New conductive ink based on carbon nanotubes and glass varnish for the construction of a disposable electrochemical sensor

Abstract

This work presents the manufacture of a new conductive ink based on glass varnish and carbon nanotubes, employed for the construction of an electrochemical sensor printed on polyethylene terephthalate (PET) sheets. In this context, the exploration of the electrochemical and analytical performance of this new, low-cost conductive ink is of great interest. The sensors prepared with the proposed ink were studied by cyclic voltammetry (CV) using ferrocenemethanol (FcMeOH) as a redox probe. The proposed sensor was applied for the detection of 3-nitro-l-tyrosine (3-NLT), a modified amino acid present in biological fluids that can serve as an indicator of oxidative stress, using square wave voltammetry (SWV). Under optimized conditions, the sensor presented a linear response ranging from 0.70 to 100.0 μmol L-1, with a limit of detection (LOD) of 0.53 μmol L-1. The sensor was applied in the analysis of 3-NLT in synthetic urine, and recovery values ranging from 95.2 to 106.0% were obtained. Also, an analytical curve in human blood serum was constructed to show the suitability of the method in complex matrices. Linear responses ranging from 3.0 to 100.0 μmol L-1 of 3-NLT and a LOD of 1.35 μmol L-1 were obtained. Furthermore, the device was simple to produce and presented a relatively low cost. The obtained data demonstrate that the developed ink showed satisfactory analytical application, corroborating with further investigations and the advance in the production of other conductive inks in laboratory settings.