Model Protein BSA Adsorption and Covalent Coupling onto Methyl Methacrylate Based Latex Particles with Different Surface Properties

The adsorption and covalent coupling of bovine serum albumin (BSA) onto methylmethacrylate (MMA) based monodisperse latex particles with different hydrophylic surfaces were investigated. P(MMA) and P(MMA/HEMA) microbeads in the size range of 1.5–2.0 mm were prepared by a dispersion homopolymerization method in the presence of poly(vinylpyrrolidone) (PVP) and poly(vinyl alcohol) (PVA) as steric stabilizer and by copolymerization of MMA and 2-hydroxethyl methacrylate (HEMA) where PVP was used as steric stabilizers. Surface properties of these particles were characterized in terms of contact angle measurements and FTIR-DRS spectra. Additionally, hydroxyl groups of PMMA _PVA and P(MMA/HEMA) particles were activated to provide aldehyde groups on surfaces. Adsorption of the BSA onto these five types of latex particles was examined as a function of initial albumin concentration, pH and ionic strength of the various cations (Na+,Ca+ and Mg− and anions (Cl ⁻ and SCN ⁻ ). The maximum adsorption capacities for all latex particles were obtained in solutions with 0.01μ m ionic strength and 1 mg/mL BSA concentration. When using PMMA _PVA , P(MMA/HEMA) and PMMA _PVP , the adsorption increased as hydrophobicity increased. Aldehyde activation of the two most hydrophobic particles elevated the coupling (immobilization) significantly in ionic strength of 0.01μ m. The adsorption and/or immobilization were maximum in the presence of monovalent cation, Na+ or anion, Cl−B for all types of latex particles.