Noncovalently Modified Carbon Nanotubes with Carboxymethylated Chitosan: A Controllable Donor-Acceptor Nanohybrid

We report here the modification of multiwalled carbon nanotubes (MWNTs) with a kind of polysaccharide, carboxymethylated chitosan (cmCs), and their potential usage as donor-acceptor nanohybrids. The modified composites (cmCs/MWNTs) were characterized by high-resolution TEM, FT-IR, TGA and time-resolved spectroscopy. The time-resolved spectroscopic experiments revealed that interfacial electron transfer readily takes place between MWNTs and surface immobilized cmCs chains. The forward electron transfer is fast (< 20 ns) while the backward recombination is slow. The recombination process strongly depends on the chain length of carboxylmethylated chitosan, i.e. a shorter recombination lifetime (~1.1 μs) for the shorter-chain cmCs coated MWNTs against that of the longer-chain cmCs coated MWNTs (~3.5 μs). The results demonstrated that the cmCs/MWNTs composite may be applied as a controllable donor-acceptor nanohybrid

Laser photolysis study of anthraquinone in binary mixtures ofionic liquid [bmim][PF6] and organic solvent

Photochemical properties of the ionic liquid (RTIL) 1-butyl-3-methylimidazoliumhexafluorophosphate [bmim][PF6] and its binary mixed solutions with organic solvent(DMF and MeCN) were investigated by laser photolysis at an excitation wavelength of 355nm, using anthraquinone (AQ) as a probe molecule. It was indicated that the triplet excitedstate of AQ (3AQ*) can abstract hydrogen from [bmim][PF6]. Moreover, along with thechange of the ratio of RTIL and organic solvent, the reaction rate constant changes regularly.Critical points were observed at volume fraction VRTIL = 0.2 for RTIL/MeCN and VRTIL =0.05 for RTIL/DMF. For both systems, before the critical point, the rate constant increasesrapidly with increasing VRTIL; however, it decreases obviously with VRTIL after the criticalpoint. We conclude that the concentration dependence is dominant at lower VRTIL, while theviscosity and phase transformation are dominant at higher VRTIL for the effect of ionic liquidon the decay of rate constant

Effect of silkworm peptide on inducting M1 type polarization and Th1 activation via TLR2‐induced MyD88‐dependent pathway

The aim of this study was to explore immune activity and molecular mechanism of silkworm peptide. The cell subsets induced by silkworm peptides were detected by flow cytometry. The IFN‐γ and IL‐4 levels in CD4+ cells were measured by ELISA. TLR2 mRNA expression in mouse CD4+ T cells was detected by qRT‐PCR. Western blot was used to detect the protein expression levels of MyD88 and p‐IκB. The growth rate of Lewis lung cancer xenografts in mice of the medium‐dose group was significantly reduced, and the tumor volume was significantly smaller than that of the control group on the 14th day. The relative vitality values of spleen lymphocytes in the medium‐dose and high‐dose groups were higher than the control group. The IFN‐γ levels in the medium‐dose and high‐dose groups were significantly higher than the control group. The levels of IL‐4 were no significant change among different groups. Compared with the control group, different doses of silkworm peptide groups could increase the levels of NO, IL‐6, IL‐12, and IL‐1β. Compared with the control group, the protein expression levels of MyD88 and p‐IκB in 10 μg/ml group and 20 μg/ml groups were significantly increased compared with the control group. Silkworm peptide could induce Th1 activation and M1 type polarization, which was dose‐dependent and was relative to the effect of silkworm peptide on inhibiting tumor growth. Silkworm peptide could directly induce M1 type polarization and Th1 activation via TLR2‐induced MyD88‐dependent pathway in vitro

International Journal of Molecular Sciences

Laser photolysis study of anthraquinone in binary mixtures of ionic liquid [bmim][PF6] and organic solven

Laser photolysis study of anthraquinone in binary mixtures ofionic liquid [bmim][PF6] and organic solvent

Photochemical properties of the ionic liquid (RTIL) 1-butyl-3-methylimidazoliumhexafluorophosphate [bmim][PF6] and its binary mixed solutions with organic solvent(DMF and MeCN) were investigated by laser photolysis at an excitation wavelength of 355nm, using anthraquinone (AQ) as a probe molecule. It was indicated that the triplet excitedstate of AQ (3AQ*) can abstract hydrogen from [bmim][PF6]. Moreover, along with thechange of the ratio of RTIL and organic solvent, the reaction rate constant changes regularly.Critical points were observed at volume fraction VRTIL = 0.2 for RTIL/MeCN and VRTIL =0.05 for RTIL/DMF. For both systems, before the critical point, the rate constant increasesrapidly with increasing VRTIL; however, it decreases obviously with VRTIL after the criticalpoint. We conclude that the concentration dependence is dominant at lower VRTIL, while theviscosity and phase transformation are dominant at higher VRTIL for the effect of ionic liquidon the decay of rate constant

Applicability Analysis of GF-2PMS and PLANETSCOPE Data for Ground Object Recognition in Karst Region

Remote sensing image with high spatial and temporal resolution is very important for rational planning and scientific management of land resources. However, due to the influence of satellite resolution, revisit period, and cloud pollution, it is difficult to obtain high spatial and temporal resolution images. In order to effectively solve the “space–time contradiction” problem in remote sensing application, based on GF-2PMS (GF-2) and PlanetSope (PS) data, this paper compares and analyzes the applicability of FSDAF (flexible spatiotemporal data fusion), STDFA (the spatial temporal data fusion approach), and Fit_FC (regression model fitting, spatial filtering, and residual compensation) in different terrain conditions in karst area. The results show the following. (1) For the boundary area of water and land, the FSDAF model has the best fusion effect in land boundary recognition, and provides rich ground object information. The Fit_FC model is less effective, and the image is blurry. (2) For areas such as mountains, with large changes in vegetation coverage, the spatial resolution of the images fused by the three models is significantly improved. Among them, the STDFA model has the clearest and richest spatial structure information. The fused image of the Fit_FC model has the highest similarity with the verification image, which can better restore the coverage changes of crops and other vegetation, but the actual spatial resolution of the fused image is relatively poor, the image quality is fuzzy, and the land boundary area cannot be clearly identified. (3) For areas with dense buildings, such as cities, the fusion image of the FSDAF and STDFA models is clearer and the Fit_FC model can better reflect the changes in land use. In summary, compared with the Fit_FC model, the FSDAF model and the STDFA model have higher image prediction accuracy, especially in the recognition of building contours and other surface features, but they are not suitable for the dynamic monitoring of vegetation such as crops. At the same time, the image resolution of the Fit_FC model after fusion is slightly lower than that of the other two models. In particular, in the water–land boundary area, the fusion accuracy is poor, but the model of Fit_FC has unique advantages in vegetation dynamic monitoring. In this paper, three spatiotemporal fusion models are used to fuse GF-2 and PS images, which improves the recognition accuracy of surface objects and provides a new idea for fine classification of land use in karst areas

Molecular dynamics simulation study on the binding mechanism between carbon nanotubes and RNA-dependent RNA polymerase

Carbon nanotubes (CNTs) have potential prospects in disease treatment, so it is of great significance to study CNTs as the possible inhibitors of RNA-dependent RNA polymerase (RdRp). Through the way of using the RdRp of SARS-COV-2 as a model, five armchair single-walled carbon nanotubes (SWCNTs) (namely Dn, which stands for CNTs (n, m = n), n = 3–7) and RdRp have been selected to study the interactions by means of molecular docking and molecular dynamics simulation. After five SWCNT-RdRp complex systems have been subjected to the molecular dynamics simulations of 100 ns, and Molecular Mechanics Poisson − Boltzmann Surface Area (MMPBSA) has been used to calculate the binding free energy, it is found that the binding free energy of the D6 system (-189.541 kJ/mol) is significantly higher than that of the other four systems, and most of the amino acids with strong positive effects on binding are usually basic amino acids. What’s more, in the further investigation of the specific interaction mechanism between CNT (6,6) and RdRp, it is revealed that the three amino acid residues LYS545, ARG553 and ARG555 located in the nucleoside triphosphate (NTP) entry channel all have strong effects. In addition, it is also observed that when ARG555 has been inserted into SWCNT, a stable structure will be formed, which will break the original NTP entry channel structure and inhibit virus replication. Therefore, it can be concluded that certain specific types of SWCNT, such as CNT (6,6), could be potential small molecule inhibitors in the treatment of coronavirus. Communicated by Ramaswamy H. Sarma</p

Molecular Insights into the Electric Double Layers of Ionic Liquids on Au(100) Electrodes

The electric double layer structure and differential capacitance of single crystalline Au(100) electrodes in the ionic liquid 1-butyl-3-methyl-imidazolium hexafluorophosphate are investigated using molecular dynamics simulations. Results show strong adsorption on the electrode surface. The potential of zero charge (pzc) and maxima of differential capacitance are strongly dependent on the adsorption layer structure. At potentials near the pzc, cations and anions adjacent to the electrode surface are coadsorbed on the same screening layer. This strong adsorption layer results in overscreening effects on the compact layer and induces both a bell-shaped differential capacitance curve and a positive pzc. Moreover, the potential required for transition from overscreening to overcrowding is about 4.0 V. This transition potential may be attributed to the higher interaction energy between the Au(100) electrode and ions compared with the binding energy in our cation–anion system