Magnetic Fe3 O4 @graphene oxide improves the therapeutic effects of embryonic stem cells on acute liver damage.

OBJECTIVE: Acute liver failure is usually associated with inflammation and oxidation of hepatocytes and has high mortality and resource costs. Mesenchymal stem cell (MSCs) has occasionally been reported to have no beneficial effect due to poor transplantation and the survival of implanted cells. Recent studies showed that embryonic stem cell (ESC)-derived MSCs are an alternative for regenerative medicine. On the other hand, graphene-based nanostructures have proven useful in biomedicine. In this study, we investigated whether magnetic graphene oxide (MGO) improved the effects of ESC-MSC conditioned medium (CM) on protecting hepatocytes and stimulating the regeneration of damaged liver cells. MATERIALS AND METHODS: To provide a rat model of acute liver failure, male rats were injected intraperitoneally with carbon tetrachloride (CCl4 ). The rats were randomly divided into six groups, namely control, sham, CCl4 , ESC-MSC-CM, MGO and ESC-MSC-CM + MGO. In the experimental groups, the rats received, depending on the group, 2 ml/kg body weight CCl4 and either ESC-MSC-CM with 5 × 106 MSCs or 300 µg/kg body weight MGO or both. Symptoms of acute liver failure appeared 4 days after the injection. All groups were compared and analysed both histologically and biochemically 4 days after the injection. Finally, the results of ESC-MSC-CM and MSC-CM were compared. RESULTS: The results indicated that the use of MGO enhanced the effect of ESC-MSC-CM on reducing necrosis, inflammation, aspartate transaminase, alanine aminotransferase and alkaline phosphatase in the CCl4 -induced liver failure of the rat model. Also, the expression of vascular endothelial growth factor and matrix metalloproteinase-9 (MMP-9) was significantly upregulated after treatment with MGO. Also, the results showed that the ESC-MSC-CM has more efficient effective compared to MSC-CM. CONCLUSION: Magnetic graphene oxide improved the hepatoprotective effects of ESC-MSC-CM on acute liver damage, probably by suppressing necrosis, apoptosis and inflammation of hepatocytes.

Suspended graphene oxide nanoparticle for accelerated multilayer osteoblast attachment.

Mimicking bone tissues having layered structures is still a significant challenge because of the lack of technologies to assemble osteoblast cell types into bone structures. One of the promising and attractive materials in biomedical and different engineering fields is graphene and graphene-based nanostructures such as graphene oxide (GO) because of their unique properties. In most studies, GO was synthesized using chemical vapor deposition method, and was coated on the substrate. In this study, we proposed a simple technique for assembly of cells that facilitates the construction of osteoblast-like structures using suspended GO synthesized by graphite powder, H2 SO4 , and KMnO4 .Toxicity effects of GO on human mesenchymal stem cells (hMSCs) derived from bone marrow were analyzed. In addition to normal MSCs, toxicity effects of GO on human cancer cell line saos-2 as an abnormal cell line that possess several osteoblastic features, was examined. The attachment and expression of osteoblast cells genes were evaluated after differentiation of MSCs to osteoblast cells in presence of suspended GO by scanning electron microscopy and real time PCR. We found that the toxicity effects of GO are dose dependent and in oseogenic medium containing suspended GO the expression level of osteoblast genes osteopontin and osteocalcin and cell adhesion markers connexin were higher than control group. Interestingly, through this method GO was found to induce multilayer osteoblast cell morphology and enhance the number of cell layer. We expect that the presented method would become a highly useful approach for bone tissue engineering. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 293-303, 2018.

Antimicrobial properties of poly (methyl methacrylate) acrylic resins incorporated with silicon dioxide and titanium dioxide nanoparticles on cariogenic bacteria.

AIM: To assess the effects of adding nano-titanium dioxide (nano-TiO2) and nano-silicon dioxide (nano-SiO2) and their mixture to poly (methyl methacrylate) (PMMA) to induce antimicrobial activity in acrylic resins. MATERIALS AND METHODS: Acrylic specimens in size of 20 mm × 20 mm × 1 mm of 0.5% and 1% of nano-TiO2 (21 nm) and nano-SiO2 (20 nm) and their mixture (TiO2/SiO2 nanoparticles) (1:1 w/w) were prepared from the mixture of acrylic liquid containing nanoparticles and acrylic powder. To obtain 0.5% and 1% concentration, 0.02 g and 0.04 g of the nanoparticles was added to each milliliter of the acrylic monomer, respectively. Antimicrobial properties of six specimens of these preparations, as prepared, were assessed against planktonic Lactobacillus acidophilus and Streptococcus mutans at 0, 15, 30, 45, 60, 75, and 90 min follow-up by broth dilution assay. The specimens of each group were divided into three subgroups: Dark, daylight, or ultraviolet A (UVA). The percent of bacterial reduction is found out from the counts taken at each time point. STATISTICAL ANALYSIS: Data were analyzed using one-way analysis of variance and Tukey's post hoc analysis. RESULTS: Exposure to PMMA containing the nanoparticles reduced the bacterial count by 3.2-99%, depending on the nanoparticles, bacterial types, and light conditions. Planktonic cultures of S. mutans and L. acidophilus exposed to PMMA containing 1% of TiO2/SiO2 nanoparticles showed a significant decrease (P < 0.001) (98% and 99%, respectively) in a time-dependent manner under UVA. The S. mutans and L. acidophilus counts did not significantly decrease in PMMA containing 0.5% nano-TiO2 and PMMA containing 0.5% nano-SiO2 in the dark. No statistically significant reduction (P > 0.05) was observed in the counts of S. mutans and L. acidophilus in PMMA without the nanoparticles exposed to UVA. CONCLUSIONS: PMMA resins incorporated with TiO2/SiO2 nanoparticles showed strong antimicrobial activity against the cariogenic bacteria.

Stabilization of carbenes via α-ylide substitutions: a computational quest for new divalents at DFT.

In our continued quest for novel stable carbenes, silylenes, and germylenes, here we compare and contrast multiplicities and relative stabilities of carbenes affected with four different α-ylides. The latter include carbon, immonium, phosphorus, and sulfur ylides substituted at the alpha positions of carbenes with acyclic, cyclic and cyclicunsaturated structural frameworks. Related thermodynamic data are calculated at B3LYP/6-311++G**//B3LYP/6-31+G* and B3LYP/AUG-cc-pVTZ//B3LYP/6-31+G* levels. Investigations reveal the enlargement of the singlet-triplet energy gaps (ΔΕs-t) in the order of immonium > phosphorus > sulfur > carbon. The observed trend, which is taken as an indication of stability, is thoroughly analyzed by applying appropriate isodesmic reactions which differentiate the substituent effects on each of our singlet or triplet carbene. The effect of unsaturation is also probed in each series of the ylide carbenes. The reactivity of the species is discussed in terms of nucleophilicity and electrophilicity.

The effect of TiO2 and SiO2 nanoparticles on flexural strength of poly (methyl methacrylate) acrylic resins.

PURPOSE: TiO(2) and SiO(2) nanoparticles are products of nanotechnology which have been incorporated to acrylic resins (AR) in order to induce antimicrobial properties. However, as additives they can affect the mechanical properties of the final product. The aim of this study was to survey the effects of TiO(2) and SiO(2) nanoparticles on flexural strength (Fs) of poly (methyl methacrylate) acrylic resins. METHODS: Acrylic specimens (Selecta Plus) in size of 5×10 (±0.2)×3.3 (±0.2)mm were prepared and divided into 7 groups: AR containing nanoTiO(2), SiO(2) and TiO(2) with SiO(2) in two concentration of 1% and 0.5%, in addition to a control group. To prepare nano AR, nanoparticles were added to the monomer. All specimens were stored in 37°C distilled water and underwent Fs test by universal testing machine (Zwick). RESULTS: The maximum mean flexural strength (43.5 MPa) belongs to the control group and AR containing 0.5% of both TiO(2) and SiO(2) demonstrated the minimum mean Fs (30.1 MPa). Resins contained TiO(2), demonstrated lower values of Fs than those contained SiO(2) with the same concentration, but the differences were not significant (P>0.05). CONCLUSION: Incorporation of TiO(2) and SiO(2) nanoparticles into acrylic resins can adversely affect the flexural strength of the final products, and this effect is directly correlated with the concentration of nanoparticles.

Effect of silver nano particles on flexural strength of acrylic resins.

PURPOSE: Poly(methyl methacrylate), PMMA, is widely used for fabrication of removable orthodontic appliances. Silver nano particles (AgNps) have been added to PMMA because of their antimicrobial properties. The aim of this study is to investigate the effect of AgNps on the flexural strength of PMMA. METHODS: Acrylic liquid containing 0.05% and 0.2% AgNps was prepared for two kinds of acrylic resins: Rapid Repair &Selecta Plus. Two groups without AgNps were used as control groups. For each one, flexural strength was investigated via Three Point Bending method for the 15 acrylic blocks. Two-way ANOVA, one way ANOVA and Tukey tests were used for statistical analysis. RESULTS: Rapid Repair without AgNps showed the highest flexural strength. Addition of 0.05% AgNps to Rapid Repair, significantly decreased its flexural strength while, continuing the addition up to 0.2% increased it nearly up to its primary level. In contrast, addition of AgNps to Selecta Plus increased its flexural strength but addition of 0.05% nano particles was more effective than 0.2%. CONCLUSIONS: The effect of AgNps on flexural strength of PMMA depends on several factors including the type of acrylics and the concentrations of nano particles.

The kinetics of interactions between fecapentaene-12 and DNA.

Fecapentaene-12 (Fp-12) is a potent colon cancer mutagen, which interacts with DNA. In this study, the kinetics of its interactions with DNA is investigated. Various pHs are used. Three first-order rates are observed at each pH. This suggests that interaction between Fp-12 and DNA occurs through three different mechanisms.