Utilizing ICG Spectroscopical Properties for Real-Time Nanoparticle Release Quantification In vitro and In vivo in Imaging Setups

Abstract

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.

Comparison of photoacoustic and fluorescence tomography for the in vivo imaging of ICG-labelled liposomes in the medullary cavity in mice

“…The manufacturing process and properties of the ICG liposomes were previously published [ 28 ], therefore the process will only be briefly described. Liposomes contained of DSPC/cholesterol/SM/DOTAP at 20:30:30:20 mol% (Avanti Polar Lipids, Alabaster, AL, USA) and were filled with ICG (Merck KGaA, Darmstadt, Germany) at a final concentration of 0.33 μg/μl inside the liposome.…”

Imaging Inflammation – From Whole Body Imaging to Cellular Resolution

“…These spatial limitations of the penetration depth are less relevant in small animal imaging, where full 3D tomography can be performed due to the small size of the animals of interest. Clinically approved fluorophores can be sensitive to their environments and give different readings based on their surroundings ( 131 ). At the moment, one brand of 3-D fluorescence optical tomography is available for a small animal.…”

Lipid-Iron Nanoparticle with a Cell Stress Release Mechanism Combined with a Local Alternating Magnetic Field Enables Site-Activated Drug Release

“…This study's purpose was to improve the drug release feature of liposomes by developing a liposomal nanoparticle system (for structure, refer to Figure 1a), which can be weakened at the disease site, thereby enabling the release of the contents in a remote-controlled manner. The cisplatin as well as the fluorescent model for drug the ICG [23] was loaded to these magnetoenzymatic (MESL) liposomes. The size of the liposomes was around 110 nm in both formulations.…”