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

It is necessary to effectively absorb trace phosphopeptides/proteins from complex phosphopeptide-containing samples for mass spectrometry (MS)-based phosphoproteomics. Here, Bi3+/Fe3+/Zr4+ co-doped TiO2 (TiO2/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 TiO2 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 TiO2/Bi/Fe/Zr nanocomposite has a lower detection limit (4 x 10(-10) M) and higher selectivity at a low weight ratio of phosphopeptides/non-phosphopeptides (1:1000). Additionally, a total of 676 phosphorylation sites were identified from the HeLa cell lysate after enrichment by the TiO2/Bi/Fe/Zr nanocomposite. In brief, the TiO2/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.