Selective adsorption of hemoglobin with polyoxometalate-derived hybrid by solidification of super-lacunary phosphotungstate polyoxoanions

A novel polyoxometalate (POM)-based hybrid P 8 W 48 -APTS is prepared by the solidification of super-lacunary P 8 W 48 O 184 40- polyoxoanions with APTS in an acidic medium. The oxygen (O − ) atoms in P 8 W 48 O 184 40- are bound to silicon atoms in APTS by the formation of Si-O linkage through dehydration condensation . The solidification is confirmed by characterizations with XRD, FT-IR, TGA , SEM and EDXS . Selective isolation of proteins of interest, hemoglobin (Hb) in this case, from complex sample matrices is achieved by using P 8 W 48 -APTS hybrid as adsorbent under controlled conditions. 5.0   mg of P 8 W 48 -APTS hybrid results in an adsorption efficiency of 93% for 100   mg   L −1 hemoglobin in 1.0   mL sample solution at pH 7. The adsorption behavior of Hb onto P 8 W 48 -APTS hybrid fits Langmuir adsorption model, corresponding to an adsorption capacity of 355.0   mg   g −1 . The retained Hb could be readily recovered with either a SDS solution (0.1   mol   L −1 ) or a Na 3 PO 4 (0.1   mol   L −1 ) solution as stripping reagent, providing recoveries of 94.6% or 83.9%, respectively. The biological activity of Hb remains 96.7% after an adsorption/desorption process (with elution by SDS), which illustrates virtually no change on the conformation of hemoglobin. The P 8 W 48 -APTS hybrid has been applied for the selective adsorption of Hb from human whole blood, and the results are demonstrated by SDS-PAGE assay.