Sharif Digital Repository

Single-layer reduced graphene oxide nanoribbons (rGONRs) were obtained through an oxidative unzipping of multi-walled carbon nanotubes and a subsequent deoxygenation by hydrazine and bovine serum albumin. Human mesenchymal stem cells (hMSCs) were isolated from umbilical cord blood and used for checking the concentration- and time-dependent cyto- and geno-toxic effects of the rGONRs and reduced graphene oxide sheets (rGOSs). The cell viability assay indicated significant cytotoxic effects of 10 μg/mL rGONRs after 1 h exposure time, while the rGOSs exhibited the same cytotoxicity at concentration of 100 μg/mL after 96 h. The oxidative stress was found as the main mechanism involved in the... 

Bacterial toxicity of graphene nanosheets in the form of graphene nanowalls deposited on stainless steel substrates was investigated for both Gram-positive and Gram-negative models of bacteria. The graphene oxide nanowalls were obtained by electrophoretic deposition of Mg2+-graphene oxide nanosheets synthesized by a chemical exfoliation method. On the basis of measuring the efflux of cytoplasmic materials of the bacteria, it was found that the cell membrane damage of the bacteria caused by direct contact of the bacteria with the extremely sharp edges of the nanowalls was the effective mechanism in the bacterial inactivation. In this regard, the Gram-negative Escherichia coli bacteria with an... 

Reduced graphene oxide nanoplatelets (rGONPs) were synthesized by sonication of covalently PEGylated GO sheets followed by a chemical reduction using hydrazine and bovine serum albumin. Human mesenchymal stem cells (hMSCs), as a fundamental factor in tissue engineering, were isolated from umbilical cord blood (as a recently proposed source for extracting fresh hMSCs) to investigate, for the first time, the size-dependent cyto- and geno-toxic effects of the rGONPs on the cells. The cell viability test showed significant cell destructions by 1.0 μg/mL rGONPs with average lateral dimensions (ALDs) of 11±4 nm, while the rGO sheets with ALDs of 3.8±0.4 μm could exhibit a significant cytotoxic...