RSC Advances最新文献

Biobased, DNA delivery vectors have been synthesized with a core motif composed of 2,5-bishydroxymethylfuran (BHMF) readily available from an important biomass feedstock 5-hydroxymethyl furfural (HMF). To generate the product, BHMF was first converted to 2,5-furan bishydroxymethyl diacrylate (2,5-FDA), which was later conjugated with different types of secondary amines. Rich in tertiary nitrogen, these oligomeric FDA-amino esters demonstrated stable electrostatic interactions with negatively charged plasmid DNA in an aqueous environment. We evaluated synthetic routes toward these plasmid DNA-binding amino esters (pFASTs), identified their nanoscale features, and attempted to establish their structure–property relationship in the context of the DNA delivery. Our preliminary studies show that the pFASTs formed stable complexes with the plasmid DNA. Dynamic light scattering indicated that the DNA polyplexes of pFASTs have hydrodynamic diameters within the size range of 100–150 nm with a surface charge (ζ-potential) ranging from −10 to +33 mV, depending on pFAST type. These oligomeric amino esters rich in furan motif were also found to successfully transfect the GFP-expressing plasmid DNA intracellularly. Collectively, this study establishes a new route to produce DNA transfection agents from sustainable resources that can be used for transferring genetic materials for humans, veterinary, and agrochemical purposes.

Below a diameter of approximately 28 nm, the surface crystal structure of anatase titania is known to change. These changes include surface bond lengths and crystal lattice parameter expansion/contractions. Concurrent with these structure changes, the materials point of zero charge (PZC) has been observed to shift toward lower pH values. Therefore, the objective of this work was to determine if a correlation exists between these known structural changes and the shift in the materials PZC values with decreasing particle size. To achieve this a method was developed to identify and minimize the effect of all known variables, save particle size, affecting the materials pH_PZC. This led to the discovery of two regions for point of zero charge. Above the average spherical primary particle diameter ≅ 29 nm for anatase titania, denoted as Region I, PZC values remain constant. In Region I the materials surface crystal structure and properties were also found to remain constant. Below the average spherical primary particle diameter ≅29 nm is the second zone, defined as Region II, where pH_PZC values decrease almost linearly. An examination of possible surface structure factors and properties responsible for the shift in these PZC values (Region II) identified three underlying causes. These being changes in the materials band gap (i.e. surface bond lengths), lattice parameters and bond ionic content.

In this work, we simulated water molecules confined in carbon, boron nitride (BN), and silicon carbide (SiC) nanotubes with similar sizes. We also simulated water molecules confined between parallel graphene, BN, and SiC surfaces in two cases: (a) a similar geometric surface density of water of 0.177/Ų, in which the number of gas molecules was 18% of the total water molecules, and (b) a similar density profile of water of 0.04–0.05 dalton per ų. To examine H₂ hydrate formation, we added guest H₂ molecules to the confined water molecules in the nanotube and surface systems. We analyzed the formed shapes, adsorption energies, radial distribution functions (RDFs), and self-diffusion coefficients of the confined molecules in gas hydrate formation. Our results showed that a more ordered heptagonal ice nanotube was formed in the BN nanotube than that in the other systems. After the addition of H₂ molecules in the different nanotubes, some of the H₂ molecules occupied the wall of the ice nanotube and some of them positioned in the hollow space. Although gas hydrates were created in all surface systems, ordered gas hydrate shapes were formed only in the graphene system. The adsorption energy for guest H₂ molecules between the different surfaces was negative, which means that the formation of H₂ hydrates between these surfaces is a spontaneous process (unlike that in the nanotube systems). According to RDF results, the BN nanotube and graphene surfaces are proper systems to form more ordered H₂ hydrate structures. The confined water molecules have much higher diffusion coefficients in the BN nanotube and graphene surfaces than in the other systems. The F₄ parameter also substantiated hydrate formation in the different nanostructures. In a new configuration of BN and SiC systems with density profiles similar to that of the graphene system, the H₂ hydrate was not formed completely as in the case of the graphene system. H₂ hydrates formed in the new BN and SiC surfaces were less than those formed in the primary structures (with a geometrical density similar to that of the graphene system) and the graphene system.

Rapid industrialization, urbanization, and human activities in catchments have presented a significant global challenge in removing heavy metal contaminants from wastewater. Here, a study was conducted to synthesize a nano-magnetic dendrimer based on a trimesoyl core that can be easily separated from the environment using an external magnet (Fe₃O₄@NR-TMD-G1, Fe₃O₄@NR-TMD-G2). The synthesized structure was characterized using various conventional techniques such as Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), powder X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX), thermogravimetric analysis (TGA), vibrating sample magnetometry (VSM), and Brunauer–Emmett–Teller surface area analysis (BET). The prepared adsorbent showed good binding ability and excellent adsorption efficiency toward Pb(II) and Cd(II) metal ions from aqueous media (98.5%, 93.6%). The effect of different conditions including pH, adsorbate concentration, adsorbent dosage, isotherm, kinetics, and adsorption mechanism was considered. The highest adsorption efficiency was achieved at 25 °C and pH 4 using 0.08 g of Fe₃O₄@NR-TMD-G1, within 25 minutes for Pb(II) and 120 minutes for Cd(II), respectively. Batch adsorption experiments revealed that Fe₃O₄@NR-TMD-G1 was more effective in removing Pb(II) and Cd(II) compared to Fe₃O₄@NR-TMD-G2, with maximum capacities of 130.2 mg g⁻¹ and 57 mg g⁻¹, respectively. The adsorption process followed the Langmuir isotherm with a high correlation coefficient (R² = 0.9952, 0.9817) and non-linear pseudo-second-order kinetic model. Density functional theory (DFT) analysis indicated that the adsorbent transferred electrons to Pb(II) and Cd(II), forming stable chelates on the nanostructure surface. The heavy metal ions could be adsorbed by coordination to the heteroatoms of the nanostructure and also by electrostatic interactions. The recycled hybrid nanomaterial was dried and applied to different adsorption–desorption tests and the desorption efficiency was found to be 98%. So, the newly synthesized dendritic magnetic nanostructure demonstrated significant potential in efficient removal of metal ions from water and wastewater, highlighting its importance in addressing the global challenge of heavy metal contamination.

Developing versatile sorption materials for radionuclides (e.g. iodine) capture has been a critical goal in nuclear energy and environmental science. At the same time, covalent organic frameworks (COFs), on account of their high porosity and functional scaffolds, have opened up a new way to develop adsorbents in recent years. Herein, two kinds of COF materials containing thiophene (TAPT-COF and TAB-COF), as iodine sorbents, are designed and synthesized by Schiff base reaction. Among them, TAB-COF has a higher surface area (TAPT-COF: 1141 m² g⁻¹, TAB-COF: 1378 m² g⁻¹), which is helpful for the physical iodine adsorption. More importantly, the COF backbone is rich in both N and S sites, which is advantageous to the chemical adsorption of iodine. These two features make the two COFs ideal iodine sorption materials. For example, TAB-COF has an excellent gaseous iodine adsorption capacity (2.81 g g⁻¹) and is one of the most efficient iodine adsorption materials. Meanwhile, TAB-COF has an excellent adsorption effect on iodine in the cyclohexane system, which can reach 200 mg g⁻¹. In addition, the DFT calculations proved that both imine N and thiophene S serve as active sites during the iodine adsorption. TAB-COF exposes more active sites on the premise of having a higher surface area, thereby leading to a higher iodine adsorption capacity. The results here indicate improved sorption efficacy by introducing thiophene in COFs for sorption applications in general and especially pave the way for developing stable and effective COF sorbents for iodine capture from various environments.

A soft and hard composite MAO coating was prepared by adding Cu particles to an alkaline phosphate-borate electrolyte to modify the MAO coating on titanium alloy. The effects of Cu particles on the thickness, structural features, and friction characteristics of the MAO coating were investigated. The MAO coating formed in Cu particle-free electrolyte mainly comprised rutile and anatase TiO₂. Cu and CuO were detected in the oxide coatings obtained in the electrolyte with Cu particles. The hardness of the coating prepared in the base electrolyte was approximately 420 HV, whereas that obtained in the electrolyte containing 2 g L⁻¹ Cu particles increased to 470 HV. While the friction coefficient of the base MAO coating exhibited significant fluctuations, the friction coefficient of the MAO coating containing Cu particles remained relatively stable. The MAO coating formed in the electrolyte containing 2 g L⁻¹ Cu particles demonstrated superior frictional performance, exhibiting a value approximately 3.6 times higher than the base coating. Cu particles enter the MAO coating through electrophoresis, mechanical agitation, and micro-melt adsorption to improve the compactness of the coating. Due to the excellent plasticity of Cu, the friction properties of Cu-containing MAO coating were enhanced.

A monochromatic red emitting nonacoordinate organoeuropium complex with the formula [Eu(hfaa)₃(Ph-TerPyr)] (Eu-1) incorporating hexafluoroacetylacetone (hfaa) primary ligands and a tridentate 4′-phenyl-2,2′:6′,2′′-terpyridine (Ph-TerPyr) ancillary ligand has been synthesized. The complex was characterized by analytical and spectroscopic methods, and its structure was established by single crystal X-ray diffraction (SC-XRD) analysis at low temperature, which explicitly confirms that the coordination sphere is composed of a EuO₆N₃ core. Under the UV excitation, Eu-1 displayed typical red emission in solution with a long-excited state lifetime (τ_obs = 1048.06 ± 9.39 μs) with a good photoluminescence quantum yield (Q^L_Eu = 41.14%). We have utilized pump-probe ultrafast transient absorption spectroscopy in tandem with the time-dependent density functional theory (TD-DFT) and the Lanthanide Luminescence Software Package (LUMPAC) to explore the intricate photophysical event that occurs in the vicinity of the ligands of Eu-1 sensitized photoluminescence (PL).

The design of the flow field structure in Proton Exchange Membrane Fuel Cells (PEMFCs) plays a pivotal role in determining their electrochemical performance. This study presents a lattice-based radial flow field configuration designed to improve PEMFC efficiency. The difference between the flow field and the traditional flow field is that the flow field is segmented by a small cylindrical rib instead of a longer rib. The research employs COMSOL Multiphysics simulation software to establish the model of the operating conditions of PEMFCs, focusing on analyzing how the number of rib branches and the minimum rib radius influence the oxygen distribution, water distribution, and pressure drop in the system. The results demonstrate that varying the number of rib branches and the minimum radius of the cylindrical ribs has a pronounced impact on the PEMFC's performance. Furthermore, a comparative analysis of multiple design configurations reveals the optimal operating parameters. Specifically, within a quarter of the computational domain, the configuration featuring a minimum rib radius of 0.135 cm and six rib branches delivers the best electrochemical performance.

Qualitative and quantitative detection of biologically important molecules such as dopamine, thyroxine, hydrogen peroxide, and glucose, using newer and cheaper technology is of paramount importance in biology and medicine. Anion exchange in lead halide perovskites, on account of its good emission yield, facilitates the sensing of these molecules by the naked eye using ultraviolet light. Simple chemistry is used to generate chloride ions from analyte molecules. Dopamine and thyroxine have an amine functional group, which forms an adduct with an equivalent amount of volatile hydrochloric acid to yield chloride ions in solution. The reducing nature of hydrogen peroxide and glucose is used to generate chloride ions through a reaction with sodium hypochlorite in stoichiometric amounts. The emission of CsPbBr₃-coated paper/glass substrates shifts to the blue region in the presence of chloride ions. This helps in the detection of the above biologically important molecules up to parts per million (ppm) levels by employing fundamental chemistry aspects and well-known anion exchange in perovskite nanocrystals. The preparation of better and more efficient sensors, which are predominantly important in science and technology, can thus be achieved by developing the above novel, cost-effective alternative sensing method.

In recent years, binder jetting technology has made significant advances across industries, expanding the range of material options to meet diverse needs. Commonly used binders may leave residues during the sintering process, affecting surface quality and performance, and some may contain harmful substances. Therefore, there is a high demand for binders that are environmentally friendly and easy to remove. This study proposes to use sodium alginate and polyvinylpyrrolidone as additives to prepare starch-based inks that are both environmentally friendly and safe. The effects of additive composition, starch content, dispersant content, and dispersant ratio on the viscosity and stability of starch-based inks were studied. Through performance testing, the particle size, surface tension, rheological properties, and printability of inks with different components were demonstrated. The optimal ink formulation consists of 1 wt% starch and 0.3 wt% additives (30 wt% sodium alginate and 70 wt% PVP). The viscosity reaches 23 mPa s and the stability is excellent. The surface tension of the ink is 69.5 mN m⁻¹, which is slightly higher than the surface tension requirements for the printhead. This article provides a new process route for binder jetting technology and lays the foundation for its application in green and environmental protection.