Frontiers of Materials Science最新文献

The in vitro expansion of stem cells is important for their application in different life science fields such as cellular tissue and organ repair. An objective of this paper was to achieve static cell culture in vitro through peptide hydrogel-supported microspheres (MSs). The peptides, with their gel-forming properties, microstructures, and mechanical strengths characterized, were found to have good support for the MSs and to be injectable. The internal structures of poly(L-lactic acid) microspheres (PLLA-MSs) and polystyrene microspheres (PS-MSs) made in the laboratory were observed and statistically analyzed in terms of particle size and pore size, following which the co-cultured MSs with cells were found to have good cell adhesion. In addition, three-dimensional (3D) culturing of cells was performed on the peptide and microcarrier composite scaffolds to measure cell viability and cell proliferation. The results showed that the peptides could be stimulated by the culture medium to self-assembly form a 3D fiber network structure. Under the peptide-MS composite scaffold-based cell culture system, further enhancement of the cell culture effect was measured. The peptide-MS composite scaffolds have great potential for the application in 3D cell culture and in vitro cell expansion.

Zinc-based flow battery is an energy storage technology with good application prospects because of its advantages of abundant raw materials, low cost, and environmental friendliness. The chemical stability of zinc electrodes exposed to electrolyte is a very important issue for zinc-based batteries. This paper reports on details of chemical stability of the zinc metal exposed to a series of solutions, as well as the relationship between the morphological evolution of zinc electrodes and their properties in an alkaline medium. Chemical corrosion of zinc electrodes by the electrolyte will change their surface morphology. However, we observed that chemical corrosion is not the main contributor to the evolution of zinc electrode surface morphology, but the main contributor is the Zn/Zn²⁺ electrode process. The morphological evolution of zinc electrodes was controlled by using ionic liquids, 1-ethyl-3-methylimidazolium acetate (EMIA), and 1-propylsulfonic-3-methylimidazolium tosylate (PSMIT), and the electrode performance was recorded during the morphological evolution process. It was observed that the reversible change of zinc electrode morphology was accompanied by better electrode performance.

Porous flower-like SnO₂/CdSnO₃ microstructures self-assembled by uniform nanosheets were synthesized using a hydrothermal process followed by calcination, and the sensing performance was measured when a gas sensor, based on such microstructures, was exposed to various volatile organic compound (VOC) gases. The response value was found to reach as high as 100.1 when the SnO₂/CdSnO₃ sensor was used to detect 100 ppm formaldehyde gas, much larger than those of other tested VOC gases, indicating the high gas sensitivity possessed by this sensor especially in the detection of formaldehyde gas. Meanwhile, the response/recovery process was fast with the response time and recovery time of only 13 and 21 s, respectively. The excellent gas sensing performance derive from the advantages of SnO₂/CdSnO₃, such as abundant n–n heterojunctions built at the interface, high available specific surface area, abundant porosity, large pore size, and rich reactive oxygen species, as well as joint effects arising from SnO₂ and CdSnO₃, suggesting that such porous flower-like SnO₂/CdSnO₃ microstructures composed of nanosheets have a high potential for developing gas sensors.

The choice of cathode and anode materials for electrochromic devices plays a key role in the performance of electrochromic smart windows. In this research, WO₃/Ag and TiO₂/NiO composite thin films were separately prepared by the hydrothermal method combined with electrodeposition. The electrochromic properties of the single WO₃ thin film were optimized, and TiO₂/NiO composite films showed better electrochromic performance than that of the single NiO film. WO₃/Ag and TiO₂/NiO composite films with excellent electrochromic properties were respectively chosen as the cathode and the anode to construct a WO₃/Ag-TiO₂/NiO electrochromic device. The response time (t_c = 4.08 s, t_b = 1.08 s), optical modulation range (35.91%), and coloration efficiency (30.37 cm²·C⁻¹) of this electrochromic device are better than those of WO₃-NiO and WO₃/Ag-NiO electrochromic devices. This work provides a novel research idea for the performance enhancement of electrochromic smart windows.

The coating-modified magnesium (Mg) alloys exhibit controllable corrosion resistance, but the insufficient antibacterial performance limits their clinical applications as degradable implants. Superhydrophobic coatings show excellent performance in terms of both corrosion resistance and inhibition of bacterial adhesion and growth. In this work, a hydroxyapatite (HA)/palmitic acid (PA) superhydrophobic composite coating was fabricated on the Mg alloy by the hydrothermal technique and immersion treatment. The HA/PA composite coating showed superhydrophobicity with a contact angle of 153° and a sliding angle of 2°. The coated Mg alloy exhibited excellent corrosion resistance in the simulated body fluid, with high polarization resistance (77.10 kΩ·cm²) and low corrosion current density ((0.491 ± 0.015) µA·cm⁻²). Meanwhile, the antibacterial efficiency of the composite coating was over 98% against E. coli and S. aureus in different periods. The results indicate that the construction of such superhydrophobic composite coating (HA/PA) on the Mg alloy can greatly improve the corrosion resistance of Mg alloy implants within the human body and avoid bacterial infection during the initial stages of implantation.

Metal–organic frameworks (MOFs) have attracted widespread attention due to their regular structures, multiple material centers, and various ligands. They are always considered as one kind of ideal templates for developing highly sensitive and selective gas sensors. In this study, the advantages of MOFs with the high specific surface area (71.9891 m²·g⁻¹) and uniform morphology were fully utilized, and urchin-like SnO₂ nanowires were obtained by the hydrothermal method followed by the calcination using Sn-MOFs consisting of the ligand of C₉H₆O₆ (H₃BTC) and Sn/Ce center ions as sacrificial templates. This unique urchin-like nanowire structure facilitated gas diffusion and adsorption, resulting in superior gas sensitivity. A series of Ce-doped SnO₂ nanowires with different doping ratios were synthesized, and their gas sensing properties towards formaldehyde were studied. The resulted Ce-SnO₂ was revealed to have high sensitivity (201.2 at 250 °C), rapid response (4 s), long-term stability, and good repeatability for formaldehyde sensing, and the gas sensing mechanism of Ce-SnO₂ exposed to formaldehyde was also systematically discussed.

The biggest challenge for organic phase change materials (PCMs) used in cold energy storage is to maintain high heat storage capacity while reducing the leakage risk of PCMs during the phase transition process. This is crucial for expanding their applications in the more demanding cold storage field. In this study, novel form-stable low-temperature composite PCMs are prepared with mesoporous materials, namely SBA-15 and CMK-3 (which are prepared using the template method), as supporting matrices and dodecane as the PCM. Owing to the combined effects of capillary forces within mesoporous materials and interactions among dodecane molecules, both dodecane/SBA-15 and dodecane/CMK-3 exhibit outstanding shape stability and thermal cycling stability even after 200 heating/cooling cycles. In comparison to those of dodecane/SBA-15, dodecane/CMK-3 exhibits superior cold storage performance and higher thermal conductivity. Specifically, the phase transition temperature of dodecane/CMK-3 is −8.81 °C with a latent heat of 122.4 J·g⁻¹. Additionally, it has a thermal conductivity of 1.21 W·m⁻¹·K⁻¹, which is 9.45 times that of dodecane alone. All these highlight its significant potential for applications in the area of cold energy storage.

In the field of bone defect repair, critical requirements for favorable cytocompatibility and optimal mechanical properties have propelled research efforts towards the development of composite materials. In this study, carbon nanotubes/polylactic acid/hydroxyapatite (CNTs/PLA/HA) scaffolds with different contents (0.5, 1, 1.5 and 2 wt.%) of CNTs were prepared by the thermally induced phase separation (TIPS) method. The results revealed that the composite scaffolds had uniform pores with high porosities over 68% and high through performances. The addition of CNTs significantly enhanced the mechanical properties of resulted PLA/HA, in which the 1.5 wt.% CNTs/PLA/HA composite scaffold demonstrated the optimum mechanical behaviors with the bending elastic modulus of (868.5 ± 12.34) MPa, the tensile elastic modulus of (209.51 ± 12.73) MPa, and the tensile strength of (3.26 ± 0.61) MPa. Furthermore, L929 cells on the 1.5 wt.% CNTs/PLA/HA scaffold displayed good spreading performance and favorable cytocompatibility. Therefore, it is expected that the 1.5 wt.% CNTs/PLA/HA scaffold has potential applications in bone tissue engineering.

To determine the contribution of non-repetitive domains to the bioactivity of the heavy chain in silk fibroin (SF) macromolecules, a gene motif f(1) encoding this fragment and its multimers (f(4) and f(8)) were biosynthesized from Escherichia coli BL21. Based on the positive application potential of SF materials for the vascular tissue engineering, this study focused on examining the active response of these polypeptides to vascular endothelial cells. Biosynthetic polypeptides F(1), F(4), and F(8) were separately grafted onto the surfaces of bioinert polyethylene terephthalate (PET) films, resulting in remarkable improvements in the spread and proliferation of human umbilical vein endothelial cells (HUVECs). Using the same grafting dose, the activity of cells on polypeptide-modified PET films enhanced with the increase of the molecular weight of those grafted polypeptides from F(1) to F(8). Meanwhile, the growth of cells on the surface of the alkaline-treated PET film was improved, indicating that the hydrophilicity of the surface material had influence on the growth of HUVECs. Moreover, on surfaces with the same water contact angle, the spread and proliferation activity of cells on PET films were significantly lower than those on polypeptide-modified PET films.

In this work, Fe₃O₄ nanoparticles (NPs) loaded inside and outside halloysite nanotubes (HNTs) were prepared and developed as the heterogeneous Fenton-like catalysts for the removal of representative organic pollutants. Characterization results indicated that the samples with Fe₃O₄ NPs loaded outside the HNTs lumen (Fe₃O₄/HNTs) and inside the HNTs lumen (Fe₃O₄@HNTs) were successfully prepared. Both samples had typical magnetic hysteresis loops, while Fe₃O₄@HNTs exhibited higher magnetization intensity. The comparative experiments showed that Fe₃O₄@HNTs had better Fenton-like catalytic ability than that of Fe₃O₄/HNTs in the degradation of various organic pollutants. Taking Rhodamine B (RhB) as an example, the adsorption thermodynamics and kinetics of RhB onto Fe₃O₄/HNTs and Fe₃O₄@HNTs were also investigated. The comparative results demonstrated that the adsorption ability of Fe₃O₄/HNTs was better than that of Fe₃O₄@HNTs. Moreover, the dissolved concentration of Fe²⁺ and production amount of hydroxyl radical (·OH) in the Fe₃O₄@HNTs-H₂O₂ system were significantly higher than those in the Fe₃O₄/HNTs-H₂O₂ system. Based on aforementioned comparison, the nano-confinement effect in the Fe₃O₄@HNTs-H₂O₂ system was verified. This work provides meaningful guidance for the cheap and convenient design of nanoreactors for Fenton-like applications.