Sugar–Lectin Interactions for Direct and Selective Detection of Escherichia coli Bacteria Using QCM Biosensor

Gaddi B. Eshun, Heather A. Crapo, Idris Yazgan, Lauren Cronmiller, Omowunmi A. Sadik

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Pathogenic Escherichia coli (E. coli) remains a safety concern in the preservation and quality of green leafy vegetables. Sugar–lectin interactions provide a reliable, specific, and effective sensing platform for the detection of bacteria as compared to the tedious conventional plate counting technique. Herein, we present the synthesis of 4-(N-mannosyl) benzoic acid (4-NMBA) and 4-thiophenyl-N-mannose (4-TNM) via a two-step reductive amination for the detection of E. coli using a quartz crystal microbalance (QCM) biosensor. The 4-NMBA was synthesized with mannose and para-aminobenzoic (4-PBA), while the 4-TNM was synthesized with mannose and 4-aminophenyl disulfide (4-AHP) using water and acetic acid in a 1:1 ratio. The resultant structure of mannose derivatives (4-NMBA and 4-TNM) was characterized and confirmed using analytical tools, such as Mass Spectrometer, SEM, and FTIR. The choice of ligands (mannose derivatives) is ascribed to the specific recognition of mannose to the FimH lectin of the type 1 pilus of E. coli. Furthermore, the 4-PBA and 4-AHP conjugated to mannose increase the ligand affinity to FimH lectins. The setup of the QCM biosensor was composed of modification of the crystal surface and the covalent attachment of ligands for the detection of E. coli. The piezoelectric effect (frequency shift of the quartz) was proportional to the change in mass added to the gold crystal surface. Both the 4-NMBA- and 4-TNM-coated QCM sensors had a limit of detection of 3.7 CFU/mL and 6.6 CFU/mL with a sensitivity of 2.56 × 103 ng/mL and 8.99 × 10−5 ng/mL, respectively, within the dynamic range of 103 to 106 CFU/mL. This study demonstrates the application of ligand-coated QCM biosensors as a cost-effective, simple, and label-free technology for monitoring pathogenic bacteria via molecular interactions on crystal surfaces.

Original languageEnglish (US)
Article number337
Issue number3
StatePublished - Mar 2023

All Science Journal Classification (ASJC) codes

  • Analytical Chemistry
  • Biotechnology
  • Biomedical Engineering
  • Instrumentation
  • Engineering (miscellaneous)
  • Clinical Biochemistry


  • E. coli
  • FimH
  • bacterial enumeration
  • ligands
  • quartz crystal microbalance
  • selectivity
  • sensor


Dive into the research topics of 'Sugar–Lectin Interactions for Direct and Selective Detection of Escherichia coli Bacteria Using QCM Biosensor'. Together they form a unique fingerprint.

Cite this