Phosphate-functionalized magnetic microspheres for immobilization of Zr(4+) ions for selective enrichment of the...

In this work, we developed phosphate functionalized magnetic Fe(3)O(4)@C microspheres to immobilize Zr(4+) ions for selective extraction and concentration of phosphopeptides for mass spectrometry analysis. Firstly, we synthesized Fe(3)O(4)@C magnetic microspheres as our previous work reported. Then, the microspheres were functionalized with phosphate groups through a simple hydrolysis reaction using 3-(trihydroxysilyl)propyl methylphosphate. And the Zr(4+) ions were immobilized on phosphate-functionalized magnetic microspheres by using phosphate chelator. Finally, we successfully employed Zr(4+)-phosphate functionalized magnetic microspheres to selectively isolate the phosphopeptides from tryptic digests of standard protein and real samples including rat brain. All the experimental results demonstrate the enrichment efficiency and selectivity of the method we reported here.