Biodistribution studies of nanoparticles using fluorescence imaging: a qualitative or quantitative method?

Area of Science:

• Nanomedicine
• Biomedical Imaging
• Drug Delivery

Background:

• Lipid/Calcium/Phosphate (LCP) nanoparticles are investigated for drug delivery.
• Accurate biodistribution assessment is crucial for nanoparticle-based therapeutics.
• Fluorescence imaging offers a non-invasive method for tracking nanoparticles in vivo.

Purpose of the Study:

• To investigate the biodistribution of LCP nanoparticles in tumor-bearing mice using fluorescence imaging.
• To quantitatively validate fluorescence imaging against radiolabeling methods.
• To assess the accuracy of fluorescence imaging in different tissue environments.

Main Methods:

• LCP nanoparticles loaded with oligonucleotides were prepared.
• Biodistribution was assessed using Texas-Red labeled oligonucleotides, (3)H-labeled oligonucleotides, and (111)In-labeled calcium phosphate.
• Fluorescence imaging and radioactivity measurements were compared.

Main Results:

• Radioactivity signals from (3)H and (111)In showed similar biodistribution, with major accumulation in the liver and spleen.
• Fluorescence imaging predominantly indicated tumor accumulation.
• Tissue absorption and scattering significantly attenuated fluorescence signals in the liver and spleen, affecting quantitative accuracy.

Conclusions:

• Fluorescence imaging can overestimate tumor accumulation of nanoparticles.
• Tissue optical properties significantly impact quantitative fluorescence imaging results.
• Careful consideration of tissue effects is necessary for accurate interpretation of fluorescence imaging data.