Development of a mass-producible on-chip plasmonic nanohole array biosensor.

Area of Science:

• * Plasmonics
• * Nanotechnology
• * Biosensing

Background:

• * Development of sensitive and mass-producible bioaffinity sensors is crucial for diagnostics.
• * Existing plasmonic devices often require complex fabrication or lack sensitivity for aqueous samples.
• * Tuning optical properties of plasmonic nanostructures is key to enhancing detection capabilities.

Purpose of the Study:

• * To develop a cost-effective, mass-producible polymer-based plasmonic device for biological sample analysis.
• * To optimize the plasmonic device for enhanced sensitivity to refractive index changes.
• * To demonstrate the device's capability for detecting specific biomarkers in aqueous samples.

Main Methods:

• * Fabrication of a circular nanohole array in a polymer film using nanoimprint lithography.
• * Deposition of a gold thin film via electron beam deposition.
• * Optimization of gold film thickness and nanohole depth for maximum spectral shift.
• * Finite-difference time-domain (FDTD) simulations to validate experimental results.
• * Integration of the plasmonic device with a microfluidic channel for sample delivery.
• * Detection of Tumor Necrosis Factor-alpha (TNF-α) using immunochemical reactions and colloidal gold amplification.

Main Results:

• * Optimized device exhibited maximum dip shift, indicating high sensitivity to refractive index changes.
• * FDTD simulations showed good agreement with experimental reflection spectra.
• * Nanohole periodicity was adjusted for measurements in the visible wavelength region, suitable for aqueous samples.
• * A detection limit of 21 ng/mL for TNF-α was achieved using colloidal gold labeling.

Conclusions:

• * The developed polymer-based plasmonic device is mass-producible and highly sensitive.
• * The device is suitable for detecting biomarkers in aqueous biological samples.
• * This technology offers a promising platform for developing advanced bioaffinity sensors.