Cytokeratins Biosensing Using Tilted Fiber Gratings

Area of Science:

• Photonics and Optical Sensing
• Biomedical Engineering
• Materials Science

Background:

• Optical fiber gratings are established biosensors, often enhanced by metal coatings for plasmonic effects.
• Current methods typically require metal films for surface plasmon resonance-based biosensing.
• There is a need for label-free biosensing platforms that utilize intrinsic fiber properties.

Purpose of the Study:

• To investigate the intrinsic properties of tilted fiber Bragg gratings (TFBGs) for label-free biosensing.
• To develop a metal-free optical fiber sensor for real-time biomarker detection.
• To evaluate different surface functionalization strategies for enhanced sensitivity.

Main Methods:

• Utilizing bare TFBGs operating at near-infrared wavelengths.
• Immobilizing bioreceptors directly onto the silica fiber surface.
• Testing electrostatic adsorption as a functionalization method for antibodies against cytokeratins.
• Monitoring guided cladding modes near the cut-off region for signal detection.

Main Results:

• Demonstrated label-free detection of cytokeratins without metal coatings.
• Identified electrostatic adsorption of antibodies as the most reliable functionalization strategy.
• Achieved a limit of detection as low as 14 pM for cytokeratins.
• Showcased the modal properties of TFBGs for biodetection.

Conclusions:

• Bare TFBGs offer significant potential for label-free biosensing by leveraging their intrinsic modal properties.
• Electrostatic adsorption provides an effective and reliable method for antibody immobilization on silica surfaces.
• This metal-free approach advances real-time biodetection capabilities in optical fiber sensing.