Non-Covalent Functionalization of Multi-Wall Carbon Nanotubes with Polyarginine: Characterization and Analytical Applications for Uric Acid Quantification

EGUÍLAZ, MARCOS; PARRADO, CONCEPCIÓN; GUTIÉRREZ, ALEJANDRO; RIVAS, GUSTAVO A.; GUTIERREZ, FABIANA

ELECTROANALYSIS

WILEY-V C H VERLAG GMBH

Año: 2018

1040-0397

We report for the first time the non-covalentfunctionalization of multiwall carbon nanotubes(MWCNTs) with polyarginine (Polyarg), the modificationof glassy carbon electrodes (GCE) with the resultingPolyarg-MWCNTs dispersion and the analytical applicationof Polyarg-MWCNTs-modified GCE for the quantificationof uric acid. The optimum MWCNT-Polyargdispersion was obtained by sonicating for 5.0 min themixture of 0.75 mgmL1 MWCNTs and 0.50 mgmL1Polyarg. The dispersion was characterized by scanningelectron microscopy, electrophoretic mobility, electrochemicalimpedance spectroscopy, cyclic voltammetry andamperometry. The presence of MWCNT-Polyarg at GCEsurface produced a drastic decrease in the overvoltages for the oxidation of hydrogen peroxide (300 mV) ascorbicacid (281 mV) and uric acid (70 mV) and for the reductionof hydrogen peroxide (200 mV), as well as an importantdecrease in the charge transfer resistances for hydrogenperoxide, hydroquinone/quinone and ferricyanide/ferrocyanidemarkers. The strong adsorption of uric acid atGCE/MWCNT-Polyarg made possible the highly sensitivedetection of this biomarker at nanomolar levels even inthe presence of 1.03104 M ascorbic acid by AdsorptiveStripping with medium exchange and linear scan voltammetrytransduction. The quantification of uric acid inuntreated human urine was very successful, demonstratingan excellent correlation (98%) with the reference methodused in clinical laboratories (Uricostat, Wiener Lab).