Black Mesoporous TiO ₂ Nanoparticles for Enhancing Surface Assisted Laser Desorption and Ionization in Mass Spectrum Analysis

Abstract Surface assisted laser desorption ionization mass spectrometry (SALDI‐MS) is a powerful analytical technology for the high‐throughput detection of metabolites, drugs, and other bioactive molecules. The performance of SALDI‐MS in enhancing molecules desorption and ionization mainly depends on the surface properties of matrix utilized. Here, black titanium dioxide (B‐TiO ₂ ) nanoparticle is used for the first time as a novel matrix for enhancing laser desorption and ionization (LDI) and demonstrates significant advantages over white titanium dioxide (W‐TiO ₂ ). Further, the black mesoporous TiO ₂ coated Fe ₃ O ₄ magnetic nanoparticles (B‐mTiO ₂ MNPs) are designed and prepared, which possess a high molar absorption coefficient, strong magnetic response, higher specific surface area, and ample phosphorylation binding sites. The B‐mTiO ₂ MNPs exhibit a superior ionization efficiency, low background signal, and good reproducibility (RSD < 10%) in the analysis of compounds with different molecular weights and practical bio‐sample. Salt tolerance of B‐mTiO ₂ MNPs up to 10 m m PBS, meanwhile, B‐mTiO ₂ MNPs also provides excellent enrichment efficiency for phosphopeptides (the detection limit low to 5 × 10 ⁻¹⁰ M).