The molecular imprinting technique was used in the synthesis of polymers having a high affinity for testosterone. These polymers thus function as receptor binding mimics for the drug. Various polymerization conditions were examined in order to determine their influence on the binding strength and selectivity of the binding mimics. Using a series of similar steroids, we were able to identify features of the molecules which affect their affinity for the polymer matrix. The efficacy of covalent and noncovalent imprinting methods was also compared. As determined by HPLC, the most selective (noncovalently imprinted) polymer bound testosterone over 4 times more strongly than did a nonimprinted polymer and at least 3 times more selectively than steroids of similar structure.

A practical optical sensing system for the determination of chloramphenicol (CAP), utilizing molecularly imprinted polymers (MIPs) and HPLC, has been developed. The method is based on competitive displacement of a chloramphenicol-methyl red (CAP-MR) dye conjugate from specific binding cavities in an imprinted polymer by the analyte. The best of these polymers was obtained using (diethylamino)ethyl methacrylate as functional monomer at a monomer:template ratio of 2:1. HPLC with a mobile phase containing CAP-MR was used as the detection system, and injection of CAP and, to a lesser degree, thiamphenicol resulted in proportional displacement of the conjugate, which was detected at 460 nm. The detection system showed a linear response over a range of 3-1000 μg/mL and effectively detected CAP extracted from serum. This system offers a tailor-made, selective, and rapid method for CAP detection, is able to discriminate between similar molecules, and is effective below and above the therapeutic range (10-20 μg/mL serum, potentially toxic above 25 μg/mL). This technique is quite general and should enable the use of MIPs in a wide variety of applications involving the detection of families of molecules which possess a distinct arrangement of functional groups.

The polymers selective to six different steroids (testosterone, Δ4‐androstene‐3,17‐dione, 1,4‐androstadiene‐3,17‐dione, β‐estradiol, progesterone, testosterone propionate) have been synthesized using molecular imprinting based on noncovalent interactions. Analysis of the influence of structural features of the steroids under study has shown that molecules with a relatively rigid structure and the OH group at C‐17 position are the most efficient templates for methacrylic acid‐containing imprinted polymers. The chromatographic study of the polymers synthesized has demonstrated a strong dependence of the selectivity and intensity of interaction with analytes on the composition of solvents used both as porogen and chromatographic mobile phase. To obtain polymers with highly selective recognition sites and to create the optimal conditions for molecular recognition, all possible interactions (between template and functional monomer, template and solvent, solvent and functional monomer) should be taken into account. The batch rebinding study of testosterone by the imprinted polymer in acetonitrile has revealed some heterogeneity of recognition sites, and permitted determination of Kass = 1.05 × 104 M−1, ΔG° = −5.4 kcal/mol and N = 1.2 μmol/g for high‐affinity sites and Kass = 0.33 × 104 M−1, ΔG° = −4.8 kcal/mol and N = 2.2 μmol/g for low‐affinity sites. The results obtained show how it is possible to regulate in different modes the molecular recognition by imprinted polymers as well as to fabricate polymers possessing the necessary properties depending on their practical application.© 1998 John Wiley & Sons, Ltd.

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