA)copolymer microspheres as the core.The core-shell structure was obtained by depositing iron trioxide on the surface of the microspheres.The effects of factors such as the particle size of the microspheres,the concentration of FeSO4·7H2O,PVP content and iron salt ratio on the size and particle size distribution of Nano-Fe3O4 particles loaded on the surface of microspheres were studied.The P(St-MAA)@Fe3O4 microspheres with different morphologies,sizes and magnetic properties were prepared.The P(St-MAA)@Fe3O4 microspheres was modified by amine groups.The research results indicate that the process of generating Nano-Fe3O4 on the surface of the P(St-MAA)microspheres using FeSO4·7H2O as an iron source is simple,the reaction conditions are mild,the coverage and magnetic properties of core-shell microspheres are easily controlled.The average particle size of the Nano-Fe3O4 on the surface of the P(St-MAA)@Fe3O4 microspheres decreases from 44 nm to 33 nm as the PVP concentration increased.The maximum saturation magnetization of the microspheres increases from 18.0 emu·g-1 to 23.6 emu·g-1.The particle size of the P(St-MAA)@Fe3O4 microspheres increases from 160 nm to 300 nm as the particle size of the copolymer microspheres increased.The degree of the Nano-Fe3O4 coating on the surface of the microspheres has been improved.The settling speed of microspheres in the aqueous phase is accelerated.The average particle size of Nano-Fe3O4 on the surface of the microspheres increases from 13 nm to 30 nm as the amount of FeSO4·7H2O increased.The maximum saturation magnetization of the microspheres increases from 4.1 emu·g-1 to 18.0 emu·g-1.The settling speed of microspheres decreases from 141 cm·d-1 to 99 cm·d-1 after adding a small amount of surfactant Tween 80 to the microsphere dispersion.The particle size of the microspheres increases from 150 nm to 158 nm after amine modification.The Nano-Fe3O4 particle size on the surface of microspheres decreases from 25 nm to 17 nm.The maximum saturation magnetization and the surface coating degree of the Nano-Fe3O4 don’t change significantly.(3)The adsorption and separation performance of the P(St-MAA)microspheres and the P(St-MAA-NH2)microspheres for the above-mentioned proteins had been studied.The research results indicate that the adsorption of proteins by both microspheres conform to the Pseudo-second-model.The groups of the microspheres plays a decisive role in adsorbing proteins through Zeta potential analysis of the microspheres.Both the P(St-MAA)microspheres and the P(St-MAA-NH2)microspheres exhibit better adsorption and separation performance for the proteins when the pH value of the system is near the isoelectric point of the proteins(4.7 and 6.0).The maximum difference in adsorption capacity measured by magnetic separation and centrifugal separation of the mixed solution of microspheres and proteins shall not exceed 1%.The isothermal adsorption models of the P(St-MAA)microspheres and the P(St-MAA-NH2)microspheres on proteins both conform to the Langmuir monolayer adsorption model.The maximum adsorption capacity of the P(St-MAA)@Fe3O4 microspheres for BSA decreases from 240 mg·g-1 to 85 mg·g-1 after amine modified.The maximum adsorption capacity of the microspheres for BHB decreases from 278 mg·g-1 to 37 mg·g-1.(4)The BSA-BHB mixed solution was used to simulate mixed protein systems.The protein adsorption properties of the microspheres were tested by ultraviolet absorption method and Coomassie Brilliant Blue method.The results show that when the pH value of the system is 6.0,the P(St-MAA)@Fe3O4 microspheres shows better adsorption capacity for BSA and BHB.The P(St-MAA)@Fe3O4 microspheres has a stronger adsorption preference for BSA.When the pH value of the system is 4.7,The P(St-MAA-NH2)@Fe3O4 microspheres exhibits a higher adsorption selectivity for BSA.When the pH value of the system is 6.0,The P(St-MAA-NH2)@Fe3O4 microspheres exhibits a better adsorption selectivity for BHB.