Molecularly imprinted polymer based quartz crystal microbalance sensor for the clinical detection of insulin

In this study, quartz crystal microbalance sensors based on molecular imprinting technology were fabricated for real-time detection of insulin in aqueous solution and artificial plasma. This study describes the preparation of insulin imprinted poly(hydroxyethyl methacrylate)-N-methacryloyl-(l)-histidine methyl ester based quartz crystal microbalance sensor for insulin determination. Poly(hydroxyethyl methacrylate)-N-methacryloyl-(l)-histidine methyl ester based film on chip surface was synthesized by ultra violet (UV) polymerization for the detection of insulin at low concentrations. At the first step, N-methacryloyl-(l)-histidine methyl ester complex was formed with insulin and then, the insulin imprinted film has been prepared. The characterization of the polymeric film has been conducted with ellipsometry, contact angle, Fourier transform infrared-attenuated total reflectance and atomic force microscopy measurements. Langmuir, Freundlich and Langmuir-Freundlich adsorption isotherm models were applied for this system. The best fitted model to explain the interactions between molecular imprinted chip and insulin molecules was the Langmuir adsorption isotherm (R²: 0.999). The repeatability of insulin imprinted chip was investigated by using of equilibration-binding-regeneration cycles for four times. The detection limit was found as 0.00158 ng/mL. According to the results, the QCM sensor has showed low-detection limit, high selectivity and sensitivity for insulin assay.