A novel hydrophobic matrix grafted with aniline for protein capture and thermodynamic study of BSA adsorption

Developing chromatographic matrices is essential for separation processes and polymeric cryogels have potential for use with macromolecules. A novel approach was used to functionalize polyacrylamide cryogels for use in hydrophobic interaction chromatography using aniline as ligand. Thermogravimetric and FTIR spectroscopy analyses indicated the functionalization process was successful. Scanning electron microscopy confirmed a macroporous structure. The swelling capacity, expansion degree and porosity decreased with functioning, indicating an increase in hydrophobicity due to aniline immobilization. The adsorption of bovine serum albumin (BSA) on the adsorbent was evaluated, with the concentration of sodium sulphate varying from (1.0 to 2.5 mol.L − 1 ) and temperature from (298.15 to 328.15 K). A maximum adsorbing capacity of 77.38 mg BSA . g − 1 adsorbent at 328.15 K and 1.5 mol.L − 1 sodium sulphate was achieved in phosphate buffer pH 6.0. The Langmuir model was adjusted to the data obtained and the variation of thermodynamic properties for the adsorbing process was determined from the non-linear van’t Hoff analysis. The adsorbing capacity increased with the increase in temperature (42.50-83.47 mg.g − 1 from 298.15 to 328.15 K) and decreased with the increase in salt concentration (42.50-24.12 mg.g − 1 from 1.5 to 2.5 mol.L − 1 ). The process occurred spontaneously, indicating enthalpic-entropic compensation, going from entropically-driven to enthalpy-driven with the increase in temperature. The matrix developed is promising and with potential for application in capture processes by hydrophobic interaction.