Cytochrome C Oxidase Deficiency Detection Using SECM in Living Cells

Abstract

Cytochrome c Oxidase Deficiency (COXD) is an inherited disorder characterized by the absence, abnormality, or mutation in the genes encoding for the Cytochrome c Oxidase protein (COX)1. COXD results in severe muscle weakness, heart, liver and kidney problems and brain damage in infants, leading to death at birth or shortly thereafter2. With no cure for this disorder, finding an efficient, inexpensive, and early way of diagnosis is essential, as muscle biopsy, the current method of detection, is expensive, invasive, and time-consuming. Using electrochemistry, Cytochrome c Oxidase activity has successfully been quantified in bacteria, specifically in Bacillus subtilis and Escherichia coli by employing the redox mediator N, N, N’,N’-tetramethyl-para-phenylene-diamine (TMPD)3. This presentation demonstrates that by means of Scanning Electrochemical Microscopy (SECM), Cytochrome c Oxidase activity can also be quantified in living human epithelial and cancer cells. Thereby, COX oxidizes TMPD to TMPD+•, which is reduced at a microelectrode, regenerating TMPD. The resulting change in electrochemical current enables the quantification of COX activity. The presented research will form the basis for an analytical assay for the detection of COXD in infants, allowing for early intervention and saving lives of children. References 1,2 NORD. (n.d.). Cytochrome c Oxidase Deficiency. National Organization for Rare Disorders (NORD). https://rarediseases.org/rare-diseases/cytochrome-c-oxidase-deficiency/ 3 Kuss, S. et al. (2017). Electrochemical recognition and quantification of cytochrome c expression in Bacillus subtilis and aerobe/anaerobe Escherichia coli using N,N,N′,N′-tetramethyl-para-phenylene-diamine (TMPD). Chemical Science, (11). https://doi.org/10.1039/c7sc03498a