A miniaturized germanium-doped silicon dioxide-based surface plasmon resonance waveguide sensor for immunoassay...

Area of Science:

• Optoelectronics
• Biosensing
• Nanotechnology

Background:

• Surface Plasmon Resonance (SPR) is a powerful label-free optical sensing technique.
• Waveguide-based SPR sensors offer enhanced sensitivity and potential for miniaturization.
• Germanium-doped silicon dioxide provides a suitable material for waveguide fabrication.

Purpose of the Study:

• To design and fabricate a novel SPR waveguide immunosensor using germanium-doped silicon dioxide.
• To investigate the sensor's performance using glycerol calibration standards and biomolecular interactions.
• To evaluate the integration of the sensor with a lateral flow nitrocellulose strip for potential point-of-care applications.

Main Methods:

• Fabrication of a waveguide sensor with SiO(2) substrate, Ge-SiO(2) channel guide, and gold film.
• Characterization using a portable spectrophotometer and micro-positioner.
• SPR spectral shift measurements with glycerol standards and immunoassay targets (Protein A, mAb ALV-J, ALVs).

Main Results:

• Glycerol calibration demonstrated a resonance wavelength shift from 628 to 758 nm with refractive index changes.
• Immunoassays showed distinct wavelength shifts: 4.17 nm (Protein A), 3.03 nm (mAb ALV-J), and 2.18 nm (ALVs).
• Successful demonstration of SPR dynamic interaction in 4 minutes with integrated nitrocellulose strip.

Conclusions:

• The developed SPR waveguide immunosensor is effective for detecting biomolecular interactions.
• Integration with a nitrocellulose strip enhances sample handling and facilitates portable diagnostic applications.
• This technology holds promise for point-of-care diagnostic systems.