Selective detection of Escherichia coli K12 and Staphylococcus aureus in mixed bacterial communities using a single-walled carbon nanotube-functionalized electrochemical immunosensor with dielectrophoretic concentration

Authors: LEE, INAE - University Of Hawaii; SO, HEEJIN - University Of Hawaii; KIM, JUNGYOON - Chung-Ang University; AUH, JOONG - Chung-Ang University; Wall, Marisa; LI, YONG - University Of Hawaii; HO, KACIE - University Of Hawaii; JUN, SOOJIN - University Of Hawaii

Submitted to: Nanomaterials
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/6/2023
Publication Date: 3/8/2023
Citation: Lee, I., So, H., Kim, J., Auh, J., Wall, M.M., Li, Y., Ho, K., Jun, S. 2023. Selective detection of Escherichia coli K12 and Staphylococcus aureus in mixed bacterial communities using a single-walled carbon nanotube (SWCNT)-functionalized electrochemical immunosensor with dielectrophoretic concentration. Nanomaterials. 13(6). Article 985. https://doi.org/10.3390/nano13060985.
DOI: https://doi.org/10.3390/nano13060985

Interpretive Summary: An electrochemical immunosensor has been developed for the rapid detection and identification of potentially harmful bacteria in food and environmental samples. In this study, a microwire-based electrochemical immunosensor (MEI sensor) was fabricated for selective detection of Escherichia coli and Staphylococcus aureus in microbial cocktail samples. Single-walled carbon nanotubes (SWCNTs) layered on the surface of the MEI sensor amplified electrical detection signals when target bacteria bound to corresponding antibodies immobilized on it. The MEI sensor functionalized with double-layered, SWCNTs and 5% bovine serum albumin (BSA) solution provided rapid, sensitive, and specific detection of target bacteria. The developed MEI sensor shows potential for selective detection of target bacteria in mixed bacterial communities.

Technical Abstract: An electrochemical immunosensor has been developed for the rapid detection and identification of potentially harmful bacteria in food and environmental samples. This study was to fabricate a microwire-based electrochemical immunosensor (MEI sensor) for selective detection of Escherichia coli and Staphylococcus aureus in microbial cocktail samples using dielectrophoresis (DEP)-based cell concentration. A gold-coated tungsten microwire was functionalized by coating polyethylenimine, single-walled carbon nanotubes (SWCNTs) suspension, streptavidin, biotinylated antibodies, and then bovine serum albumin (BSA) solutions. Double-layered SWCNTs and 5% of BSA solution were found to be optimized for enhanced signal enhancement and non-specific binding barrier. The selective capture of E. coli K12 or S. aureus cells was achieved when the electric field in bacterial sample solution was generated at a frequency of 3 MHz and 20 Vpp. A linear trend of the change in the electron transfer resistance was observed as E. coli concentrations increased from 5.32 × 102 to 1.30 × 108 CFU/mL (R2 = 0.976). The S. aureus MEI sensor fabricated with the anti-S. aureus antibodies also showed an increase in resistance with the concentrations of S. aureus (8.90 × 102 - 3.45 × 107 CFU/mL) at the correlation, R2 = 0.983. Salmonella Typhimurium and Listeria monocytogenes were used to evaluate the specificity of the MEI sensors. The functionalization process developed for the MEI sensor is expected to contribute to the sensitive and selective detection of other harmful microorganisms in food and environmental industries.