Gold Nanostar Spatial Distribution Impacts the Surface-Enhanced Raman Scattering Detection of Uranyl on Amidoximated...

Area of Science:

• Materials Science
• Analytical Chemistry
• Nanotechnology

Background:

• Developing sensitive and accurate methods for detecting uranium(VI) oxide (uranyl) is crucial for environmental monitoring and nuclear safety.
• Plasmonic sensors offer high sensitivity but often face challenges with reproducibility and quantification accuracy.
• Gold nanostars exhibit unique optical properties that can be leveraged for enhanced spectroscopic detection.

Purpose of the Study:

• To develop a user-friendly and highly accurate surface-enhanced Raman scattering (SERS) based sensor for the quantitative detection of uranyl species.
• To investigate the correlation between the plasmonic properties of gold nanostars and SERS intensities for uranyl detection.
• To optimize sensor fabrication and measurement protocols to minimize sampling bias and enhance measurement precision.

Main Methods:

• Fabrication of amidoximated polyacrylonitrile (AO PAN) electrospun polymer films functionalized for uranyl capture.
• Two-step deposition of carboxylated gold nanostars onto the functionalized polymer films.
• Utilizing spatially resolved localized surface plasmon resonance (LSPR) and SERS spectroscopy for analysis.
• Employing an inverted drop-coating geometry for nanostar deposition and coffee ring analysis.

Main Results:

• Plasmonic properties of gold nanostars directly correlate with SERS intensities for uranyl.
• Second-derivative analysis of LSPR spectra accurately quantifies local nanostar density, reducing background variations.
• Uranyl signals become independent of nanostar concentration at densities between 140-200 pM·cm.
• Estimated Gibbs free energy of uranyl adsorption to carboxylated nanostars is 8.4 ± 0.2 kcal/mol.
• Demonstrated a linear dynamic range from ~0.3 to 3.4 μg U/mg polymer with signal variations of 10% or less.

Conclusions:

• The developed sensor demonstrates uniform plasmonic activity and quantitative uranyl detection through spatially resolved spectroscopy.
• The approach reduces dependence on user expertise and sampling region selection, paving the way for user-friendly SERS sensors.
• This composite nanomaterial sensor interface offers a promising platform for sensitive and precise uranyl detection.