Graphene oxide functionalized long period grating for ultrasensitive label-free immunosensing

Area of Science:

• Biophotonics
• Nanomaterials
• Biosensing

Background:

• Graphene oxide (GO) nanosheets offer a high surface-to-volume ratio and excellent optical/biochemical properties, making them ideal for bioaffinity binding interfaces.
• Developing stable and repeatable GO deposition techniques is crucial for reliable biosensor fabrication.

Purpose of the Study:

• To develop an ultrasensitive, label-free immunosensor using GO-functionalized dual-peak long period gratings (dLPG) for antibody-antigen detection.
• To investigate a novel GO deposition method for enhanced biosensor performance and durability.

Main Methods:

• Fabrication of dLPG biosensors functionalized with GO nanosheets using a combined chemical-bonding and physical-adsorption technique.
• Characterization of GO surface morphology using Atomic Force Microscopy, Scanning Electron Microscopy, and Raman Spectroscopy.
• Immobilization of IgG onto the GO-dLPG surface via EDC/NHS chemistry for real-time immunosensing of anti-IgG.

Main Results:

• The GO-dLPG biosensor exhibited a 200% increase in refractive index sensitivity compared to non-coated dLPG.
• Achieved an ultrahigh sensitivity with a limit of detection of 7 ng/mL for anti-IgG, 10-fold better than non-coated dLPG.
• Demonstrated excellent reusability through a simple regeneration procedure.

Conclusions:

• The GO-dLPG biosensor provides an ultrasensitive platform for label-free immunosensing.
• This technology holds significant potential for applications in food safety, environmental monitoring, and clinical diagnostics.