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.　©　The　Royal　Society　of　Chemistry.