A novel organic–inorganic hybrid polyoxometalate for the selective adsorption/isolation of β-lactoglobulin

Abstract

A novel polyoxometalate (POM)-based organic–inorganic hybrid [C₃₃H₂₄O₄]H₃PMo₁₂O₄₀, namely, TPPA–PMo₁₂, is prepared via a one-pot hydrothermal reaction between a Keggin POM (H₃PMo₁₂O₄₀, PMo₁₂) and a star-like N-donor ligand (tri(4-pyridylphenyl)amine, TPPA). The hybrid polyoxometalate is confirmed by characterization with XRD, FT-IR, TGA, SEM and EDS. It exhibits excellent adsorption performance towards β-lactoglobulin, and thus a solid-phase extraction procedure was established for the efficient and selective isolation of β-lactoglobulin from complex sample matrices. At pH 5.0, an adsorption efficiency of 99.2% is achieved for processing 100 μg mL⁻¹ β-lactoglobulin in 1.0 mL aqueous solution with 0.5 mg TPPA–PMo₁₂ as an adsorbent. The adsorption behavior of β-lactoglobulin fits the Langmuir model, corresponding to a theoretical adsorption capacity of 1428 mg g⁻¹. The retained β-lactoglobulin could be readily recovered by rinsing with 0.05 mol L⁻¹ Tris-HCl buffer, facilitating a recovery of 91.5%. The hybrid polyoxometalate was practically applied to the selective isolation of β-lactoglobulin from milk whey, and SDS-PAGE assay results clearly indicate that β-lactoglobulin of high-purity is obtained.