Macroporous Architecture Research Articles

Preparation of a thermosensitive and antibacterial in situ gel using poloxamer-quaternized chitosan for sustained ocular delivery of Levofloxacin hydrochloride

In this study, a thermosensitive in situ gel with porous structure was developed using poloxamer (Po) and N-(2-hydroxy-3-trimethyl ammonium) propyl chitosan chloride (HTCC). The poloxamer-quaternized chitosan (Po-HTCC) in situ gel exhibited superior rheological property, water absorption capacity and antibacterial activity against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Streptococcus pyogenes, making it well-suited for ocular applications. Scanning electron microscope revealed a macroporous architecture with pore sizes ranging from 1 to 2 μm, suggesting that the gel has desirable breathability, corneal adhesion capability, and overall conformability. In vitro drug release assay was conducted with levofloxacin hydrochloride, demonstrating that sustained release over 48 h could be achieved at 34 °C, with approximately 80 % of the drug released within this timeframe. Computational simulations revealed substantial binding affinity between the material and the Escherichia coli outer membrane lipopolysaccharide-associated protein and corneal mucin. The protein showing the strongest binding energy to N-(2-hydroxy-3-trimethyl ammonium) propyl chitosan chloride (HTCC), as calculated by the Molecular Mechanics Generalized Born Surface Area Method (MM-GBSA), was LptD-LptE, with a binding energy of −61.14 ± 4.72 kcal/mol. These results underscore the potential of this system for effective and convenient ocular delivery with sustained drug release.

Tuning porosity of macroporous hydrogels enables rapid rates of stress relaxation and promotes cell expansion and migration

Extracellular matrix (ECM) viscoelasticity broadly regulates cell behavior. While hydrogels can approximate the viscoelasticity of native ECM, it remains challenging to recapitulate the rapid stress relaxation observed in many tissues without limiting the mechanical stability of the hydrogel. Here, we develop macroporous alginate hydrogels that have an order of magnitude increase in the rate of stress relaxation as compared to bulk hydrogels. The increased rate of stress relaxation occurs across a wide range of polymer molecular weights (MWs), which enables the use of high MW polymer for improved mechanical stability of the hydrogel. The rate of stress relaxation in macroporous hydrogels depends on the volume fraction of pores and the concentration of bovine serum albumin, which is added to the hydrogels to stabilize the macroporous structure during gelation. Relative to cell spheroids encapsulated in bulk hydrogels, spheroids in macroporous hydrogels have a significantly larger area and smaller circularity because of increased cell migration. A computational model provides a framework for the relationship between the macroporous architecture and morphogenesis of encapsulated spheroids that is consistent with experimental observations. Taken together, these findings elucidate the relationship between macroporous hydrogel architecture and stress relaxation and help to inform the design of macroporous hydrogels for materials-based cell therapies.

Engineering the conductive network of missing-linker metal-organic framework for improved performance in aqueous zinc-ion batteries

Aqueous zinc-ion batteries (ZIBs) face critical challenges such as interfacial side reactions, corrosion, and passivation of the zinc anode. In this work, we introduce a novel zinc anode featuring a 3D ordered macroporous (3DOM) architecture based on a missing-linker ZIF-8 framework (Zn@Fc-ZIF-8). This innovative design achieves remarkable stability, maintaining performance for over 4000 h at a current density of 0.25 mA cm−2 in a symmetric cell-over 30 times longer than a bare Zn anode. Additionally, by integrating carbon nanotubes (CNTs) within the 3DOM Fc-ZIF-8 skeleton to create a highly conductive network (3DOM Fc-ZIF-8/CNTs), we extend the anode's lifetime to 1500 h at a high current density of 5 mA cm−2. The strategic regulation of the ZIF-8 structure using ferrocene formic acid (Fc) and the incorporation of CNTs result in a full cell with the bi-functional Zn@Fc-ZIF-8/CNTs anode, achieving a high specific capacity of 380.5 mAh g−1 and a coulombic efficiency (CE) of 99.8 %. These findings underscore the significant potential of MOF-based anodes in addressing dendrite formation and advancing the practical application of ZIBs.

Photothermal Oxidation of Volatile Organic Compounds Over Co3O4‐Based Inverse Opal

AbstractThe growing preference for photothermal catalysis stems from its minimal energy consumption and heightened catalytic efficacy. Nonetheless, material photon utilization efficiency is frequently hindered by catalyst structural design constraints and bandgap limitations. Herein, we present a Co3O4‐based inverse opal featuring a three‐dimensional ordered macroporous (3DOM‐Co3O4) architecture tailored for photothermal VOCs oxidation. The 3DOM‐Co3O4 exhibits superior catalytic performance in carbon monoxide oxidation, methane oxidation, and toluene oxidation, with a photothermal enhancement of more than 100 %. Further experimental and theoretical analyses reveal that the three‐dimensional periodic array of pores facilitates the slow photon effect, augmenting the light absorption capabilities of the catalyst. Thus, it generates more photoexcited electrons, promoting VOCs molecular activation. Additionally, the well‐ordered porous structure facilitates the diffusion of reactants and products, further accelerating the catalytic reaction. This work highlights promising prospects for leveraging inverse opals as an innovative strategy towards enhancing photothermal catalytic VOCs oxidization efficiency.

Arginine-loaded globular BSAMA/fibrous GelMA biohybrid cryogels with multifunctional features and enhanced healing for soft gingival tissue regeneration

Mucogingival surgery has been widely used in soft gingival tissue augmentation in which autografts are predominantly employed. However, the autografts face grand challenges, such as scarcity of palatal donor tissue and postoperative discomfort. Therefore, development of alternative soft tissue substitutes has been an imperative need. Here, we engineered an interconnected porous bovine serum albumin methacryloyl (BSAMA: B, as a drug carrier and antioxidant)/gelatin methacryloyl (GelMA: G, as a biocompatible collagen-like component)-based cryogel with L-Arginine (Arg) loaded as an angiogenic molecule, which could serve as a promising gingival tissue biohybrid scaffold. BG@Arg cryogels featured macroporous architecture, biodegradation, sponge-like properties, suturability, and sustained Arg release. Moreover, BG@Arg cryogels promoted vessel formation and collagen deposition which play an important role in tissue regeneration. Most interestingly, BG@Arg cryogels were found to enhance antioxidant effects. Finally, the therapeutic effect of BG@Arg on promoting tissue regeneration was confirmed in rat full-thickness skin and oral gingival defect models. In vivo results revealed that BG@Arg2 could promote better angiogenesis, more collagen production, and better modulation of inflammation, as compared to a commercial collagen membrane. These advantages might render BG@Arg cryogels a promising alternative to commercial collagen membrane products and possibly autografts for soft gingival tissue regeneration.

Ruthenium Anchored Laser-Induced Graphene as Binder-Free and Free-Standing Electrode for Selective Electrosynthesis of Ammonia from Nitrate.

Developing effective electrocatalysts for the nitrate reduction reaction (NO3RR) is a promising alternative to conventional industrial ammonia (NH3) synthesis. Herein, starting from a flexible laser-induced graphene (LIG) film with hierarchical and interconnected macroporous architecture, a binder-free and free-standing Ru-modified LIG electrode (Ru-LIG) is fabricated for electrocatalytic NO3RR via a facile electrodeposition method. The relationship between the laser-scribing parameters and the NO3RR performance of Ru-LIG electrodes is studied in-depth. At -0.59 VRHE, the Ru-LIG electrode exhibited the optimal and stable NO3RR performance (NH3 yield rate of 655.9µgcm-2h-1 with NH3 Faradaic efficiency of up to 93.7%) under a laser defocus setting of +2mm and an applied laser power of 4.8W, outperforming most of the reported NO3RR electrodes operated under similar conditions. The optimized laser-scribing parameters promoted the surface properties of LIG with increased graphitization degree and decreased charge-transfer resistance, leading to synergistically improved Ru electrodeposition with more exposed NO3RR active sites. This work not only provides a new insight to enhance the electrocatalytic NO3RR performance of LIG-based electrodes via the coordination with metal electrocatalysts as well as identification of the critical laser-scribing parameters but also will inspire the rational design of future advanced laser-induced electrocatalysts for NO3RR.

Cost-effective and natural-inspired lotus root/GelMA scaffolds enhanced wound healing via ROS scavenging, angiogenesis and reepithelialization

Skin wounds, prevalent and fraught with complications, significantly impact individuals and society. Wound healing encounters numerous obstacles, such as excessive reactive oxygen species (ROS) production and impaired angiogenesis, thus promoting the development of chronic wound. Traditional clinical interventions like hemostasis, debridement, and surgery face considerable challenges, including the risk of secondary infections. While therapies designed to scavenge excess ROS and enhance proangiogenic properties have shown effectiveness in wound healing, their clinical adoption is hindered by high costs, complex manufacturing processes, and the potential for allergic reactions. Lotus root, distinguished by its natural micro and macro porous architecture, exhibits significant promise as a tissue engineering scaffold. This study introduced a novel scaffold based on hybridization of lotus root-inspired and Gelatin Methacryloyl (GelMA), verified with satisfactory physicochemical properties, biocompatibility, antioxidative capabilities and proangiogenic abilities. In vivo tests employing a full-thickness wound model revealed that these scaffolds notably enhanced micro vessel formation and collagen remodeling within the wound bed, thus accelerating the healing process. Given the straightforward accessibility of lotus roots and the cost-effective production of the scaffolds, the novel scaffolds with ROS scavenging, pro-angiogenesis and re-epithelialization abilities are anticipated to have clinical applicability for various chronic wounds.

Cryogel with Modular and Clickable Building Blocks: Toward the Ultimate Ideal Macroporous Medium for Bacterial Separation.

The lack of practical platforms for bacterial separation remains a hindrance to the detection of bacteria in complex samples. Herein, a composite cryogel was synthesized by using clickable building blocks and boronic acid for bacterial separation. Macroporous cryogels were synthesized by cryo-gelation polymerization using 2-hydroxyethyl methacrylate and allyl glycidyl ether. The interconnected macroporous architecture enabled high interfering substance tolerance. Nanohybrid nanoparticles were prepared via surface-initiated atom transfer radical polymerization and immobilized onto cryogel by click reaction. Alkyne-tagged boronic acid was conjugated to the composite for specific bacteria binding. The physical and chemical characteristics of the composite cryogel were analyzed systematically. Benefitting from the synergistic, multiple binding sites provided by the silica-assisted polymer, the composite cryogel exhibited excellent affinity toward S. aureus and Salmonella spp. with capacities of 91.6 × 107 CFU/g and 241.3 × 107 CFU/g in 0.01 M PBS (pH 8.0), respectively. Bacterial binding can be tuned by variations in pH and temperature and the addition of monosaccharides. The composite was employed to separate S. aureus and Salmonella spp. from spiked tap water, 40% cow milk, and sea cucumber enzymatic hydrolysate, which resulted in high bacteria separation and demonstrated remarkable potential in bacteria separation from food samples.

3D printing calcium phosphate ceramics with high osteoinductivity through pore architecture optimization

The osteoinductivity of 3D printed calcium phosphate (CaP) ceramics has a large gap compared with those prepared by conventional foaming methods, and improving the osteoinductivity of 3D printing CaP ceramics is crucial for successful application in bone regeneration. Pore architecture plays a critical role in osteoinductivity. In this study, CaP ceramics with a hexagonal close-packed (HCP) spherical pore structure were successfully fabricated using DLP printing technology. Additionally, octahedral (Octahedral), diamond (Diamond), and helical (Gyroid) structures were constructed with similar porosity and macropore diameter. CaP ceramics with the HCP structure exhibited higher compression strength (8.39 ± 1.82 MPa) and lower permeability (6.41 × 10−11 m2) compared to the Octahedral, Diamond, and Gyroid structures. In vitro cellular responses indicated that the macropore architecture strongly influenced the local growth rate of osteoblast-formed cell tissue; cells grew uniformly and formed circular rings in the HCP group. Furthermore, the HCP group promoted the expression of osteogenic genes and proteins more effectively than the other three groups. The outstanding osteoinductivity of the HCP group was confirmed in canine intramuscular implantation studies, where the new bone area reached up to 8.02 ± 1.94 % after a 10-week implantation. Additionally, the HCP group showed effective bone regeneration in repairing femoral condyle defects. Therefore, our findings suggest that 3D printed CaP bioceramics with an HCP structure promote osteoinductivity and can be considered as candidates for personalized precise treatment of bone defects in clinical applications. Statement of significance1. 3D printing BCP ceramics with high osteoinductivity were constructed through pore architecture optimization.2. BCP ceramics with HCP structure exhibited relatively higher mechanical strength and lower permeability than those with Octahedral, Diamond and Gyroid structures.3. BCP ceramics with HCP structure could promote the osteogenic differentiation of MC3T3-E1, and showed the superior in-vivo osteoinductivity and bone regeneration comparing with the other structures.

Regulating nitrogen/sulfur terminals on 3D porous Ti3C2 MXene with enhanced reaction kinetics toward high-performance alkali metal ion storage

In this paper, we have developed a simple and efficient sulfur-amine chemistry strategy to prepare a three-dimensional (3D) porous Ti3C2Tx composite with large amounts of N and S terminal groups. The well-designed 3D macroporous architecture presents enlarged interlayer spacing, large specific surface area, and unique porous structure, which successfully solves the re-stacking issue of MXene during storage and electrode fabrication. It is the amount of concentrated hydrochloric acid added to the S-EDA (ethylenediamine)/MXene colloidal suspension that is critical to the formation of 3D morphology. In addition, N and S terminals on MXene could improve the adsorption ability of K+. Owing to the synergistic effect of the structure design and terminal modification, the N, S codoped three-dimensional porous Ti3C2Tx (3D-NSPM) material shows a high surface capacitive contribution and rapid diffusion kinetics for K+ and Na+. As a result, the as-prepared 3D-NSPM delivers high reversible capacity (237 and 273 mAh g−1 at 0.1 A g−1 for PIBs and SIBs, respectively), superb cycling stability (84.9% capacity retention after 10,000 cycles at 1 A g−1 in PIBs and 74.0% capacity retention after 2200 cycles at 1 A g−1 in SIBs), and excellent rate capability (111 and 196 mAh g−1 at 5 A g−1 for PIBs and SIBs, respectively), which are superior to other MXene-based anodes for PIBs and SIBs. Moreover, the described strategy provides a new insight for constructing the 3D porous structure from 2D building blocks beyond MXene.

Constructing a buffer macroporous architecture on silicon/carbon anode for high-performance lithium-ion battery

Constructing a buffer macroporous architecture on silicon/carbon anode for high-performance lithium-ion battery

Hierarchically Periodic Macroporous Niobium Oxide Architecture for Enhanced Hydrogen Evolution.

The fabrication of periodic macroporous (PM) in Nb2O5 via morphological control is crucial for improving the photocatalytic hydrogen evolution efficiency. In this study, Nb2O5 with PM is synthesized using a straightforward colloidal crystal templating approach. This material features an open, interconnected macroporous architecture with nanoscale walls, high crystallinity, and substantial porosity. Extensive characterization reveals that this hierarchically structured Nb2O5 possesses abundant surface active sites and is capable of capturing light effectively, facilitating rapid mass transfer and diffusion of reactants and markedly suppressing the recombination of photoexcited charge carriers. Macroporous Nb2O5 exhibits superior water-splitting hydrogen evolution performance compared with its bulk and commercial counterparts, achieving a hydrogen production rate of 405µmol g-1 h-1, surpassing that of bulk Nb2O5 (B-Nb2O5) and commercial Nb2O5 (C-Nb2O5) by factors of 5 and 33, respectively. This study proposes an innovative strategy for the design of hierarchically structured PM, thereby significantly advancing the hydrogen evolution potential of Nb2O5.

Design of sol-gel bioactive glasses: Towards tailored architecture and ion-supply for bone tissue regeneration

This paper reports the synthesis of borosilicate bioactive glasses nanoparticles containing ions of interest (calcium, strontium or silver ions) for the purpose of bone tissue regeneration using a modified Stöber method and their shaping by robocasting to produce macroporous grid-like architectures with controlled interconnected porosity. Main focus is on the design of a paste formulation, the optimization of the robocasting process to produce 3D scaffolds and ion release from the sintered scaffold in solution. Pastes were developed (40 vol% powder loading), characterized, and extruded layer-by-layer to form three-dimensional scaffolds with a grid-like macrostructure (400 μm diameter of the rods). After drying under controlled atmosphere, scaffolds were sintered. The sintering study revealed that the addition of silver reduced the densification point of the borosilicate glass. After immersion in a buffer solution, ionic release (Si, B and Sr) of the sintered scaffold was evaluated, and compared with the synthetized powder. The shaping process did not affect Sr dissolution. This controllable ion-release behavior of the scaffolds are promising for their therapeutic application.

Macroporous Granular Hydrogels Functionalized with Aligned Architecture and Small Extracellular Vesicles Stimulate Osteoporotic Tendon-To-Bone Healing.

Osteoporotic tendon-to-bone healing (TBH) after rotator cuff repair (RCR) is a significant orthopedic challenge. Considering the aligned architecture of the tendon, inflammatory microenvironment at the injury site, and the need for endogenous cell/tissue infiltration, there is an imminent need for an ideal scaffold to promote TBH that has aligned architecture, ability to modulate inflammation, and macroporous structure. Herein, a novel macroporous hydrogel comprising sodium alginate/hyaluronic acid/small extracellular vesicles from adipose-derived stem cells (sEVs) (MHA-sEVs) with aligned architecture and immunomodulatory ability is fabricated. When implanted subcutaneously, MHA-sEVs significantly improve cell infiltration and tissue integration through its macroporous structure. When applied to the osteoporotic RCR model, MHA-sEVs promote TBH by improving tendon repair through macroporous aligned architecture while enhancing bone regeneration by modulating inflammation. Notably, the biomechanical strength of MHA-sEVs is approximately two times higher than the control group, indicating great potential in reducing postoperative retear rates. Further cell-hydrogel interaction studies reveal that the alignment of microfiber gels in MHA-sEVs induces tenogenic differentiation of tendon-derived stem cells, while sEVs improve mitochondrial dysfunction in M1 macrophages (Mφ) and inhibit Mφ polarization toward M1 via nuclear factor-kappaB (NF-κb) signaling pathway. Taken together, MHA-sEVs provide a promising strategy for future clinical application in promoting osteoporotic TBH.

Additive Manufacturing of Wet-Spun Polysulfone Medical Implants.

Research on additive manufacturing (AM) of high-performance polymers provides novel materials and technologies for advanced applications in different sectors, such as aerospace and biomedical engineering. The present article is contextualized in this research trend by describing a novel AM protocol for processing a polysulfone (PSU)/N-methyl-2-pyrrolidone (NMP) solution into medical implant prototypes. In particular, an AM technique involving the patterned deposition of the PSU/NMP mixture in a coagulation bath was employed to fabricate PSU implants with different predefined shape, fiber diameter, and macropore size. Scanning electron microscopy (SEM) analysis highlighted a fiber transversal cross-section morphology characterized by a dense external skin layer and an inner macroporous/microporous structure, as a consequence of the nonsolvent-induced polymer solidification process. Physical-chemical and thermal characterization of the fabricated samples demonstrated that PSU processing did not affect its macromolecular structure and glass-transition temperature, as well as that after post-processing PSU implants did not contain residual solvent or nonsolvent. Mechanical characterization showed that the developed PSU scaffold tensile and compressive modulus could be changed by varying the macroporous architecture. In addition, PSU scaffolds supported the in vitro adhesion and proliferation of the BALB/3T3 clone A31 mouse embryo cell line. These findings encourage further research on the suitability of the developed processing method for the fabrication of customized PSU implants.

Defect-activated ternary carbon composite: A multifunctional electrocatalyst for efficient oxidation of water, urea, glucose, ORR, and zinc-air batteries

Designing a low-cost multifunction electrocatalyst that can synergistically catalyze multiple reactions in alkaline media while operative for long periods is of paramount importance for the hydrogen economy. Particularly, defect-activated electrocatalysts can significantly improve electrolytic performance by altering their chemical properties and electronic structures. However, developing defect-rich electrocatalysts with multiple active sites for efficient electro-oxidation of water remains challenging. In this respect, we present a straightforward strategy to design a defect-activated multifunctional ternary carbon composite by integrating graphene oxide (GO), Mxene (Mx), and graphitic carbon nitride (CN). Benefiting from the well-integrated 2D interfacial coupling of different carbon nanostructures, carbon composite has several advantageous properties including superior electric conductivity, higher specific surface area, activated surface defects, and highly accessible multicomponent surface-active sites. In addition, carbon composite exhibited macroporous 3D architecture for free migration of oxygen species and electrons. Accordingly, the carbon composite served as a multifunctional electrocatalyst in alkaline media, displaying superior electrolytic activities toward oxygen evolution reaction (OER), urea oxidation reaction (UOR), glucose oxidation reaction (GOR), and oxygen reduction reaction (ORR). Moreover, the Zn-air batteries (ZABs) fabricated with Zn anode and carbon composite as air-cathode demonstrated to have a high-power density, high discharge voltage, and excellent cycling stability in alkaline media. The exceptional electrolytic performance is attributed to the defect-rich interfaces and the synergistic interactions between the multi-components of carbon composite, which not only facilitate free accessible volume for rapid diffusion of oxygen-related species but also maintain the structural integrity during the reaction, thus allowing its comparable fast reaction kinetics. Overall, this work presents a simple and scalable strategy to design an efficient, stable, and eco-friendly multifunctional electrocatalyst that has the potential to be used in a wide range of applications in energy conversion and storage.

3D‐Printed Inherently Porous Structures with Tetrahedral Lattice Architecture: Experimental and Computational Study of Their Mechanical Behavior

AbstractIncreasing demand in automotive, construction, and medical industries for materials with reduced weight and high mechanical durability has given rise to porous materials and composites. Materials combining nano‐ and microporosity and a well‐defined cellular macroporous architecture offer great potential weight reduction while maintaining mechanical durability. To achieve predictable mechanical performance, it is essential to apply experimental and computational efforts to precisely describe material structure–properties relationships. This study explores polymer structures with polymerization‐inherited porosity and well‐defined macroporous geometry, fabricated via digital light processing (DLP) 3Dprinting. Pore size and relative density are varied by ink composition and printing parameters to track their influence on the structure stiffness. Simulated stiffness values for the base polymer correspond to the experimentally determined elastic properties, showing Young's moduli of 554–722 MPa depending on the cosolvent ratio, which confirms the structure–properties relationship. Macroporosity is introduced in the form of a 3D tetrahedral bending‐dominated architecture with the resulting specific Young's moduli of 79.5 MPa cm3 g−1, comparable to foams. To merge the gap in stiffnesses, further investigation of structure–property relationships of various 3D–printed lattice architectures, as well as its application to other stereolithography methods to eliminate the negative effects from printing artifacts and resolution limit of the DLP 3D‐printing, are envisioned.

Characteristics of the soil macropore and root architecture of alpine meadows during the seasonal freezing-thawing process and their impact on water transport in the Qinghai Lake watershed, northeastern Qinghai–Tibet Plateau

Low temperatures, freezing-thawing cycles, and short growing seasons characterize alpine soils. The mattic epipedon, a special diagnostic surface horizon with an intensive root network, is widely distributed in alpine ecosystems. Studies on the soil macropores and roots of the mattic epipedon layer in response to seasonal freezing-thawing processes on the Qinghai–Tibet Plateau are lacking. This study characterized the soil macropores and roots of alpine meadows during the seasonal freezing-thawing process using X-ray computed tomography and revealed the influence of soil macropores and roots structure on water transport in the mattic epipedon layer of the alpine meadows. The results showed that the soil pore distribution was more uniform during the unstable freezing stage (UFP) and the unstable thawing stage (UTP), whereas there was a clear mattic epipedon layer during the completely thawed stage (TP) and the completely frozen stage (FP). Soils in the TP stage had a higher total surface area density (0.1898 mm² mm⁻³), length density (225.28 mm mm⁻³), node density (1,592 no. mm⁻³), and connectivity (0.3144) of soil macropores than those in the UFP, UTP, and FP stages. In the TP stages, the density, surface area density, branch density, length density, and node density of roots had significant correlations with the macroporosity, surface area density, length density, node density, and tortuosity of soil macropores. In the FP stage, there were no correlations between the root and soil macropore characteristics. Vertical water is expected to move more readily through the mattic epipedon in the TP stage than in the UFP and UTP stages. Roots were the preferential pathways for water transport into the soil layer of the alpine meadow. Therefore, the mattic epipedon is a key layer for water and nutrient storage and plays an important role in the water-holding function of the Tibetan Plateau due to its greater root development.

Fabrication of ordered macro-mesoporous single-crystalline Prussian blue and their derivatives for rechargeable sodium ion batteries

Benefiting from their improved accessibility of active sites and accelerated ion diffusion processes, ordered macro-mesoporous materials have received substantial attention in energy storage fields. However, preparing ordered hierarchical porous materials with single-crystal nature remains a huge challenge. Herein, we successfully prepare ordered macro-mesoporous single-crystalline Fe-based Prussian blue (denoted as OMMS-Fe-HCF) by chelating-agent-assisted in-situ crystallization strategy within a three-dimensional (3D) ordered polystyrene spheres (PS) template interstice. Subsequently, 3D ordered macroporous iron diselenide@carbon hybrid tetradecahedron (denoted as 3DOM-FeSe2@C) is favorably prepared by in-situ selenization of the OMMS-Fe-HCF template. The resulting composite can commendably inherit and reserve the macroporous architecture and cubo-octahedron morphology of the precursor. In particular, FeSe2 nanoparticles are homogeneously encapsulated into the macroporous carbon matrix, significantly improving the mass transfer performance while maintaining the structural integrity. By virtue of hierarchical structure advantages and excellent conductivity, the 3DOM-FeSe2@C exhibits high-rate capability (361.6 mAh g−1 at 20 A g−1) and excellent cycling durability (306.4 mAh g−1 after 900 cycles at 2 A g−1) for sodium-ion batteries. Considering the rational design and accurate construction of OMMS-Fe-HCF, our work provides a new perspective on the preparation of such highly ordered macro-mesoporous composite for application in the energy storage fields.

Designing Viscoelastic Gelatin-PEG Macroporous Hybrid Hydrogel with Anisotropic Morphology and Mechanical Properties for Tissue Engineering Application

The mechanical properties of scaffolds play a vital role in regulating key cellular processes in tissue development and regeneration in the field of tissue engineering. Recently, scaffolding material design strategies leverage viscoelasticity to guide stem cells toward specific tissue regeneration. Herein, we designed and developed a viscoelastic Gel-PEG hybrid hydrogel with anisotropic morphology and mechanical properties using a gelatin and functionalized PEG (as a crosslinker) under a benign condition for tissue engineering application. The chemical crosslinking/grafting reaction was mainly involved between epoxide groups of PEG and available functional groups of gelatin. FTIR spectra revealed the hybrid nature of Gel-PEG hydrogel. The hybrid hydrogel showed good swelling behavior (water content > 600%), high porosity and pore interconnectivity suitable for tissue engineering application. Simple unidirectional freezing followed by a freeze-drying technique allowed the creation of structurally stable 3D anisotropic macroporous architecture that showed tissue-like elasticity and was capable of withstanding high deformation (50% strain) without being damaged. The tensile and compressive modulus of Gel-PEG hybrid hydrogel were found to be 0.863 MPa and 0.330 MPa, respectively, which are within the range of normal human articular cartilage. In-depth mechanical characterizations showed that the Gel-PEG hybrid hydrogel possessed natural-tissue-like mechanics such as non-linear and J-shaped stress-strain curves, stress softening effect, high fatigue resistance and stress relaxation response. A month-long hydrolytic degradation test revealed that the hydrogel gradually degraded in a homogeneous manner over time but maintained its structural stability and anisotropic mechanics. Overall, all these interesting features provide a potential opportunity for Gel-PEG hybrid hydrogel as a scaffold in a wide range of tissue engineering applications.