Grafting l-valine on polyamidoamine dendrimer-modified magnetic microspheres for enantioselective adsorption of dansyl amino acids

Chiral selector-functionalized magnetic microspheres have significantly potential in the recognition and separation of chiral compounds. In this work, novel chiral selector-functionalized magnetic microspheres ( l -Val@G3.0-PMMPs) were achieved by grafting l -valine ( l -Val) on polyamidoamine (PAMAM) dendrimer-modified magnetic microspheres, which were confirmed by various characterization methods. The synthesized l -Val@G3.0-PMMPs had clearly three-layer structure, with a mean diameter of 590   nm and exhibited good dispersion and strong magnetic response. The immobilization amounts of l -Val determined by high performance liquid chromatography with mass spectrometry (HPLC–MS) increased with increasing PAMAM generation, and the results indicated that the PAMAM dendrimer bonded onto the surface of magnetic microspheres obviously improved the immobilization amounts of l -Val. The synthesized l -Val@G3.0-PMMPs as chiral magnetic selectors were used to conduct the enantioselective adsorption of dansyl amino acids. The chiral discrimination ability of the l -Val@G3.0-PMMPs was investigated through determining the enantiomeric excess of the l -Val@G3.0-PMMPs with capillary electrophoresis. Under the optimal amount of l -Val@G3.0-PMMPs and interaction times, the enantiomeric excess of dansyl amino acids adsorbed onto the surface of the l -Val@G3.0-PMMPs was calculated to be 20.1%. The results of enantiomeric excess indicated that the l -Val@G3.0-PMMPs selectively interacted with dansyl amino acid and exhibited excellent chiral discrimination ability. In the future research, the novel l -Val@G3.0-PMMPs are possible to be an efficient and suitable chiral selector for the enantioseparation of chiral compounds.