Determination of the Highly Sensitive Carboxyl-Graphene Oxide-Based Planar Optical Waveguide Localized Surface...

Area of Science:

• Nanotechnology
• Biomedical Engineering
• Materials Science

Background:

• Localized surface plasmon resonance (LSPR) biosensors offer high sensitivity for biomolecular detection.
• Graphene oxide (GO) possesses abundant carboxyl groups, enhancing capture molecule immobilization.
• Optical waveguide (OW) platforms provide a robust base for integrated sensing systems.

Purpose of the Study:

• To develop a highly sensitive, low-cost carboxyl-graphene-oxide-based planar optical waveguide LSPR biosensor (GO-OW LSPR biosensor).
• To enhance the refractive index sensitivity of the biosensor using a silver-coated reflective film.
• To evaluate the biosensor's performance for detecting specific biomolecules, including immunoglobulin G (IgG) and streptavidin.

Main Methods:

• Fabrication of a sensing chip integrating an optical waveguide (OW)-slide glass with a microfluidic-poly (methyl methacrylate) (PMMA) substrate.
• Surface modification of the OW-slide glass with gold nanoparticles (AuNPs) and graphene oxide (GO).
• Utilizing a silver-coated reflective film to amplify refractive index sensitivity.

Main Results:

• The GO-OW LSPR biosensor achieved a refractive index sensitivity of 5.48 RIU⁻¹ and a resolution of 2.52 ± 0.23 × 10⁻⁶ RIU.
• Detection limits for IgG and streptavidin were 23.41 ± 1.54 pg/mL and 5.18 ± 0.50 pg/mL, respectively.
• The biosensor demonstrated good repeatability (CV < 10.6%) and high affinity constants for IgG and streptavidin detection.

Conclusions:

• The developed GO-OW LSPR biosensor is highly sensitive and cost-effective.
• The integration of GO and a silver-coated reflective film significantly enhances sensing performance.
• The biosensor shows potential for detecting low concentrations of small biomolecules.