Search Results (98)

Background/Objective: Staphylococcus aureus (S. aureus) is a clinically significant pathogenic bacterium. Daptomycin (DAP) is a cyclic lipopeptide antibiotic used to treat infections caused by multidrug-resistant Gram-positive bacteria, including S. aureus. However, DAP currently faces clinical limitations due to its short half-life, toxic side effects, and increasingly severe drug resistance issues. This study aimed to develop a biomimetic nano-drug delivery system to enhance targeting ability, prolong blood circulation, and mitigate resistance of DAP. Methods: DAP-loaded chitosan nanocomposite particles (DAP-CS) were prepared by electrostatic self-assembly. Macrophage membrane vesicles (MM) were prepared by fusion of M1-type macrophage membranes with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC). A biomimetic nano-drug delivery system (DAP-CS@MM) was constructed by the coextrusion process of DAP-CS and MM. Key physicochemical parameters, including particle diameter, zeta potential, encapsulation efficiency, and membrane protein retention, were systematically characterized. In vitro immune escape studies and in vivo zebrafish infection models were employed to assess the ability of immune escape and antibacterial performance, respectively. Results: The particle size of DAP-CS@MM was 110.9 ± 13.72 nm, with zeta potential +11.90 ± 1.90 mV, and encapsulation efficiency 70.43 ± 1.29%. DAP-CS@MM retained macrophage membrane proteins, including functional TLR2 receptors. In vitro immune escape assays, DAP-CS@MM demonstrated significantly enhanced immune escape compared with DAP-CS (p < 0.05). In the zebrafish infection model, DAP-CS@MM showed superior antibacterial efficacy over both DAP and DAP-CS (p < 0.05). Conclusions: The DAP-CS@MM biomimetic nano-drug delivery system exhibits excellent immune evasion and antibacterial performance, offering a novel strategy to overcome the clinical limitations of DAP. Full article

Noncorrosive concrete reinforcement, such as polymer fibers, is needed to overcome the current issues caused by corroded steel reinforcements. Fibers made of polypropylene show a low bonding behavior in concrete. Fillers can help to overcome this issue but often lead to reduced mechanical properties. Core-shell fibers, which split the mechanical properties and the bonding behavior between the core and the shell component, could be a solution. This study investigates mono-material and core-shell fibers produced with calcium carbonate and bentonite fillers and compares their behavior in tensile tests, density measurements, contact angle measurements, topography measurements, single fiber pull-out tests, reflected light microscopy, and thermogravimetric analysis. The fillers caused an increased drawability, resulting in higher mechanical properties. Further, in the core-shell fibers, the calcium carbonate increased the surface roughness, which led to a better anchoring of the fiber in concrete, which was also visible in the deformation during pull-out observed in reflected light microscopy pictures. The thermogravimetric analysis showed a delay in onset of degradation for fibers containing bentonite. Full article

Additive manufacturing (AM) is one of the most frequently used technologies to produce complex configuration products. Moreover, AM is very well known as a technology which is characterized by a low amount of generated waste and the potential to be called zero-waste technology. As is known, there are seven main groups of technologies described in the ISO/ASTM 52900 standard that allow the use of very different materials from polymers to metals, ceramics, and composites. However, the increased utilization of additively manufactured composites for different applications requires a deeper analysis of production processes and materials’ characteristics. Various AM technologies can be used to produce complex composite structures reinforced with short fibers; however, only material extrusion (MEX)-based technology is used for the production of composites reinforced with continuous fibers (CFs). At this time, five different methods exist to produce CF-reinforced composite structures. This study focuses on co-extrusion with the towpreg method. Because of the complexity and layer-by-layer nature of the process, defects can occur during production, such as poor interlayer adhesion, increased porosity, insufficient impregnation, and others. To eliminate or minimize defects’ influence on mechanical properties and structural integrity of additively manufactured structures, a hypothesis was proposed involving heat treatment. Carbon fiber’s conductive properties can be used to heal the composite structures, by heating them up through the application of electric current. In this research article, an experimental evaluation of conditions for additively manufactured composites with continuous carbon fiber reinforcement for self-healing processes is presented. Mechanical testing was conducted to check the influence of heat treatment on the flexural properties of the composite samples. Full article

Polymer co-extrusion experiments are described simulating the dynamics of two different magmas (e.g., silicic and mafic having different viscosities) flowing simultaneously in a vertical volcanic pipe or conduit which results in the effusion of composite lava domes on the surface. These experiments, involving geologically realistic conduit length-to-diameter aspect ratios of 130:1 or 380:1, demonstrate that co-extrusion of magmas having different viscosities can explain not only the observed normal zoning observed in planar dikes and the pipelike conduits that evolve from dikes but also the compositional layering of effused lava domes. The new results support earlier predictions, based on observations of induced core-annular flow (CAF), that dike and conduit zoning along with dome layering are found to depend on the viscosity contrast of the non-Newtonian (shear-thinning) magmas. Any magma properties creating viscosity differences, such as crystal content, bubble content, water content and temperature may also give rise to the CAF regime. Additionally, codependent flow behavior involving the silicic and mafic magmas may play a significant role in modifying the nature of volcanic eruptions. For example, lubrication of the flow by an annulus of a more mafic, lower-viscosity component allows a more viscous but more volatile-charged magma to be injected rapidly to greater vertical distances along a dike into a lower pressure regime that initiates exsolving of a gas phase, further assisting ascent to the surface. The rapid ascent of magmas exsolving volatiles in a dike or conduit is associated with explosive silicic eruptions. Full article

Background/Objectives: Posaconazole is an antifungal agent from triazoles with variable bioavailability. To avoid its irregular absorption caused by gastric conditions and ensure more repeatable pharmacokinetic enabling the maximization of its absorption regardless of food intake without the need to administer multiple doses, can be provided by the technology of enteric drug preparations. The cross-linking of polysaccharide polymers with divalent and trivalent cations enables multi-unit formulations to be obtained that prevent drug absorption in the stomach. Microcapsules, as an example of multi-unit drug dosage forms, provide more predictable gastric emptying, depending on nutritional status, and spread extensively throughout the gastrointestinal tract. Methods: Therefore, the utilization of zinc acetate for the cross-linking of the alginate and pectin mixture was evaluated. The obtained formulations were evaluated for the impact of cross-linking process and pectin’s presence on their pharmaceutical, mucoadhesive, physicochemical and antifungal properties. Results: It was shown that cross-linked microcapsules by zinc acetate provided delayed posaconazole release. Additionally, the cross-linking process with Zn²⁺ ions significantly enhanced antifungal activity against the analyzed Candida strains. It was observed that pectin content in the formulation enhanced the swelling ability in an intestinal condition and increased the mucoadhesive properties of drug-loaded formulations to the intestinal mucosa. Full article

Additive manufacturing is gaining importance in a number of application areas, and there is an increased demand for mechanically resilient components. A way to improve the mechanical properties of parts made of thermoplastics is by using reinforcing material. The study demonstrates the development of a monitoring procedure for a fused filament fabrication-based co-extrusion process for manufacturing wire-reinforced thermoplastic components. Test components in two variants are produced, and data acquisition is carried out with a laser line scanner. The collected data are employed to train deep neural networks to classify the printed layers, aiming for the deep neural networks to be able to classify four different classes and identify layers with insufficient quality. A dedicated convolutional neural network is designed taking into account various factors such as layer architecture, data pre-processing and optimization methods. Several network architectures, including transfer learning (based on VGG16 and ResNet50), with and without fine-tuning, are compared in terms of their performance based on the F1 score. Both the transfer learning model with ResNet50 and the fine-tuning model achieve an F1 score of 84% and 83%, respectively, for the decisive class ‘wire bad’ classifying inadequate reinforcement. Full article

The present study introduces an innovative blown coextrusion die technology designed to address a critical gap in the production of multilayer films. Unlike conventional systems, this novel die allows for the creation of films with a high number of layers, ensuring layer integrity even in the micro-nano scale. A key advancement of this die is its ability to increase the number of layers without extending the residence time since it does not require an additional multiplier element. The risk of thermal degradation can, thus be, minimized. The die can easily be combined with existing cast coextrusion technologies, making it very versatile. Stability maps were developed to define processability and, in association with rheological analysis, optimal processing windows were determined. This study highlights the potential of enhancing material efficiency by increasing the number of layers while reducing the need for high percentages of EVOH. The produced multilayer films exhibited strong layer adhesion without the use of tie layers, thus improving recyclability and supporting sustainability goals. Full article

Additive manufacturing (AM) plays a significant role in the 4th Industrial Revolution due to its flexibility, allowing AM equipment to be connected, monitored, and controlled in real time. In advance, the minimum waste of material, the agility of manufacturing complex geometries, and the ability to use recycled materials can provide an advantage to this manufacturing method. On the other hand, the poor strength and durability of the thermoplastics used in the manufacturing process are the major drawback that keeps AM behind common production methods such as casting and machining. Fibre-reinforced polymers can enhance mechanical properties, advance AM from the commonly used polymers, and make AM competitive against conventional production methods. The main focus of the current review is to examine the work conducted in the field of reinforced additively manufactured technologies in the literature of recent years. More specifically, this review discusses the conducted research in the composite fibre coextrusion (CFC) additive manufacturing techniques developed over the past years and the materials that can be used. In addition, this study includes an up-to-date comprehensive review of the evaluation of fibre-reinforced 3D printing along with its benefits in terms of mechanical response, namely tensile, flexural, compression and energy absorption, anisotropy, and dynamic properties. Finally, this review highlights possible research gaps regarding fibre-reinforced AM and proposes future directions, such as deeper investigations into energy absorption and anisotropy, to position fibre-reinforced AM as a preferred fabrication method for ready-to-use parts in cutting-edge industries, including automotive, aerospace, and biomedical sectors. Full article

Composite materials, particularly carbon fiber-reinforced polymers (CFRPs), have become a cornerstone in industries requiring high-performance materials due to their exceptional mechanical properties, such as high strength-to-weight ratios, and their inherent lightweight nature. These attributes make CFRPs highly desirable in aerospace, automotive, and other advanced engineering applications. However, the compressive behavior of CFRP structures remains a challenge, primarily due to the material sensitivity to structural instability, leading to matrix cracking and premature failure under compressive loads. Isogrid structures, characterized by their unique geometric patterns, have shown promise in enhancing the compressive behavior of CFRP panels by providing additional support that mitigates these issues. Traditionally, these structures are manufactured using automated techniques like automated fiber placement (AFP) and automated tape laying (ATL), which, despite their efficacy, are often cost-prohibitive for small-scale or custom applications. Recent advancements in 3D-printing technology, particularly those involving continuous fiber reinforcement, present a cost-effective and flexible alternative for producing complex CFRP structures. This study investigates the compressive behavior of 3D-printed isogrid structures, fabricated using continuous carbon fiber reinforcement via an Anisoprint Composer A3 printer equipped with towpreg coextrusion technology. A total of eight isogrid panels with varying infill percentages were produced and subjected to buckling tests to assess their performance. The experimental results indicate a direct correlation between infill density and buckling resistance, with higher infill densities leading to increased buckling loads. Additionally, the failure modes were observed to shift from local to global buckling as the infill density increased, suggesting a more uniform distribution of compressive stresses. Post-test analyses using optical microscopy and scanning electron microscopy (SEM) revealed the presence of voids within the 3D-printed structures, which were found to negatively impact the mechanical performance of the isogrid panels. The findings of this study demonstrate that 3D-printed isogrid CFRP structures can achieve significant buckling resistance, making them a viable option for high-performance applications. However, the presence of voids remains a critical issue, highlighting the need for process optimizations in 3D-printing techniques to enhance the overall performance and reliability of these structures. Full article

To face the challenges in preparing hydrogel fibers with complex structures and functions, this study utilized a microfluidic coaxial co-extrusion technique to successfully form functional hydrogel fibers through rapid ionic crosslinking. Functional hydrogel fibers with complex structures, including linear fibers, core–shell structure fibers, embedded helical channels, hollow tubes, and necklaces, were generated by adjusting the composition of internal and external phases. The characteristic parameters of the hydrogel fibers (inner and outer diameter, helix generation position, pitch, etc.) were achieved by adjusting the flow rate of the internal and external phases. As biocompatible materials, hydrogel fibers were endowed with electrical conductivity, temperature sensitivity, mechanical enhancement, and freeze resistance, allowing for their use as temperature sensors for human respiratory monitoring and other biomimetic application developments. The hydrogel fibers had a conductivity of up to 22.71 S/m, a response time to respiration of 37 ms, a recovery time of 1.956 s, and could improve the strength of respiration; the tensile strength at break up to 8.081 MPa, elongation at break up to 159%, and temperature coefficient of resistance (TCR) up to −13.080% °C⁻¹ were better than the existing related research. Full article

Storing ground beef at frozen temperatures prior to refrigerated display when using thermoforming vacuum packaging is not a common manufacturing practice. However, limited data on thermoforming packaging film and its interaction with meat quality suggests that more information is needed. The current study aimed to identify the influences of thermoforming packaging on the surface color and lipid oxidation of ground beef. Ground beef was portioned into 454 g bricks and packaged into one of three thermoforming films: T1 (150 µ polyethylene/EVOH/polyethylene coextrusion), T2 (175 µ polyethylene /EVOH/polyethylene coextrusion), and T3 (200 µ polyethylene/EVOH/polyethylene coextrusion), stored for 21 days at −20.83 °C (±1.50 °C), and displayed for 42 days at 3.0 °C ± 1.5 °C. There were no statistical differences for the packaging treatment of lipid oxidation (p = 0.0744), but oxidation increased throughout storage day (p < 0.0001). The main effects of treatment and day resulted in altered (p < 0.05) surface lightness (L*), redness (a*), yellowness, hue angle (°), red-to-brown (RTB), and relative myoglobin for met-myoglobin (MET), deoxymyoglobin (DMB), and oxymyoglobin (OMB). Surprisingly, there was an interaction between treatment and day for the calculated relative values of chroma (p = 0.0321), Delta E (p = 0.0155), and the ratio of a*:b* (p < 0.0001). These results indicate that thermoforming vacuum packaging can reduce the rate of deterioration that occurs to ground beef color and the rate of oxidation. Full article

miRNAs have been shown to be involved in the regulation of a variety of physiological and pathological processes, but their use in the treatment of diseases is still limited due to their instability. Biomimetic nanomaterials combine nanomaterials with cellular components that are readily modifiable and biocompatible, making them an emerging miRNA delivery vehicle. In this study, adipose-derived MSC membranes were wrapped around PLGA-PEI loaded with miR-21 through co-extrusion and later transplanted into C57BL/6 mice wounds. The wound-healing rate, epithelialization, angiogenesis, and collagen deposition were assessed after treatment and corroborated in vitro. Our study demonstrated that m/NP/miR-21 can promote wound healing in terms of epithelialization, dermal reconstruction, and neovascularization, and it can regulate the corresponding functions of keratinocytes, fibroblasts, and vascular endothelial cells. m/NP/miR-21 can inhibit the expression of PTEN, a gene downstream of miR-21, and increase the phosphorylation activation of AKT, which can then regulate the functions of fibroblasts. In conclusion, this provides a new approach to therapy for skin wounds using microRNA transporters and biomimetic nanoparticles. Full article

This study introduces the synthesis and detailed characterization of a novel thermochromic material capable of reversible alterations in its thermotropic transmittance. Through an emulsion polymerization process, this newly developed material is composed of 75–85% octadecyl acrylate and 0–7% allyl methacrylate, demonstrating a pronounced discoloration effect across a narrow yet critical temperature range of 24.5–39 °C. The synthesized powder underwent a battery of tests, including differential scanning calorimetry and thermogravimetric analysis, as well as scanning electron microscopy. These comprehensive evaluations confirmed the material’s exceptional thermal stability, uniform particle size distribution, and strong anchoring properties. Building upon these findings, we advanced the development of thermochromic polyvinyl butyral films and laminated glass products. By utilizing a coextrusion technique, we integrated these films into laminated glass, setting a new benchmark against existing glass technologies. Remarkably, the incorporation of thermochromic PVB films into laminated glass led to a significant reduction in solar irradiance of 20–30%, outperforming traditional double silver low-emissivity glass. This achievement demonstrates the exceptional shading and thermal insulation properties of the material. The research presented herein not only pioneers a valuable methodology for the engineering of smart materials with tunable thermotropic transmittance but also holds the key to unlocking enhanced energy efficiency across a spectrum of applications. The potential impact of this innovation on the realm of sustainable building materials is profound, promising significant strides toward energy conservation and environmental stewardship. Full article

Biobased and biodegradable plastics have emerged as promising alternatives to conventional plastics offering the potential to reduce environmental impacts while promoting sustainability. This study focuses on the production of multilayer blown films with enhanced functional properties suitable for food packaging applications. Films were developed through co-extrusion in a three-layer film configuration, with Polybutylene Succinate (PBS) and Polybutylene Succinate Adipate (PBSA) as the external and internal layers, respectively. The functional layer consisted of Polyhydroxybutyrate (PHB) enhanced with nanoclays Cloisite^® 30B at varying weight ratios. Films were also processed by manipulating the extruder screw speed of the functional layer to investigate its impact on the functional properties. Rheology, mechanical strength, and barrier performance were characterised to establish correlations between processing conditions and functional layer blends (Cloisite^® 30B/PHB) on the properties of the resultant films. Rheological test results indicated that the system with 5% Cloisite^® had the best polymer/nanofiller matrix dispersion. Mechanical and permeability tests showed that by varying the process conditions (the alteration of the thickness of the functionalized layer) resulted in an improvement in mechanical and barrier properties. Furthermore, the addition of the nanofiller resulted in a stiffening of the film with a subsequent decrease in permeability to oxygen and water vapour. Full article

This article demonstrates scalable production of liquid metal (LM)-based microwires through the thermal drawing of extrudates. These extrudates were first co-extruded using a eutectic alloy of gallium and indium (EGaIn) as a core element and a thermoplastic elastomer, styrene–ethylene/butylene–styrene (SEBS), as a shell material. By varying the feed speed of the co-extruded materials and the drawing speed of the extrudate, it was possible to control the dimensions of the microwires, such as core diameter and shell thickness. How the extrusion temperature affects the dimensions of the microwire was also analyzed. The smallest microwire (core diameter: 52 ± 14 μm and shell thickness: 46 ± 10 μm) was produced from a drawing speed of 300.1 mm s⁻¹ (the maximum attainable speed of the apparatus used), SEBS extrusion speed of 1.50 mm³ s⁻¹, and LM injection rate of 5 × 105 μL s⁻¹ at 190 °C extrusion temperature. The same extrusion condition without thermal drawing generated significantly large extrudates with a core diameter of 278 ± 26 μm and shell thickness of 430 ± 51 μm. The electrical properties of the microwires were also characterized under different degrees of stretching and wire kinking deformation which proved that these LM-based microwires change electrical resistance as they are deformed and fully self-heal once the load is removed. Finally, the sewability of these microwires was qualitatively tested by using a manual sewing machine to pattern microwires on a traditional cotton fabric. Full article