DOI: 10.1002/chem.201201428 An Artificial Estrogen Receptor through Combinatorial Imprinting Eric Schillinger, [a] Monika Mçder, [c] Gustaf D. Olsson, [d] Ian A. Nicholls, [d, e] and Bçrje Sellergren* [a, b] Introduction A serious threat to wildlife and humans is posed by xenobi- otic chemicals antagonizing or mimicking the effect of en- dogenous hormones. [1, 2] These so called estrogen active com- pounds (EACs) encompass a wide variety of chemicals, for example, synthetic hormones, pesticides, plasticizers, and surfactants, many of which are either persistent or are re- leased at such high levels that they accumulate in the envi- ronment. [2, 3] Those exerting estrogenic activities are particu- larly common and their accumulation in environmental waters has been shown to cause feminization of fish popula- tions, raising concerns about their effect on the reproductive system of humans. [4] In view of these hazards, governments face a number of challenges: first, to provide effective water-purification technologies capable of assuring the effec- tive removal of trace amounts of EACs, which presently, owing to insufficient remediation, escape the water treat- ment plants; [5] second, to develop analytical methods allow- ing an efficient monitoring of the EAC presence in environ- mental or food samples; [6] and third, to provide a means of determining if a chemical is a potential EAC and hence, should be removed, that is, to develop screening techniques for hormone activity. [7, 8] As recent reports have suggested, these challenges could benefit from robust mimics of the es- trogen receptor in the form of molecularly imprinted poly- mers (MIPs) that are capable of filtering out all chemicals with estrogen-like activity for the purpose of removal [9] or detection. [8, 10] The preparation of these MIPs has followed well-established procedures, [11] starting from prepolymeriza- tion mixtures containing 17-b-estradiol (E2) as template, methacrylic acid (MAA) or vinylpyridine (VPy) as function- al monomers, and ethylenglycoldimethacrylate (EGDMA) as crosslinking monomer. After free radical polymerization, Abstract: Polymeric sorbents targeting endocrine-disrupting estrogen active compounds (EAC) were prepared by terpolymer imprinting using 17b-estra- diol (E2) as template. From a group of eight functional monomers represent- ing Brønsted acids, bases, hydrogen- bond donors and acceptors, as well as p-interacting monomers, a terpolymer library that comprises all possible binary combinations of the functional monomers was prepared. Binding tests revealed that imprinted polymers ex- hibit a markedly higher affinity for E2 compared to nonimprinted polymers (NIPs) or polymers prepared by using single functional monomers. A combi- nation of methacrylic acid (MAA) and p-vinylbenzoic acid offered a particu- larly promising lead polymer, display- ing an imprinting factor of 17 versus 2.4 for a benchmark polymer prepared by using only MAA as functional monomer. The saturation capacities as- cribed to imprinted sites were four to five times higher for this polymer com- pared to previously reported imprinted polymers. NMR titrations and molecu- lar dynamics simulations corroborated these results, indicating an orthogonal preference of the two functional mono- mers with respect to the E2 3-OH and 17-OH groups. The optimized polymer exhibited a retentivity for EACs that correlates with their inhibitory effect on the natural receptor. By using the optimized molecularly imprinted poly- mers (MIPs) in a model water-purifica- tion system, they were capable of com- pletely removing ppb levels of a small group of EACs from water. This is in contrast to the performance of nonim- printed polymers and well-established sorbents for water purification (e.g., active carbon), which still contained detectable amounts of the compounds after treatment. Keywords: endocrine disruptor · estrogen · imprinting · receptors · recognition · water treatment [a] Dr. E. Schillinger, Priv.-Doz. Dr. B. Sellergren INFU, Technical University of Dortmund Otto Hahn Strasse 6, 44221 Dortmund (Germany) E-mail : borje@infu.uni-dortmund.de [b] Priv.-Doz. Dr. B. Sellergren Faculty of Health and Society Malmç University, SE-205 06 Malmç (Sweden) [c] Prof. M. Mçder Helmholtz-Centre for Environmental Research UFZ, Department of Analytical Chemistry Permoserstrasse 15, 04318 Leipzig (Germany) [d] Dr. G. D. Olsson, Prof. I. A. Nicholls School of Natural Sciences, Linnaeus University SE-39182 Kalmar (Sweden) [e] Prof. I. A. Nicholls Department of Biochemistry & Organic Chemistry Uppsala University, 751 23 Uppsala (Sweden) Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/chem.201201428. It contains experi- mental details describing polymer synthesis and library preparation, HPLC analysis, EDC screening, SPE experiments, and removal tests. Chem. Eur. J. 2012, 00,0–0  2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim These are not the final page numbers! ÞÞ &1& FULL PAPER