The Application of Ultrasmall Gold Nanoparticles (2 nm) Functionalized with Doxorubicin in Three-Dimensional Normal and Glioblastoma Organoid Models of the Blood-Brain Barrier.

Among brain tumors, glioblastoma (GBM) is very challenging to treat as chemotherapeutic drugs can only penetrate the brain to a limited extent due to the blood-brain barrier (BBB). Nanoparticles can be an attractive solution for the treatment of GBM as they can transport drugs across the BBB into the tumor. In this study, normal and GBM organoids comprising six brain cell types were developed and applied to study the uptake, BBB penetration, distribution, and efficacy of fluorescent, ultrasmall gold nanoparticles (AuTio-Dox-AF647s) conjugated with doxorubicin (Dox) and AlexaFluor-647-cadaverine (AF647) by confocal laser scanning microscopy (CLSM), using a mixture of dissolved doxorubicin and fluorescent AF647 molecules as a control. It was shown that the nanoparticles could easily penetrate the BBB and were found in normal and GBM organoids, while the dissolved Dox and AF647 molecules alone were unable to penetrate the BBB. Flow cytometry showed a reduction in glioblastoma cells after treatment with AuTio-Dox nanoparticles, as well as a higher uptake of these nanoparticles by GBM cells in the GBM model compared to astrocytes in the normal cell organoids. In summary, our results show that ultrasmall gold nanoparticles can serve as suitable carriers for the delivery of drugs into organoids to study BBB function.

Development of triple-functionalized calcium phosphate nanoparticles as an advanced drug delivery system for bone tissue repair.

Introduction: During tissue repair or regeneration, several bioactive molecules are released and interact with each other and act as complex additives or inhibitors for tissue reconstruction. In this study, the bone-healing effects of the combination treatment with tumor necrosis factor-α (TNF-α) inhibition, vascular endothelial growth factor A (VEGF-A) and bone morphogenetic protein-7 (BMP-7) release by gene silencing, and gene transfection with calcium phosphate nanoparticles (CaP) in the rat femoral head was histologically, morphologically, and biochemically evaluated. Methods: A triple-functionalized paste of CaP carrying plasmid DNA encoding for BMP-7 and for VEGF), and siRNA against TNF-α was developed and denoted as CaP3mix. To compare the effects of 3mixCaP, CaP with plasmid DNA encoding BMP-7, VEGF, or siRNA encoding TNF-α was prepared and denoted as CaP/PEI/pBMP-7/SiO2, CaP/PEI/pVEGF/SiO2, or CaP/PEI/siRNA-TNF-α/SiO2, respectively. The bone healing in bone defects in the rat femoral head was investigated after 10 and 21 days of implantation. Results: The levels of bone formation-related markers OCN, Runx2, and SP7 increased at the protein and gene levels in 3mixCaP after 10 days, and 3mixCaP significantly accelerated bone healing compared with the other treatments after 21 days of implantation. Conclusion: The triple-functionalized CaP paste loading plasmid DNA encoding BMP-7 and VEGF and siRNA encoding TNF-α is a promising bioactive material for bone tissue repair.

Uptake of Functional Ultrasmall Gold Nanoparticles in 3D Gut Cell Models.

Ultrasmall gold nanoparticles (2 nm) easily penetrate the membranes of intestinal murine epithelial cells (MODE-K) and colorectal cancer cells (CT-26). They are also taken up by 3D spheroids (400 µm) of these cell types and primary gut organoids (500 µm). In contrast, dissolved dyes are not taken up by any of these cells or 3D structures. The distribution of fluorescent ultrasmall gold nanoparticles inside cells, spheroids, and gut organoids is examined by confocal laser scanning microscopy. Nanoparticles conjugated with the cytostatic drug doxorubicin and a fluorescent dye exhibit significantly greater cytotoxicity toward CT-26 tumor spheroids than equally concentrated dissolved doxorubicin, probably because they enter the interior of a spheroid much more easily than dissolved doxorubicin. Comprehensive analyses show that the cellular uptake of ultrasmall gold nanoparticles occurs by different endocytosis pathways.