Ion-selective imprinted superporous monolith for cadmium removal from human plasma

Abstract

Molecular recognition based separation systems have received much attention because of their high selectivity for target molecules. Molecular imprinting has been recognized as a promising technique for the development of affinity adsorbents. Molecularly imprinted polymers (MIP) are easy to prepare, stable, inexpensive, and capable of molecular recognition. Cadmium is a carcinogenic and mutagenic element. The limit value of cadmium in blood should be no higher than 50 pg/L when exposure to cadmium is unavoidable in industry. There is no specific treatment available for acute or chronic metal poisoning. Besides supportive therapy and hemodialysis, metal poisoning is often treated with commercially available chelating agents including EDTA and dimercaprol. However, there is histopathological evidence for increased toxicity in animals when these agents are utilized. The aim of this study is to prepare superporous ion-imprinted polymer monolith which can be used for the selective removal of Cd(2+) ions from Cd(2+) -overdosed human plasma. N-methacryloly-(L)-cysteinemethylester (MAC) was chosen as the complexing monomer. In the first step, MAC synthesized by using methacryloyl chloride and cysteine. Cd(2+) was complexed with MAC monomer and the Cd(2+) -imprinted poly(HEMA-MAC) monoliths were synthesized by bulk polymerization. After that, Cd(2+) ions were removed by 0.1 M thiourea and 0.1 M HNO(3) solutions, respectively. Cd(2+) -imprinted poly(HEMA-MAC) monoliths had a specific surface area of 226.8 m(2) /g and the swelling ratio was determined to be 76%. According to the elemental analysis results, monoliths contain approximately 58.3 mu mol/g of MAC. The maximum adsorption capacity for Cd(2+) ions was 26.6 mu mol/g of the dry weight of monolith. The adsorption capacity decreased significantly from 23.25 mu mol/g to 3.08 mu mol/g polymer with the increase of the flow-rate from 1 mL/min to 4 mL/min. The Cd(2+) -imprinted poly(HEMA-MAC) monolith could be used many times without decreasing their adsorption capacities significantly.