Highly Excretable Gold Supraclusters for Translatable In Vivo Raman Imaging of Tumors

Area of Science:

• Biomedical Imaging
• Nanotechnology
• Spectroscopy

Background:

• Raman spectroscopy offers high specificity for in vivo imaging.
• Surface-enhanced Raman scattering (SERS) using large gold nanoparticles improves sensitivity but poses excretion challenges.
• Limitations in nanoparticle biodegradability hinder clinical translation of Raman imaging.

Purpose of the Study:

• To develop novel Raman-active gold nanostructures that are biodegradable and excretable.
• To achieve sensitive in vivo Raman imaging with improved safety profiles.
• To demonstrate the potential of these nanostructures for preclinical and clinical applications.

Main Methods:

• Fabrication of Raman-active metallic gold supraclusters with high loading of Raman dyes.
• Assessment of Raman scattering properties, including pH-responsiveness.
• Evaluation of biodegradability, excretion pathways, and biodistribution in mice.
• In vivo Raman imaging of acidic tumors in a preclinical mouse model.

Main Results:

• Gold supraclusters exhibited bright, pH-responsive Raman scattering comparable to large SERS nanoparticles.
• Supraclusters demonstrated efficient dissociation into smaller, excretable nanoclusters.
• 73% of administered supraclusters were excreted from mice within 4 months, unlike persistent large gold nanoparticles.
• Successful in vivo Raman imaging of acidic tumors was achieved.

Conclusions:

• Biodegradable and excretable gold supraclusters offer a promising alternative for in vivo Raman imaging.
• These nanostructures overcome the safety concerns associated with large, non-excretable nanoparticles.
• The developed supraclusters hold significant potential for advancing clinical applications of Raman spectroscopy.