Vector Beam-Enhanced Raman Decodes DNA Nucleobases

Area of Science:

• Spectroscopy and Analytical Chemistry
• Biophysical Chemistry
• Nanotechnology

Background:

• Challenges in DNA Raman analysis include strong backbone signals, spectral overlap, and background noise.
• Existing methods struggle with selective detection of DNA nucleobases.
• Label-free optical methods are needed for specific DNA nucleobase identification.

Purpose of the Study:

• To develop a surface-enhanced Raman scattering (SERS) method for overcoming limitations in DNA nucleobase Raman analysis.
• To achieve selective enhancement of DNA nucleobase signals and suppression of background noise.
• To enable label-free optical identification of specific DNA nucleobases.

Main Methods:

• Employing a k-space filter-assisted radial vector beam (RVB) coupled with gold nanospheres (AuNPs).
• Utilizing a spatial frequency-modulated RVB to excite AuNPs and generate a localized plasmonic field.
• Leveraging orientation-dependent near-field selection based on plasmonic field and vibrational polarizability projections.

Main Results:

• Effective suppression of DNA backbone signals (900-1250 cm-1) by up to 90%.
• Clearer assignment of nucleobase-related Raman bands (1350-1500 cm-1) facilitated by density functional theory (DFT).
• Accurate identification and decoupling of overlapping spectral peaks through combined SERS and DFT analysis.

Conclusions:

• The proposed SERS method with RVB and AuNPs provides a physical mechanism for selective enhancement and noise suppression.
• This approach enables label-free optical detection and identification of specific DNA nucleobases.
• The technique offers improved sensitivity and specificity for DNA analysis.