Gold Nanoraspberries for Surface-Enhanced Raman Scattering: Synthesis, Optimization, and Characterization

Area of Science:

• Nanotechnology
• Surface-enhanced Raman scattering (SERS)
• Biomedical applications

Background:

• Surface-enhanced Raman scattering (SERS) is a powerful technique for molecular detection, but challenges remain in synthesizing bright gold nanoparticles and selecting optimal Raman labels.
• Understanding the influence of nanoparticle shape and dispersion stability in physiological media is crucial for developing effective SERS-based diagnostic tools.

Purpose of the Study:

• To synthesize gold nanoraspberries (AuNRB) and compare their physicochemical properties and SERS performance against gold nanospheres (AuNS).
• To investigate the dispersion stability of AuNRB and AuNS in various physiological media (ultrapure water, PBS, FBS).
• To evaluate the SERS and surface-enhanced resonance Raman scattering (SERRS) efficiency using nonresonant (BPE, BPT) and resonant (IR820) reporters.

Main Methods:

• Synthesis of AuNRB using HEPES buffer at room temperature.
• Characterization of gold nanoparticles (AuNRB and AuNS) including size, ζ-potential, and UV-vis absorption.
• Dispersion stability tests in ultrapure water, PBS, and FBS.
• SERS/SERRS measurements using BPE, BPT, and IR820 as reporter molecules.

Main Results:

• AuNRB and AuNS exhibited highest stability in ultrapure water; aggregation was observed in PBS.
• Protein corona formation in FBS led to increased particle size and a shift in surface plasmon absorbance.
• AuNRB consistently outperformed AuNS in SERS efficiency across all tested reporters.
• The resonant reporter IR820 yielded a significantly higher SERS signal compared to nonresonant reporters.

Conclusions:

• AuNRB are a promising nanoparticle platform for enhanced SERS applications due to their superior performance over AuNS.
• The resonant reporter IR820, being FDA-approved, presents a strong candidate for future in vivo SERS applications.
• Nanoparticle shape, dispersion stability, and reporter molecule properties significantly impact SERS efficacy.