Organic redox-active crystalline layers for reagent-free electrochemical antibiotic susceptibility testing (ORACLE-AST)

• Published in: Biosensors & bioelectronics 2021-01, Vol.172, p.112615-112615, Article 112615
• Main Authors: Bolotsky, Adam, Muralidharan, Ritvik, Butler, Derrick, Root, Kayla, Murray, William, Liu, Zhiwen, Ebrahimi, Aida
• Format: Article
• Language: English
• Subjects: Anti-Bacterial Agents - pharmacology; Biosensing Techniques; Electrochemical sensor; Escherichia coli; Humans; Indicators and Reagents; Metabolic activity; Microbial Sensitivity Tests; Organic crystal; Oxidation-Reduction; Rapid antibiotic susceptibility testing; Reagent-free; Redox-active
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2020.112615

Rapid antibiotic susceptibility testing (AST) is critical in determining bacterial resistance or susceptibility to a particular antibiotic. Simple-to-use phenotype-based AST platforms can assist care-givers in timely prescription of the right antibiotic. Monitoring the change of bacterial viability by measuring electrochemical Faradaic current is a promising approach for rapid AST. However, the existing works require mixing redox-active reagents in the solution which can interfere with the antibiotics. In this paper, we developed a facile electrodeposition process for creating a redox-active crystalline layer (denoted as RZx) on pyrolytic graphite sheets (PGS), which was then utilized as the sensing layer for reagent-free electrochemical AST. To demonstrate the proof-of-principle, we tested the sensors with Escherichia coli (E. coli) K-12 treated with two antibiotics, ampicillin and kanamycin. While the sensors enable detection of bacterial metabolism mainly due to pH-sensitivity of RZx (∼ 53 mV/pH), secreted redox-active metabolites/compounds from whole cells are likely contributing to the signal as well. By monitoring the differential voltammetric signals, the sensors enable accurate prediction of the minimum inhibitory concentration (MIC) in 60 min (p