Novel shish-kebab structured nanofibrous decorating chitosan unidirectional scaffolds to mimic extracellular matrix for tissue engineering.

Electrospun nanofibrous scaffolds are renowned for their ability to mimic the microstructure of the extracellular matrix (ECM). However, they often fail to replicate the geometry of target tissues, and the biocompatibility of these scaffolds those made from synthetic polymers is always limited due to the lack of cell binding sites. To address these issues, we proposed an innovative approach that combined unidirectional freeze-drying and electrospinning. During this process, electrospun polycaprolactone (PCL) nanofibers were chopped into nanofibrils, which range in size up to several hundred micrometers, and were incorporated into the chitosan scaffolds via unidirectional freeze-drying. In these scaffolds, the chitosan phase was responsible for maintaining the structural integrity at the macroscale, while the embedded nanofibers enhanced the surface topography at the microscale. The resulting scaffolds exhibited a high porosity of 90% and an impressive water uptake capacity of 2500%. Furthermore, 3T3 fibroblast cells showed strong interactions with the scaffolds, characterized by high rates of cell proliferation and viability. The cells also displayed significant orientation along the direction of the pores, suggesting that the scaffolds effectively guided cellular growth.

Low cost and biocompatible Marine algae derived scaffolds: enhancing tissue regeneration in oral cancer surgery.

Efficient tissue regeneration following oral cancer surgery is crucial for maintaining function. Seaweed-derived scaffold materials, with their resemblance to oral tissue structure, promote cell adhesion and differentiation. Their high porosity aids in exudate absorption, reducing infection risks and tissue maceration. Further scaffold breakdown releases growth factors, aiding tissue regeneration. Easily integrated into dressings or gels, these scaffolds accelerate healing and protect against contaminants. Their biocompatibility and safety ensure minimal adverse effects. Seaweed-derived scaffolds offer a natural, sustainable approach to tissue repair, making them ideal for post-oral surgery dressing, facilitating effective tissue regeneration.

Synthesis and Physicochemical Characterization of Gelatine-Based Biodegradable Aerogel-like Composites as Possible Scaffolds for Regenerative Medicine.

Regenerative medicine is an interdisciplinary field aiming at restoring pathologically damaged tissues and whole organs by cell transplantation in combination with proper supporting scaffolds. Gelatine-based ones are very attractive due to their biocompatibility, rapid biodegradability, and lack of immunogenicity. Gelatine-based composite hydrogels, containing strengthening agents to improve their modest mechanical properties, have been demonstrated to act as extracellular matrices (ECMs), thus playing a critical role in "organ manufacturing". Inspired by the lysyl oxidase (LO)-mediated process of crosslinking, which occurs in nature to reinforce collagen, we have recently developed a versatile protocol to crosslink gelatine B (Gel B) in the presence or absence of LO, using properly synthesized polystyrene- and polyacrylic-based copolymers containing the amine or aldehyde groups needed for crosslinking reactions. Here, following the developed protocol with slight modifications, we have successfully crosslinked Gel B in different conditions, obtaining eight out of nine compounds in high yield (57-99%). The determined crosslinking degree percentage (CP%) evidenced a high CP% for compounds obtained in presence of LO and using the styrenic amine-containing (CP5/DMAA) and acrylic aldehyde-containing (CPMA/DMAA) copolymers as crosslinking agents. ATR-FTIR analyses confirmed the chemical structure of all compounds, while optical microscopy demonstrated cavernous, crater-like, and labyrinth-like morphologies and cavities with a size in the range 15-261 µm. An apparent density in the range 0.10-0.45 g/cm3 confirmed the aerogel-like structure of most samples. Although the best biodegradation profile was observed for the sample obtained using 10% CP5/DMAA (M3), high swelling and absorption properties, high porosity, and good biodegradation profiles were also observed for samples obtained using the 5-10% CP5/DMAA (M4, 5, 6) and 20% CPMA/DMAA (M9) copolymers. Collectively, in this work of synthesis and physicochemical characterization, new aerogel-like composites have been developed and, based on their characteristics, which fit well within the requirements for TE, five candidates (M3, M4, M5, M6, and M9) suitable for future biological experiments on cell adhesion, infiltration and proliferation, to confirm their effective functioning, have been identified.

On reactive Ion Etching of Parylene-C with Simple Photoresist Mask for Fabrication of High Porosity Membranes to Capture Circulating and Exfoliated Tumor Cells.

A high porosity micropore arrayed parylene membrane is a promising device that is used to capture circulating and exfoliated tumor cells (CTCs and ETCs) for liquid biopsy applications. However, its fabrication still requires either expensive equipment or an expensive process. Here, we report on the fabrication of high porosity (>40%) micropore arrayed parylene membranes through a simple reactive ion etching (RIE) that uses photoresist as the etching mask. Vertical sidewalls were observed in etched parylene pores despite the sloped photoresist mask sidewalls, which was found to be due to the simultaneous high DC-bias RIE induced photoresist melting and substrate pedestal formation. A theoretical model has been derived to illustrate the dependence of the maximum membrane thickness on the final pore-to-pore spacing, and it is consistent with the experimental data. A simple, yet accurate, low number (<50) cell counting method was demonstrated through counting cells directly inside a pipette tip under phase-contrast microscope. Membranes as thin as 3 µm showed utility for low number tumor cell capture, with an efficiency of 87-92%.

Fabrication Method for Shape-Controlled 3D Tissue Using High-Porosity Porous Structure.

Shape-controlled 3D tissues resemble natural living tissues in human and animal bodies and are essential materials for developing and improving technologies in regenerative medicine, drug discovery, and biological robotics. In previous studies, shape-controlled 3D tissues were fabricated using scaffold structures or 3D bioprinting techniques. However, controlling the shape of 3D tissues without leaving non-natural materials inside the 3D tissue and efficiently fabricating them remains challenging. In this paper, we propose a novel method for fabricating shape-controlled 3D tissues free of non-natural materials using a flexible high-porosity porous structure (HPPS). The HPPS consisted of a micromesh with pore sizes of 14.87 ± 1.83 µm, lattice widths of 2.24 ± 0.10 µm, thicknesses of 9.96 ± 0.92 µm, porosity of 69.06 ± 3.30%, and an I-shaped microchamber of depth 555.26 ± 11.17 µm. U-87 human glioma cells were cultured in an I-shaped HPPS microchamber for 48 h. After cultivation, the 3D tissue was released within a few seconds while maintaining its I-shape. Specific chemicals, such as proteolytic enzymes, were not used. Moreover, the viability of the released cells composed of shape-controlled 3D tissues free of non-natural materials was above 90%. Therefore, the proposed fabrication method is recommended for shape-controlled 3D tissues free of non-natural materials without applying significant stresses to the cells.

Preparation and Compression Behavior of High Porosity, Microporous Open-Cell Al Foam Using Supergravity Infiltration Method.

By employing a method that combines a NaCl compacting template and supergravity infiltration, open-cell aluminum (Al) foam with varying porosities was prepared. The Al foam fabricated has a pore size of 400 µm and porosity ranging from 0.72 to 0.88. The experimental results indicate that, with an increase in compaction pressure during the NaCl compacting process, the porosity of the foam Al increases and the struts become finer. As the gravity coefficient increases, the density and integrity of the foam Al also increase. Due to the effectiveness of supergravity in overcoming the infiltration resistance between the NaCl preform and molten Al, the supergravity infiltration method holds promise as a practical new technique for fabricating high-porosity open-cell Al foam.

Mycelium Composite with Hierarchical Porous Structure for Thermal Management.

High-performance porous materials with a low carbon footprint provide sustainable alternatives to petroleum-based lightweight foams and can help meet carbon neutrality goals. However, these materials generally face a trade-off between thermal management capabilities and structural strength. Here, a mycelium composite with a hierarchical porous structure, including both macro- and microscale pores, produced from multiple and advanced mycelial networks (elastic modulus of 1.2 GPa) binding loosely distributed sawdust is demonstrated. The morphological, biological, and physicochemical properties of the filamentous mycelium and composites are discussed in terms of how they are influenced by the mycelial system of the fungi and the way they interact with the substrate. The composite shows a porosity of 0.94, a noise reduction coefficient of 0.55 at a frequency range of 250-3000 Hz (for a 15 mm thick sample), a thermal conductivity of 0.042 W m-1  K-1 , and an energy absorption of 18 kJ m-3 at 50% strain. It is also hydrophobic, repairable, and recyclable. It is expected that the hierarchical porous structural composite with excellent thermal and mechanical properties can make a significant impact on the future development of highly sustainable alternatives to lightweight plastic foams.

Hydrophobic Modified Ceramic Aeration Membrane for Effective Treatment of Brine Wastewater.

A novel approach to evaporate brine wastewater using a ceramic aeration membrane was proposed. A high-porosity ceramic membrane was selected as the aeration membrane and was modified with hydrophobic modifiers to avoid undesired surface wetting. The water contact angle of the ceramic aeration membrane reached 130° after hydrophobic modification. The hydrophobic ceramic aeration membrane showed excellent operational stability (up to 100 h), high salinity (25 wt.%) tolerance, and excellent regeneration performance. The evaporative rate reached 98 kg m-2 h-1, which could be restored by ultrasonic cleaning after the membrane fouling occurred. Furthermore, this novel approach shows great promise for practical applications toward a low cost of only 66 kW·h·m-3.

Manufacturing hydroxyapatite scaffold from snapper scales with green phenolic granules as the space holder material.

Hydroxyapatite (HA) scaffold was made using the powder metallurgy with an use of a space holder method with a pore-forming agent from green phenolic (GP) granules. The novelty of this study was the use of GP granules as an agent that does not melt at high temperatures to avoid damaging the tangential contact between the HA powder during the sintering process. HA from snapper scales was added and mixed with polyvinyl alcohol (PVA) and ethanol to form a slurry. The ethanol content was then removed by drying at room temperature. The HA, which contained PVA, was added with GP granules as a pore-forming agent in various amounts to get the desired porosity. The green body was made using a stainless steel mold with the uniaxial pressing process under a pressure of 100 MPa. To make a scaffold sintered body, a sintering process ran at 1200 °C with a holding time of 2 h while maintaining the heating and cooling rates at 5 °C/min. The physical properties of the scaffold sintered body were characterized through linear shrinkage test, pore measurement, porosity test, phase observation by X-ray diffraction (XRD), and microstructure observation by scanning electron microscopy (SEM) and digital microscopy (DM). So were the mechanical ones through a compressive strength test. The results showed that the sintered body had a compressive strength value of 1.6 MPa at a porosity of 60.7% with a pore size of 129-394 µm. The scaffold contained interconnections between pores at a HA:GP ratio of 55:45 wt%, which matched the condition required for cell tissue growth. The conclusion is that GP granules are good enough to be used as a pore-making agent on scaffolds using the space holder method because they do not damage the tangential contact between the HA powder during the sintering process. However, efforts are needed to remove the remaining GP ash on the scaffold.

A Novel Design Method of Gradient Porous Structure for Stabilized and Lightweight Mandibular Prosthesis.

Compared to conventional prostheses with homogenous structures, a stress-optimized functionally gradient prosthesis will better adapt to the host bone due to its mechanical and biological advantages. Therefore, this study aimed to investigate the damage resistance of four regular lattice scaffolds and proposed a new gradient algorithm for stabilized and lightweight mandibular prostheses. Scaffolds with four configurations (regular hexahedron, regular octahedron, rhombic dodecahedron, and body-centered cubic) having different porosities underwent finite element analysis to select an optimal unit cell. Meanwhile, a homogenization algorithm was used to control the maximum stress and increase the porosity of the scaffold by adjusting the strut diameters, thereby avoiding fatigue failure and material wastage. Additionally, the effectiveness of the algorithm was verified by compression tests. The results showed that the load transmission capacity of the scaffold was strongly correlated with both configuration and porosity. Scaffolds with regular hexahedron unit cells can withstand stronger loads at the same porosity. The optimized gradient scaffold showed higher porosity and lower maximum stress than the target stress value, and the compression tests also confirmed the simulation results. A mandibular prosthesis was established using a regular hexahedron unit cell, and the strut diameters were gradually changed according to the proposed algorithm and the simulation results. Compared with the initial homogeneous prosthesis, the optimized gradient prosthesis reduced the maximum stress by 24.48% and increased the porosity by 6.82%, providing a better solution for mandibular reconstruction.

Boosting the enantioresolution of zwitterionic-teicoplanin chiral stationary phases by moving to wide-pore core-shell particles.

A novel zwitterionic-teicoplanin chiral stationary phase (CSP), based on superficially porous particles (SPPs) of 2.7 µm particle diameter and 160 Å pore size, has been prepared and evaluated towards the enantioseparation of important classes of compounds, including chiral drugs, pesticides, and N-derivatized amino acids. The comparison with two analogous CSPs prepared on SPPs with 2.7 and 2.0 µm particle diameter and 90 Å pore size has revealed that the use of large-pore particles allows to dramatically improve both the enantioselectivity and the resolution-per-analysis-time, at the point that the column prepared with the new CSP outperformed the one packed with the finest particles. On the novel wide-pore CSP, the separation of fifteen racemates of pratical importance was significantly improved in terms of both enantioselectivity and resolution-per-analysis time-compared to the CSPs based on SPPs with smaller pores (90 Å). Such a CSP would be suitable for very fast enantioseparations allowing the saving of solvent for greener high-efficiency/high-throughput applications.

Electrochemical Energy Storage Properties of High-Porosity Foamed Cement.

Foamed porous cement materials were fabricated with H2O2 as foaming agent. The effect of H2O2 dosage on the multifunctional performance is analyzed. The result shows that the obtained specimen with 0.6% H2O2 of the ordinary Portland cement mass (PC0.6) has appropriate porosity, leading to outstanding multifunctional property. The ionic conductivity is 29.07 mS cm-1 and the compressive strength is 19.6 MPa. Furthermore, the electrochemical energy storage performance is studied in novel ways. The PC0.6 also shows the highest areal capacitance of 178.28 mF cm-2 and remarkable cycle stability with 90.67% of initial capacitance after 2000 cycles at a current density of 0.1 mA cm-2. The superior electrochemical energy storage property may be attributed to the high porosity of foamed cement, which enlarges the contact area with the electrode and provides a rich ion transport channel. This report on cement-matrix materials is of great significance for large scale civil engineering application.

Preparation of Super Absorbent and Highly Active Fish Collagen Sponge and its Hemostatic Effect in vivo and in vitro.

Effective control of acute wound hemorrhage caused by battlefields, car accidents, natural disasters can highly improve patients' survival rates. Nevertheless, hemostatic materials on present market have various defects and limitations. This study utilizes tilapia to extract macromolecular type I collagen to prepare a new hemostatic sponge for controlling acute wound bleeding. The extracted fish collagen has high purity, uniform molecular size and high hydroxyproline content. The peptide chain structure and natural high-level structure are intactly preserved. The infrared absorption spectrum showcases that it preserves all the characteristic absorption bands of type I collagen. The developed hemostatic sponge has a uniform honeycomb-shaped porous structure and high water absorption capacity. The biological safety test illustrates that the sponge cell has good compatibility and it will not trigger any inflammatory reaction or immune rejection reactions in the body. The sponge cell could be degraded gradually and completely, which has good biocompatibility and degradation performance. The result of in vitro experiments shows that certain groups or structures in fish collagen molecules can combine specific sites on the surface of blood cells and platelets, which can quickly activate platelets and coagulation system to obtain better coagulation function. The result of In vivo experiments further shows that the fish collagen sponge has fast coagulation speed and low bleeding during the hemostasis process of rabbit ear arteries and rat liver wounds, which proves that it has excellent coagulation performance.

Co-digestion of biofuel by-products: Enhanced biofilm formation maintains high organic matter removal when methanogenesis fails.

Ethanol and biodiesel industries generate large volumes of by-products, such as vinasse and glycerol, which are suitable for biogas exploitation. This paper assessed the applicability and process performance of the anaerobic structured-bed reactor (AnSTBR) for the mesophilic (30 °C) continuous (105 days) anaerobic co-digestion of sugarcane vinasse and distilled glycerol under increasing organic loading rates (OLR) (0.5-5.0 kgCOD m-3d-1). The highest methane yield (211 NmL g-1CODrem.) and volumetric production (668 NmL L-1d-1) occurred at an OLR of 3.5 kgCOD m-3d-1. The performance of the AnSTBR showed high removal efficiencies of total COD (77.1%), carbohydrates (81.9%), and glycerol content (99.7%). Biofilm growth enhancement within the reactor offset the impairment of methanogenesis activity at high organic loads. The prompt biodegradability of glycerol reinforced the importance of gradually increase the organic load to prevent the buildup of volatile acids and maintain a stable long-term co-digestion system.

A Fiber-Based 3D Lithium Host for Lean Electrolyte Lithium Metal Batteries.

3D hosts are promising to extend the cycle life of lithium metal anodes but have rarely been implemented with lean electrolytes thus impacting the practical cell energy density. To overcome this challenge, a 3D host that is lightweight and easy to fabricate with optimum pore size that enables full utilization of its pore volume, essential for lean electrolyte operations, is reported. The host is fabricated by casting a VGCF (vapor-grown carbon fiber)-based slurry loaded with a sparingly soluble rubidium nitrate salt as an additive. The network of fibers generates uniform pores of ≈3 µm in diameter with a porosity of 80%, while the nitrate additive enhances lithiophilicity. This 3D host delivers an average coulombic efficiency of 99.36% at 1 mA cm-2 and 1 mAh cm-2 for over 860 cycles in half-cell tests. Full cells containing an anode with 1.35-fold excess lithium paired with LiNi0.8 Mn0.1 Co0.1 O2 (NMC811) cathodes exhibit capacity retention of 80% over 176 cycles at C/2 under a lean electrolyte condition of 3 g Ah-1 . This work provides a facile and scalable method to advance 3D lithium hosts closer to practical lithium-metal batteries.

Nanofibrous tissue engineering scaffold with nonlinear elasticity created by controlled curvature and porosity.

Micro-crimped fibers have been widely used in the field of tissue repair to mimic the natural tissue structure and mechanical properties. However, the electrospun nanofibrous membrane is a kind of dense structure, which cannot meet the requirements of mechanical properties and permeability. In this study, we prepared nanofibrous scaffold with controllable porosity and crimpness by sacrificing fiber components and releasing residual stress. The results show that the crimpness of the fiber is positively related to the porosity, and with the increase of porosity, the fiber crimpness increases greatly. Meanwhile, the scaffold modulus was reduced by 86% and the elongation at break doubled, which is similar to natural blood vessels. Moreover, it is found that the porous micro-crimped fiber scaffold promotes the adhesion and diffusion of endothelial cells, and facilitates the rapid endothelialization of the scaffold, which has a great potential for practical application.

High-Porosity Foam-Based Iontronic Pressure Sensor with Superhigh Sensitivity of 9280 kPa-1.

Flexible pressure sensors with high sensitivity are desired in the fields of electronic skins, human-machine interfaces, and health monitoring. Employing ionic soft materials with microstructured architectures in the functional layer is an effective way that can enhance the amplitude of capacitance signal due to generated electron double layer and thus improve the sensitivity of capacitive-type pressure sensors. However, the requirement of specific apparatus and the complex fabrication process to build such microstructures lead to high cost and low productivity. Here, we report a simple strategy that uses open-cell polyurethane foams with high porosity as a continuous three-dimensional network skeleton to load with ionic liquid in a one-step soak process, serving as the ionic layer in iontronic pressure sensors. The high porosity (95.4%) of PU-IL composite foam shows a pretty low Young's modulus of 3.4 kPa and good compressibility. A superhigh maximum sensitivity of 9,280 kPa-1 in the pressure regime and a high pressure resolution of 0.125% are observed in this foam-based pressure sensor. The device also exhibits remarkable mechanical stability over 5,000 compression-release or bending-release cycles. Such high porosity of composite structure provides a simple, cost-effective and scalable way to fabricate super sensitive pressure sensor, which has prominent capability in applications of water wave detection, underwater vibration sensing, and mechanical fault monitoring.

Structural, photocatalytic and photoelectrochemical properties of porous ZnO nanosheets prepared by air cold plasma.

Porous ZnO nanosheets with different thickness were prepared on zinc substrate by air cold plasma for photocatalytic degradation and photoelectrochemical water splitting. The ZnO nanosheets consisted of nanocrystallines with high-density oxygen-related defects characterized by the strong red luminescence. The UV absorption tended to be saturated as the thickness increased, and the saturation occurred at a thickness of about 2.3µm. Under UV irradiation (365 nm), the 2.3µm thick sample with higher content of oxygen vacancies and oxygen interstitials showed the highest photocatalytic activity (and higher than P25 TiO2) in degradation of gaseous ethyl acetate. Due to the excellent UV-vis absorption ability and the effective transfer of photogenerated carriers, the ZnO nanosheets with thickness of 3.3µm showed a photocurrent density as high as 0.22 mA cm-2at -0.28 V (versus Ag/AgCl) under AM 1.5 G 100 mW cm-2.

Derivation of Luminescent Mesoporous Silicon Nanocrystals from Biomass Rice Husks by Facile Magnesiothermic Reduction.

High-quality silicon (Si) nanocrystals that simultaneously had superior mesoporous and luminescent characteristics were derived from sticky, red, and brown rice husks via the facile and cost-effective magnesiothermic reduction method. The Si nanocrystals were confirmed to comprise an aggregated morphology with spherical nanocrystals (e.g., average sizes of 15-50 nm). Due to the surface functional groups formed at the nanocrystalline Si surfaces, the Si nanocrystals clearly exhibited multiple luminescence peaks in visible-wavelength regions (i.e., blue, green, and yellow light). Among the synthesized Si nanocrystals, additionally, the brown rice husk (BRH)-derived Si nanocrystals showed to have a strong UV absorption and a high porosity (i.e., large specific surface area: 265.6 m2/g, small average pore diameter: 1.91 nm, and large total pore volume: 0.5389 cm3/g). These are indicative of the excellent optical and textural characteristics of the BRH-derived Si nanocrystals, compared to previously reported biomass-derived Si nanocrystals. The results suggest that the biomass BRH-derived Si nanocrystals hold great potential as an active source material for optoelectronic devices as well as a highly efficient catalyst or photocatalyst for energy conversion devices.

Binder Jetting Additive Manufacturing of High Porosity 316L Stainless Steel Metal Foams.

High porosity (40% to 60%) 316L stainless steel containing well-interconnected open-cell porous structures with pore openness index of 0.87 to 1 were successfully fabricated by binder jetting and subsequent sintering processes coupled with a powder space holder technique. Mono-sized (30 µm) and 30% (by volume) spherically shaped poly(methyl methacrylate) (PMMA) powder was used as the space holder material. The effects of processing conditions such as: (1) binder saturation rates (55%, 100% and 150%), and (2) isothermal sintering temperatures (1000 ○C to 1200 ○C) on the porosity of 316L stainless steel parts were studied. By varying the processing conditions, porosity of 40% to 45% were achieved. To further increase the porosity values of 316L stainless steel parts, 30 vol. % (or 6 wt. %) of PMMA space holder particles were added to the 3D printing feedstock and porosity values of 57% to 61% were achieved. Mercury porosimetry results indicated pore sizes less than 40 µm for all the binder jetting processed 316L stainless steel parts. Anisotropy in linear shrinkage after the sintering process was observed for the SS316L parts with the largest linear shrinkage in the Z direction. The Young's modulus and compression properties of 316L stainless steel parts decreased with increasing porosity and low Young's modulus values in the range of 2 GPa to 29 GPa were able to be achieved. The parts fabricated by using pure 316L stainless steel feedstock sintered at 1200 ○C with porosity of ~40% exhibited the maximum overall compressive properties with 0.2% compressive yield strength of 52.7 MPa, ultimate compressive strength of 520 MPa, fracture strain of 36.4%, and energy absorption of 116.7 MJ/m3, respectively. The Young's modulus and compression properties of the binder jetting processed 316L stainless steel parts were found to be on par with that of the conventionally processed porous 316L stainless steel parts and even surpassed those having similar porosities, and matched to that of the cancellous bone types.