Polarization modulated spectroscopic ellipsometry-based surface plasmon resonance biosensor for E. coli K12...

Area of Science:

• Biomedical Engineering
• Optoelectronics
• Biosensing Technology

Background:

• Surface plasmon resonance (SPR) is a label-free optical sensing technique.
• Phase-sensitive SPR methods typically employ complex optical setups.
• Sensitive detection of microorganisms is crucial for diagnostics and environmental monitoring.

Purpose of the Study:

• To develop a simpler optical setup for sensitive microorganism detection using SPR.
• To apply polarization modulated spectroscopic ellipsometry for phase-sensitive SPR measurements.
• To demonstrate the detection of Escherichia coli (E. coli) using the developed system.

Main Methods:

• Utilized polarization modulated spectroscopic ellipsometry with a fast electro-optic phase modulator (beta barium borate crystal).
• Employed Kretschmann configuration for surface plasmon resonance excitation.
• Functionalized a gold surface with anti-E. coli antibodies for specific bacteria capture.

Main Results:

• Achieved a refractive index resolution of 1.0 x 10^-6 RIU.
• Demonstrated a limit of detection of 50 CFU/mL for E. coli K12.
• The developed system shows performance comparable to more complex SPR detection methods.

Conclusions:

• Polarization modulated spectroscopic ellipsometry offers a simplified yet sensitive approach for SPR-based biosensing.
• The method is effective for detecting microorganisms like E. coli.
• Future work includes optical model development and application to other biological targets.