Search Results (1,689)

Introduction: Magnetic nanoparticles are widely investigated as multifunctional platforms for drug delivery and theranostic applications, yet their biomedical implementation is hindered by aggregation, limited colloidal stability, and insufficient biocompatibility. Hybrid biopolymer coatings can mitigate these issues while supporting drug incorporation. Aim: This study aimed to develop casein–pullulan-coated Fe₃O₄ nanocomposites loaded with xanthohumol, enhancing stability and enabling controlled release for potential theranostic use. Methods: Fe₃O₄ nanoparticles were synthesized through co-precipitation and incorporated into a casein–pullulan matrix formed via polymer complexation and glutaraldehyde crosslinking. A 3² full factorial design evaluated the influence of casein:pullulan ratio and crosslinker concentration on physicochemical performance. Nanocomposites were characterized for size, zeta potential, morphology, composition, and stability, while drug loading, encapsulation efficiency, and release profiles were determined spectrophotometrically. Molecular docking was performed to examine casein–pullulan interactions. Results: Uncoated Fe₃O₄ nanoparticles aggregated extensively, displaying mean sizes of ~292 nm, zeta potential of +80.95 mV and high polydispersity (PDI above 0.2). Incorporation into the biopolymer matrix improved colloidal stability, yielding particles of ~185 nm with zeta potentials near –35 mV. TEM and SEM confirmed spherical morphology and uniform magnetic core incorporation. The optimal formulation, consisting of a 1:1 casein:pullulan ratio with 1% glutaraldehyde, achieved 5.7% drug loading, 68% encapsulation efficiency, and sustained release of xanthohumol up to 84% over 120 h, fitting Fickian diffusion (Korsmeyer–Peppas R² = 0.9877, n = 0.43). Conclusions: Casein–pullulan hybrid coatings significantly enhance Fe₃O₄ nanoparticle stability and enable controlled release of xanthohumol, presenting a promising platform for future targeted drug delivery and theranostic applications. Full article

Shape-memory polymers (SMPs) are a class of smart materials capable of recovering their original shape from a programmed temporary shape in response to external stimuli such as heat, light, or magnetic fields. SMPs have attracted significant interest for biomedical devices and soft robotics due to their large recoverable strains, programmable mechanical and thermal properties, tunable activation temperatures, responsiveness to various stimuli, low density, and ease of processing via additive manufacturing techniques, as well as demonstrated biocompatibility and potential bioresorbability. This review summarises recent progress in the fundamentals, classification, activation mechanisms, and fabrication strategies of SMPs, focusing particularly on design principles that influence performance relevant to specific applications. Both thermally and non-thermally activated SMP systems are discussed, alongside methods for controlling activation temperatures, including plasticisation, copolymerisation, and modulation of cross-linking density. The use of functional nanofillers to enhance thermal and electrical conductivity, mechanical strength, and actuation efficiency is also considered. Current manufacturing techniques are critically evaluated in terms of resolution, material compatibility, scalability, and integration potential. Biodegradable SMPs are highlighted, with discussion of degradation behaviour, biocompatibility, and demonstrations in devices such as haemostatic foams, embolic implants, and bone scaffolds. However, despite their promising potential, the widespread application of SMPs faces several challenges, including non-uniform activation, the need to balance mechanical strength with shape recovery, and limited standardisation. Addressing these issues is critical for advancing SMPs from laboratory research to clinical and industrial applications. Full article

Spider silk, as a natural polymer fiber, possesses high tensile strength, good toughness, as well as unique thermal, optical, and biocompatibility properties. It has attracted much attention in various fields. The field of optical fiber sensors has a promising future. Given the excellent performance of spider silk, introducing spider silk into the field of optical fiber sensors can broaden its application scope. This paper comprehensively reviews the outstanding characteristics of spider silk and spider silk sensors based on these characteristics, such as pH sensors, breath humidity sensors, cell temperature sensors, and blood glucose sensors applied in living organisms, as well as magnetic field sensors and refractive index sensors applied in industrial fields. It also analyzes in detail the problems faced during the collection and synthesis of spider silk, aiming to provide a reference for research on the application of spider silk in the field of optical fiber sensors. Full article

Magnetic filaments for fused deposition modeling, 3D printing, were produced by depositing polyamide 11 (PA11), by liquid–liquid phase separation and precipitation, onto exchange-coupled nanocomposite magnetic powders, SmCo₅ + 20 wt% Fe produced by mechanical milling and subsequent annealing. The produced filaments have good mechanical properties, a tensile strength of 32 MPa and a maximum elongation of slightly over 40%. The filaments also present good magnetic properties: a high coercive field of 1 T at 300 K and nearly double the saturation magnetization and remanence, compared to filaments made by depositing PA11 on commercial SmCo₅ and recycled SmCo₅ powders and four times the energy product. This work shows that magnetic filaments made by encapsulating exchange-coupled magnetic nanocomposite powders in PA11 may be a viable option for the production of 3D-printed isotropic bonded magnets, as the high energy product and remanence especially can lead to a reduction in both magnetic powder quantity and rare earth elements required for high performance magnetic filaments. This in turn may reduce costs and improve sustainability. Full article

Liquid Crystal Elastomers combine the elasticity of polymer networks with the anisotropic ordering of liquid crystals, thus enabling reversible shape modifications and stimulus responsive actuation. Unfortunately, manual LCE fabrication remains limited by operator-dependent variability, which can lead to inconsistent film thickness and manufacturing times inadequate for a mass production. This work presents a low-cost, automated manufacturing framework that redesigns the mechanical assembly steps of the traditional one-step LCE fabrication process. The design includes rubbing, slide alignment, spacer placement, and infiltration cell assembly to ensure consistent film quality and scalability. A customized Cartesian robot, built by adapting a modified X–Y core 3D printer, integrates specially designed manipulator systems, redesigned magnetic slide holders, automated rubbing tools, and supporting fixtures to assemble infiltration devices in an automated way. Validation tests demonstrate reproducible infiltration, improved mesogen alignment confirmed via polarized optical microscopy, and high geometric repeatability, although glass-slide thickness variability remains a significant contributor to deviations in final film thickness. By enabling parallelizable low-cost production, the designed hardware demonstrates its effectiveness in devising the scalable manufacturing of LCE films suited for advanced therapeutic and engineering applications. Full article

Magneto-photoluminescent hybrid materials (MPHMs) were prepared by incorporating cobalt ferrite nanoparticles (CFNs) into the fluorescent polymer poly(terephthalaldehyde-undecan-2-one) (PT2U). The CFNs, with a mean size of 3.95 nm, formed aggregates within the PT2U matrix (650–1042 nm) due to surface and interfacial interactions, modulating aggregate morphology and interparticle coupling. Magnetization studies revealed non-monotonic variations in saturation magnetization (30.3–16.2 emu/g), mean blocking temperature (39.3–43.1 K) and effective magnetic anisotropy energy density (2.14 × 10⁶–1.31 × 10⁶ erg/cm³) with increasing CFN content, consistent with the presence of canted surface spins and enhanced magnetizing interparticle interactions. Photoluminescence exhibited progressive quenching, dominated by collisional mechanisms at low CFN content and by interfacial CFN–PT2U interactions at higher loadings. Under a magnetic field (800 Oe), additional quenching occurred, attributed to magnetically induced polymer-chain rearrangements that disrupted the molecular stacking required for efficient aggregation-induced emission. These results demonstrate tunable magneto-photoluminescent coupling in MPHMs governed by surface and interfacial phenomena, providing insights for the design of functional and responsive hybrid materials. Full article

This study compares the mechanisms of organic (Hydroxypropyl Methyl Cellulose, HPMC) and inorganic (bentonite) thickeners in regulating the bleeding behavior and surface homogeneity of cement pastes. In situ low-field nuclear magnetic resonance (LF-NMR) was employed to monitor water migration, while X-ray diffraction (XRD), scanning electron microscopy (SEM), and carbonation tests were conducted to evaluate the property disparities between the top surface and bottom layers. Results indicate fundamentally different working modes: HPMC reduces bleeding by swelling to block capillary channels, exhibiting a saturation threshold at 0.2% dosage. Beyond this point, as the primary transport channels are effectively sealed, additional HPMC merely densifies the polymer “plugs” without further suppressing the bleeding rate. XRD and SEM analyses reveal that despite the reduction in total bleeding, HPMC-modified pastes still exhibit significant stratification; the top layer retains a loose, granular morphology with higher carbonation susceptibility compared to the dense bottom layer. In contrast, bentonite mitigates bleeding through a volume-filling mechanism and thixotropic structuring, demonstrating a continuous, dosage-dependent efficacy up to 1.2%. At a 0.6% dosage, bentonite effectively eliminates microstructural disparities, yielding a top surface with a dense matrix and hydration product distribution nearly identical to the bottom layer. These findings demonstrate that the specific inorganic thickener (bentonite) utilized in this work is more effective in restoring surface homogeneity and enhancing carbonation resistance than the evaluated organic polymer (HPMC). Full article

The contamination of water bodies by polycyclic aromatic hydrocarbons (PAHs) poses a significant concern for the ecological systems, along with public health. Magnetic adsorption stands out as a green and practical solution for treating polluted water. To make the process more efficient and economical, it is important to create materials that not only absorb contaminants effectively but also allow for easy recovery and reuse. This study proposes a simple yet effective method for coating Fe₃O₄ nanoparticles with hydroxypropyl-β-cyclodextrin polymer (HP-β-CDCP). The physicochemical properties of the synthesized sorbent were characterized using a transmission electron microscope (TEM), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and Vibrating Sample Magnetometer (VSM) analysis. The adsorption performance of HP-β-CDCP/Fe₃O₄ nanoparticles was well-described by the pseudo-second-order kinetic model, thermodynamic analysis, and the Freundlich isotherm model, indicating multiple interaction mechanisms with PAHs, such as π–π interactions, hydrogen bonding, and van der Waals forces. Using HP-β-CDCP/Fe₃O₄ nanoparticles as the adsorbent, the purification rates for the fifteen representative PAHs were achieved within the range of 33.9–93.1%, compared to 15.3–64.8% of the unmodified Fe₃O₄ nanoparticles. The adsorption of all studied PAHs onto HP-β-CDCP/Fe₃O₄ nanocomposites was governed by pH, time, and temperature. Equilibrium in the uptake mechanism was obtained within 15 min, with the largest adsorption capacities for PAHs in competitive adsorption mode being 6.46–19.0 mg·g⁻¹ at 20 °C, pH 7.0. This study points to the practical value of incorporating cyclodextrins into tailored polymer frameworks for improving the removal of PAHs from polluted water. Full article

This work reports on the synthesis and ring-opening metathesis polymerization (ROMP) of two novel homologous sulfonyl-containing norbornene dicarboximide monomers, specifically, N-4-(trifluoromethylsulfonyl)phenyl-norbornene-5,6-dicarboximide (1a) and N-4-(trifluoromethylsulfonyl)phenyl-7-oxanorbornene-5,6-dicarboximide (1b) using the Grubbs 2nd generation catalyst (I). The polymers are thoroughly characterized by nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR), thermomechanical analysis (TMA), thermogravimetric analysis (TGA), atomic force microscopy (AFM), and X-ray diffraction (XRD), among other techniques. A comparative study of gas transport in membranes based on these ROMP-prepared polymers is performed and the gases studied are hydrogen, oxygen, nitrogen, carbon dioxide, methane, ethylene and propylene. It is found that the presence of sulfonyl pendant groups in the polymer backbone increases the gas permselectivity in slight detriment of the gas permeability compared to a polynorbornene dicarboximide lacking sulfonyl groups. The membrane of the sulfonyl-containing polymer with an oxygen heteroatom in the cyclopentane ring, 2b, is also found to have one of the largest permselectivity coefficients reported to date for the separation of H₂/C₃H₆ in glassy polynorbornene dicarboximides. Full article

Multi-component polymer hydrogels present complex physiochemical interactions that make accurate compositional analysis challenging. This study evaluates three analytical techniques: Nuclear Magnetic Resonance (NMR), Advanced Polymer Chromatography (APC), and Thermogravimetric Analysis (TGA) to quantify polyvinyl alcohol (PVA) and polyethylene glycol (PEG) content in hybrid freeze-thaw derived PVA/PEG/PVP hydrogels. Hydrogels were synthesized using an adapted freeze–thaw method across a wide range of PVA:PEG ratios, with PVP included at 1 wt% to assess potential intermolecular effects. NMR and APC reliably quantified polymer content with low average errors of 2.77% and 2.01%, respectively, and were unaffected by phase separation or hydrogen bonding within the composite matrix. TGA enabled accurate quantification at PVA contents ≤ 62.5%, where PEG and PVA maintained distinct thermal decomposition behaviors. At higher PVA concentrations, increased hydrogen bonding and crystalline restructuring, confirmed by FTIR through shifts near 1140 cm⁻¹ and significant changes in the -OH region, altered thermal profiles and reduced TGA accuracy. Together, these findings establish APC as a high-throughput alternative to NMR for multi-component polymer analysis and outline critical thermal and structural thresholds that influence TGA-based quantification. This work provides a framework for characterizing complex polymer networks in biomedical hydrogel systems. Full article

In response to the requirements of wellbore plugging and lost circulation control, this study designed and prepared a new type of thixotropic polymer gel system. The optimal formula was obtained through systematic screening of the types and concentrations of high molecular polymers, cross-linking agents, flow pattern regulators, and resin curing agents. Comprehensive characterization of the gel’s gelling performance, thixotropic properties, high-temperature stability, shear resistance, and plugging capacity was conducted using methods such as the Sydansk bottle test, rheological testing, high-temperature aging experiments, plugging performance evaluation, as well as infrared spectroscopy, nuclear magnetic resonance, and thermogravimetric analysis, and its mechanism of action was revealed. The results show that the optimal formula is 1.2% AM-AA-AMPS terpolymer + 0.5% hydroquinone + 0.6% S-Trioxane + 0.8% modified montmorillonite + 14% modified phenolic resin. This gel system has a gelling time of 6 h, a gel strength reaching grade H, and a storage modulus of 62 Pa. It exhibits significant shear thinning characteristics in the shear rate range of 0.1~1000 s⁻¹, with a viscosity recovery rate of 97.7% and a thixotropic recovery rate of 90% after shearing. It forms a complete gel at a high temperature of 160 °C, with a dehydration rate of only 8.5% and a storage modulus retention rate of 80% after aging at 140 °C for 7 days. Under water flooding conditions at 120 °C, the converted pressure-bearing capacity per 100 m reaches 24.0 MPa. Mechanism analysis confirms that the system forms a stable composite network through the synergistic effect of “covalent cross-linking—hydrogen bonding—physical adsorption”, providing a high-performance material solution for wellbore plugging in high-temperature and high-salt environments. Full article

A naturally sourced phenolic compound, umbelliferone, has been used to synthesize four monofunctional benzoxazines, two of which have been previously synthesized from aniline and furfurylamine. This study contributes two more—using benzylamine and phenethylamine—to provide insight into how the amine’s aromatic group and aliphatic chain length influence resulting properties. The proposed chemical structures of the novel monomers are confirmed by ¹H nuclear magnetic resonance (¹H-NMR) and ¹H-¹H nuclear Overhauser effect spectroscopy (NOESY). The polymerization behavior of each resin is determined by differential scanning calorimetry (DSC). The thermal degradation pattern and the flammability of each polymer are assessed by thermogravimetric analysis (TGA) and microscale combustion calorimetry (MCC), respectively. Char yields between 49% and 63% suggest the thermoset materials to be thermally stable and competitive for thermally demanding applications. All four polybenzoxazines demonstrate non-ignitable behavior, with heat release capacities below 100 J/g·K. Structure–property analyses on the two newly synthesized compounds have been provided to deepen our existing understanding of umbelliferone-benzoxazine systems, particularly regarding the effect of the aminic moiety on thermal properties. Full article

Superparamagnetic iron oxide nanoparticles (SPIONs) are commonly produced through wet-chemical methods that require high temperature and pressure and involve multiple synthesis steps. Our research group has developed an innovative, sustainable, and patented one-step aqueous synthesis operating at ambient temperature and pressure, enabling the direct production of SPIONs in suspension. In this work, we investigated the extension of this method to obtain polymer-coated SPIONs for biomedical imaging applications. Two water-soluble and biocompatible polymers—poly(ethylene glycol) (PEG) and poly(vinyl alcohol) (PVA)—were selected and prepared into twelve samples varying in polymer concentration and iron precursor molarity. Each formulation was characterized and compared to bare SPIONs synthesized with the same approach using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and alternating gradient magnetometry (AGM). The results confirm that the one-step method yields polymer-coated nanoparticles with a cubic spinel magnetite core. PEG produced spherical, monodisperse particles (10–30 nm) exhibiting superparamagnetic behavior but lower magnetization values (1–5 emu/g). In contrast, PVA-coated nanoparticles showed a morphology dependent on polymer concentration and reagent molarity, while maintaining an average size of ~10 nm and superparamagnetic behavior, with magnetization comparable to bare SPIONs (25–50 emu/g). A preliminary MRI evaluation of a selected PVA-coated sample revealed relaxivity values of r₁ = 0.12 mM⁻¹ s⁻¹ and r₂ = 6.44 mM⁻¹ s⁻¹, supporting the potential of this synthesis route for imaging-oriented nanomaterials. Full article

The integration of bioethanol into transportation fuels requires efficient purification methods to overcome the ethanol–water azeotrope, which cannot be separated by conventional distillation. Pervaporation has become an attractive alternative, offering high selectivity while minimising energy consumption. To further improve membrane performance, this study analyses sodium alginate-based hybrid membranes containing binary mixtures of chromite selenides with varying magnetic properties (ZnCr₂Se₄, CdCr₂Se₄, and CuCr₂Se₄). Pairwise combinations of these fillers were introduced to create complex magnetic structures that can influence polymer–filler interactions and molecular transport. Structural, magnetic, and functional characterisation showed that membrane properties were strongly dependent on the type and proportion of fillers. In particular, the CdCr₂Se₄ with CuCr₂Se₄ combination exhibited the most favourable balance between permeation flux and selectivity, achieving the highest parameters, including pervaporation separation index (PSI) reaching 747 kg·m⁻²·h⁻¹. This superior performance is attributed to the synergistic interaction of these two magnetic fillers, which enhances membrane selectivity while maintaining its integrity. This work presents a novel approach to membrane-based separation, advancing the development of energy-efficient, environmentally sustainable bioethanol purification technologies. Full article

Microfluidics is considered a revolutionary interdisciplinary technology with substantial interest in various biomedical applications. Many non-Newtonian fluids often used in microfluidics systems are notably influenced by the external active fields, such as acoustic, electric, and magnetic fields, leading to changes in rheological behavior. In this study, a numerical investigation is carried out to explore the rheological behavior of non-Newtonian fluids in a T-shaped microfluidics channel integrated with complex micropillar structures under the influence of acoustic, electric, and magnetic fields. For this purpose, COMSOL Multiphysics with laminar flow, pressure acoustic, electric current, and magnetic field physics is used to examine rheological characteristics of non-Newtonian fluids. Three polymer solutions, such as 2000 ppm xanthan gum (XG), 1000 ppm polyethylene oxide (PEO), and 1500 ppm polyacrylamide (PAM), are used as a non-Newtonian fluids with the Carreau–Yasuda fluid model to characterize the shear-thinning behavior. Moreover, numerical simulations are carried out with different input parameters, such as Reynolds numbers (0.1, 1, 10, and 50), acoustic pressure (5 Mpa, 6.5 Mpa, and 8 Mpa), electric voltage (200 V, 250 V, and 300 V), and magnetic flux (0.5 T, 0.7 T, and 0.9 T). The findings reveal that the incorporation of active fields and micropillar structures noticeably impacts fluid rheology. The acoustic field induces higher shear-thinning behavior, decreasing dynamic viscosity from 0.51 Pa·s to 0.34 Pa·s. Similarly, the electric field induces higher shear rates, reducing dynamic viscosities from 0.63 Pa·s to 0.42 Pa·s, while the magnetic field drops the dynamic viscosity from 0.44 Pa·s to 0.29 Pa·s. Additionally, as the Reynolds number increases, the shear rate also rises in the case of electric and magnetic fields, leading to more chaotic flow, while the acoustic field advances more smooth flow patterns and uniform fluid motion within the microchannel. Moreover, a proposed experimental framework is designed to study non-Newtonian fluid mixing in a T-shaped microfluidics channel under external active fields. Initially, the microchannel was fabricated using a high-resolution SLA printer with clear photopolymer resin material. Post-processing involved analyzing particle distribution, mixing quality, fluid rheology, and particle aggregation. Overall, the findings emphasize the significance of considering the fluid rheology in designing and optimizing microfluidics systems under active fields, especially when dealing with complex fluids with non-Newtonian characteristics. Full article