Aluminium glycinate functionalized silica nanoparticles for highly specific separation of phosphoproteins

Selective separation of intact phosphoproteins from complex biological samples is essential for ongoing, top-down phosphoproteomics but challenges still remain. Herein, aluminium glycinate functionalized silica nanoparticles (denoted as AGNP) were synthesized by a facile approach and applied for the specific capture of phosphoproteins. The selectivity and binding capacity of AGNP were evaluated using caseins (α-casein and β-casein) as phosphoproteins and bovine haemoglobin, bovine serum albumin, horseradish peroxidase, myoglobin and lysozyme as nonphosphoproteins. The results indicated that AGNP showed high binding capacity and selectivity for phosphoproteins (α-casein 1190 mg g−1 and β-casein 1060 mg g−1). In addition, AGNP was used to selectively capture and enrich phosphoproteins from protein mixtures and drinking milk samples. The good results demonstrate the potential of AGNP in phosphoproteomics analysis.