Materials Advances最新文献

Innovative delivery platforms based on biopolymer matrices are attracting increasing interest as effective tools to enhance the protection, solubility, and therapeutic outcome of sensitive bioactive compounds and macromolecules. This research focuses on the formulation and study of multilayered microsystems composed of naturally occurring polymers – specifically, alginate and chitosan – designed to encapsulate and gradually release lactoferrin, a multifunctional iron-binding glycoprotein with potent antimicrobial properties. Particularly, the iron-free lactoferrin form (apo-lactoferrin) plays a key role in the innate immune defense by exerting antimicrobial activity through two primary mechanisms: bacteriostatic and bactericidal. Lactoferrin-loaded microspheres were produced using a gentle ionic gelation technique and subsequently coated with a positively charged chitosan layer to maintain protein stability and regulate its release. Detailed morphological, thermal and physicochemical characterization studies were performed, along with release kinetics studies under various pH conditions. Additionally, the antimicrobial activity of the system was tested against clinically relevant bacterial strains, including S. aureus, P. aeruginosa and E. coli, at variable proton concentrations. The results showed that this core–shell platform enhances protein stability and selectively increases the antimicrobial efficacy under different pH conditions, demonstrating its potential for targeted intervention in infection-prone tissues with altered pH profiles. These findings suggest promising applications in pH-responsive topical treatments, particularly for managing chronic wounds and infection-prone tissues, where local pH alterations influence antimicrobial efficacy.

This study introduces a sustainable method for valorizing Alcea rosea (hollyhock) floral waste by developing two novel TiO₂-based photocatalysts modified with biomass-derived materials: a natural dye (HH dye) and carbon dots (HHCDs). The HHCDs were synthesized via a one-pot hydrothermal process at 180 °C, yielding oxygen-rich, amorphous carbon dots. TiO₂ nanoparticles were prepared by a sol–gel method and subsequently modified with either HH dye or HHCDs through environmentally benign procedures. Comprehensive characterization (FTIR, XRD, UV-vis, and FE-SEM) confirmed the successful incorporation of both modifiers and their interaction with the TiO₂ surface. Optical analysis indicated a significant reduction in the bandgap for both composites, with HH dye@TiO₂ (∼2.67 eV) exhibiting a lower bandgap than HHCDs@TiO₂ (∼2.89 eV). Electrochemical measurements revealed that HHCDs@TiO₂ facilitated more effective charge carrier separation, whereas HH dye@TiO₂ demonstrated superior light-harvesting capabilities due to its anthocyanin content. In photocatalytic degradation experiments under visible light, HHCDs@TiO₂ demonstrated superior performance, achieving 97.1% degradation of Congo red dye within 80 minutes, compared to 96.8% in 120 minutes for HH dye@TiO₂. Both composites exhibited remarkable long-term stability, retaining over 95% of their efficiency after 180 days of storage. Optimal degradation conditions were identified at mildly acidic to neutral pH using 0.04 g of HHCDs@TiO₂ and 0.06 g of HH dye@TiO₂. This work presents a novel, dual-approach strategy for fabricating efficient and eco-friendly photocatalysts, highlighting their significant potential for solar-driven water purification and environmental remediation.

We consider the condensation and evaporation of a volatile partially wetting liquid on a soft substrate in contact with a homogeneously saturated gas phase. Recent experiments demonstrated a strong dependence of nucleation density on the substrate softness. Motivated by these experiments, we approach the problem considering both macroscale and mesoscale models. On the macroscale, we employ thermodynamic considerations to determine the critical nuclei energies and the resulting nucleation probabilities in the limits of rigid and liquid substrates. On the mesoscale, we use a gradient dynamics model for a drop of volatile liquid on a soft substrate with Kelvin–Voigt viscoelasticity in Winkler-foundation form. The governing energy functional incorporates elastic and interface energies as well as bulk liquid energy. We show that nucleation probabilities obtained with the two models agree for small supersaturation, but display differences when drop nuclei are small. Finally, we use the mesoscopic model to investigate the condensation and evaporation dynamics of drops in the intermediate elastic regime and relate the results to the experimental findings.

Lead halide perovskites (APbX₃) have demonstrated exceptional opto-electronic properties, but their inherent toxicity and environmental hazards hindered their practical deployment in display technologies such as liquid crystal display (LCD) backlights. Herein, we report for the first time a facile, water-mediated synthesis of red-emitting CsMnBr₃ thin films from an aqueous solution of CsBr and MnBr₂ precursors at a low temperature of ∼50 °C. Unlike traditional synthesis routes reported for synthesis of CsMnBr₃ powders or nanocrystals, relying heavily on toxic solvents, high temperatures, or inert atmospheres, the green approach utilizes water as a benign medium to facilitate the [MnBr₆] octahedral coordination assembly, yielding continuous red films with strong photoluminescence (λ: ∼644 nm, FWHM: ∼75 nm). The as-synthesized CsMnBr₃ films exhibit remarkable optical quality with an ultra-wide color gamut coverage (∼132% of NTSC 1953 and ∼186% of sRGB color standards), making them a promising alternative for traditional red phosphors in LCD backlight applications. The characterization of electrical and photo-responses reveals a negative photoconductivity under UV irradiation, attributed to the powdered microstructure and hygroscopic nature of MnBr₂ under ambient air conditions. The photo-response of the red-emissive CsMnBr₃ films exhibits a power-law dependence on high-energy irradiation under ambient conditions at ∼18 °C and a relative humidity of ∼65%, along with faster self-recovery behavior, highlighting the complex role of defect-mediated charge transport. This green, low-cost, and scalable synthesis route offers a promising pathway toward sustainable and lead-free phosphor materials for next-generation wide-color-gamut display technologies.

Evaluation of the wear behavior of composite coatings based on Stellite 6 with additions of WC-Ni and Cr₃C₂, produced via high-velocity oxygen fuel (HVOF) spraying at an elevated temperature. Evaluation of the effects of these carbides on the wear mechanism and to determine their impact on the formation of protective tribolayers. Stellite 6, a cobalt-based alloy, is widely known for its resistance to wear and corrosion, and the incorporation of carbides such as WC-Ni and Cr₃C₂ further enhances these properties. Two types of composite coatings were developed: SW (Stellite 6 with WC-Ni) and SWC (Stellite 6 with WC-Ni and Cr₃C₂). Microstructural analysis revealed that the carbides were uniformly distributed in the Stellite 6 matrix, with higher hardness and improved wear performance compared to similar coatings without carbides. Wear tests were conducted at room temperature and 300 °C. The results indicate that both coatings exhibit low wear rates caused by different wear mechanisms when tested at elevated temperatures.

The development of sustainable biodegradable polymers or biopolymer-based composites is vital for addressing environmental challenges posed by petroleum-derived materials. However, the practical applications of biopolymers remain constrained by the poor mechanical strength, low chemical stability and poor thermal conductivity. In this study, a multifunctional bio-composite film with excellent mechanical strength and enhanced hydrophobicity was fabricated by incorporating exfoliated boron nitride nanoplates (BNNPs) and cellulose nanofibers (CNFs) into the chitosan (CH) matrix. The influence of BNNP loading on the structural, thermal and surface properties of the film was systematically investigated. Increasing the loading of BNNPs alters the wettability of the resulting films, while significantly enhancing their mechanical strength, thermal stability, and UV shielding performance. At an optimum BNNP loading of 2 wt%, the composite film achieved a tensile strength of 46.3 MPa (an ∼82% increase relative to the CH–CNF film), enhanced hydrophobicity with a contact angle of 117.1° and a thermal conductivity of 0.68 W m⁻¹ °C. The film also demonstrated excellent resistance to acidic and alkaline environments. Structural and morphological analyses confirmed uniform dispersion of BNNPs and strong interfacial interaction with CNFs, promoting effective stress transfer and phonon transport. Furthermore, the bio-composite film displayed sensitivity towards ammonia (NH₃), showing a decrease in resistance as observed in Cole–Cole plots upon exposure to ammonia, depicting improved charge transfer. These findings highlight the synergistic role of BNNPs and CNFs in engineering high-performance, eco-friendly films suitable for packaging, protective coatings, and flexible electronics as well as the film's potential for ammonia sensing applications.

Memristors have emerged as a promising technology for next-generation memory and neuromorphic computing due to their ability to mimic synaptic behavior and retain previous resistance states, while showing potential as future energy-efficient devices. Various materials have been investigated for resistive switching applications, including valve metals, Hf, Nb, Ta, Ti, etc., which stand out due to their ability to form stable oxide layers with tuneable oxide growth and ability for controlled defect engineering. These properties are crucial for obtaining reliability and scalability in memristive devices. A significant advantage of anodic memristor fabrication in comparison to other methods is the anodization process. It is a simple, cost-effective electrochemical method, which can ensure precise control over the oxide thickness, composition, and intrinsic defect structuring. By adjusting anodization parameters, it is possible to influence oxygen vacancy distribution and interfacial properties, thus enhancing resistive switching capabilities such as formation voltage, switching voltage, endurance, and retention. This review provides a detailed evaluation of memristive devices based on anodic oxides, from their fabrication, resistive switching mechanisms, and defect structuring to applications in memory and neuromorphic computing. Furthermore, a comparison of various valve metals and their alloys is presented, identifying their individual advantages and limitations in memristive performance.

The detection of glucose holds significant importance in clinical medicine, particularly for the diagnosis and management of diabetes. In this study, a complexation-mediated strategy was employed to synthesize nanostructured potassium copper ferrocyanide (PCFC) nanoparticles within the size range of 2 to 5 nm, which were subsequently investigated for their potential application in non-enzymatic electrochemical and field-effect transistor-based glucose sensing platforms. Key performance metrics of the sensor, including sensitivity, detection limit, linear response range, response time and selectivity towards glucose in an alkaline electrolyte medium, were systematically investigated. Electrochemical measurements, utilizing cyclic voltammetry (CV) and differential pulse voltammetry (DPV), confirmed the electrocatalytic activity of the synthesized material for glucose oxidation, primarily attributed to the crucial role of the Cu²⁺/Cu³⁺ redox couple. The CV and DPV techniques yielded sensitivities of 0.41 mA mM⁻¹ cm⁻² and 0.50 mA mM⁻¹ cm ⁻², with limits of detection of 1.09 mM and 1.01 mM, respectively. Application of potassium copper ferrocyanide within an extended gate-field effect transistor architecture showed promising glucose sensing performance, as evidenced by linear shifts in transfer characteristics and effective modulation of drain current upon glucose addition, with the sensitivity and limit-of-detection values of 0.033 mA mM⁻¹ cm⁻² and 0.28 mM, respectively. The sensor exhibited good sensitivity, a low detection limit and excellent selectivity in the presence of common biological interferents. The practical applicability of the transistor-based sensor was also demonstrated through real-sample analysis, which showed high accuracy and repeatability, suggesting its potential for practical biomedical and clinical diagnostic applications.

Lithium titanate oxide (LTO) has gained significant attention recently as a promising candidate for anode materials in lithium-ion batteries because of its stable operating potential and unique zero-strain behavior. Despite these advantages, its use is limited because of poor electronic conductivity and sluggish lithium-ion diffusion. This review highlights how the atomic-level understanding of various strategies, such as structural architecture engineering, doping, and defect engineering, is gained through advanced computational approaches. Computational studies on lithium vacancies and defects reveal how dopants like Nb⁵⁺ and Al³⁺ influence the charge transport and introduce charge compensation. Furthermore, density functional theory (DFT) based studies illustrate that the diffusion barrier of lithium ions at engineered sites is significantly lower than that of the bulk structure. The impact of these three modification strategies on the LTO structure is examined along with experimental validation of the computational results. Finally, this review highlights future directions of the role of computational tools in accelerating the performance and rational design of high-performance LTO anodes.

Herein, we introduce a composite membrane comprising polyvinylidene fluoride/graphene nanosheets (PVDF/graphene) for applications in piezoelectric nanogenerators (PENGs) and lithium-ion batteries (LIBs), where the graphene nanosheets play a vital role in enhancing the piezoelectric properties, surface energy, and porosity. A comparative analysis of the pure PVDF and the PVDF/graphene is conducted to evaluate their piezoelectric performance and suitability as separators in LIBs. The PVDF/graphene composite membrane produced a significantly improved piezoelectric output of ∼10.8 V under a force of 75 N, while the pure PVDF membrane exhibited only ∼3.7 V under the same conditions. Additionally, the Li//PVDF/graphene//graphite half-cell retained ∼81.3% of its specific capacity and maintained a coulombic efficiency of over 99.2% after 100 cycles at a 0.2 C rate. In contrast, the Li//pure PVDF//graphite half-cell retained only ∼48.6% specific capacity. Furthermore, in a full-cell configuration, the graphite//PVDF/graphene//LCO cell demonstrated excellent stability, retaining ∼88% of its specific capacity after 50 cycles, whereas the cell with pure PVDF membrane retained only 38%. Therefore, the PVDF/graphene nanosheet composite membrane has the potential to be used as a piezoelectric membrane in PENGs and as a separator in LIBs.