In vitro cadmium removal from human serum by Cibacron Blue F3GA thionein-complex conjugated affinity membranes

Abstract

A new membrane affinity biosorbent carrying thionein has been developed for selective removal of cadmium ions from human serum. Microporous poly(2-hydroxyethyl methacrylate) (pHEMA) membranes were prepared by photopolymerization of HEMA. The pseudo dye ligand Cibacron Blue F3GA (CB) was covalently immobilized on the pHEMA membranes. Then, the cysteine-rich metallopeptide thionein was conjugated onto the CB-immobilized membrane. The maximum amounts of CB immobilized and thionein conjugated on the membranes were 1.07 μmolcm-2 and 0.92 μmolcm-2, respectively. The hydrophilic pHEMA membrane had a swelling ratio of 58% (w/w) with a contact angle of 45.8°. CB-immobilized and CB-immobilized-thionein-conjugated membranes were used in the Cd(II) removal studies. Cd(II) ion adsorption appeared to reach equilibrium within 30 min and to follow a typical Langmuir adsorption isotherm. The maximum capacity (qm) of the CB-immobilized membranes was 0.203 (μmol Cd(II)) cm-2 membrane and increased to 1.48 (μmol Cd(II)) cm-2 upon CB-thionein-complex conjugation. The pHEMA membranes retained their cadmium adsorption capacity even after 10 cycles of repeated use. © 2000 Society of Chemical Industry.