Polytyramine Film-Coated Single-Walled Carbon Nanotube Electrochemical Chemosensor with Molecularly Imprinted Polymer Nanoparticles for Duloxetine-Selective Determination in Human Plasma

Abstract

We devised, fabricated, and tested differential pulse voltammetry (DPV) and impedance spectroscopy (EIS) chemosensors for duloxetine (DUL) antidepressant determination in human plasma. Polyacrylic nanoparticles were synthesized by precipitation polymerization and were molecularly imprinted with DUL (DUL-nanoMIPs). Then, together with the single-walled carbon nanotube (SWCNT) scaffolds, they were uniformly embedded in polytyramine films, i.e., nanoMIPs-SWCNT@(polytyramine film) surface constructs, deposited on gold electrodes by potentiodynamic electropolymerization. These constructs constituted recognition units of the chemosensors. The molecular dynamics (MD) designing of DUL-nanoMIPs helped select the most appropriate functional and cross-linking monomers and determine the selectivity of the chemosensor. Three different DUL-nanoMIPs and non-imprinted polymer (nanoNIPs) were prepared with these monomers. DUL-nanoMIPs, synthesized from respective methacrylic acid and ethylene glycol dimethyl acrylate as the functional and cross-linking monomers, revealed the highest affinity to the DUL analyte. The linear dynamic concentration range, extending from 10 pM to 676 nM DUL, and the limit of detection (LOD), equaling 1.6 pM, in the plasma were determined by the DPV chemosensor, outperforming the EIS chemosensor. HPLC-UV measurements confirmed the results of DUL electrochemical chemosensing.

In Situ Ratiometric Determination of Cerebral Ascorbic Acid after Ischemia Reperfusion

“…Fabrication of CNT −COOH -Modified CFEs. To synthesize the CNT −COOH , 100 mg of single-walled CNTs 43 was suspended into 100 mL of a concentrated HNO 3 and H 2 SO 4 (1:3 volume ratio) mixture. The suspension was ultrasonicated in a water bath at 45 °C for 2.5 h. After cooling, the suspension was washed with Milli-Q water to neutral and finally dried in a vacuum oven overnight.…”