Synthesis and characterization of amino-functionalized single magnetic core–silica shell composites

The thermal decomposition approach, reverse micro-emulsion system and surface modification technique had been successfully used to synthesis single magnetic core Fe3O4@Organic Layer@SiO2–NH2 complex microspheres. The magnetization of the magnetic microspheres core could be easily tuned between 28 and 56 emu/g by adjusting the amount of 2-mercaptobarbituric acid. It was found that the Organic Layer to some extent had a protective effect on avoiding Fe3O4 being oxidized into Fe2O3. Each Fe3O4@Organic Layer microsphere could be coated uniformly by about 30 nm of silica shell. The average diameter of the Fe3O4@Organic Layer@SiO2 composites was about 538 nm. The saturation magnetization of the Fe3O4@Organic Layer@SiO2 complex microspheres was 12.5% less than magnetic microspheres cores. The Fe3O4@Organic Layer@SiO2–NH2 composites possessed a huge application potentiality in specificity enriching and separating biological samples.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► We prepared single magnetic core Fe3O4@Organic Layer@SiO2–NH2 microspheres. ► The Organic Layer had a protective effect on avoiding Fe3O4 being oxidized into Fe2O3. ► The magnetization of Fe3O4@Organic Layer could be tuned between 28 and 56 emu/g. ► All Fe3O4@Organic Layer microspheres were coated by about 30 nm of silica shell.