Facile synthesis of novel magnetic silica nanoparticles functionalized with layer-by-layer detonation nanodiamonds for secretome study

Abstract

Novel magnetic silica nanoparticles functionalized with layer-by-layer detonation nanodiamonds (dNDs) were prepared by coating single submicron-size magnetite particles with silica and subsequently modified with dNDs. The resulting layer-by-layer dND functionalized magnetic silica microspheres (Fe₃O₄@SiO₂@[dND]_n) exhibit a well-defined magnetite–core–silica–shell structure and possess a high content of magnetite, which endow them with high dispersibility and excellent magnetic responsibility. Meanwhile, dNDs are known for their high affinity and biocompatibility towards peptides or proteins. Thus, a novel convenient, fast and efficient pretreatment approach of low-abundance peptides or proteins was successfully established with Fe₃O₄@SiO₂@[dND]_n microspheres. The signal intensity of low-abundance peptides was improved by at least two to three orders of magnitude in mass spectrometry analysis. The novel microsphere also showed good tolerance to salt. Even with a high concentration of salt, peptides or proteins could be isolated effectively from samples. Therefore, the convenient and efficient enrichment process of this novel layer-by-layer dND-functionalized microsphere makes it a promising candidate for isolation of protein in a large volume of culture supernatant for secretome analysis. In the application of Fe₃O₄@SiO₂@[dND]_n in the secretome of hepatoma cells, 1473 proteins were identified and covered a broad range of pI and molecular weight, including 377 low molecular weight proteins.