title: Real-time electrocatalytic sensing of cellular respiration.
abstract: In the present work we develop a real-time electrochemical mediator assay to enable the assessment of cell numbers and chemical toxicity. This allowed us to monitor metabolism down to a single cell in a low cost easy to use rapid assay which is not possible with current technology. The developed assay was based on the determination of oxygen. This was made possible via the use of electrochemical mediator ferrocene carboxylic acid (FcA). The FcA showed distinctive catalytic properties in interacting with reactive oxygen species generated from oxygen when compared to ferrocene methanol (FcMeOH). A deeper insight into the chemistry controlling this behaviour is provided. The behaviour is then taken advantage of to develop a cellular aerobic respiration assay. We describe the properties of the FcA system to detect, in real-time, the oxygen consumption of Escherichia coli DH5-α (E. coli). We demonstrated that the FcA-based oxygen assay is highly sensitive, and using a population of cells, oxygen consumption rates could be calculated down to a single cell level. More importantly, the results can be accomplished in minutes, considerably outperforming current commercially available biooxygen demand assays. The developed assay is expected to have a significant impact in diverse fields and industries, ranging from environmental toxicology through to pharmaceutical and agrochemical industries.
authors.affiliation: School of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom.
authors.forename: Nga-Chi
authors.initials: NC
authors.lastname: Yip
authors.affiliation: Laboratory of Biophysics and Surface Analysis, School of Pharmacy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.
authors.forename: Frankie J
authors.initials: FJ
authors.lastname: Rawson
authors.affiliation: School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom.
authors.forename: Chi Wai
authors.initials: CW
authors.lastname: Tsang
authors.affiliation: School of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom. Electronic address: p.m.mendes@bham.ac.uk.
authors.forename: Paula M
authors.initials: PM
authors.lastname: Mendes
mesh_terms: D057919:Biological Oxygen Demand Analysis / Q000379:methods*; D015374:Biosensing Techniques / Q000379:methods*; D055664:Electrochemical Techniques / Q000379:methods*; D004926:Escherichia coli / Q000302:isolation & purification / Q000378:metabolism*; D005296:Ferrous Compounds / Q000737:chemistry / Q000378:metabolism*; D000075163:Metallocenes; D010100:Oxygen / Q000032:analysis / Q000378:metabolism*
chemical_list: D005296:Ferrous Compounds; D000075163:Metallocenes; C032949:ferrocenecarboxylic acid; C071550:ferrocenemethanol; D010100:Oxygen
keywords: Biochemical oxygen demand assay; Electrocatalyst; Electrochemical assay; Ferrocene carboxylic acid; Toxicity