Effects of Raman Labeling Compounds on the Stability and Surface-Enhanced Raman Spectroscopy Performance of Ag...

Area of Science:

• Nanomaterials Science
• Spectroscopy
• Analytical Chemistry

Background:

• Surface-enhanced Raman spectroscopy (SERS) tagging using silica@silver (SiO₂@Ag) nanoparticles offers high SERS activity and ease of handling for applications like SERS imaging and immunoassays.
• A key challenge is the structural instability of silver nanoparticles (Ag NPs) on SiO₂ surfaces due to Ostwald ripening, leading to inconsistent SERS signals and reduced usability.
• Existing research has focused on stabilizing individual Ag NPs, but strategies for stabilizing SiO₂@Ag NPs specifically for SERS tagging remain underexplored.

Purpose of the Study:

• To enhance the stability of SiO₂@Ag nanoparticles as SERS tagging materials by preventing structural deformation.
• To investigate the efficacy of Raman labeling compounds (RLCs) in stabilizing SiO₂@Ag NPs against environmental factors.
• To identify an optimal RLC for creating robust and reliable SERS tags.

Main Methods:

• SiO₂@Ag nanoparticles were synthesized and subsequently coated with various Raman labeling compounds (RLCs).
• The structural stability of the modified nanoparticles (SiO₂@Ag@RLC-Pre NPs) was evaluated under different conditions (e.g., pH, temperature) over a 2-month period.
• The SERS signal consistency and stability of the optimized SERS tags were assessed.

Main Results:

• 4-mercaptobenzoic acid (4-MBA) was identified as the most effective RLC, significantly enhancing the structural stability of SiO₂@Ag NPs for at least 2 months.
• The SiO₂@Ag@4-MBA NPs demonstrated superior stability compared to unmodified SiO₂@Ag NPs under various pH and temperature conditions.
• The developed SERS tags exhibited high stability and consistent SERS signal output.

Conclusions:

• The incorporation of a Raman labeling compound, specifically 4-MBA, effectively prevents structural deformation in SiO₂@Ag NPs, addressing the Ostwald ripening issue.
• SiO₂@Ag@4-MBA NPs represent a promising SERS-tagging material with enhanced stability and signal consistency.
• These stable SERS tags have broad potential applications in SERS-based assays and imaging due to their improved reliability.