New Model for Quantifying the Nanoparticle Concentration Using SERS Supported by Multimodal Mass Spectrometry.

Area of Science:

• Nanotechnology
• Spectroscopy
• Analytical Chemistry

Background:

• Surface-enhanced Raman scattering (SERS) is crucial for studying biological mechanisms.
• Absolute quantitation of nanoparticles using SERS remains a significant challenge.
• Accurate nanoparticle quantification is vital for understanding biological processes.

Purpose of the Study:

• To develop a novel 2D quantitation model for SERS.
• To calibrate SERS response against absolute SERS nanotag concentration.
• To enable accurate nanoparticle quantification in biological applications.

Main Methods:

• Developed a novel printing approach for gelatin-based calibration standards with SERS nanotags (gold nanoparticles and 1,2-bis(4-pyridyl)ethylene).
• Utilized single particle inductively coupled plasma mass spectrometry (spICP-MS) for nanotag characterization (Au mass and particle number concentration).
• Employed laser ablation ICP-TOF-MS imaging for distribution analysis and SERS mapping with an "active-area" approach for calibration.

Main Results:

• Demonstrated homogeneous distribution of SERS nanotags in printed standards (RSD < 14%).
• Established a linear response of ¹⁹⁷Au with increasing nanotag concentration (R² = 0.99634).
• Validated a novel calibration model correlating SERS response to absolute Au concentration and particle number concentration.

Conclusions:

• The developed 2D quantitation model enables accurate SERS nanotag quantification.
• This breakthrough facilitates quantitative SERS imaging in biological contexts.
• Potential to correlate nanoparticle concentration with biological responses for disease mechanism elucidation.