Tunable Au-Ag nanobowl arrays for size-selective plasmonic biosensing

Area of Science:

• Nanotechnology
• Biosensing
• Surface Chemistry

Background:

• Localized surface plasmon resonance (LSPR) biosensing faces selectivity challenges in complex biological samples.
• Shape complementarity on nanoparticle surfaces can introduce an additional layer of selectivity.
• Nanoparticle design is crucial for improving biosensor performance in biological solutions.

Purpose of the Study:

• To fabricate substrate-bound gold-silver (Au-Ag) nanobowl arrays for enhanced biosensing.
• To investigate the size-selective detection capabilities of these nanobowl arrays using LSPR and surface-enhanced Raman spectroscopy (SERS).
• To demonstrate the utility of nanobowl arrays for differentiating large analytes in biological solutions.

Main Methods:

• Fabrication of Au-Ag nanobowl arrays via galvanic ion replacement of silver nanodisk arrays.
• Utilized localized surface plasmon resonance (LSPR) spectroscopy to monitor analyte binding.
• Employed surface-enhanced Raman spectroscopy (SERS) for high-sensitivity analyte detection.

Main Results:

• Nanobowl arrays exhibited significantly enhanced LSPR and SERS responses for small analytes that could enter the nanobowls.
• Analytes too large to access the interior of the nanobowls showed diminished LSPR and SERS responses.
• Demonstrated size-dependent analyte detection, confirming the shape-complementarity effect.

Conclusions:

• Au-Ag nanobowl arrays provide a versatile platform for size-selective biosensing.
• This approach overcomes selectivity limitations in LSPR-based biosensing for complex biological samples.
• The technology holds promise for size determination and differentiation of large biological entities like viruses and cells.