Facile Preparation of Chitosan‐modified Mesoporous Titanium Dioxide Film on Fused‐silica Capillary for Selective Enrichment of Phosphopeptides

Abstract Chitosan (Cts), a positively charged natural polysaccharide, is employed to functionalize mesoporous titanium dioxide (mTiO₂) nanoparticles. The prepared Cts/mTiO₂ composite was used as a stationary phase to coat the inner wall of fused‐silica capillary and obtain uniform Cts/mTiO₂ film. The Cts/mTiO₂ film is applied to detect and enrich phosphopeptides in complex biological samples based on typical in‐tube solid phase microextraction (IT‐SPME) system. This unique Cts/mTiO₂ film exhibits excellent enrichment performances of high selectivity (β‐casein and BSA in molar ratio of 1 : 1000), sensitivity (detection limit as low as 40 fmol of β‐casein tryptic digest solution) and high adsorption capacity (124.5 μg mg⁻¹). Meanwhile, the Cts/mTiO₂ film possesses preferable reusability and can be reused more than 10 times. These results confirm that the Cts/mTiO₂ film possesses potential and satisfactory prospects in phosphoproteomics analysis.