Demonstration of a Label-Free and Low-Cost Optical Cavity-Based Biosensor Using Streptavidin and C-Reactive Protein.

Area of Science:

• Biomedical Engineering
• Optical Biosensing
• Point-of-Care Diagnostics

Background:

• Current point-of-care (POC) diagnostics often require complex sample preparation and lack sensitivity.
• Label-free biosensing methods offer advantages by eliminating the need for secondary labels, simplifying detection.
• Optical cavity-based biosensors (OCBs) present a promising platform for sensitive and cost-effective biosensing.

Purpose of the Study:

• To develop and validate a cost-effective, label-free optical cavity-based biosensor (OCB) for point-of-care (POC) applications.
• To optimize the OCB's optical cavity structure for enhanced sensitivity and fluid control.
• To determine the limit of detection (LOD) for streptavidin and C-reactive protein (CRP) using the developed OCB.

Main Methods:

• Fabrication of an OCB using low-cost components and simple processes.
• Optimization of the optical cavity structure and utilization of polymer swelling for fine-tuning.
• Label-free detection experiments using streptavidin and C-reactive protein (CRP) with differential detection.
• Determination of LOD through serial dilution experiments and triplicate measurements.

Main Results:

• The OCB demonstrated a limit of detection (LOD) of 1.35 nM for streptavidin.
• The OCB successfully detected C-reactive protein (CRP) with an LOD of 377 pM.
• All measurements were performed using a small sample volume (15 µL) within 30 minutes.

Conclusions:

• The developed OCB is a sensitive, cost-effective, and rapid biosensor suitable for POC applications.
• Further optimization could potentially reduce the LOD to the femto-molar range.
• The OCB shows significant potential as a versatile platform for various diagnostic targets.