Silver nanoparticles-based localized surface plasmon resonance biosensor for Escherichia coli detection

Area of Science:

• Nanotechnology
• Biosensing
• Microbiology

Background:

• Escherichia coli (E. coli) poses significant public health risks.
• Accurate and sensitive detection of E. coli is crucial for food safety and clinical diagnostics.
• Localized Surface Plasmon Resonance (LSPR) biosensors offer potential for rapid and label-free detection.

Purpose of the Study:

• To develop and characterize a novel LSPR biosensor for sensitive E. coli detection.
• To investigate the role of L-Histidine (L-His) functionalized silver nanoparticles (Ag NPs) in enhancing biosensor performance.
• To determine the limit of detection for E. coli using the developed biosensor.

Main Methods:

• Synthesis of Ag NPs using trisodium citrate and L-Histidine.
• Deposition of Ag NPs on gold thin film-coated prisms.
• Utilizing Kretschmann configuration with a He-Ne laser for LSPR measurements.
• Characterization of Ag NPs using electron microscopy and spectroscopy.
• Varying E. coli concentrations to assess sensor response.

Main Results:

• Ag NPs functionalized with L-His exhibited a face-centered cubic crystal structure.
• The L-His-Ag NPs showed characteristic functional groups (OH, CH, C=O bonds).
• The LSPR angle and minimum reflectance significantly shifted upon E. coli detection, confirming the role of L-His-Ag NPs in signal amplification.
• A low limit of detection of 0.47 CFU/mL for E. coli was achieved.

Conclusions:

• L-Histidine functionalization of silver nanoparticles is essential for amplifying the SPR signal.
• The developed LSPR biosensor demonstrates enhanced performance for sensitive E. coli detection.
• This approach holds promise for developing advanced diagnostic tools for bacterial contamination.