Electrochemical sensor based on GCE modified with E-rGO/Poly (B-CD)/magnetic ZIF-67 nanocomposite for the measurement of Linagliptin

Linagliptin (LNG) is one of the drugs that was entered the market in 2011 to treat type 2 diabetes. The drug inhibits the dipeptidyl peptidase-4 enzyme in human body and regulates the insulin level which decreases blood sugar in diabetics. In this work, firstly, GO and magnetic ZIF-67 were synthesized. The modification of the glassy carbon electrode (GCE) was performed layered by layer. GO was reduced on the electrode surface by the electrochemical method (E-rGO). Then beta-cyclodextrin was electrodeposited (Poly (beta-CD)) on the E-rGO. Finally, Fe3O4 @ZIF-67 (magnetic ZIF-67) nanocomposite was cast on the E-rGO-Poly (beta-CD) and was let dry at room temperature completely and was used as a very sensitive sensor to measure the LNG. The performance of the prepared electrodes was evaluated using cyclic voltammetry, electrochemical impedance, spectroscopy, and field emission scanning electron microscopy methods. The results showed that the oxidation current of LNG on the surface of the modified electrodes at a potential of 1.0 V is much higher than that of the GCE. The high surface area of GCE/E-rGO/Poly (B-CD)/magneticZIF-67 showed that the effective synergistic effect of rGO, B-CD, and magneticZIF-67 for the oxidation of LNG, so that the current at the surface of GCE/E-rGO/Poly (B-CD)/magnetic ZIF-67 was 4 times that of the unmodified electrode. Applicability of the sensor was monitored in various concentrations of LNG under linear ranges of 0.03-200 mu M and a limit of detection of 0.01 mu M was resulted. Also, the sensor showed a good ability to measure LNG in the presence of other species.