Polyaniline and poly(2-methoxyaniline) based molecular imprinted polymer sensors for amoxicillin voltammetric determination

Abstract

In this work, sensors based on molecular imprinted polyaniline (MIPANI) and poly-2-methoxyaniline (MIPMOA) for amoxicillin (AMX) determination were developed and compared with each other. MIPANI and MIPMOA were deposited on the surface of modified by graphene oxide (GO) glassy carbon electrode (GCE) through electrochemical polymerization using cyclic voltammetry, which was carried out in a 1 M sulfuric acid solution containing the corresponding monomer and amoxicillin as a template, followed by removal of the template. Using a scanning electron microscopy and electrochemical impedance spectroscopy, the morphology and electrochemical properties of the modified surface of GCE were studied. The applying PANI and PMOA on the GCE/GO surface leads to a decrease in [Fe(CN)6]3-/4− currents. The electron transfer resistance on PMOA sensor (62 ± 4 Ω) is lower than on PANI sensor (71 ± 5 Ω). The areas of the electroactive surface of GCE/GO/PANI and GCE/GO/PMOA are 6.64 ± 0.12 mm2 and 7.75 ± 0.14 mm2, respectively. After the removal of the AMX, the electron transfer rate increases due to the formation of pores in the polymers through which [Fe(CN)6]3-/4− ions penetrate. Using FTIR spectroscopy, it was shown that amoxicillin is incorporated into both polymer films. In this case, the binding of AMX to PMOA is stronger, which is confirmed by quantum chemical modeling. The optimal conditions for analysis were selected: the number of polymerization cycles was 7, the template concentration was 1 mM, and the pH of the analyzed solution was 7.00. Square wave voltammograms MIPANI and MIPMOA sensors show a pronounced electrooxidation peak, which are linear over the AMX concentration range of 1.0 × 10−5 – 5.0 × 10−3 and 5.0 × 10−6 – 5.0 × 10−3 M with detection limits of 2.6 × 10−6 and 6.1 × 10−7 M, respectively. It is shown that the MIPMOA sensor exhibits higher sensitivity and selectivity to AMX than MIPANI sensor, as well as high accuracy in determining AMX in urine and blood plasma.