Multifunctional Fe3O4@SiO2-Au Satellite Structured SERS Probe for Charge Selective Detection of Food Dyes

Area of Science:

• Materials Science
• Nanotechnology
• Analytical Chemistry

Background:

• Developing multifunctional surface-enhanced Raman scattering (SERS) substrates is crucial for advanced chemical sensing.
• Existing nanofabrication methods face challenges in creating versatile SERS platforms.
• The need for selective detection of analytes in complex mixtures drives innovation in substrate design.

Purpose of the Study:

• To design and fabricate a versatile core-satellite Fe3O4@SiO2-Au (FA) hetero-nanostructure for SERS applications.
• To demonstrate the substrate's capability for charge-selective detection of food dye molecules.
• To investigate the mechanisms underlying SERS enhancement and molecular selectivity.

Main Methods:

• Fabrication of Fe3O4@SiO2-Au (FA) core-satellite hetero-nanostructures.
• Utilized three-dimensional finite difference time domain (FDTD) simulations to optimize nanoparticle gaps.
• Employed layer-by-layer deposition of charged polyelectrolytes for selective adsorption.
• Conducted molecular dynamics (MD) and density functional theory (DFT) calculations to understand interactions.

Main Results:

• Optimizing the gold nanoparticle (Au NP) gap to sub-10 nm significantly enhanced Raman signals.
• The magnetic SERS substrate, functionalized with polyelectrolytes, achieved selective adsorption and detection of oppositely charged food dyes.
• MD simulations indicated high affinity and close proximity (within 20 Å) between the substrate and molecules, contributing to selectivity.
• DFT calculations confirmed charge transfer from food dye molecules to Au NPs through polyelectrolytes.

Conclusions:

• The developed FA hetero-nanostructure serves as a multifunctional SERS platform.
• The substrate enables easy magnetic separation and selective detection of charged molecules.
• This platform offers a promising approach for analyzing complex chemical mixtures.