Cortisol AuPd plasmonic unclad POF biosensor.

Area of Science:

• Biosensing
• Optical Sensors
• Analytical Chemistry

Background:

• Cortisol detection is crucial for diagnosing various health conditions.
• Existing biosensors often face challenges with sensitivity, selectivity, and cost.
• Surface Plasmon Resonance (SPR) offers a label-free detection method with high sensitivity.

Purpose of the Study:

• To develop and test a novel cortisol immunosensor.
• To enhance sensitivity and selectivity using SPR on a plastic optical fiber (POF).
• To evaluate the sensor's performance for cortisol detection in biological samples.

Main Methods:

• Fabrication of an unclad POF coated with a gold/palladium (AuPd) alloy.
• Functionalization of the AuPd surface with anti-cortisol antibodies.
• Detection of cortisol via antibody-antigen binding causing a shift in the SPR wavelength.
• Testing across a range of cortisol concentrations (0.005–10 ng/mL).

Main Results:

• The SPR-based POF immunosensor exhibited a high sensitivity with a total wavelength shift of 15 nm.
• A low limit of detection (LOD) of 1 pg/mL was achieved for cortisol.
• Excellent selectivity was demonstrated, with a 15-fold lower response to hCG compared to cortisol at high concentrations.

Conclusions:

• The developed SPR-based POF cortisol immunosensor is highly sensitive and selective.
• The sensor offers a low-cost, straightforward, and effective method for cortisol detection.
• This technology holds significant potential for applications in various biological and medical fields.