The Preparation And Application Of Polydopamine-based Chiral Magnetic Nanoparticles For Enantioseparation

Chirality is one of the universal phenomena in nature.In general,the enantiomers of chiral compounds have similar physical and chemical properties,but exhibit different pharmacological or biological activities.Thus,the chiral separation of racemates to obtain optical pure enantiomers is of great significance in pharmaceutical and biochemical fields.A number of chiral separation methods proposed in the previous studies,are usually time-consuming,complicated and costly,especially when used for preparative purpose.Therefore,it is an urgent task to develop simple and effective methods for preparative enantioseparation.Recently,magnetic nanoparticles?MNPs?have gained more and more attention due to their superior properties,including unique magnetic properties,nanometer-scale effect,excellent biocompatibilities,ease of surface modification.Thus,the preparation and application of MNPs possessing chiral recognition abilities have been a focus.Thus,a novel chiral separation method was developed.The first research work are listed in the following aspects:with polydopamine?PDA?layer as a multifunctional platform,teicoplanin?TE?modified Fe₃O₄ NPs were prepared and the preparation method was facile,mild and enviromentally friendly.To improve the efficiency of chiral separation,several important factors,involving reaction time,solution pH and TE amounts added were varied and optimized.Various characterization techniques,such as TEM,elemental analysis,zeta potential etc,were applied to affirm the successful modification of TE to Fe₃O₄ NPs.The enantioselectivity of the resulting materials was validated by one-step or multi-step adsorption experiments for aromatic amino acid enantiomers.Parameters affecting enantioseparation were also investigated in detail.Experimental results proved that the new chiral materials had good performance in terms of preparative enantioseparation and could be reused for at least three times.Mercapto-?-cyclodextrin?SH-?-CD?modified Fe₃O₄ nanoparticles were successfully synthesized by employing the unique properties of PDA,polyethyleneimine?PEI?,and Au nanopaticles?Au NPs?.Among them,PEI was used as intermediate link layer and reducing agent,thus HAuCl₄ solution was reduced and the obtained Au NPs grafted on the surface of PEI modified Fe₃O₄ NPs;Then,mercapto-?-cyclodextrin was covalently bonded on the Au NPs.In order to affirm the successful modification of PEI,Au and CD to NPs,various techniques,such as SEM,TEM,elemental analysis,zeta potential etc,were applied to characterized the nano-composite materials.On one hand,Au-Fe₃O₄ nanocomposite have wide application in the separation and enrichment of trace samples;on the other hand,due to the existence of CD,many chiral recognition sites have been added to the materials,so they could also be applied to the separation of chiral compounds.