Electrochemical sensors using gold submicron particles modified electrodes based on calcium complexes formed with alizarin red S for determination of Ca(2+) in isolated rat heart mitochondria.

A simple glassy carbon electrode (GCE) modified with gold submicron particles (AuSPs), characterized by a mean diameter of about0.15-0.20μm has been developed. Herein, the complexation reaction of Ca(2+) with alizarin red S (ARS), in 0.1M KOH, has been followed by electrochemical methods using the modified electrode which is able to catalyze the electro-reduction of ARS. When the stoichiometry ratio of Ca(2+) and ARS is 1:2, a new reduction peak at a higher negative potential of -0.975V appeared, and the peak of ARS at -0.815V disappeared. The peak current of ARS in alkaline solution is proportional to the concentration of Ca(2+) in the range 6.0×10(-7)-1.2×10(-4)M with a limit of detection (LOD) of 5.1×10(-7)M. Furthermore, the complex site of Ca(2+) with ARS was analysized by the experimental UV-vis and infrared spectrums and those calculated electronic and vibrational spectroscopies with density functional theory (DFT). The good accordance between theoretical and experimental data confirms that chelation of calcium ion preferentially occurs at the deprotonated catechol site. Then, we implemented an electrochemical assay for the investigation of Ca(2+) in preparations of isolated rat heart mitochondria, which demonstrates the submicron particles modified electrode is a simple and rapid sensor for determining the Ca(2+) in the biological samples.