We investigate the encapsulation in hybridosomes®, a type of capsules unique regarding their structure and method of elaboration. Hybridosomes® are made of a single shell of inorganic nanoparticles ...(~5 nm) crosslinked with a polymer and are easily obtained via spontaneous emulsification in a ternary mixture THF/water/butylated hydroxytoluene (BHT). Our main finding is that an exceptionally high concentration of a hydrophobic model dye can be loaded in the hybridosomes®, up to 0.35 mol.L−1 or equivalently 170 g.L−1 or 450,000 molecules/capsule. The detailed investigation of the encapsulation mechanism shows that the dye concentrates in the droplets during the emulsification step simultaneously with capsule formation. Then it precipitates inside the capsules during the course of solvent evaporation. In vitro fluorescence measurements show that the nano-precipitated cargo can be transferred from the core of the hybridosomes® to the membrane of liposomes. In vivo studies suggest that the dye diffuses through the body during several days. The released dye tends to accumulate in body-fat, while the inorganic nanoparticles remain trapped into the liver and the spleen macrophages.
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•The Ouzo effect enables high loading of Hybridosomes (hybrid capsule).•The cargo is nanoprecipitated within the core of Hybridosomes.•The cargo is released to the body while the capsule is captured by the macrophages.
Lipid nanovesicles associated with bioactive phytochemicals from spruce needle homogenate (here called nano-sized hybridosomes or nanohybridosomes, NSHs) were considered.
We formed NSHs by mixing ...appropriate amounts of lecithin, glycerol and supernatant of isolation of extracellular vesicles from spruce needle homogenate. We visualized NSHs by light microscopy and cryogenic transmission electron microscopy and assessed them by flow cytometry, dynamic light scattering, ultraviolet-visual spectroscopy, interferometric light microscopy and liquid chromatography-mass spectrometry.
We found that the particles consisted of a bilayer membrane and a fluid-like interior. Flow cytometry and interferometric light microscopy measurements showed that the majority of the particles were nano-sized. Dynamic light scattering and interferometric light microscopy measurements agreed well on the average hydrodynamic radius of the particles R
(between 140 and 180 nm), while the concentrations of the particles were in the range between 10
and 10
/mL indicating that NSHs present a considerable (more than 25%) of the sample which is much more than the yield of natural extracellular vesicles (EVs) from spruce needle homogenate (estimated less than 1%). Spruce specific lipids and proteins were found in hybridosomes.
Simple and low-cost preparation method, non-demanding saving process and efficient formation procedure suggest that large-scale production of NSHs from lipids and spruce needle homogenate is feasible.
Glioblastoma remains a cancer for which the effectiveness of treatments has shown little improvement over the last decades. For this pathology, multiple therapies combining resection, chemotherapy ...and radiotherapy remain the norm. In this context, the use of high-Z nanoparticles such as gold or hafnium to potentiate radiotherapy is attracting more and more attention. Here, we evaluate the potentiating effect of hollow shells made of gold and iron oxide nanoparticles (hybridosomes®) on the radiotherapy of glioblastoma, using murine GL261-Luc+ brain tumor model. While iron oxide seems to have no beneficial effect for radiotherapy, we observe a real effect of gold nanoparticles—despite their low amount—with a median survival increase of almost 20% compared to radiotherapy only and even 33% compared to the control group. Cellular and in vivo studies show that a molecule of interest nano-precipitated in the core of the hybridosomes® is released and internalized by the surrounding brain cells. Finally, in vivo studies show that hybridosomes® injected intra-tumorally are still present in the vicinity of the brain tumor more than 5 days after injection (duration of the Stupp protocol's radiation treatment). Interestingly, one mouse treated with radiotherapy in the presence of gold-containing hybridosomes® survived 78 days. Monitoring of the tumoral growth of this long-term survivor using both MRI and bioluminescence revealed a decrease of the tumor size after treatment. These very encouraging results are a proof-of-concept that hybridosomes® are really effective tools for the development of combined therapies (chemo-radiotherapy).
Legend: Intratumoral injection of iron oxide–gold nanocapsules (hybridosomes®) with radiotherapy increases the survival of brain tumor-bearing mice. The bioluminescence can be monitored as the tumoral cells express luciferase. Display omitted
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