Background:
Nanoparticle imaging and the imaging of the release of the loaded material from a nanoparticle system have attracted great attention in recent years. If the release of loaded molecules from delivery vehicles could be monitored reliably in vivo, it would speed up the development of drug delivery systems remarkably.
Methods:
Here we test a system that uses indocyanine green (ICG) as a fluorescent agent for studying release kinetics in vitro and in vivo of a lipid iron nanoparticle delivery system. The ICG spectral properties like its concentration, sensitivity and its fluctuations of absorption and emission wavelengths of the fluorescence can be utilized for gathering information about the change of the ICG surroundings.
Results:
We have found that the absorption, fluorescence, and photoacoustic spectra of the ICG in lipid iron nanoparticles differ from the spectra of ICG in the pure water and in plasma. We followed the ICG containing liposomal nanoparticle uptake into the squamous carcinoma cells (SCC) under a fluorescence microscopy and into SCC tumor in the nude mice orthotopic xenografts model under a surgical microscope.
Conclusion:
Absorption and emission properties of ICG in different solvent environment, like in plasma and human serum albumin, differ from those in aqueous solution. Photoacoustic spectral imaging confirmed a peak shift towards longer wavelengths and an intensity increase of ICG when bound to lipid. The SCC cells showed that the ICG containing liposomes bind to cell surface but are not internalized in the SCC-9 cells in 30 minutes’ incubation. We also showed here that ICG containing liposomal nanoparticles can be traced under a surgical camera in vivo in orthotopic SCC xenografts in mice.
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