To enhance efficacy of chemotherapy and achieve real-time imaging of cancer cells, it is crucial to develop nanocarriers with targeted drug delivery capacity and fluorescence property for cancer ...theranostics. Herein, a dual-targeting DNA tetrahedron nanocarrier (MUC1-Td-AS1411) was constructed for breast cancer cell imaging and targeted drug delivery. This nanocarrier consisted of three components: (i) DNA tetrahedron core for multivalent conjugation of function ligands and loading doxorubicin (Dox); (ii) activatable MUC1 aptamer probe (MUC1-probe), formed by the hybridization of MUC1 aptamer sequence with fluorophore extended from one vertex and complementary sequence with quencher, for targeting and imaging MUC1 protein on cytomembrane; (iii) AS1411 aptamer, which was hybridized to the overhang on three vertexes via prolonged sequence, for binding to nucleolin. Firstly, MUC1-probe of this nanocarrier targeted MUC1 protein of MUC1-positive cells, causing a conformational reorganization of MUC1 aptamer, releasing complementary sequence with quencher and leading to fluorescence recovery. Subsequently, after internalizing into cells, AS1411 aptamer moiety of nanocarrier bound to nucleolin selectively, then the whole nanocarrier targeted nucleus and released Dox into nucleus. MUC1-positive cells and MUC1-negative cells could be differentiated by means of fluorescence imaging. Versus free Dox, Dox-loaded MUC1-Td-AS1411 showed lower cytotoxicity to MUC1-negative HL-7702 cells (P < 0.01), approximately equal lethality to sensitive MCF-7 cells (P > 0.05) whereas more effective to doxorubicin-resistant MCF-7 cells (P < 0.01). Therefore, this nanocarrier could be used as a promising candidate for cancer theranostics.
Display omitted
•A dual-targeting DNA tetrahedron nanocarrier was constructed.•This nanocarrier could specifically recognize MUC1-positive cells.•This nanocarrier could minimize toxic side effect and cope with drug resistance.
Contact-electrification is a universal effect for all existing materials, but it still lacks a quantitative materials database to systematically understand its scientific mechanisms. Using an ...established measurement method, this study quantifies the triboelectric charge densities of nearly 30 inorganic nonmetallic materials. From the matrix of their triboelectric charge densities and band structures, it is found that the triboelectric output is strongly related to the work functions of the materials. Our study verifies that contact-electrification is an electronic quantum transition effect under ambient conditions. The basic driving force for contact-electrification is that electrons seek to fill the lowest available states once two materials are forced to reach atomically close distance so that electron transitions are possible through strongly overlapping electron wave functions. We hope that the quantified series could serve as a textbook standard and a fundamental database for scientific research, practical manufacturing, and engineering.
The power conversion efficiency of perovskite polycrystalline thin film solar cells has rapidly increased in recent years, while the stability still lags behind due to its low thermal stability as ...well as the fast ion migration along the massive grain boundaries. Here, stable and efficient lateral-structure perovskite solar cells (PSCs) are achieved based on perovskite single crystals. By optimizing anode contact with a simple surface treatment, the open circuit voltage and fill factor dramatically increase and promote the efficiency of the devices exceeding 11% (0.05 to 1 Sun) compared to that of 5.9% (0.25 Sun) of the best lateral-structure single crystal PSCs previously reported. Devices show excellent operational stability and no degradation observed after 200 h continuous operation at maximum power point under 1 Sun illumination. Devices with scalable architectures are investigated by utilizing interdigital electrodes, which show huge potential to realize low cost and highly efficient perovskite photovoltaic devices.
The power density and durability of fuel cells strongly rely on the properties of high-temperature (100 °C–200 °C) proton exchange membranes (HT-PEMs). Phosphoric acid-doped polybenzimidazole ...(PA-PBI) membranes are one of the most promising materials for HT-PEMs. However, the performance and durability of PA-PBI membranes still need to be improved. In this work, crosslinked branched PBI was chosen as polymer matrix due to its excellent chemical stability and high conductivity. The metal-organic framework (MOF) UiO-66 was introduced to constructed proton transport channels in crosslinked branched PBI composite membranes. As a result, a high proton conductivity (0.100 S cm−1) of the composite membrane at relatively low PA uptake (126%) was obtained and the long-term stability was improved significantly. The best peak power density of 607 mW cm−2 at 160 °C under anhydrous conditions was achieved for the composite membrane-based MEA in a fuel cell test. The fuel cell exhibits excellent durability and only a slight decrease in the load voltage value (36.0 μV h−1) is observed. These results indicate that introducing UiO-66 MOF into cross-linked branched PBI membranes may provide a valid method towards developing high-performance HT-PEMs.
The fuel cell based on the composite membrane exhibits excellent power density under low PA uptake due to efficient proton transport of the membrane. Display omitted
•Proton transport channel was constructed by UiO-66 in the composite membranes.•The composite membranes exhibited high proton conductivity under low PA uptake.•The fuel cell based on the membranes show high power density and long-term stability.
► Chitosan/graphene oxide composites were prepared and used for the adsorption of Au(III) and Pd(II). ► Atomic adsorption spectrophotometer (FAAS) was applied to determine the concentrations of metal ...ions. ► Chitosan/graphene oxide composite with 5wt% GO was found owning the largest adsorption capacity. ► Due to the addition of GO into chitosan, the composites can be used in a larger pH range.
In this work, graphene oxide (GO) was firstly prepared, following by element analysis. Glutaraldehyde cross-linked chitosan (GCCS) and chitosan/graphene oxide (CSGO) composite with three different amounts of GO (5wt%, 10wt% and 15wt%) were also prepared for the adsorption of Au(III) and Pd(II) in aqueous solution. The properties of the adsorbents were investigated by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and surface area analysis. Batch adsorption studies were carried out. The adsorption of Au(III) and Pd(II) onto CSGO composites was optimum at pH 3.0–5.0 for Au(III) and pH 3.0–4.0 for Pd(II), which was much wider than that of GCCS. The adsorption isotherms obeyed the Langmuir isotherm models for the adsorption of Au(III) and Pd(II). Chitosan with 5wt% graphene oxide (CSGO5) composite had the largest adsorption capacity for Au(III) and Pd(II) compared with the other prepared adsorbents, where the maximum adsorption capacity were 1076.649mg/g for Au(III) and 216.920mg/g for Pd(II), respectively. The adsorption kinetics of Au(III) and Pd(II) onto CSGO5 followed a pseudo-second-order kinetic model, indicating that the chemical adsorption was the rate-limiting step. Thermodynamic parameters, such as Gibbs energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°), were calculated, showing that the adsorption of Au(III) and Pd(II) onto CSGO5 were spontaneous, endothermic and feasible. The desorption studies of Au(III) and Pd(II) onto CSGO5 showed that CSGO5 can be used repeatedly without significantly changing its adsorption capacity and desorption percentage after 3cycles. Besides CSGO5 was successfully applied for the determination and separation of Au(III) and Pd(II) in ore samples.
The early-stage (1 h) corrosion behavior of AZ91 alloy before and after microarc oxidation treatment in a 3.5% NaCl solution was revealed using open circuit potential, potentiodynamic polarization, ...electrochemical impedance spectroscopy, and the observations of corroded surfaces at different immersion time (5, 25 and 45 min). The coating offers excellent corrosion resistance for the substrate for 1 h immersion corrosion by serving as a physical barrier. For the alloy, pitting corrosion initiates easily, but propagates difficultly, due to the formation of oxides/hydroxides in the pits. By comparison, the localized corrosion of the coated alloy proceeds continuously via the through pores, and the newly formed corrosion products inside the pores are easily damaged. Based on the electrochemical results, the alloy exhibits quasi-uniform corrosion, and the coated alloy reveals localized corrosion, both of which are under cathodic control.
While low-cost particle sensors are increasingly being used in numerous applications, most of them have no heater or dryer at the inlet to remove water from the sample before measurement. ...Deliquescent growth of particles and the formation of fog droplets in the atmosphere can lead to significant increases in particle number concentration (PNC) and mass concentrations reported by such sensors. We carried out a detailed study using a Plantower PMS1003 low-cost particle sensor, both in the laboratory and under actual ambient field conditions, to investigate its response to increasing humidity and the presence of fog in the air. We found significant increases in particle number and mass concentrations at relative humidity above about 75 %. During a period of fog, the total PNC increased by 28 %, while the PNC larger than 2.5 µm increased by over 50 %. The PM10 concentration reported by the PMS1003 was 46 % greater than that on the standard monitor with a charcoal dryer at the inlet. While there is a causal link between particle pollution and adverse health effects, the presence of water on the particles is not harmful to humans. Therefore, air quality standards for particles are specifically limited to solid particles and standard particle monitoring instruments are fitted with a heater or dryer at the inlet to remove all liquid material from the sample before the concentrations are measured. This study shows that it is important to understand that the results provided by low-cost particle sensors, such as the PMS1003, cannot be used to ascertain if air quality standards are being met.
Display omitted
Marine fouling is one of the major challenges facing humanity in marine industrial production and transport activities. Traditional antifouling coatings use toxic antifouling agents, ...which have not only poor antifouling longevity but also cause serious environmental problems. Humans have discovered that nature's creatures have evolved over a long period of time, optimized their respective anti-fouling strategies, and wanted to seek answers from them to get a near-perfect idea to obtain efficient, long-term, broad-spectrum anti-pollution and eco-friendly anti-pollution strategies. Therefore, more and more scientists are committed to developing green antifouling coatings. This paper summarizes the design strategy of bionic marine antifouling coatings, evaluates the antifouling performance, antifouling mechanism and antifouling effect of the coatings, and summarizes the development trend of bionic antifouling coatings. Finally, we present our views on the challenges of antifouling coatings and provide an outlook on future research directions and prospects.
Graphene oxide (GO) was prepared and characterized by Fourier transform infrared spectrometry (FT-IR) and scanning electron micrographs (SEM). Batch adsorption studies were carried out to investigate ...the adsorption data, including the effects of pH, initial concentration, contact time, and temperature. The adsorption of Au(III), Pd(II), and Pt(IV) was optimum at pH 6.0. The adsorption isotherms all obeyed the Langmuir equation in the case of Au(III), Pd(II), and Pt(IV), and the maximum adsorption capacities were 108.342 mg·g–1, 80.775 mg·g–1, and 71.378 mg·g–1, respectively. The adsorption kinetics of Au(III), Pd(II), and Pt(IV) onto GO followed a pseudosecond-order kinetic model, indicating that the chemical adsorption was the rate-limiting step. Thermodynamic parameters such as Gibbs energy (ΔG o), enthalpy (ΔH o), and entropy (ΔS o) were calculated, indicating that the adsorption were spontaneous, endothermic, and feasible. The desorption studies showed that the best desorption reagents were 0.5 mol·dm–3 thiourea–0.5 mol·dm–3 HCl for Au(III) and 1.0 mol·dm–3 thiourea–0.5 mol·dm–3 HCl for both Pd(II) and Pt(IV).
The peptide WEKPPVSH from walnut protein hydrolyzate was used to evaluate the antioxidant and anti-inflammatory protective effect on lipopolysaccharide (LPS)-activated BV-2 microglia and its possible ...mechanism. The results indicated that WEKPPVSH significantly decreased nitric oxide (NO) and reactive oxygen species (ROS) generation in a dose-dependent manner, and significantly up-regulated superoxide dismutase and catalase activities (P < 0.01). Results of enzyme-linked immunosorbent assay (ELISA) showed that WEKPPVSH significantly mitigated the secretion of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6) (P < 0.01). Immunofluorescence analysis exhibited that WEKPPVSH down-regulated p65 translocation to the cell nucleus. Western blotting showed that WEKPPVSH up-regulated the expression of nuclear factor erythroid 2-related factor (Nrf2) and heme oxygenase-1 (HO-1), and down-regulated the expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), p-IκB/IκB, p-p65/p65 and p-p38/p38. In summary, WEKPPVSH might protect against oxidative stress and inflammation in LPS-stimulated BV-2 microglia by enhancing the Nrf2/HO-1 signaling pathway and blocking the nuclear factor-κB/p38 mitogen – activated protein kinase (NF-κB/p38 MAPK) signaling pathway. The results provided an experimental basis for the research and development of walnut peptide products.
Display omitted
PDF
