Localized surface plasmon resonance sensors based on wavelength-tunable spectral dips

Area of Science:

• Nanotechnology
• Plasmonics
• Chemical Sensing

Background:

• Localized surface plasmon resonance (LSPR) sensors offer high sensitivity for chemical and biosensing.
• Conventional LSPR sensors require monodisperse nanoparticles for specific wavelength monitoring.
• Synthesizing monodisperse nanoparticles is a critical and often challenging step.

Purpose of the Study:

• To develop LSPR sensors capable of operating at arbitrary wavelengths without requiring monodisperse nanoparticles.
• To enable wavelength selection post-synthesis through photoexcitation.
• To enhance sensitivity and cost-effectiveness in LSPR-based sensing platforms.

Main Methods:

• Photocatalytic deposition of polydisperse silver nanospheroids/nanorods onto TiO2.
• Formation of absorption dips at desired wavelengths via photoexcitation.
• Characterization of dip wavelength shifts in response to refractive index changes.

Main Results:

• Achieved LSPR sensor operation at arbitrary wavelengths through preirradiation.
• Demonstrated linear redshift of absorption dips with refractive index changes.
• Observed a linear increase in refractive index sensitivity with dip wavelength, reaching 356 nm RIU⁻¹ at 1832 nm.
• Successfully applied the dip-based sensor to detect biotin-streptavidin binding.

Conclusions:

• The developed system allows for tunable wavelength operation in LSPR sensors.
• This method bypasses the need for monodisperse nanoparticle synthesis.
• The sensor system shows potential for miniaturized, cost-effective, and highly sensitive biosensing.