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The binding affinity of molecularly imprinted polymers (MIPs) relies on the mechanisms and the extent of the functional monomertemplate interactions present in the prepolymerization mixture. Thus, a clear understanding and optimizing the physiochemical parameters governing these interactions is key in designing and modeling MIPs with good selectivity. Quantum chemical method was applied here for the theoretical investigation into the interaction between cortisol and pyrrole in a molecularly imprinted prepolymerization mixtures. Since polypyrrole (PPy) is one of the most extensively used conducting polymers in design of bioanalytical sensors, pyrrole is chosen as a functional monomer. The pre-assembly system of possible conformations of cortisol/pyrrole monomer systems have been optimized with the use of density functional theory (DFT) at B3LYP/6-311G (d) level using Gaussian 09 software. The binding energy calculations of a range of structurally related steroids (cortisol, progesterone, prednisolone, 21-deoxycortisol and 6-methyprednisolone) with functional monomer have been analyzed through computational modelling. The most stable configurations of cortisol/functional monomer complexes have been optimized and selected. Based on the conformational analysis and the calculated binding energies of steroid/pyrrole molecular imprinted systems, we have concluded that the interactions between cortisol and pyrrole are more specific and stronger in comparison to the interactions between other steroid hormones (progesterone, prednisolone, 21-deoxycortisol and 6-methyprednisolone) and pyrrole. In the recent years, molecularly imprinted polymers (MIPs) have become one of the most useful materials for designing new analytical methodologies as they are selective molecular recognition phases. 1They are similar to immunosorbents in that MIPs can be tailored for different target analysis.2-4 During the molecular imprinting process highly cross-linked co-polymers are formed around analyte molecules acting as cavity-creating templates. After extractive removal of the template, the remaining molecularly imprinted polymer matrix contains 3-dimensional binding cavities facilitating rebinding due to complementary shape and functionality for the template molecule (Figure 1). Depending upon the nature of chemical bonds involved, MIPs synthesis techniques can be classified into two common approaches: (i) covalent imprinting and (ii) non-covalent imprinting. Non-covalent imprinting has been most widely adopted in many laboratories due its flexibility in choice of functional monomers and template molecules. The main non-covalent interactions responsible for molecular recognition in biomimetic systems are hydrogen bonding, ion-pairing, and π-π interactions. Hydrogen-bonding interactions is a strong interaction that plays a crucial role in biological recognition systems and in determining the structures of proteins and nucleic acids. The combination of utilizing strong hydrogen-bonding interactions with MIPs will create imprinted polymers wi...

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