Binding Behavior of Fe 3 Ions on Ion-Imprinted Polymeric Beads for Analytical Applications O ¨ zgen Saatc ¸ılar, 1 Nuray S ¸ atırog ˘ lu, 1 Rıdvan Say, 2 Sema Bektas ˛, 1 Adil Denizli, 1 1 Department of Chemistry, Hacettepe University, Ankara, Turkey 2 Department of Chemistry, Anadolu University, Eskis ˛ehir, Turkey Received 15 September 2005; accepted 14 March 2006 DOI 10.1002/app.24591 Published online in Wiley InterScience (www.interscience.wiley.com). ABSTRACT: We used a molecular imprinting approach to achieve specific metal binding utilizing N-methacryloyl-(l)- cysteine methyl ester (MAC) as a metal-complexing ligand. MAC was synthesized using methacryloyl chloride and cys- teine methyl ester. Then, Fe 3+ was complexed with MAC monomer. Fe 3+ -imprinted poly(hydroxyethyl methacrylate- N-methacryloyl-(l)-cysteine methyl ester) [poly(HEMA- MAC)] beads with average size of 63–140 m were produced by suspension polymerization. After that, the tem- plate ions (i.e. Fe 3+ ions) were removed by 0.1M HCl. Fe 3+ - imprinted beads were characterized by swelling studies, FTIR, and elemental analysis. The Fe 3+ -imprinted beads with a swelling ratio of 72%, and containing 3.9 mmol MAC/g were used in the binding of Fe 3+ ions from aqueous solutions, tap water, certified reference serum sample, and real serum sample. Maximum binding capacity, optimum pH, and equilibrium binding time were 107 mol/g, pH 3.0, and 30 min, respectively. It was observed that even in the presence of other ions, Fe 3+ -imprinted beads selectively bound Fe 3+ ions with 97% efficiency. Removal of Fe 3+ ions from certified reference serum sample was approximately found to be 33%. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3520 –3528, 2006 Key words: molecular imprinting; ion-imprinting polymer; Fe 3+ removal INTRODUCTION Iron is used primarily in the production of steel. Iron and iron compounds are also used in the production of magnets, pigments, abrasives, and polishing com- pounds. Iron is released to the environment through recycling, waste incineration, and through the use of municipal sewage-sludge that contain iron. Nonoccu- pational exposure to iron occurs from contact with soil and from ingestion of plant and animal tissue. Iron is an essential trace element for almost all or- ganisms. 1 The toxic effects of iron overload are well known, especially since the human body has no phys- iological route for the elimination of excess iron. 2 The toxicity of iron is related to its ability to induce oxida- tive stress in cells. 3 In an occupational setting, inhala- tion exposure to iron oxide may cause siderosis. In the nonoccupational population, ingestion of large quan- tities of iron salts may cause nausea, vomiting, and intestinal bleeding. There is accumulating evidence suggesting that an increase in iron storage may be associated with an increasing risk of developing can- cer. 4 Studies have demonstrated that there is an in- creased risk for developing colorectal carcinoma fol- lowing ingestion of high amounts of iron. 5 There is also an increase in hepatocellular carcinoma in pa- tients with hereditary hemochromatosis, an inherited disorder in which there is hyperabsorption of iron from the intestinal tract and in lung cancer from ex- posure to asbestos fibers, which contains 30% iron by weight. 6 It has been a long term dream of researchers to build such structures de novo, creating tailor-made receptors that are capable of recognizing and binding the de- sired molecular target with a high affinity and selec- tivity. 7 Such synthetic materials should be easier to produce and process, less costly, and more stable than biomacromolecules. Moreover, they should be acces- sible to target molecules for which natural receptors do not exist are difficult to obtain. One surprisingly simple way of generating artificial macromolecular receptors is through the molecular imprinting of poly- mers. 8 –11 Molecular imprinting is a technology to cre- ate recognition sites in a macromolecular matrix using a molecular template. 12 In other words, both the shape image of the target and alignment of the functional moieties to interact with those in the target are mem- orized in the macromolecular matrix for the recogni- tion or separation of the target during formation of the polymeric materials themselves. 13 Molecularly im- printed polymers (MIPs) are easy to prepare, stable, inexpensive, and capable of molecular recognition. Therefore, MIPs can be considered as artificial affinity media. Molecular recogition-based separation tech- Correspondence to: A. Denizli (denizli@hacettepe.edu.tr). Journal of Applied Polymer Science, Vol. 101, 3520 –3528 (2006) © 2006 Wiley Periodicals, Inc.