Biodistribution Studies of Nanoparticles Using Fluorescence Imaging: A Qualitative or Quantitative Method?
The biodistribution of Lipid/Calcium/Phosphate (LCP) nanoparticles (NPs) in tumor-bearing mice was investigated using fluorescence imaging. A quantitative validation of this method was done by 3H and 111In labeling of the nanoparticles.
The biodistribution of LCP NPs containing oligonucleotides was investigated using three different probes: Texas-Red labeled oligonucleotides, 3H-labeled oligonucleotides, and 111In-labled calcium phosphate.
A discrepancy was found between the radioactivity and the fluorescence signals. Signals from 3H and 111In exhibited very similar distribution patterns, suggesting that liver and spleen were the major accumulation sites. However, fluorescence imaging indicated that tumor accumulation was predominant. We further confirmed that the fluorescence signals in both liver and spleen were greatly attenuated compared with those in the tumor due to the intrinsic tissue absorption and scattering. Near-infrared (NIR) dye Cy5.5 also suffered from the same problem, in that the quantitative data from whole organs was dramatically affected by absorption and scattering properties of the tissue.
Careful attention must be paid to the quantification and interpretation of fluorescence imaging measurements when comparing different tissues.
KEY WORDSbiodistribution fluorescence imaging nanoparticle quantitation
- 4.Beverly MB. Applications of mass spectrometry to the study of siRNA. Mass Spectrom Rev. 30(6):979–98. Epub 2010/03/05.Google Scholar
- 7.Hilderbrand SA, Weissleder R. Near-infrared fluorescence: application to in vivo molecular imaging. Curr Opin Chem Biol.14(1):71-9. Epub 2009/11/03.Google Scholar
- 8.Li J, Yang Y, Huang L. Calcium phosphate nanoparticles with an asymmetric lipid bilayer coating for siRNA delivery to the tumor. J Control Release. Epub 2011/11/08.Google Scholar
- 10.Abdelmawla S, Guo S, Zhang L, Pulukuri SM, Patankar P, Conley P, et al. Pharmacological characterization of chemically synthesized monomeric phi29 pRNA nanoparticles for systemic delivery. Mol Ther: The Journal of the American Society of Gene Therapy. 2011;19(7):1312–22. Epub 2011/04/07.CrossRefGoogle Scholar