Functionalization of MWNTs with hyperbranched PEI for highly selective isolation of BSA.

Cationic hyperbranched BPEI was immobilized on the surface of MWNTs via electrostatic interactions between the positively charged protonated amines within the polymer and the carboxyl groups on the chemically oxidized MWNT surface. The functionalized BPEI-MWNTs were characterized by FT-IR, TGA, TEM and surface charge analysis, and it was used as a bio-sorbent for the adsorption of proteins. CD spectra showed no conformational change of BSA during the adsorption/desorption process. A dynamic adsorption capacity of 167 mg · g⁻¹ for BSA was achieved. With a sample volume of 2.0 mL, an enrichment factor of 10 was obtained along with an adsorption efficiency of 100%, a recovery of 100%, a sampling frequency of 10 h⁻¹ and a RSD of 2.6% at 25 µg · mL⁻¹ BSA.