Gene therapy has arisen as a pioneering technique to treat diseases by direct employment of nucleic acids as medicine. The major historical problem is to develop efficient and safe systems for the ...delivery of therapeutic genes into the target cells. Carbon nanotubes (CNTs) have demonstrated considerable promise as delivery vectors due to their (i) high aspect ratio and (ii) capacity to translocate through plasma membranes, known as the nanoneedle effect. To leverage these advantages, close attention needs to be paid to the physicochemical characteristics of the CNTs used. CNTs with different diameters (thinner and thicker) were treated by chemical oxidation to produce shorter fragments. Rigid (thick) and flexible (thin) CNTs, and their shortened versions, were coated with polyallylamine (ppAA) by plasma-enhanced chemical vapor deposition. The ppAA coating leads to a positively charged CNT surface that is able to electrostatically bind the green fluorescent protein plasmid reporter. This study shows how rigidity and length can affect their (i) behavior in biological media, (ii) ability to transfect in vitro, and (iii) biodistribution in vivo. This study also generates a set of basic design rules for the development of more efficient CNT-based gene-delivery vectors.
Two-dimensional pristine M2X MXenes are proposed as highly active catalytic materials for carbon dioxide (CO2) greenhouse gas conversion into carbon monoxide (CO) on the basis of a multiscale ...modeling approach, coupling calculations carried out in the framework of density functional theory and newly developed kinetic phase diagrams. The extremely facile CO2 conversion into CO leaves the MXene surfaces partially covered by atomic oxygen, recovering its pristine nature by a posterior catalyst regeneration by hydrogen (H2) treatment at high temperatures, with MXenes effectively working as two-step catalysts for the reverse water–gas shift reaction.
The water vapor conductance (GH2O) of the neosauropod eggs from the Lower Cretaceous Sanagasta nesting site in La Rioja Province, Argentina, was examined and compared with other Cretaceous ...Argentinean oological material. The 2900 mgH2O/day·Torr GH2O of the Sanagasta eggshells confirms an extremely moist nesting environment and supports field observations of dug-out nests in a geothermal setting. The observed thinning of the outer eggshell surface during incubation increases gas conductance and concomitantly decreases eggshell mechanical resistance during the late ontogenetic stages, thus facilitating embryonic development and hatching. The Sanagasta and Entre Ríos Province faveoloolithid eggs display the highest and comparable GH2O values and share several morphological and diagenetic characters, indicating comparable nesting strategy in geothermal settings. However, the faveoloolithid Yaminué and La Pampa Province specimens cluster together with lower GH2O values closer to the megaloolithid eggs. The GH2O of the megaloolithid egg Megaloolithus patagonicus was reconsidered and new results are now congruent with other reported megaloolithid GH2O values. Additionally, we hypothesize that Y-shaped pore canals of M. patagonicus, which upper sections reach only the top third or half eggshell thickness and, a wider section in the middle would not compromise the overall egg mechanical resistance like vertical pores connecting directly the outer to the inner eggshell surfaces. Such pore spatial arrangement and geometry would enhance, as the eggshell thins during incubation, a greater GH2O, GO2 and GCO2 and facilitate embryonic development in high moisture nesting contents. Overall, data suggests that neosauropod nesting and brooding behaviors were dependent on elevated moisture nesting environments.
We report on the enhanced terahertz (THz) emission from SI-GaAs and n-GaAs wafer surfaces grown with aluminum nitride (AlN) thin films, by more than a factor of 2 and 4, respectively. This is ...attributed to the increased GaAs surface electric field as confirmed by calculations and photoreflectance measurements. The deposition of AlN on an n-InAs substrate, however, produces no change in the THz emission despite the presence of a strong field as obtained from calculations. These results show that for semiconductors in which the THz radiation is primarily due to drift current, an increase in interface electric field results to an increase in the THz emission. For semiconductors whose primary source of THz radiation is carrier diffusion however, an increase in the interface electric field has a no effect in THz emission intensity.
As a first step to validate the use of carbon nanotubes as novel vaccine or drug delivery devices, their interaction with a part of the human immune system, complement, has been explored. Haemolytic ...assays were conducted to investigate the activation of the human serum complement system via the classical and alternative pathways. Western blot and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) techniques were used to elucidate the mechanism of activation of complement via the classical pathway, and to analyse the interaction of complement and other plasma proteins with carbon nanotubes. We report for the first time that carbon nanotubes activate human complement via both classical and alternative pathways. We conclude that complement activation by nanotubes is consistent with reported adjuvant effects, and might also in various circumstances promote damaging effects of excessive complement activation, such as inflammation and granuloma formation. C1q binds directly to carbon nanotubes. Protein binding to carbon nanotubes is highly selective, since out of the many different proteins in plasma, very few bind to the carbon nanotubes. Fibrinogen and apolipoproteins (AI, AIV and CIII) were the proteins that bound to carbon nanotubes in greatest quantity.
Ursolic acid (UA) is being investigated due to its anti-inflammatory potential, and structural modifications can enhance its biological activities. The aim of this study was to evaluate the ...immunomodulatory effect of the ursolic acid derivatives (UAD) in macrophages and in the carrageenan-induced paw edema model. RAW264.7 cells were cultured in the presence or absence of UA or UAD (1-18). Nitric oxide (NO), nuclear factor kappa B (NF-κB), tumor necrosis factor (TNF), and cellular viability were measured. 30 min before the carrageenan-induced paw edema, the UAD1 and UAD2 (200 mg kg-1) were administered intraperitoneally. The results showed that UAD2-4, UAD7, UAD9-11 had half maximal inhibitory concentration (IC50) greater than 90 µM and were able to reduce NO, NF-κB and TNF production. Moreover, UAD1 and UAD2 reduced paw edema and IL-6 production. In conclusion, the results obtained demonstrated a variation in the response between the derivatives due to the chemical modifications, showing potential to reduce the inflammatory mediators, deserving further investigations.
Four pyrolyzed carbonaceous materials were reacted with 950 ppm of nitric oxide (in N
2) in an entrained flow furnace at temperatures between 800 and 1,000°C. Their apparent reactivities, corrected ...for mass transfer, when calculated on a BET area basis displayed a wide spread of values. However, when recalculated for the surface area estimated for pores greater than 20 nm in size, as measured by mercury porosimetry, far better agreement was obtained. The results are consistent with other data in the literature, for which equivalent surface areas were available.
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