Accessible Sensing Sites in Metal-Insulator-Metal Plasmonic Nanostructure for Biosensing Applications

Area of Science:

• Nanotechnology
• Biomolecular Detection
• Plasmonics

Background:

• Localized surface plasmon resonance (LSPR) is a key technique for sensitive biomolecular detection.
• Metal-insulator-metal (MIM) nanostructures offer high sensitivity due to near-field hotspots but face challenges in analyte-gap accessibility and directed binding.
• Existing methods lack precise control over analyte interaction with high-sensitivity regions.

Purpose of the Study:

• To design and fabricate accessible metal-insulator-metal (MIM) nanostructures for enhanced localized surface plasmon resonance (LSPR) biosensing.
• To develop a method for directing analyte binding specifically to the high-sensitivity gap regions of MIM nanostructures.
• To demonstrate the efficacy of this approach for refractive index sensing.

Main Methods:

• Utilized Finite-Difference Time-Domain (FDTD) simulations to optimize the design of accessible MIM (aMIM) nanostructures (Au-SiO2-Au).
• Fabricated the designed aMIM nanostructures and experimentally validated their refractive index sensitivity.
• Implemented a three-way copatanning strategy using protein-rejecting brush polymers to functionalize nanostructures, enabling site-specific protein coupling within the gaps.

Main Results:

• Successfully designed and fabricated Au-SiO2-Au MIM nanostructures with accessible gaps (aMIM).
• Demonstrated high refractive index sensitivity of the aMIM nanostructures.
• Showcased site-specific binding of streptavidin within the nanostructure gaps using the developed polymer patterning technique.

Conclusions:

• Developed a novel approach for creating accessible MIM nanostructures for LSPR biosensing.
• The site-specific binding strategy enhances the efficiency and specificity of biomolecular detection.
• This method holds significant potential for advancing various biosensing applications requiring high sensitivity and targeted analyte capture.