3D Sponge Research Articles

3D multiscale sponges with plant-inspired controllable superhydrophobic coating for oil spill cleanup

A facile and universal layer-by-layer self-assembly method was used to construct superhydrophobic sponge. This superhydrophobic sponge can be fabricated by surface functionalization of melamine sponge with gallic acid (GA) and iron (Fe) ions chelate for the enhancement of its micro/nano roughness first, followed by incorporation of hexadecyl thiol (HT) to achieve surface superhydrophobic modification. The GA-Fe-HT melamine sponge exhibits high adsorption capacity as much as 65–105 times its own weight for various oils/organic solvents. This coating endows the substrate with stable superhydrophobicity and reusability. After 100 times extrusion adsorption test, the modified porous melamine sponge still shows superhydrophobicity and good oils/organic solvents adsorption capacity. It is exciting that this superhydrophobic coating exhibits excellent hydrophobic properties after long-term treatment with strong alkali, strong acid and salt solution. Additionally, this eco-friendly, highly-efficient and low-cost design strategy can be applied for various substrates to prepare hydrophobic interface. The results obtained in this work will have a good promising prospect for many environmental applications.

In vitro biological response of human osteoblasts in 3D chitosan sponges with controlled degree of deacetylation and molecular weight

We have studied the effect of chitosan sponges, produced from chitosan batches with distinct degree of deacetylation (DDA) and molecular weight (Mw), on the adhesion, growth and differentiation of primary human osteoblasts with an aim to offer a suitable tool for guided bone regeneration. All the chitosan sponges revealed similar microstructure, irrespective of the DDA (58, 73, 82, 88, and 91 %) and Mw (749, 547, 263, 215, and 170 kDa, respectively). Cell spreading was higher on sponges having a higher DDA. Higher DDA induced a more pronounced increase in alkaline phosphatase activity, osteopontin (OPN), vascular endothelial growth factor-A (VEGF), interleukin-6 (IL-6), and reduction in monocyte chemoattractant protein-1 (MCP-1), sclerostin (SOST) and dickkopf related protein-1 as compared to lower DDA. Lower DDA induced the increased secretion of osteoprotegerin and SOST as compared to higher DDA. The combination of higher DDA and Mw induced an increased secretion of VEGF and IL-6, however reduced the secretion of OPN as compared to chitosan with similar DDA but with lower Mw. In summary, the variations in cellular responses to the different chitosan sponges indicate a potential for individual tailoring of desired responses in guided bone regeneration.

Efficient-heat-utilization 3D T-shaped porous sponge assists 2D photothermal films to achieve self-acting salt rejection and extra evaporation under high-concentration brine

Solar-driven interfacial steam generation (SISG) technology for seawater desalination is a green solution to the current freshwater crisis. However, salt accumulation and heat loss in the SISG system under high-concentration brine still have not been solved simultaneously. Inspired by the 3D evaporation structure design, we proposed a strategy to achieve self-acting salt rejection and extra evaporation. The strategy is based on a 3D T-shaped porous sponge (3DTPS), which helps various 2D photothermal films achieving self-acting salt rejection and extra evaporation simultaneously. 3DTPS provides a large number of water exchange channels for the 2D photothermal film. Therefore, under one sun (1 kW m−2), even if the brine concentration is as high as 20 wt%, salt-free can be maintained. When the hot is transferred downward, the T-shaped structure enables the 3DTPS to expose its heated surface to a greater extent in the air. 3DTPS (D = 2.5 cm) is used as an additional evaporation structure for extra evaporation, resulting in an increase of evaporation efficiency for an extra more than 21%.

Sponge Assembled by Graphene Nanocages with Double Active Sites to Accelerate Alkaline HER Kinetics.

Elaborate design of novel hybrid structures for hydrogen-evolution electrocatalysts is a crucial strategy for synergistically accelerating the reaction kinetics of water splitting. Herein, we prepare a three-dimensional (3D) sponge assembled by graphene nanocages (SGNCs) in which Ni nanoparticles and Ni single atoms coexist via a facile one-pot self-templating and self-catalytic strategy. Driven by simultaneous atomization and agglomeration under higher temperature, dual active sites of single atoms and nanoparticles are formed on graphene nanocages. Benefiting from the unique 3D porous structure and dual active sites, the SGNCs exhibit excellent hydrogen evolution reaction (HER) performance, which affords the current density of 10 mA cm-2 at a low overpotential of 27 mV. Theoretical calculations reveal that the interaction between single atoms and nanoparticles promotes HER kinetics. The controlled engineering strategy of non-noble metal-based hybrid materials provides prospects for innovative electrocatalyst development.

A 3D porous nitrogen-doped carbon nanotube sponge anode modified with polypyrrole and carboxymethyl cellulose for high-performance microbial fuel cells

Enhancing anode performance is a critical step to improving the power output and energy storage of microbial fuel cells (MFCs). In this study, MFCs containing pseudocapacitive anode materials, such as polypyrrole-carboxymethyl cellulose (PPy-CMC) composite films, were used to coat the nitrogen-doped carbon nanotube (N-CNT)/sponge (S) for use in MFCs. The capacitive anode could function as a bioanode, store electrons generated from the microbial oxidation of a substrate, and release the accumulated charge as needed. Scanning electron microscopy results indicated that the composite anode had a three-dimensional macroporous structure with a large specific surface area, providing more sites for microbial attachment and growth. Experimental results showed that MFCs equipped with PPy-CMC/N-CNT/S capacitive bioanodes had a maximum power density of 4.88 W m−3, which was 1.34 and 1.71 times as much as those of PPy/N-CNT/S and N-CNT/S bioanodes (3.65 and 2.85 W m−3), respectively. Moreover, the charge–discharge time of 60–90 min, the total charge Qm of the MFC equipped with the PPy-CMC/N-CNT/S anode was the largest (5154.08 mC cm−2)—5.7 times higher than that of the N-CNT/S anode. The excellent performance of the MFC equipped with the PPy-CMC/N-CNT/S anode was attributable to the composite materials, which exhibited a large-pore structure, good biocompatibility, large capacitance, and high specific surface area. Therefore, this synthesized composite exhibited potential as a capacitive and biocompatible anode material in MFCs.

Determining effective conductivities of fractal objects

We develop formulas to approximate the effective thermal conductivity of composite materials consisting of a matrix with nominal dimensionless conductivity Kmat=1 containing inclusions (holes) with a conductivity Khole≤1 laid out in fractal patterns: 2D Sierpinski carpets and 3D Menger sponges. Direct simulation of steady state heat conduction in finite stages of construction of these objects provide benchmark conductivity values. Recent theory on random walks in fractal media provides conductivity estimates for Sierpinski carpets for the case where Khole=0. Recognizing that the estimate in the fractal generators is related to the classic Rayleigh model, we obtain an expression for the conductivity in the more general case 0≤Khole≤1. Comparison with direct simulated values shows a relative error below 6% when the conductivity contrast is high (Khole≈0) and below 1% when the contrast is low. This significantly improves the accuracy of estimates obtained from simple resistor networks, which are interpreted as upper and lower bounds. The extension of this approach to Menger sponges gives a conductivity estimator related to the classic Maxwell conductivity model. This estimator, accounting for the effects of pattern correlations, has relative errors in the same range as the carpet estimator. A conjecture for the random walk dimension in sponges is also derived. The effective conductivities for 2D and 3D patterns, with low volume fractions of the matrix and high conductivity contrast, also represent a significant improvement over the classic formulas for uncorrelated distributions of inclusions.

Electrospun Nanofibers: Maneuvering the Migration and Differentiation of Stem Cells with Electrospun Nanofibers (Adv. Sci. 15/2020)

Enabled by their unique capability of mimicking some of the features of the extracellular matrix, Dario Pisignano, Younan Xia, and Jiajia Xue describe how to apply electrospun nanofibers to construct scaffolding materials, from 2D membranes to 3D sponges, for maneuvering the differentiation of various types of stem cells into different phenotypes, in article number 2000735.

Coupling a Sponge Metal Fibers Skeleton with In Situ Surface Engineering to Achieve Advanced Electrodes for Flexible Lithium-Sulfur Batteries.

Lithium-sulfur batteries (LSBs) are regarded as promising next-generation energy storage systems, however, the uncontrollable dendrite formation and serious polysulfide shuttling severely hinder their commercial success. Herein, a powerful 3D sponge nickel (SN) skeleton plus in situ surface engineering strategy, to address these issues synergistically, is reported, and a high-performance flexible LSB device is constructed. Specifically, the rationally designed spray-quenched lithium metal on the SN matrix (solid electrolyte interface (SEI)@Li/SN), as dendrite inhibitor, combines the merits of the 3D lithiophilic SN skeleton and the in situ formed SEI layer derived from the spray-quenching process, and thereby exhibits a steady overpotential within 75 mV for 1500 h at 5 mA cm-2 /10 mA h cm-2 . Meanwhile, in situ surface sulfurization of the SN skeleton hybridizing with the carbon/sulfur composite (SC@Ni3 S2 /SN) serves as efficient lithium polysulfide adsorbent to catalyze the overall reaction kinetics. COMSOL Multiphysics simulations and density functional theory calculations are further conducted to explore the underlying mechanisms. As a proof of concept, the well-designed SEI@Li/SN||SC@Ni3 S2 /SN full cell shows excellent electrochemical performance with a negative/positive ratio in capacity of ≈2 and capacity retention of 99.82% at 1 C under mechanical deformation. The novel design principles of these materials and electrodes successfully shed new light on the development of flexible LSBs.

In situ precipitation of amorphous calcium phosphate nanoparticles within 3D porous collagen sponges for bone tissue engineering.

Amorphous calcium phosphate (ACP) plays an important role in biomineralization within the three-dimensional (3D) collagen network in human hard tissues, and exhibits osteoconductivity. Porous collagen sponges coated with ACP nanoparticles could be considered as potential scaffolds for use in bone tissue engineering. In this study, such composite materials were fabricated via homogeneous ACP precipitation using a supersaturated calcium phosphate (CaP) solution. Homogeneous ACP precipitation was induced in situ within the sponges by a temperature-controlled coating process composed of two steps. In the first step, the CaP solution was cooled to 4°C to suppress precipitation until the solution penetrated fully into the sponge's internal pores. In the second step, the CaP solution was warmed up to 25°C with continuous shaking to induce ACP precipitation within the sponges. The resulting sponges were therefore coated with ACP nanoparticles on their inner and outer surfaces. A simulated body fluid (SBF) test indicated osteoconductivity of the collagen sponges coated with ACP nanoparticles. Further, ACP-coated collagen sponges immobilizing basic fibroblast growth factor (bFGF) were fabricated using the CaP solution supplemented with bFGF. The fabricated sponges allowed the sustained release of bFGF in a culture medium and enhanced proliferation of osteoblastic MC3T3-E1 cells. Such ACP-coated collagen sponges have the potential to be used as scaffolds in bone tissue engineering if pursued for further in vitro and in vivo studies.

3D Superhydrophobic Sponge Coated with Magnesium Hydroxide for Effective Oil/Water Mixture and Emulsion Separation

One of the main challenges for the treatment of oily wastewater is emulsion separation. However, emulsions are generally more stable and difficult to separate. Herein, we report a facile strategy f...

A hybrid sponge with guanidine and phytic acid enriched surface for integration of antibiofouling and uranium uptake from seawater

In seawater, biofouling caused by marine organisms’ adhesion on the surface of adsorbent would lead to a significant decrease in adsorption property. Herein, a poly (guanidine-hexamethylenediamine-phytic acid) hybrid sponge (PGHPA-PDF-MF) was synthesized for integration of uranium uptake from seawater with antibiofouling property. The PGHPA-PDF-MF sponge exhibited the superhydrophilicity and retained nearly 29 kPa of compression stress after 1000 cycles. Noteworthy, the PGHPA-PDF-MF sponge showed obviously anti-algae growth behavior (88% cell death rate) due to its guanidine and phytic acid groups, as well as inhibit adhesion of algae (Nitzschia) and mussels (Mytilus edulis) by the co-effect of its function groups, 3D porous sponge structure and superhydrophilic surface. The saturated U-uptake amount of PGHPA-PDF-MF sponge was high as 531.9 mg/g at nearly seawater pH (~8.0). At 5th cycle, the sponge still had superior reusability and maintained a high removal amount (200.7 mg/g). The uranium uptake amount of PGHPA-PDA-MF sponge was 44.75 mg/g with 90.9% of removal efficiency in uranium and Nitzschia contained artificial seawater at 7 days. Furthermore, more than 80% of uranium removal rate for the PGHPA-PDF-MF sponge in natural seawater (Bohai, China) also showed its great potentiality for actual application.

Humidity and Pressure Dual-Responsive Metal-Water Batteries Enabled by Three-In-One All-Polymer Cathodes for Smart Self-Powered Systems.

A conceptually new class of humidity and pressure dual-responsive smart metal-water batteries (SMWBs) is presented, which displays self-tunable energy release and intriguing perceptibility of human respiration and environmental pressure. This battery is enabled by the direct contact of a metal (e.g., Mg or Zn) anode and a well-designed all-polymer dual-sensitive moisture electrode (DSME) made from semiconductive polymer (e.g., polypyrrole)-wrapped 3D macroporous polyurethane sponge, without additional electrolytes and separator. A DSME is cost-effective, easily scalable, compressible, and able to act as a moisture carrier, a hydrogen evolution catalyst, and a pressure and humidity dual-sensitive unit simultaneously. Unique three-in-one integration in the DSME enables favorable modulation of electron/mass transport or redox reactions in the SMWB upon different stimulations. Thus, the assembled SMWB not only delivers good discharge performance with smart energy management but also serves as a reliable self-powered bifunctional responsor for the real-time monitoring of respiration and the perceptibility of pressure. Based on various active metal-polymer pairs (Mg/Zn vs polypyrrole/polyaniline), we also developed a series of dual-responsive batteries, demonstrating a general design idea.

Carbon nanotube-based electrodes for flexible supercapacitors

Flexible supercapacitors (SCs) have attracted increasing attention as the power supply unit for portable/wearable electronics. Carbon nanotubes (CNTs) are promising candidate materials for flexible SC electrodes because of their outstanding mechanical property, high electrical conductivity, large surface area, and functionability. CNTs can assemble into various macroscopic materials with different dimensions. In this review, flexible CNT assemblies including 1D fibers, 2D films, and 3D aerogels and sponges are introduced with a focus on the design strategies and fabrication techniques. The recent developments and state-of-the-art applications of such structures as electrodes in flexible SCs are summarized based on device configurations including sandwiched, interdigital in-plane, and cable-type configurations. The flexible CNT-based electrodes have shown great advantages in bendability, stretchability and/or compressibility, as well as a long cycle lifetime. The current challenges and future research opportunities in this field are also discussed.

A smart microfluidic platform for rapid multiplexed detection of foodborne pathogens

Rapid and sensitive detection of foodborne pathogens in food industry is of high importance in day-to-day practice to ensure safe food. To address this issue, multiple foodborne pathogens are targeted for rapid identification based in DNA amplification. A 3D PDMS sponge was fabricated using salt crystals as scarifying mold and functionalized with a ligand, apolipoprotein-H (ApoH), to test bacterial capturing for both Gram positive (L. monocytogenes) and negative bacteria (Salmonella spp.), in a microfluidic device. Pure culture of both pathogens in a range of ~10–105 CFU/mL were tested and the application of the developed automated pre-concentration protocol in real samples was verified using spiked surface samples after swab sampling. Bacterial DNA was extracted directly from the sponge and used for Real Time quantitative Polymerase Chain Reaction (qPCR) detection. The sponges did not show any significant resistance to sample flow and could easily be incorporated in a microfluidic device. A capture efficiency above 70% was observed for both targeted (Gram positive and Gram negative) pathogens and a Limit of Detection (LoD) in the range of 103 and 104 CFU/mL was obtained for Salmonella spp. and L. monocytogenes, respectively. Using this approached, we are able to perform multiplexed (Gram positive and Gram negative) capturing and reduce the enrichment time compared to the gold standard plate culture (over 1-day) method. The use of a 3D sponge for direct capturing of multiplexed pathogen on microfluidic device, followed by qPCR detection is an efficient and versatile method to stratify the presence of bacteria. This approach and methodology has potential to be integrated in full automatized device and used as point of need (PoN) system for foodborne pathogen stratification in food packaging/production industries.

Development of a 3D porous sponge as a bioanode coated with polyaniline/sodium alginate/nitrogen-doped carbon nanotube composites for high-performance microbial fuel cells

The structure and biocompatibility of anode materials significantly affect the performance of microbial fuel cells (MFCs). A biocompatible polyaniline–sodium alginate (PANI–SA) composite was prepared in situ oxidation polymerization on the 3D porous nitrogen-doped carbon nanotube/sponge (NCNT/S) to construct a high-performance microbial fuel cell in this investigation. The SEM showed that PANI–SA composite anode had a three-dimensional macroporous structure, and nitrogen-doped nanotubes were wound around the sponge skeleton, which had a large specific surface area, provided more places for the attachment and growth of microorganisms. A dual-chamber MFC equipped with a PANI–SA/NCNT/S bioanode to achieve a power density of 4380 mW m−3, which was much greater than the other MFCs. During the charge–discharge time of 60–90 min, the PANI–SA/NCNT/S bioanode had the highest total charge value of 26,617.86 C m−2, which was 3.23 times higher than that of NCNT/S (8231.87 C m−2). High-throughput sequencing results showed that the PANI–SA/NCNT/S bioanode exhibited high community diversity and selective enrichment of electrogenic bacteria. The excellent performance of the MFC equipped with PANI–SA/NCNT/S anode was attributed to the composite materials, which could be attributed to the large-pore network structure, better biocompatibility, large capacitance and high specific surface area. Illustration of the process for the preparation of PANI–SA

Strontium-substituted biphasic calcium phosphate scaffold for orthopedic applications

Strontium ion-substituted calcium phosphate-based ceramic scaffolds enhance osteogenesis. The objective of the present study was to optimize the strontium hydroxyapatite (Sr-HA) and beta tricalcium phosphate (β-TCP) ratio in the fabricated scaffolds to enhance their mechanical strength and bioactivity with controlled biodegradability. Porous polyurethane sponge scaffolds containing Sr-HA and β-TCP in varying concentration were developed by dipping 3D sponge pieces into a slurry containing 10% gelatin, proper concentration of biphasic calcium phosphate (BCP) and 3% poly vinyl alcohol. Four different samples [Sr-BCP, Sr-BCP (20/80), Sr-BCP (30/70), Sr-BCP (40/60)] were prepared and were characterized for biodegradability, water uptake capability and cytotoxicity using various techniques. Pure, crystalline, cytocompatible Sr-BCP Scaffolds possessing both micropores and macropores with porosity greater than 80% and water uptake capability above 100% were obtained. Thus, the effective substitution of Sr-HA and β-TCP in varying proportion makes the composite scaffold a distinctive material of bone tissue engineering.

Silk fibroin/sericin 3D sponges: The effect of sericin on structural and biological properties of fibroin

Among naturally occurring polymers, silk fibroin and sericin have attracted much attention in the field of tissue engineering; however, clinical application of silk fibroin/sericin scaffolds in a combined form has been questioned due to the possible pro-inflammatory reaction against native silk and fibroin/sericin 3D constructs. The objective of this study was to fabricate 3D spongy fibroin/sericin scaffolds and to explore the structural, biological and immunological properties of different ratios of fibroin and sericin. Structural characterization revealed a highly porous structure (>91%) with a large surface area and water uptake capacity for all different fibroin/sericin scaffolds. Notably, the scaffolds showed enhanced mechanical properties and a higher degradation rate with increasing sericin content. Excellent cell attachment and no significant cytotoxicity were observed in all scaffold types 7 days after seeding of osteoblast-like MG63 cells. Gene expression of pro-inflammatory markers TNF-α, CXCL10 and CD197 as well as TNF-α secretion by THP-1-derived macrophages revealed no significant immune response to all fibroin/sericin scaffold types when compared to sericin-free F1:S0 samples and a TCP (Mɸ) control group. These results demonstrate that spongy fibroin/sericin scaffolds are able to support the growth of osteoblast-like cells without eliciting a pro-inflammatory response, thus being a promising material for bone tissue engineering.

3D Chitin Scaffolds of Marine Demosponge Origin for Biomimetic Mollusk Hemolymph-Associated Biomineralization Ex-Vivo.

Structure-based tissue engineering requires large-scale 3D cell/tissue manufacture technologies, to produce biologically active scaffolds. Special attention is currently paid to naturally pre-designed scaffolds found in skeletons of marine sponges, which represent a renewable resource of biomaterials. Here, an innovative approach to the production of mineralized scaffolds of natural origin is proposed. For the first time, a method to obtain calcium carbonate deposition ex vivo, using living mollusks hemolymph and a marine-sponge-derived template, is specifically described. For this purpose, the marine sponge Aplysin aarcheri and the terrestrial snail Cornu aspersum were selected as appropriate 3D chitinous scaffold and as hemolymph donor, respectively. The formation of calcium-based phase on the surface of chitinous matrix after its immersion into hemolymph was confirmed by Alizarin Red staining. A direct role of mollusks hemocytes is proposed in the creation of fine-tuned microenvironment necessary for calcification ex vivo. The X-ray diffraction pattern of the sample showed a high CaCO3 amorphous content. Raman spectroscopy evidenced also a crystalline component, with spectra corresponding to biogenic calcite. This study resulted in the development of a new biomimetic product based on ex vivo synthetized ACC and calcite tightly bound to the surface of 3D sponge chitin structure.

3D porous chitin sponge with high absorbency, rapid shape recovery, and excellent antibacterial activities for noncompressible wound

Effective hemostasis as well as antibacterial infection are the urgent challenge for deep, narrow, irregular, and non-compressible wounds. In this work, a robust 3D porous sponges with quaternary chitin/partially deacetylated chitin nanofibers as its skeleton (QCNS) was reported. Thanks to the interconnected microporous, hydrophilicity and robust mechanical properties, QCNS possessed high-water absorption ratio (7534 ± 151%–13044 ± 275%) and even displayed superfast water/blood-trigged shape recovery performance (less than 1 s), allowing it to be delivered into the wound cavity in the shape of small particle and fleetly expand its volume on contacting the blood to fill the wound. Furthermore, due to its high-water uptake and positive-charge feature, QCNS could attract and stimulate blood cells/platelets, thus further promoting blood coagulation. When applied in the cylindrical wound on rat liver as noncompressible wound models, QCNS displayed superior hemostatic performance than traditional hemostatic materials such as medical gauze, gelatin sponge and Celox™. More importantly, QCNS displayed excellent antibacterial activity, cytocompatibility, and hemocompatibility. These outstanding superiorities in water absorption, water-trigged shape recovery, mechanical properties, blood-clotting ability, cytocompatibility, hemocompatibility, as well as antibacterial activity endow QCNS high potential application in hemostasis for noncompressible trauma and ballistic injuries.

A Dual Protection System for Heterostructured 3D CNT/CoSe2/C as High Areal Capacity Anode for Sodium Storage.

3D electrode design is normally opted for multiple advantages, however, instability/detachment of active material causes the pulverization and degradation of the structure, and ultimately poor cyclic stability. Here, a dually protected, highly compressible, and freestanding anode is presented for sodium‐ion batteries, where 3D carbon nanotube (CNT) sponge is decorated with homogeneously dispersed CoSe2 nanoparticles (NPs) which are protected under carbon overcoat (CNT/CoSe2/C). The 3D CNT sponge delivers enough space for high mass loading while providing high mechanical strength and faster conduction pathway among the NPs. The outer amorphous carbon overcoat controls the formation of solid electrolyte interphase film by avoiding direct contact of CoSe2 with electrolyte, accommodates large volume changes, and ultimately enhances the overall conductivity of cell and assists in transmitting electron to an external circuit. Moreover, the hybrid can be densified up to 11‐fold without affecting its microstructure that results in ultrahigh areal mass loading of 17.4 mg cm−2 and an areal capacity of 7.03 mAh cm−2 along with a high gravimetric capacity of 531 mAh g−1 at 100 mA g−1. Thus, compact and smart devices can be realized by this new electrode design for heavy‐duty commercial applications.