Reprint of: l-Cysteine determination in embryo cell culture media using Co (II)-phthalocyanine modified disposable screen-printed electrodes

Abstract

Thiol-containing compounds such as l-cysteine have been demonstrated to play an important role in metabolism and cellular growth, acting as powerful antioxidants. Consequently, their analytical determination in biological media has received a considerable amount of attention. In this work, an electrochemical sensor for the accurate electroanalytical determination of l-cysteine is proposed, based upon a Co(II)-phthalocyanine bulk modified disposable screen-printed graphite electrode (CoPc-SPE). Cyclic (CV) and Square Wave (SWV) voltammetry experiments have demonstrated an excellent electrocatalytic activity towards the electrochemical oxidation of l-cysteine using CoPc-SPEs within optimum neutral or basic pH. Moreover, the SWV response of l-cysteine is found to exhibit a linear range of 2.6–200 μM, with a low limit of detection of 4 μM (S/N = 3) and a sensitivity of 0.78 μA cm− 2 μM− 1. Coefficient of variation for reproducibility and repeatability of l-cysteine determination using the CoPc-SPE are 3 and 0.4%, respectively. The effect of inherent interferences such as naturally occurring amino acids, cystine and cysteic acid has been also evaluated. Finally, the applicability of the l-cysteine electrochemical sensor based upon CoPc-SPEs has been successfully demonstrated for the first time for the assessment of l-cysteine in a complex embryo cell culture medium.