A novel molybdenum disulfide nanosheet loaded Titanium/Zirconium bimetal oxide affinity probe for efficient enrichment of phosphopeptides in A549 cells

In this paper, we developed a facile route for the preparation of a novel bimetal oxide affinity chromatography (MOAC) material. The TiO 2 /ZrO 2 @MoS 2 was constructed by the electrostatic interaction between titanium oxide/zirconia ( w : w , 10:1) and molybdenum disulfide nanosheet. The nanocomposite has the large specific surface area (186.30 m 2 ⋅g −1 ) and pore volume (0.37 cm 3 ⋅g −1 ). Compared with single-metal probes, the combination of bimetallic oxides probe (TiO 2 /ZrO 2 ) and hydrophilicity MoS 2 support offered multitudinous affinity sites for phosphopeptides capturing from tryptic digests of protein samples under 50% acetonitrile-1% trifluoroacetate conditions. Singnificant feasibility of the TiO 2 /ZrO 2 @MoS 2 nanomaterial for the enrichment of phosphopeptides under optimal conditions was proved via the bovine serum albumin (BSA) and the mixtures of β-casein. The phosphopeptide expression was identified using ultra-performance liquid chromatography (uHPLC) separation and-linear ion trap mass spectrometry (MS n ). With these affinity characters of TiO 2 /ZrO 2 @MoS 2 , it exhibited higher binding capacity (25 mg⋅g −1 ), better selectivity for phosphopeptides from β-casein/BSA (1:2000) tryptic digests, high sensitivity (1 fmol⋅µL −1 ) towards phosphopeptides from β-casein tryptic digests, and great reusability of 8 cycles test for capturing phosphopeptides. In addition, the TiO 2 /ZrO 2 @MoS 2 with high sensitivity and selectivity was successfully applied to enriching phosphopeptides from nonfat milk and human serum samples. More importantly, the TiO 2 /ZrO 2 @MoS 2 was further successfully applied to multi-phosphopeptides enrichment, 1779 serine, threonine and tyrosine phosphosites can be identified in A549 cell protein tryptic digest. Compared with commercial TiO 2 from enrichening 416 phosphopeptide from A549 cell lysates, the successful locating of 44 phosphosites were overlapped.