Graphene is a single layer of sp(2)-bonded carbons that has unique and highly attractive electronic, mechanical, and thermal properties. Consequently, the potential impact of graphene and its derivatives (e.g., graphene oxide, GO) on human and environmental health has raised considerable concerns. In this study, we have carried out a systematic investigation on cellular effects of GO nanosheets and identified the effect of fetal bovine serum (FBS), an often-employed component in cell culture medium, on the cytotoxicity of GO. At low concentrations of FBS (1%), human cells were sensitive to the presence of GO and showed concentration-dependent cytotoxicity. Interestingly, the cytotoxicity of GO was greatly mitigated at 10% FBS, the concentration usually employed in cell medium. Our studies have demonstrated that the cytotoxicity of GO nanosheets arises from direct interactions between the cell membrane and GO nanosheets that result in physical damage to the cell membrane. This effect is largely attenuated when GO is incubated with FBS due to the extremely high protein adsorption ability of GO. The observation of this FBS-mitigated GO cytotoxicity effect may provide an alternative and convenient route to engineer nanomaterials for safe biomedical and environmental applications.
Overproduction of oxidants (reactive oxygen species and reactive nitrogen species) in the human body is responsible for the pathogenesis of some diseases. The scavenging of these oxidants is thought to be an effective measure to depress the level of oxidative stress of organisms. It has been reported that intake of vegetables and fruits is inversely associated with the risk of many chronic diseases, and antioxidant phytochemicals in vegetables and fruits are considered to be responsible for these health benefits. Antioxidant phytochemicals can be found in many foods and medicinal plants, and play an important role in the prevention and treatment of chronic diseases caused by oxidative stress. They often possess strong antioxidant and free radical scavenging abilities, as well as anti-inflammatory action, which are also the basis of other bioactivities and health benefits, such as anticancer, anti-aging, and protective action for cardiovascular diseases, diabetes mellitus, obesity and neurodegenerative diseases. This review summarizes recent progress on the health benefits of antioxidant phytochemicals, and discusses their potential mechanisms in the prevention and treatment of chronic diseases.
The oxidative stress imposed by reactive oxygen species (ROS) plays an important role in many chronic and degenerative diseases. As an important category of phytochemicals, phenolic compounds universally exist in plants, and have been considered to have high antioxidant ability and free radical scavenging capacity, with the mechanism of inhibiting the enzymes responsible for ROS production and reducing highly oxidized ROS. Therefore, phenolic compounds have attracted increasing attention as potential agents for preventing and treating many oxidative stress-related diseases, such as cardiovascular diseases, cancer, ageing, diabetes mellitus and neurodegenerative diseases. This review summarizes current knowledge of natural polyphenols, including resource, bioactivities, bioavailability and potential toxicity.
Both fluorine and ester substituted monothiophene yielded a novel thiophene derivative FE-T. The resulting polymer donor S1 enabled single-junction non-fullerene solar cell with over 16% efficiency.
Various delivery vectors have been integrated within biologically derived membrane systems to extend their residential time and reduce their reticuloendothelial system (RES) clearance during systemic circulation. However, rational design is still needed to further improve the in situ penetration efficiency of chemo-drug-loaded membrane delivery-system formulations and their release profiles at the tumor site. Here, a macrophage-membrane-coated nanoparticle is developed for tumor-targeted chemotherapy delivery with a controlled release profile in response to tumor microenvironment stimuli. Upon fulfilling its mission of tumor homing and RES evasion, the macrophage-membrane coating can be shed via morphological changes driven by extracellular microenvironment stimuli. The nanoparticles discharged from the outer membrane coating show penetration efficiency enhanced by their size advantage and surface modifications. After internalization by the tumor cells, the loaded drug is quickly released from the nanoparticles in response to the endosome pH. The designed macrophage-membrane-coated nanoparticle (cskc-PPiP/PTX@Ma) exhibits an enhanced therapeutic effect inherited from both membrane-derived tumor homing and step-by-step controlled drug release. Thus, the combination of a biomimetic cell membrane and a cascade-responsive polymeric nanoparticle embodies an effective drug delivery system tailored to the tumor microenvironment.
The gut microbiota plays an important role in maintaining intestinal homeostasis. Dysbiosis is associated with intestinal tumorigenesis. Deoxycholic acid (DCA), a secondary bile acid increased by a western diet, correlates with intestinal carcinogenesis. However, evidence relating bile acids, intestinal microbiota and tumorigenesis are limited. In our study, we investigated the effect of DCA on induction of intestinal dysbiosis and its roles in intestinal carcinogenesis. Alteration of the composition of the intestinal microbiota was induced in DCA-treated APC mice, which was accompanied by impaired intestinal barrier, gut low grade inflammation and tumor progression. The transfer of fecal microbiota from DCA-treated mice to another group of Apc mice increased tumor multiplicity, induced inflammation and recruited M2 phenotype tumor-associated macrophages. Importantly, the fecal microbiota transplantation activated the tumor-associated Wnt/β-catenin signaling pathway. Moreover, microbiota depletion by a cocktail of antibiotics was sufficient to block DCA-induced intestinal carcinogenesis, further suggesting the role of dysbiosis in tumor development. Our study demonstrated that alteration of the microbial community induced by DCA promoted intestinal carcinogenesis.
Graphene oxide (GO) is an excellent bacteria-killing nanomaterial. In this work, macroscopic applications of this promising nanomaterial by fixing GO sheets onto cotton fabrics, which possess strong antibacterial property and great laundering durability, are reported. The GO-based antibacterial cotton fabrics are prepared in three ways: direct adsorption, radiation-induced crosslinking, and chemical crosslinking. Antibacterial tests show that all these GO-containing fabrics possess strong antibacterial property and could inactivate 98% of bacteria. Most significantly, these fabrics can still kill >90% bacteria even after being washed for 100 times. Also importantly, animal tests show that GO-modified cotton fabrics cause no irritation to rabbit skin. Hence, it is believed that these flexible, foldable, and re-usable GO-based antibacterial cotton fabrics have high promise as a type of new nano-engineered antibacterial materials for a wide range of applications.
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