Enantioselective Molecular Detection by Surface Enhanced Raman Scattering at Chiral Gold Helicoids on Grating...

Area of Science:

• Plasmonics
• Chiral Nanotechnology
• Spectroscopy

Background:

• Surface-enhanced Raman scattering (SERS) offers advantages for molecular detection and enantioselective discrimination.
• Current SERS methods often lack versatility and require analyte-specific anchors for chiral recognition.
• Developing adaptable SERS techniques for distinguishing molecular configurations is crucial.

Purpose of the Study:

• To propose and validate a versatile SERS approach for enantioselective recognition using helicoid-shaped chiral gold nanoparticles.
• To investigate the role of plasmon coupling and chiral near-field interactions in SERS-based enantioseparation.
• To demonstrate the broad applicability of the method for various chiral molecules.

Main Methods:

• Fabrication of ordered arrays of helicoid-shaped chiral gold nanoparticles on a gold grating surface.
• Utilizing plasmon coupling between nanoparticle multimers and the grating for enhanced SERS.
• Employing model chiral compounds (naproxen, propranolol, penicillamine enantiomers) for testing.
• Conducting numerical simulations to understand electric field and optical helicity effects.

Main Results:

• Achieved homogeneous distribution of chiral plasmonic hot spots, enhancing SERS response.
• Demonstrated clear enantioselective SERS recognition of naproxen enantiomers based on gold helicoid chirality.
• Validated the universality of the approach with propranolol and penicillamine enantiomers.
• Numerical simulations elucidated the contribution of intensified local electric fields and optical helicity.

Conclusions:

• The proposed method enables enantioselective SERS recognition by exciting chiral plasmonic near-fields that interact with analyte chirality.
• This approach obviates the need for enantioselective entrapment, offering greater versatility than previous methods.
• The technique is applicable to a broad range of chiral molecules, not limited to specific classes.