Materials Advances最新文献

The concurrent integration of ferroelectricity and ferromagnetism in BaTiO₃ (BT) introduces a promising paradigm for multifunctional applications. This study delves into the structural, magnetic, and dielectric characteristics of Ba_1−xCe_xTiO₃ (BCT) ceramics with Ce substitution varying from 0 to 2%. Notably, BT in its pristine state exhibited weak ferromagnetism at a lower applied magnetic field. However, the introduction of Ce³⁺ led to an augmentation in the M_s values, attributed to the elevated presence of oxygen vacancies. Rietveld analysis of the X-ray diffraction patterns and the Raman spectra of all the samples revealed the unaltered tetragonal structure of BT despite increasing the Ce content to 1.5%. Simultaneously, an increase in the unit cell volume and crystalline size was noted, whereas the tetragonality factor (c/a) diminished with increasing Ce substitution. Field emission scanning electron microscopy (FESEM) analysis highlighted a transition in the average grain size from 738 nm to 899 nm with increasing Ce content. The investigation of dielectric properties showed a proportional reduction in the dielectric constant with increasing Ce concentration. Additionally, dielectric measurements revealed that AC conductivity increased with frequency, and Ce doping further enhanced the conductivity by introducing additional charge carriers. Despite the reduction in the dielectric constant, the minimal dielectric loss made these materials highly suitable for high-frequency applications. This study underscores the significance of Ce incorporation into BT, introducing magnetic behaviour to an otherwise non-magnetic, lead-free BT system. The observed phenomena open avenues for exploring previously limited multiferroic and magnetoelectric properties of BT ceramics, a promising direction in the realm of lead-free ferroelectrics.

Bacterial antimicrobial resistance (AMR) has emerged as a global challenge, exacerbated by the formation of biofilms. To address this issue, the bactericidal effect of gold nanoparticle photothermia has been explored. Gold nanoparticles with different morphologies: spherical (AuNSP), rods (AuNRO), stars (AuNST), and flower-shaped (AuNFL) were synthesised and characterised. Scanning and transmission electron microscopy images confirm the morphologies and give dimensions for the different types of nanoparticles in good agreement with those from dynamic light scattering measurements. Their photothermal capacities under irradiation at 808 and 1064 nm were assessed. The specific absorption rates were determined, and light-to-heat conversion efficiencies evaluated in the heating and cooling phases. Phothermally induced localized hyperthermia significantly increased the mortality rate of planktonic Escherichia coli in the stationary phase, approaching 100% for AuNRO, AuNST, and AuNFL, while AuNSP was ineffective. This demonstrates that bactericidal efficacy is highly dependent on nanoparticle morphology. These findings highlight the potential of shape-tailored gold nanoparticles for developing effective antibacterial treatments.

Photopatterning of polymers enables the microfabrication of numerous microelectronic, micromechanical, and microchemical systems. The incorporation of inorganics into a patterned polymer material can generate many new interesting properties such as enhanced stability, optical performance, or electrical properties. Vapor phase infiltration (VPI) allows for the creation of hybrid organic–inorganic materials by infiltrating polymers with gaseous metalorganic precursors. This study seeks to explore the potential of integrating VPI with existing photopatterning techniques to achieve top-down hybridization and property modification of polymer structures of different complexity. For this, VPI of diethylzinc (DEZ) is studied for four highly crosslinked acrylate networks that can be patterned by photolithography and two-photon polymerization (2PP): pentaerythritol triacrylate (PETA), pentaerythritol tetraacrylate (PETeA), trimethylolpropane triacrylate (TMPTA) and ethoxylated trimethylolpropane triacrylate (ETPTA). The findings show that for highly crosslinked polymer networks, VPI can be limited by slow precursor diffusion. However, by introducing flexible segments (e.g., ethoxylated chains), the polymer's free volume can be increased, and infiltration is accelerated, leading to faster infiltration times and higher and more uniform inorganic loading. Finally, selective infiltration of ZnO into photolithographically patterned copolymer networks of TMPTA and ETPTA on non-infiltrating poly(methyl methacrylate) (PMMA) is demonstrated illustrating the potential of VPI for advanced maskless patterning strategies.

We report the synthesis of two rotaxanes (1 and 2) whose rings have appended thiourea units for the selective recognition of Cl⁻ anions. Rotaxane 1 transports Cl⁻ across synthetic lipid bilayers more efficiently than 2, exhibiting EC₅₀ values of 0.243 mol% versus 0.736 mol%, respectively. A control rotaxane (3) without the thiourea units and the individual axle (4) also showed Cl⁻ transport, although with much lower efficiency (EC₅₀ values of 4.044 mol% and 4.986 mol%). The unthreaded ring (5) showed the lowest transport activity. This trend highlights the advantage of the interlocked system with a ring containing thiourea units. We also investigated how the membrane composition of liposomes influences the transport activity of 1 and 2, observing higher Cl⁻ transport in membranes with higher fluidity. Additionally, we demonstrated that rotaxane 1 can kill drug-resistant and osmotolerant Staphylococcus aureus when used in combination with NaCl or arachidonic acid. The latter is known to increase the fluidity of the membrane in S. aureus, highlighting cooperative behavior. This work provides new insights into how various structural features and the membrane environment influence the anion transport activity of rotaxanes, offering important design principles for optimizing future rotaxanes for biomedical and other applications.

Li-rich garnet solid electrolytes are promising candidates for all-solid-state batteries, allowing for increased energy densities, compatibility with Li-metal anodes and improved safety by replacing flammable organic-based liquid electrolytes. Li-stuffed garnets typically require aliovalent doping to stabilise the highly ionic conductive Iad cubic phase. The role of dopants and their location within the garnet framework can greatly affect the conduction properties of these garnets, yet their impact on the structure and resulting ion transport is not fully understood. Here, we evaluate the effect of aliovalent doping with Al³⁺, Ga³⁺ and Zn²⁺ in the Li₆BaLa₂Ta₂O₁₂ (LBLTO) garnet material. A combination of PXRD and XAS reveals a linear cell parameter contraction with an increase in doping and the preference of the 24d Li⁺ sites for Al³⁺ and Zn²⁺ dopants, with Ga³⁺ occupying both the 24d and 48g Li⁺ sites. Macroscopic ionic conductivity analyses by EIS demonstrate an enhancement of the transport properties where addition of small amounts of Al³⁺ decreases the activation energy to Li⁺ diffusion to 0.35(4) eV. A detrimental effect on ionic conductivities is observed when dopants were introduced in Li⁺ pathways and upon decreasing the Li⁺ concentration. Insights into this behaviour are gleaned from microscopic diffusion studies by muon spin relaxation (μ⁺SR) spectroscopy, which reveals a low activation energy barrier for Li⁺ diffusion of 0.16(1) eV and a diffusion coefficient comparable to those of Li₇La₃Zr₂O₁₂ (LLZO) benchmark garnet materials.

Incorporation of magnetic components enables flexible conductive hydrogels to exhibit strain-response properties in the presence of a magnetic field. However, the utilization of flexible conductive hydrogels is constrained under low-temperature conditions, and the mechanical properties of most magnetic hydrogels are poor. In this work, a conductive sensor was developed through Ca²⁺-initiated radical polymerization, utilizing the synergistic effects of sodium lignosulfonate (SL), calcium chloride (CaCl₂), and Fe₃O₄@laponites (XLG). Fe₃O₄@XLG not only served as a physical crosslinking agent but also functioned as a magnetic component. Due to the presence of both physical and chemical crosslinking, the Ca²⁺-Fe₃O₄@XLG/SL/polyacrylamide (PAM) hydrogel had good mechanical properties. After being placed at −20 °C for 24 h, the Ca²⁺-Fe₃O₄@XLG/SL/PAM hydrogel remained intact, soft, and tough, and it still exhibited good stretchability (1029%) and strength (69.7 kPa). In addition, the hydrogel also exhibited good adhesion with various substrates. Strain sensors assembled from the nanocomposite hydrogels achieved a gauge factor of 5.14, a response time of 166 ms, and good stability. The Ca²⁺-Fe₃O₄@XLG/SL/PAM hydrogels had magnetic response properties, and they could respond quickly to magnetic field changes in the form of resistance changes. Thus, they have potential applications in magnetic field signal monitoring and soft actuators.

Herein, the fabrication of a new Cu(II)-based coordination polymer {[Cu₂(DPP)₂(H₂O)₂]·DPP·2NO₃}_n (CP-1) (DPP = 1,3-di(4-pyridyl)propane) and its composite (rGO@CP-1) has been done using solvothermal and mechanochemical methods. The crystal structure of the synthesized CP-1 was confirmed utilizing single-crystal X-ray diffraction (SC-XRD). Furthermore, the structural features of the as-synthesized CP-1 and rGO@CP-1 were examined using PXRD, FTIR, TGA, SEM, and HR-TEM analysis. The topological framework of CP-1 shows a 1,3M4-1 underlying net for two fragments and the hydrogen-bonded network shows a 2C1 underlying net topology. The fluorescence detection of transition metal ions and solvents using CP-1 showed promising results of 97.4% DMF and 96.8% Zn²⁺. Electrochemical study of CP-1 and rGO@CP-1 was performed in an acidic medium (1 M H₂SO₄) electrolyte utilizing cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) techniques with a specific capacity of 244.17 F g⁻¹ and 899.54 F g⁻¹ for CP-1 and rGO@CP-1, respectively at 1 A g⁻¹ (current density). Moreover, 98.6% columbic efficiency with 94.62% capacity retention of rGO@CP-1 was obtained at 8 A g⁻¹ up to 2000 cycles.

Hydrophobic ion-pairing is an established solubility engineering technique that uses amphiphilic surfactants to modulate drug lipophilicity and facilitate encapsulation in polymeric and lipid-based drug delivery systems. For proteins, surfactant complexation can also lead to unfolding processes and loss in bioactivity. In this study, we investigated the impact of two surfactants, sodium dodecyl sulphate (SDS) and dioctyl sulfosuccinate (DOSS) on lysozyme's solubility, activity, and structure. SDS and DOSS were combined with lysozyme at increasing charge ratios (4 : 1, 2 : 1, 1 : 1, 1 : 2 and 1 : 4) via hydrophobic ion pairing at pH 4.5. Maximum complexation efficiency at the 1 : 1 charge ratio was confirmed by protein quantitation assays and zeta potential measurements, showing a near neutral surface charge. Lysozyme lipophilicity was successfully increased, with log D n-octanol/PBS values up to 2.5 with SDS and 1.8 with DOSS. Bioactivity assays assessing lysis of M. lysodeikticus cell walls showed up to a 2-fold increase in lysozyme's catalytic ability upon complexation with SDS at ratios less than stoichiometric, suggesting favourable mechanisms of stabilisation. Secondary structural analysis using Fourier-transform infrared spectroscopy indicated that lysozyme underwent a partial unfolding process upon complexation with low SDS concentrations. Molecular dynamic simulations further confirmed that at these low concentrations, a positive conformation was obtained with the active site residue Glu 35 more solvent-exposed. Combined, this suggested that sub-stoichiometric SDS altered the active site's secondary structure through increased backbone flexibility, leading to higher substrate accessibility. For DOSS, low surfactant concentrations retained lysozyme's native function and structure while still increasing the protein's lipophilic character. Our research findings demonstrate that modulation of protein activity can be related to surfactant chemistry and that controlled ion-pairing can lead to re-engineering of lysozyme solubility, activity, and structure. This has significant implications for advanced protein applications in healthcare, particularly towards the development of formulation strategies for oral biotherapeutics.

Traditional Lithium-ion batteries may not satisfy the requirements of advanced batteries, demanding higher energy and power density, broader operating temperature ranges, and faster charging speeds. Solid-state Li–S batteries (SSLSBs) offer significant advantages, including higher theoretical specific capacity, cost-effectiveness, and environmental benefits. This mini-review exclusively introduces design protocols with emphasis on key governing parameters of SSLSBs towards achieving a specific energy of more than 500 W h kg⁻¹. In addition, the distinct fading mechanisms of SSLSBs compared to non-aqueous electrolyte systems and other ASSB systems are summarized and compared. Then, we outline the state-of-the-art strategies to enhance the electrochemical performance of SSLSBs and suggest insightful directions for future research. This review may be of significance to the design of advanced SSLSBs, by mitigating technical challenges, and hence facilitating their practical implementation in energy storage technologies.

Many composites in nature are formed in the course of biomineralization. These biocomposites are often produced via an amorphous precursor such as amorphous calcium carbonate (ACC), demonstrating a layered structure. In the current study, robocasting, a 3D-printing technique, was used to print layered structures inspired by the mineralized tissues of Ophiomastix wendtii and Odontodactylus scyllarus, which exhibit a layered organization. Various biodegradable organic matrices with a high percentage (>94%) of ACC reinforcements were compared, and their mechanical properties were studied. With the organic matrix protection, ACC was stabilized for long periods, exceeding even three years, when stored at ambient conditions. The layered structures were printed and fractured using the three-point bending method to evaluate their strength. The fracture interface was examined to weigh the benefits an amorphous precursor may offer in the 3D printing processes of ceramic materials. The fracture interface presented bulk behavior with no distinct layering, resembling the formation of mineral single crystalline tissue in nature and overcoming one of the most critical challenges in 3D printing, namely the inter-layer interfaces. Herein, a bio-inspired, low-temperature route to form layered structures is presented. By fusing the layers together following low-temperature sintering, a composite structure composed of stabilized ACC integrated with biodegradable, environmentally friendly matrices can be obtained.