(657g) Insight the Rational Design of Molecularly Imprinted Polymer for the Development of Biomimetic Receptors

Innovation on clinical devices is essential to enhance the accuracy and efficiency on patients' diagnosis, and how their clinical treatments are monitored. Molecular imprinting technique has gained attention to generate novel biosensor and clinical diagnostic devices with high sensitivity and specificity which demonstrated affinities compared to their natural counterparts. A method for the rational design of biomimetic sensor based on molecularly imprinted polymer for the detection of hydrocortisone is described and applied. The thermodynamic of the association between hydrocortisone and the functional monomer, methacrylic acid (MAA) was investigated by Nuclear Magnetic Resonance (NMR) spectroscopy. Dissociation constants for the complex formation between hydrocortisone and a functional monomer analogue, acetic acid, as a function of solvent nature were estimated by NMR titration. The stoichiometry of the complex formation between hydrocortisone and an acetic acid on each solvent was evaluated by Job method of continuous variation. Dimethyl sulfoxide and ethanol were selected as porogens to assess solvent effect. The dissociation constants obtain for ethanol-d₆ reflects a greater proximity of interaction between solution adducts compared to dimethyl sulfoxide-d₆. It is consequently associated by their dielectric constant of the solvents. Job plot results suggested a complex mole ratio of 1.5:1 and 1:2 for dymethyl sulfoxide-d6 and ethanol-d₆, respectively. The collective analysis of NMR titration and Job plot method indicated the extent of shifts displacement is proportional to their proximity to the interaction site that is not apparently associated with its stoichiometric capabilities of complex formation. To evaluate synthesis condition, in situ free radical copolymerization was monitored by ATR-FTIR spectroscopy with methacrylic acid (MAA) as the functional monomer and tetra(ethylene glycol) dimethacrylate (EGDMA) as the crosslinking agent at different solvents. The synthesis was performed in presence and absence of the template molecule. The combined set of analysis allowed a better understanding of the recognition events giving rise to the imprinting effect during MIP synthesis and to ligand-MIP binding events. In situ polymerization results demonstrated a delay the onset autoaccelaration during imprinting process. In essence, the propagation kinetics was reduced by the decrease of monomer mobility which suggested the functional monomer-template complexation already confirm by the NMR spectroscopic studies. Consequently, the information was applied for the design of thin films MIP which can be for seen where the collapse-swelling transition could be programmed to promote binding capabilities and enhance template diffusion. To this aims, hydrocortisone imprinted polymers were synthesized in aqueous medium. To determine the suitability of hydrogel-based MIPs, swelling behavior, structural parameters (e.g. mesh size, ε) and template permeation was investigated as function of pH and copolymer composition. The MIP characterization results demonstrated an increase on template permeation direct influenced by mesh size at pH equal to 5.5 at 37°C and ionic strength of 0.1M. A different behavior was shown for the characterization at pH equal to 6.0 at 37°C and ionic strength of 0.1M. A reduction was observed on the permeability coefficient for MIP with a MAA/EGDMA ratio of 17:1. It suggested the influence of MIP-ligand binding on hydrocortisone transport through the polymeric network synthesized by molecular imprinting technique. Further biding capacity studies will allow estimating the association constants of polymeric receptors. Overall, this work reported the evaluation of the principal factors affecting the stabilization of functional monomer-template complex before and during imprinting process which provides essential information for the rational design of molecularly imprinted polymers.