Graphene (GN) and its derivatives (rGOs) show anticancer properties in glioblastoma multiforme (GBM) cells in vitro and in tumors in vivo. We compared the anti-tumor effects of rGOs with different oxygen contents with those of GN, and determined the characteristics of rGOs useful in anti-glioblastoma therapy using the U87 glioblastoma line. GN/ExF, rGO/Term, rGO/ATS, and rGO/TUD were structurally analysed via transmission electron microscopy, Raman spectroscopy, FTIR, and AFM. Zeta potential, oxygen content, and electrical resistance were determined. We analyzed the viability, metabolic activity, apoptosis, mitochondrial membrane potential, and cell cycle. Caspase- and mitochondrial-dependent apoptotic pathways were investigated by analyzing gene expression. rGO/TUD induced the greatest decrease in the metabolic activity of U87 cells. rGO/Term induced the highest level of apoptosis compared with that induced by GN/ExF. rGO/ATS induced a greater decrease in mitochondrial membrane potential than GN/ExF. No significant changes were observed in the cytometric study of the cell cycle. The effectiveness of these graphene derivatives was related to the presence of oxygen-containing functional groups and electron clouds. Their cytotoxicity mechanism may involve electron clouds, which are smaller in rGOs, decreasing their cytotoxic effect. Overall, cytotoxic activity involved depolarization of the mitochondrial membrane potential and the induction of apoptosis in U87 glioblastoma cells.

Introduction and objective Degradation of the extracellular matrix (ECM) changes the physicochemical properties and dysregulates ECM–cell interactions, leading to several pathological conditions, such as invasive cancer. Carbon nanofilm, as a biocompatible and easy to functionalize material, could be used to mimic ECM structures, changing cancer cell behavior to perform like normal cells. Methods Experiments were performed in vitro with HS-5 cells (as a control) and HepG2 and C3A cancer cells. An aqueous solution of fullerene C 60 was used to form a nanofilm. The morphological properties of cells cultivated on C 60 nanofilms were evaluated with light, confocal, electron and atomic force microscopy. The cell viability and proliferation were measured by XTT and BrdU assays. Immunoblotting and flow cytometry were used to evaluate the expression level of proliferating cell nuclear antigen and determine the number of cells in the G2/M phase. Results All cell lines were spread on C 60 nanofilms, showing a high affinity to the nanofilm surface. We found that C 60 nanofilm mimicked the niche/ECM of cells, was biocompatible and non-toxic, but the mechanical signal from C 60 nanofilm created an environment that affected the cell cycle and reduced cell proliferation. Conclusion The results indicate that C 60 nanofilms might be a suitable, substitute component for the niche of cancer cells. The incorporation of fullerene C 60 in the ECM/niche may be an alternative treatment for hepatocellular carcinoma.

Finding an effective muscle regeneration technique is a priority for regenerative medicine. It is known that the key factors determining tissue formation include cells, capable of proliferating and/or differentiating, a niche (surface) allowing their colonization and growth factors. The interaction between these factors, especially between the surface of the artificial niche and growth factors, is not entirely clear. Moreover, it seems that the use of a complex of complementary growth factors instead of a few strictly defined ones could increase the effectiveness of tissue maturation, including muscle tissue. In this study, we evaluated whether graphene oxide (GO) nanofilm, chicken embryo muscle extract (CEME), and GO combined with CEME would affect the differentiation and functional maturation of muscle precursor cells, as well as the ability to spontaneously contract a pseudo-tissue muscle. CEME was extracted on day 18 of embryogenesis. Muscle cells obtained from an 8-day-old chicken embryo limb bud were treated with GO and CEME. Cell morphology and differentiation were observed using different microscopy methods. Cytotoxicity and viability of cells were measured by lactate dehydrogenase and Vybrant Cell Proliferation assays. Gene expression of myogenic regulatory genes was measured by Real-Time PCR. Our results demonstrate that CEME, independent of the culture surface, was the main factor influencing the intense differentiation of muscle progenitor cells. The present results, for the first time, clearly demonstrated that the cultured tissue-like structure was capable of inducing contractions without externally applied impulses. It has been indicated that a small amount of CEME in media (about 1%) allows the culture of pseudo-tissue muscle capable of spontaneous contraction. The study showed that the graphene oxide may be used as a niche for differentiating muscle cells, but the decisive influence on the maturation of muscle tissue, especially muscle contractions, depends on the complexity of the applied growth factors.

Despite advanced techniques in medicine, breast cancer caused the deaths of 627,000 women in 2018. Melittin, the main component of bee venom, has lytic properties for many types of cells, including cancer cells. To increase its toxic effect, carbon nanoparticles, graphene oxide, pristine graphene, and diamond were used as carriers of melittin to breast cancer cells. To date, the effects of carbon nanoparticles as carriers of melittin on cancer cells have not been studied. The present study was carried out on MCF-7 and MDA-MB-231 cell lines. The investigation consisted of structural analysis of complexes using transmission electron microscopy, zeta potential measurements, evaluation of cell morphology, assessment of cell viability and membrane integrity, investigation of reactive oxygen species production, and investigation of mitochondrial membrane potential. Cell death was examined by flow cytometry and a membrane test for 43 apoptotic proteins. The results indicate that melittin complex with nanographene oxide has a stronger toxic effect on breast cancer cells than melittin alone. Moreover, nanodiamonds can protect cells against the lytic effects of melittin. All complexes reduced, but not completely eliminated the level of necrosis, compared to melittin. Thus, results suggest that the use of carbon nanoparticles as carriers for melittin may find use in medicine in the future.

The physiological process of muscle regeneration is quite limited due to low satellite cell quantity and also the inability to regenerate and reconstruct niche tissue. The purpose of the study was to examine whether a graphene oxide scaffold is able to stimulate myogenic progenitor cell proliferation and the endocrine functions of differentiating cells, and therefore, their active participation in the construction of muscle tissue. Studies were carried out using mesenchymal cells taken from 6-day-old chicken embryos and human umbilical vein endothelial cells (HUVEC) were used to assess angiogenesis. The graphene scaffold was readily colonized by myogenic progenitor cells and the cells dissected from heart, brain, eye, and blood vessels did not avoid the scaffold. The scaffold strongly induced myogenic progenitor cell signaling pathways and simultaneously activated proangiogenic signaling pathways via exocrine vascular endothelial growth factor (VEGF) secretion. The present study revealed that the graphene oxide (GO) scaffold initiates the processes of muscle cell differentiation due to mechanical interaction with myogenic progenitor cell.