Pore-Forming Toxin-Driven Recovery of Peroxidase-Mimicking Activity in Biomass Channels for Label-Free Electrochemical Bacteria Sensing

Anal Chem. 2024 May 14;96(19):7661-7668. doi: 10.1021/acs.analchem.4c00589. Epub 2024 Apr 30.

Abstract

The development of sensitive, selective, and rapid methods to detect bacteria in complex media is essential to ensuring human health. Virulence factors, particularly pore-forming toxins (PFTs) secreted by pathogenic bacteria, play a crucial role in bacterial diseases and serve as indicators of disease severity. In this study, a nanochannel-based label-free electrochemical sensing platform was developed for the detection of specific pathogenic bacteria based on their secreted PFTs. In this design, wood substrate channels were functionalized with a Fe-based metal-organic framework (FeMOF) and then protected with a layer of phosphatidylcholine (PC)-based phospholipid membrane (PM) that serves as a peroxidase mimetic and a channel gatekeeper, respectively. Using Staphylococcus aureus (S. aureus) as the model bacteria, the PC-specific PFTs secreted by S. aureus perforate the PM layer. Now exposed to the FeMOF, uncharged 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) molecules in the electrolyte undergo oxidation to cationic products (ABTS•+). The measured transmembrane ionic current indicates the presence of S. aureus and methicillin-resistant S. aureus (MRSA) with a low detection limit of 3 cfu mL-1. Besides excellent specificity, this sensing approach exhibits satisfactory performance for the detection of target bacteria in the complex media of food.

MeSH terms

  • Bacterial Toxins / analysis
  • Bacterial Toxins / metabolism
  • Biosensing Techniques
  • Electrochemical Techniques*
  • Metal-Organic Frameworks / chemistry
  • Methicillin-Resistant Staphylococcus aureus / isolation & purification
  • Peroxidase / chemistry
  • Peroxidase / metabolism
  • Staphylococcus aureus* / isolation & purification
  • Staphylococcus aureus* / metabolism