Novel Ti4+-chelated magnetic nanostructured affinity microspheres containing N-methylene phosphonic chitosan for highly selective enrichment and rapid separation of phosphopeptides

Magnetic composite particles immobilized with metal affinity ions show high potential in the phosphoproteome mass-spectrometric (MS) analysis. However, the preparation of this kind of material still suffers from a complicated synthesis procedure and high cost. In this work, the magnetic nanostructured composite microspheres (MPCS) incorporated into N-methylene phosphonic chitosan were first fabricated via a facile one-pot synthesis strategy and titanium ions (Ti4+) were subsequently immobilized onto the MPCS to form MPCS-Ti4+ affinity particles. The uniform spherical MPCS-Ti4+ affinity particles with abundant chelated titanium ions have a particle size distribution between 126 nm and 280 nm, and they display superparamagnetism with a saturation magnetization (Ms) value of 44.75 emu g−1. The amount of the immobilized Ti4+ ions was estimated to be 11.6 wt% by EDS. The MPCS-Ti4+ exhibited excellent dispersibility in aqueous solution, high affinity selectivity for phosphopeptides and quite fast magnetic separation within 10 s as well as good reusability. Thus, the prepared magnetic MPCS-Ti4+ nanostructured affinity materials will possess great potential in phosphoproteome research.