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

Abstract

A novel polyoxometalate (POM)-based hybrid P8W48-APTS is prepared by the solidification of super-lacunary P8W48O18440- polyoxoanions with APTS in an acidic medium. The oxygen (O−) atoms in P8W48O18440- 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 P8W48-APTS hybrid as adsorbent under controlled conditions. 5.0mg of P8W48-APTS hybrid results in an adsorption efficiency of 93% for 100mgL−1 hemoglobin in 1.0mL sample solution at pH 7. The adsorption behavior of Hb onto P8W48-APTS hybrid fits Langmuir adsorption model, corresponding to an adsorption capacity of 355.0mgg−1. The retained Hb could be readily recovered with either a SDS solution (0.1molL−1) or a Na3PO4 (0.1molL−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 P8W48-APTS hybrid has been applied for the selective adsorption of Hb from human whole blood, and the results are demonstrated by SDS-PAGE assay.