Preparation of TiO2/Bi/Fe/Zr nanocomposite for the highly selective enrichment of phosphopeptides

Abstract It is necessary to effectively absorb trace phosphopeptides/proteins from complex phosphopeptide-containing samples for mass spectrometry (MS)-based phosphoproteomics. Here, Bi 3+ /Fe 3+ /Zr 4+ co-doped TiO 2 (TiO 2 /Bi/Fe/Zr) nanocomposite with a high surface-to-volume ratio was synthesized by sol-gel method for selective enrichment of phosphopeptides. The enrichment ability of this modified TiO 2 toward phosphopeptides was evaluated by using standard phosphoproteins and HeLa cell lysate. The results demonstrated that, compared with commercial titanium dioxide for phosphopeptides enrichment, this proposed TiO 2 /Bi/Fe/Zr nanocomposite has a lower detection limit (4 × 10 −10 M) and higher selectivity at a low weight ratio of phosphopeptides/nonphosphopeptides (1:1000). Additionally, a total of 676 phosphorylation sites were identified from the HeLa cell lysate after enrichment by the TiO 2 /Bi/Fe/Zr nanocomposite. In brief, the TiO 2 /Bi/Fe/Zr nanocomposite exhibits better performance on the selectively absorption of phosphopeptides from either simple or complex biological samples, indicating the great potential application in phosphoproteomics study.