Molecularly imprinted sol-gel electrochemical sensor for sildenafil based on a pencil graphite electrode modified by Preyssler heteropolyacid/gold nanoparticles/MWCNT nanocomposite.

An electrochemical sensor based on the imprinted sol-gel on pencil graphite electrode (PGE) modified with functionalized multiwalled carbon nanotube (MWCNT), gold nanoparticles (AuNPs), and Preyssler heteropolyacid (PHPA) nanohybrid was fabricated for the determination of trace amounts of sildenafil. The pencil graphite electrode was first deposited by the AuNPs@PHPA-MWCNT nanohybrids, and then, the modified electrode of MIP-sol-gel/AuNPs@PHPA-MWCNTs was prepared by the electrochemical method. The synthesized nanohybrids and prepared modified electrodes were characterized with FE-SEM, FTIR, EDX, XRD, and UV/Vis. Cyclic voltammetry, electrochemical impedance spectroscopy, and differential pulse voltammetry techniques were applied for the electrochemical analysis using the modified electrodes. By measuring the oxidation and reduction currents of the potassium ferricyanide probe, the efficiency of this sensor was evaluated for the detection of sildenafil. The anodic peak current was measured at 0.2 V vs. Ag/AgCl by differential pulse voltammetry in the potential range - 0.1 to 0.5 V (vs. Ag/AgCl). Under the optimum conditions, the current response for the detection of sildenafil was linear in two concentration ranges of 0.1-2 and 2-30 nM and the obtained limit of detection was 0.033 nM. The constructed sensor was used for the measurement of sildenafil in real samples.