Morphology and Chemical Purity of Water Suspension of Graphene Oxide FLAKES Aged for 14 Months in Ambient Conditions. A Preliminary Study

Graphene and its derivatives have attracted scientists’ interest due to their exceptional properties, making them alluring candidates for multiple applications. However, still little is known about the properties of as-obtained graphene derivatives during long-term storage. The aim of this study was to check whether or not 14 months of storage time impacts graphene oxide flakes’ suspension purity. Complementary micro and nanoscale characterization techniques (SEM, AFM, EDS, FTIR, Raman spectroscopy, and elemental combustion analysis) were implemented for a detailed description of the topography and chemical properties of graphene oxide flakes. The final step was pH evaluation of as-obtained and aged samples. Our findings show that purified flakes sustained their purity over 14 months of storage.

Gold Nanoparticles and Graphene Oxide Flakes Enhance Cancer Cells' Phagocytosis through Granzyme-Perforin-Dependent Biomechanism

The study aimed to investigate the roles of gold nanoparticles (GNPs) and graphene oxide flakes (GOFs) as phagocytosis enhancers against cancer cells. The nanomaterials were characterized through SEM and UV-VIS absorptions. The GNPs and GOFs increased the macrophages’ phagocytosis ability in engulfing, thereby annihilating the cancer cells in both in vitro and in vivo conditions. The GNPs and GOFs augmented serine protease class apoptotic protein, granzyme, passing through the aquaporin class protein, perforin, with mediated delivery through the cell membrane site for the programmed, calibrated, and conditioned cancer cells killing. Additionally, protease inhibitor 3,4-dichloroisocoumarin (DCI) significantly reduced granzyme and perforin activities of macrophages. The results demonstrated that the GOFs and GNPs increased the activation of phagocytic cells as a promising strategy for controlling cancer cells by augmenting the cell mortality through the granzyme-perforin-dependent mechanism.

Gold Nanoparticles and Graphene Oxide Flakes Synergistic Partaking in Cytosolic Bactericidal Augmentation: Role of ROS and NOX2 Activity

Gold nanoparticles (GNPs) and graphene oxide flakes (GOFs) exerted significantly (p < 0.0001) supportive roles on the phagocytosis bioactivity of the immune cells of phagocytic nature against the Gram-positive and Gram-negative human pathogenic bacteria Staphylococcus aureus and Escherichia coli. Under experimental conditions, upon bacterial exposure, the combined GNPs and GOFs induced significant clearance of bacteria through phagosome maturation (p < 0.0001) from time-points of 6 to 30 min and production of reactive oxygen species (ROS, p < 0.0001) through the NADPH oxidase 2 (NOX2, p < 0.0001)-based feedback mechanism. The effects of the combined presence of GNPs and GOFs on phagocytosis (p < 0.0001) suggested a synergistic action underway, also achieved through elevated signal transduction activity in the bone-marrow-derived macrophages (BMDM, p < 0.0001). The current study demonstrated that GNPs’ and GOFs’ bactericidal assisting potentials could be considered an effective and alternative strategy for treating infections from both positive and negative bacterial strains.