▎ 摘　　要

A novel multifunctional composite comprising mesocrystalline SnO, nanorods (NRs) vertically aligned on reduced graphene oxide (rGO) sheets was synthesized and developed for sequential capture of endogenous peptides and phosphopeptides. With the hydrophobicity of rGO and high affinity of SnO2 nanorods, sequential enrichment of endogenous peptides and phosphopeptides could be easily achieved through a modulation of elution buffer. With this multifunctional nanomaterial, 36 peptides were observed from diluted bovine serum albumin (BSA) tryptic digest and 4 phosphopeptides could be selectively captured from beta-casein digest. The detection limit of tryptic digest of beta-casein was low to 4 X 10(-10) M, and the selectivity was up to 1:500 (molar ratio of beta-casein and BSA digest). The effectiveness and robustness of rGO-SnO2 NRs in a complex biological system was also confirmed by using human serum as a real sample. Our work is promising for small peptide enrichment and identification especially in complicated biological sample preparation, which also opens a new perspective in the design of multifunctional affinity probes for proteome or peptidome.