A Self-Referenced Diffraction-Based Optical Leaky Waveguide Biosensor Using Photofunctionalised Hydrogels.

Area of Science:

• Biomaterials Science
• Optical Biosensing
• Nanotechnology

Background:

• Label-free optical biosensors are crucial for detecting analytes in real-world samples.
• Environmental fluctuations and non-specific binding often compromise sensor accuracy.
• Existing referencing methods struggle with complex sample matrices and field applications.

Purpose of the Study:

• To develop a novel self-referenced diffraction-based leaky waveguide (LW) biosensor.
• To utilize photofunctionalisable hydrogels for creating integrated sensor and reference regions.
• To enhance the accuracy and reliability of label-free biosensing in complex samples.

Main Methods:

• Fabrication of a ~2 µm thin film of photofunctionalisable hydrogel on a leaky waveguide.
• Covalent attachment of a biotinylated photocleavable linker to chitosan.
• Selective removal of streptavidin using 365 nm light to create patterned sensor and reference regions.
• Differential measurements between sensor and reference regions for analyte detection.

Main Results:

• Achieved selective protein patterning on the hydrogel surface via photocleavage.
• Demonstrated significant reduction of environmental and non-specific effects (~98-99%).
• Successfully measured analyte concentrations (biotin protein A, IgG) with enhanced accuracy.

Conclusions:

• The developed self-referenced LW biosensor effectively mitigates environmental and non-specific interferences.
• Combining photofunctionalisable hydrogels with diffraction-based LWs offers a robust platform for label-free biosensing.
• This technology enables accurate sample analysis outside laboratory settings, addressing real-world challenges.