Trace-Amount Detection of Chiral Molecules Based on Plasmonic Racemic Arrays Fabricated via Direct Laser Writing

Area of Science:

• Plasmonics
• Chiral sensing
• Nanotechnology

Background:

• Chiral plasmonic structures enhance chiral molecule sensing through superchiral fields.
• Distinguishing molecular chirality from nanostructure response is challenging.
• Existing methods for plasmonic racemic mixtures are complex and costly.

Purpose of the Study:

• To develop a facile and cost-effective method for fabricating plasmonic racemic arrays.
• To enable sensitive detection and discrimination of chiral molecules.
• To create a sensing platform that isolates the molecule's intrinsic chirality.

Main Methods:

• Fabrication of plasmonic racemic arrays using direct laser writing with vector beams.
• Characterization of the arrays' optical properties, focusing on local superchiral fields.
• Application of the arrays for enantiomer discrimination of phenylalanine.

Main Results:

• Successfully fabricated facile, cost-effective, and controllable plasmonic racemic arrays.
• Demonstrated arrays with no inherent circular differential scattering but strong local superchiral fields.
• Achieved a limit of detection (LOD) of 10.0 ± 2.8 μM for phenylalanine enantiomers, significantly lower than conventional circular dichroism spectroscopy.

Conclusions:

• Plasmonic racemic arrays fabricated by direct laser writing offer a superior sensing platform for chiral molecules.
• This method effectively reflects intrinsic molecular chirality, overcoming limitations of previous approaches.
• The technology holds significant promise for biomedical detection and enantioselective drug development.