Biomimetic Composites Research Articles

Impact resistance of biomimetic gradient sinusoidal composites by 3D printing: Tunable structural stiffness and damage tolerance

Taking inspiration from the remarkable impact resistance of the dactyl club of Odontodactylus scyllarus and utilizing the material extrusion-based 3D printing process for continuous fiber reinforced composites (CFRCs), the biomimetic gradient sinusoidal CFRCs (BGS-CFRCs) was designed and manufactured. This material combines the bidirectional sinusoidal structure with a gradient layering configuration, mimicking the natural design found in the dactyl club. Experimental tests revealed that BGS-CFRCs achieved a Charpy impact strength of up to 63.24 kJ/m2, surpassing flat-layered polylactic acid (PLA) and continuous carbon fiber reinforced PLA (CCF/PLA) specimens by 143 % and 80 %, respectively. Moreover, BGS-CFRCs exhibited tunable structural stiffness and damage tolerance. This can be attributed to the innovative in-plane fiber architecture and out-of-plane material gradient, revealing the synergistic effects of composite materials, bidirectional sinusoidal structure, and gradient layering configuration. Overall, this study combines multi-degree-of-freedom 3D printing of CFRCs with biomimetic structural design, providing new dimensions of design space. This breakthrough surpasses the limitations of traditional additive manufacturing techniques and structural design of composites, opening new possibilities for developing next-generation high-performance structural materials.

A novel composites of laser 3D printed CoCrFeNiMn/Ti6Al4V lattice structure with B4C/AlSi10Mg interpenetrating phases

Impact-resistant materials frequently encounter inherent trade-offs among damping, toughness, light weighting and strength. This study employed laser 3D printing combined with spark plasma sintering techniques to fabricate a novel biomimetic composites of CoCrFeNiMn/Ti6Al4V lattice structure with B4C/AlSi10Mg interpenetrating phase, showing the potential application of this composite as a novel impact-resistant material. Experimental results demonstrated that the composites exhibited outstanding compressive strength and strain energy absorption, attributed to their intricate interpenetrating dual-phase structure and interface bonding mechanism. The interpenetrating phase structure and the formation of interface nano-Ti3AlSi5 phases promote effective stress transfer within the composite material, resisting the propagation of local damage. During mechanical loading, cracks originating in the CoCrFeNiMn/Ti6Al4V lattice were mechanically interlocked by B4C/AlSi10Mg infiltration, thereby conferring heightened strengthening efficacy and exceptional damage tolerance. Effects of strain rate (10−3/s to 1/s) and temperature (from room temperature to 300 °C) on dynamic impact performance of the composites indicated a very competitive strain rate hardening and thermal softening performance.

Exploring the mechanical and biological properties of a resin-ceramic composite with biomimetic nacre structure containing zinc used for prosthodontics

Enhancement of the mechanical and biological properties of dental restoration materials is of significant importance. Drawing inspiration from the architecture and mechanical properties of natural nacre, we employed a low-cost accumulative rolling process to develop resin-ceramic composites with suitable hardness and high toughness. Plate-like aluminum oxide powder with diameters of 5–10 μm and nano-zinc oxide (ZnO) with antibacterial properties were mixed as the ceramic phase of the composite. Aluminum oxide ceramic plates were stacked using an accumulative rolling process to achieve a consistent orientation, followed by sintering to obtain porous ceramic scaffolds. The ceramic scaffolds were subsequently immersed in methyl methacrylate resin to complete the fabrication of the biomimetic composites. The mechanical and biological properties of the composites were comprehensively tested. The composites had a suitable hardness (1.09–1.63 GPa), excellent flexural strength (156.7–167.8 MPa), and fracture toughness (KIC = 2.66–3.59 MPa m1/2). Biomimetic composites are expected to mitigate the wear of natural teeth without developing fractures or deformations, while also exhibiting excellent cytocompatibility and antibacterial activity. This study investigated the factors influencing crack propagation in fracture tests and provided insights into enhancing the toughness of dental restorative materials. The biomimetic resin-ceramic composites containing Zn developed in this study have the potential to be used as functional dental restoration materials.

Regulation of transmembrane current through modulation of biomimetic lipid membrane composition.

Ion transport through biological channels is influenced not only by the structural properties of the channels themselves but also by the composition of the phospholipid membrane, which acts as a scaffold for these nanochannels. Drawing inspiration from how lipid membrane composition modulates ion currents, as seen in the activation of the K+ channel in Streptomyces A (KcsA) by anionic lipids, we propose a biomimetic nanochannel system that integrates DNA nanotechnology with two-dimensional graphene oxide (GO) nanosheets. By modifying the length of the multibranched DNA nanowires generated through the hybridization chain reaction (HCR) and varying the concentration of the linker strands that integrate these DNA nanowire structures with the GO membrane, the composition of the membrane can be effectively adjusted, consequently impacting ion transport. This method provides a strategy for developing devices with highly efficient and tunable ion transport, suitable for applications in mass transport, environmental protection, biomimetic channels, and biosensors.

Humanized In Vivo Bone Tissue Engineering: In Vitro Preculture Conditions Control the Structural, Cellular, and Matrix Composition of Humanized Bone Organs.

Bone tissue engineering (BTE) has long sought to elucidate the key factors controlling human/humanized bone formation for regenerative medicine and disease modeling applications, yet with no definitive answers due to the high number and co-dependency of parameters. This study aims to clarify the relative impacts of in vitro biomimetic 'preculture composition' and 'preculture duration' before in vivo implantation as key criteria for the optimization of BTE design. These parameters are directly related to in vitro osteogenic differentiation (OD) and mineralization and are being investigated across different osteoprogenitor-loaded biomaterials, specifically fibrous calcium phosphate-polycaprolactone (CaP-mPCL) scaffolds and gelatin methacryloyl (GelMA) hydrogels. The results show that OD and mineralization levels prior to implantation, enhanced by a mineralization medium supplement to the osteogenic medium (OM), significantly improve ectopic BTE outcomes, regardless of the biomaterial type. Specifically, preculture conditions are pivotal in achieving more faithful mimicry of human bone structure, cellular and extracellular matrix composition and organization, and provide control over bone marrow composition. This work emphasizes the potential of using biomimetic culture compositions, specifically the addition of a mineralization medium as a cost-effective and straightforward approach to enhance BTE outcomes, facilitating rapid development of bone models with superior quality and resemblance to native bone.

Reinforcing biomimetic cementitious composites by aligned hierarchical carbon fibers

Cementitious composites reinforced by carbon-based fibers of varied length scales still face limitations of a single dimension, anisotropic alignment, smooth surface, or poor dispersion. In this study, we developed a bioinspired, hierarchical reinforcing structure that enables multiscale coupling of mechanical properties and directional fiber alignment, significantly improving the load-bearing capacity of cementitious composite. The aligned hierarchical reinforcing structure was synthesized by grafting CNTs onto microscale CFs-COOH via an esterification reaction and a nozzle-injected technique. Parameters for synthesizing the CNTs grafted aligned CF (ACF-CNTs) were optimized considering oxidation solutions, grafting techniques, CNTs geometry, and CNTs concentrations. The chemical bond between CF and CNTs was examined by Laser Raman Spectrometer (LRS), Fourier Transform Infrared Spectrometer (FTIR), and X-ray photoelectron spectroscopy (XPS), respectively. Results indicate that CNTs are uniformly and densely grafted onto CF via ester linkage, forming a hierarchical reinforcing structure. Mechanical measurements show that 1 wt% ACF-CNTs results in a maximum flexural strength of 34.76 MPa and a maximum improvement of 297.12 % (compared to plain cement paste) in the biomimetic cementitious composites. Analysis based on fiber alignment, interface transition zone, and failure mode of CF-CNTs/CNTs suggests that multiscale coupling of mechanical properties and directional fiber alignment are the main reinforcing mechanisms.

Biomimetic structure-driven high strength and toughness in continuous SiC skeleton-reinforced graphite composites

Graphite-matrix structural composites with excellent mechanical properties and long-term reliability are ungently required in aerospace and nuclear industries. However, the enhancement of graphite-matrix composites by mainstream surface coating techniques or second-phase particle reinforcement is rather limited. Inspired by the structural-functional feature of plant cells, silicon carbide (SiC, cytoderm) coated mesocarbon microbeads (MCMB, cytoplasm) powders were prepared by combustion synthesis (CS), which were then densified via spark plasma sintering (SPS) to obtain the biomimetic cellular-structured SiC-reinforced MCMB (M@SiC) composites. The in-situ formed SiC ‘cytoderm’ ensures good interfacial bonding and contributed to the densification of the composites. Additionally, the continuous SiC skeleton and cellular-structured configuration improved the mechanical properties of M@SiC composites. Owing to the complex crack deflection, branching and bridging effects at the MCMB/SiC interfaces and graphite nanoflakes inside MCMB, the biomimetic M@SiC composite with SiC content of 47 vol% exhibited strengthening and toughening, with flexural strength and fracture toughness of 245 MPa and 3.82 MPa m1/2, respectively. The developed biomimetic graphite-matrix composites with excellent mechanical properties are expected to be applied in reusable spacecrafts and high-temperature gas-cooled reactors.

Biomimetic 3D-printed Composites: Ballistic Impact Resistance with Nacre-Inspired and Tubulane Structures

This research delves into nature-inspired designs for creating materials with exceptional impact resistance, leveraging cutting-edge 3D printing techniques. Our composite design features a nacre-like outer layer combined with a tubulane-resembling core, aiming to enhance energy dissipation significantly. By emulating the dense aragonite structure found in natural nacre and the unique porosity of tubulane, to enhance ballistic impact resistance. To validate its effectiveness, we conducted ballistics tests using a 40-grain lead-tipped .22 LR bullet at an initial velocity of 330.7 m/s, with a specialized chronograph setup to measure both initial and post-penetration bullet velocities, quantifying energy absorption precisely. This study opens new frontiers in aviation safety, structural engineering, and personal protective equipment, showcasing the transformative potential of biomimicry and additive manufacturing in advancing public safety and material science.

Efficient Zn-Ion Pouch Cell Assembling Based on Aramid Nanofiber Hydrogel

With the fast advancement of portable and wearable electronics, it is urgent to develop safe, stable and flexible power supply devices. Safe and environmentally friendly aqueous zinc-ion batteries (AZIBs) have a low-cost and are perfect candidates for energy storage device in such applications [1-4]. Giving the general challenges, such as the formation of the dendrites on the Zn anodes and hydrogen evolution and side reactions, extensive and wide research has focused on building stable AZIBs with high performance, but less attention was paid to making Zn ion pouch cells which are flexible and with high capacity In this presentation, we developed an efficient method to assemble Zn-ion pouch cells based on the process of formation of the aramid nanofiber hydrogel. The method involves the dipping precursor solution, solvent exchanging, and in-situ electrodeposition of MnO2. The assembled Zn-ion pouch cells exhibit excellent mechanical performance, flexibility and electrochemical performance, which are ideal for portable and wearable electronics. Based on this method, we successfully assembled 3-layer (cathode/anode/cathode, A/C/A) and 5 layer (A/C/A/C/A) pouch cells with over 100 times higher capacity compared with coin cell. In addition, the pouch cell with aramid nanofiber hydrogel and in-situ electrodeposited MnO2 cathode on carbon nanotube mat demonstrates superior cycling stability [5,6]. More details about our assembling method for flexible and stable pouch cells for AZIBs and experimental measurements related to the cycling and stability characteristics, will be presented at the meeting.[1] Yu, Peng, et al. "Flexible Zn‐ion batteries: recent progresses and challenges." Small 15.7 (2019): 1804760.[2] Li, Yingbo, et al. "Recent advances in flexible zinc‐based rechargeable batteries." Advanced Energy Materials 9.1 (2019): 1802605.[3] Li, Chunyang, et al. "High-rate and high-voltage aqueous rechargeable zinc ammonium hybrid battery from selective cation intercalation cathode." ACS Applied Energy Materials 2.10 (2019): 6984-6989.[4] Yu, Feng, et al. "Aqueous alkaline–acid hybrid electrolyte for zinc-bromine battery with 3V voltage window." Energy Storage Materials 19 (2019): 56-61.[5] Wang, Peng, and Petru Andrei. "High Performance Separator and Hydrogel Based on Aramid Fibers for Zn Ion Batteries." Electrochemical Society Meeting s 242. No. 4. The Electrochemical Society, Inc., 2022.[6] Xu, Lizhi, et al. "Water‐rich biomimetic composites with abiotic self‐organizing nanofiber network." Advanced Materials 30.1 (2018): 1703343.

(Battery Student Slam 8 Award Winner) A Simple and Fast Method to Assemble Flexible and Stable Quasi-Solid-State Zn Ion Pouch Cell

Aqueous zinc-ion batteries (AZIBs) have been investigated intensively as effective energy storage devices that are environmentally friendly, safe, and have a lower cost than current Li-ion batteries.[1-5] Being outstandingly safe due to usage of non-organic electrolyte, AZIBs could also be used as power supply for wearable electronics. This also put high standard requirements in terms of flexibility, stability and electrochemical performance to AZIBs. On the other hand, the general challenges, such as the formation of the dendrites on the Zn anodes, hydrogen evolution and side reactions, have been obstructing the practical application of AZIBs. In this presentation, a simple method to assemble quasi-solid-state Zn ion pouch cell with excellent mechanical performance, flexibility and electrochemical performance was developed, combining in-situ electrodeposition of MnO2 cathode and aramid nano fiber-based hydrogel with Zn plate as anode. In-situ and cycling measurements of the electrodeposition of MnO2 on carbon nanotube mat shows excellent capacitance and superior cycling stability. In addition, Kevlar derivatized aramid nanofiber-based hydrogel shows extremely strong strength when combined with polyvinyl alcohol, which prolonged the lifetime of the cell by preventing Zn dendrite growth largely.[5,6] Moreover, the method to assemble the AZIBs pouch cell enables us to optimize the process, decrease the steps, and save time effectively by taking advantage of hydrogel formation stage and avoiding conventional verbose slurry-casting-drying steps. This work paves an efficient path to assemble flexible and stable AZIBs pouch cells with high capacity and cycling stability.[1] Tang, Boya, et al. "Issues and opportunities facing aqueous zinc-ion batteries." Energy & Environmental Science 12.11 (2019): 3288-3304.[2] Li, Chang, et al. "Toward practical aqueous zinc-ion batteries for electrochemical energy storage." Joule 6.8 (2022): 1733-1738.[3] Yu, Feng, et al. "An aqueous rechargeable zinc-ion battery on basis of an organic pigment." Rare Metals 41.7 (2022): 2230-2236.[4] Lin, Yuexing, et al. "Dendrite-free Zn anode enabled by anionic surfactant-induced horizontal growth for highly-stable aqueous Zn-ion pouch cells." Energy & Environmental Science 16.2 (2023): 687-697.[5] Wang, Peng, and Petru Andrei. "High Performance Separator and Hydrogel Based on Aramid Fibers for Zn Ion Batteries." Electrochemical Society Meeting s 242. No. 4. The Electrochemical Society, Inc., 2022.[6] Xu, Lizhi, et al. "Water‐rich biomimetic composites with abiotic self‐organizing nanofiber network." Advanced Materials 30.1 (2018): 1703343.

Experimental and numerical investigation on crack propagation in biomimetic nacreous composites with gradient structures

Combining interlocking structures and gradient design, this paper proposes a 2D biomimetic nacreous composite material with a gradient interlocked structure. Experimental and numerical simulation methods are employed to investigate the initiation and propagation behavior of cracks in the regular interlocking and gradient interlocked biomimetic nacreous composite materials. Samples of biomimetic nacreous composite materials with pre-existing cracks are manufactured using 3D printing technology, and uniaxial tensile tests are conducted to explore their crack propagation behavior. For biomimetic nacreous composite materials with periodic interlocking structures, the interlocking angle is found to play an important role in the toughening mechanism of composites. In biomimetic composite materials with large interlocking angles, crack inhibition effects are achieved through structural gradient design, effectively preventing catastrophic failure. Within the numerical analysis framework, a cohesive zone modeling approach is employed to represent the softer phase of the material, and the numerical simulation are validated by direct comparison with experimental results. In addition, a comprehensive numerical analysis is carried out to comprehend how the structural gradient affects the spread of cracks in these nacreous composites. This research not only illuminate the underlying deformation and toughening mechanisms intrinsic to interlocking nacreous composites but also pave the way for innovative strategies in the design of biomimetic materials through the incorporation of structural gradients.

Influence of Biphasic Calcium Phosphate Incorporation Into Alginate Matrices

Biphasic calcium phosphate (BCP), containing β-tricalcium phosphate and hydroxyapatite, was synthesized by co-precipitation method to obtain a biomimetic artificial bone-like composite using calcium nitrate tetrahydrate [Ca(NO3)∙4H2O] as calcium precursor and ammonium dihydrogen phosphate (NH4H2PO4) as phosphorous precursor, maintaining Ca/P ratio of 1.67. The synthesized biphasic calcium phosphate mixture was dispersed in a sodium alginate (Alg) matrix dissolved in distilled water and lyophilized. The chemical structure, possible interactions between components and morphology of the obtained powder and scaffolds were studied through Fourier transform infrared (FT- IR) spectroscopy, X-ray diffraction (XRD) thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) in order to observe the interactions between BCP and the polymer. The particle size of the powder was also analyzed using the dynamic light scattering (DLS) analysis. Calcined powder had a particle size of 1.8 �m. In addition to the low crystalline hydroxyapatite (HA), as the main phase in the dried samples, β-tricalcium phosphate (β-TCP) was formed after the thermal treatment of 1000˚C as shown by XRD and FT-IR. The obtained composite material presented a highly porous microstructure with interconnected layers where the BCP particles were well dispersed. The micro-structure of the scaffolds was influenced with the change in pore dimensions and rearrangement of the layers due to the incorporation of the BCP particles and by the treatment of the scaffolds with CaCl2.

Ant‐Nest‐Inspired Biomimetic Composite for Self‐Cleaning, Heat‐Insulating, and Highly Efficient Electromagnetic Wave Absorption

AbstractThe pursuit of eco‐friendly electromagnetic wave absorption (EMWA) materials with multifunctional capabilities has garnered significant attention in practical applications. However, achieving these desired qualities simultaneously poses a significant challenge. This study introduces a single‐step calcination and chemical polymerization process to obtain an environmentally friendly ant‐nest‐inspired hybrid composite by optimizing conductive polypyrrole nanotubes (PNTs) within a 3D carbonaceous structure. The biomimetic composite forms a highly efficient conductive network, providing a pathway for free electrons within the carbonaceous barriers and enhancing the conduction loss. Remarkably, the EMWA performance of the composite achieves ultrathin (1.6 mm), wide effective absorption band (5.4 GHz), and strong absorption intensity (−67.6 dB) features. Moreover, due to the complex and intertwined 3D continuous network, the obtained samples exhibit excellent thermal insulation and superhydrophobic behavior by inhibiting heat transfer and preventing localized areas from being prone to water absorption. These findings not only offer a sustainable and low‐cost production route for biomimetic carbonaceous composites but also demonstrate a high‐efficiency absorber with great multifunctionality as a green alternative to traditional EMWA materials.

Hierarchical Composite with Self-Adaptive Anisotropic Deformation for Thermal Protection System.

Rigid thermal protection materials such as ultra-high-temperature ceramics are desirable for applications in aerospace vehicles, but few materials can currently satisfy the emerging high-temperature sealing requirements for dynamic gaps created by the mismatch of the thermal expansion of different protection layers. Here, we design and fabricate a flexible biomimetic anisotropic deformation composite by multilayer cocuring onto fiber fabrics. It displays superior anisotropic deformation, whose longitudinal expansion ratio is 48 times greater than the transverse expansion ratio at specific temperatures. Furthermore, the ordered carbon structure created by transition-metal-catalyzed graphitization and the C/Si synergistic effect resulting from the combination of biomimetic fiber fabrics and SR enable the in situ formation of a high-temperature-resistant SiC crystalline phase within the char layer, ultimately resulting in exceptional thermal protection properties. By constructing hollow structures in situ, the back temperature of the composite, which is only 4.33 mm thick, is stabilized at 140 °C under the condition of continuous butane flame ablation (1300 °C) for 420 s. Multilayer structure and flexible features can facilitate large-scale preparation and arbitrary cutting and bending, adapted to different thermal protection areas.

An experimental and theoretical study of biomimetic cement-epoxy resin composites: structure, mechanical properties, and reinforcement mechanisms

There is an urgent demand within the engineering community for a material that possesses both high strength and toughness, especially for the widely-used cement-based composites, with an inherent defect of brittleness. Usually, introducing polymer emulsions into cements enhances the toughness at the expense of compressive strength. Taking Inspiration from the ‘brick-and-mortar’ structure found in shells, this study utilized the ice template method to create a layered cement framework and then filled epoxy resin into the gaps between adjacent cement lamellae, thereby preparing an ordered-microstructure composite with cement and epoxy resin lamellae alternatively arranged. Compared with traditional cement paste, the composite exhibited an impressive increase of up to 197% in flexural strength, 464% in flexural toughness, and 82% in compressive strength. It can be ascribed to the distinctive layered structure and the tightly bonded interface between the organic resin and inorganic cement, which lead to crack deflection and energy adsorption.

Citrus flavonoids-loaded chitosan derivatives-route nanofilm as drug delivery systems for cutaneous wound healing

This study focuses on creating new forms of biomimetic nanofiber composites by combining copolymerizing and electrospinning approaches in the field of nanomedicine. The process involved utilizing the melt polymerization of proline (Pr) and hydroxyl proline (Hyp) to synthesize polymers based on Pr (PPE) and Hyp (PHPE). These polymers were then used in a grafting copolymerization process with chitosan (CS) to produce PHPC (1560 ± 81.08 KDa). A novel electrospun nanofiber scaffold was then produced using PHPC and/or CS, hyaluronic acid, polyvinyl alcohol, and naringenin (NR) as a loading drug. Finally, Mouse Dermal Fibroblast (MDF) cells were introduced to the wound dressing and assessed their therapeutic potential for wound healing in rats. The scaffolds were characterized by FTIR, NMR, DSC, and SEM analysis, which confirmed the amino acid grafting, loading drug, and porous and nanofibrous structures (>225 nm). The results showed that the PHPC-based scaffolds were more effective for swelling/absorption of wound secretions, had more elasticity/elongation, faster drug release, more MDF-cytocompatibility, and antibacterial activity against multidrug-resistant S. aureus compared to CS-based scaffolds. The in vivo studies showed that NR in combination with MDF can accelerate cell migration/proliferation, and remodeling phases of wound healing in both PHPC/CS-based scaffolds. Moreover, PHPC-based scaffolds promote collagen content, and better wound contraction, epithelialization, and neovascularization than CS-based, showing potential as wound-dressing.

Bio-inspired and biomimetic composites based on biodegradable polymers for sensing applications with emphasis on early diagnosis of cancer

With the increasing demand for tissue adhesive, soft self-healing, antifouling, biodegradable and biocompatible biosensors, the use of biomimetic polymers has paved the way for the development of these advanced sensing systems. Especially, biomimetic polymers have provided new opportunities and development directions for the soft implantable and wearable biosensors. In fact, the impressive development in the bio-inspired and biomimetic composites based on biodegradable polymers has led to the creation of tissue-adhesive implantable biosensors with the minimal immune response or biofouling. This review aims to cover the advances in the mimetic biodegradable polymers (natural or synthetic) with an emphasis on the state-of-the-art sensing devices based on these composites. It also highlights the unique properties of biomimetic polymers such as self-healing, self-adhesion, enzyme-like activity, antibacterial activity, regenerative activity, etc. Considering the high rate of cancer in the world, especially in developing countries, a separate section is dedicated to the use of mimetic biopolymers-based sensors for early diagnosis of cancer. Finally, an outlook on the current challenges and future developments of this field is presented.

3D bioartificial stretchable scaffolds mimicking the mechanical hallmarks of human cardiac fibrotic tissue.

Human cardiac fibrotic tissues are characterized by a higher stiffness relative to healthy cardiac tissues. These tissues are unable to spontaneously contract and are subjected to passive mechanical stimulation during heart functionality. Moreover, scaffolds that can recapitulate the in vivo mechanical properties of the cardiac fibrotic tissues are lacking. Herein, this study aimed to design and fabricate mechanically stretchable bioartificial scaffolds with biomimetic composition and stiffness comparable to human cardiac fibrotic tissues. Poly(ε-caprolactone) (PCL) scaffolds with a stretchable mesh architecture were initially designed through structural and finite element method (FEM) analyses and subsequently fabricated by melt extrusion additive manufacturing (MEX). Scaffolds were surface functionalized by 3,4-dihydroxy-DL-phenylalanine (DOPA) polymerization (polyDOPA) to improve their interaction with natural polymers. Scaffold pores were then filled with different concentrations (5%, 7%, and 10% w/v) of gelatin methacryloyl (GelMA) hydrogels to support in vitro human cardiac fibroblasts (HCFs) 3D culture, thereby producing bioartificial PCL/GelMA scaffolds. Uniaxial tensile mechanical tests in static and dynamic conditions (1 Hz; 22% maximum strain) demonstrated that the bioartificial scaffolds had in vivo-like stretchability and similar stiffness to that of pathological cardiac tissue (tailored as a function of the number of PCL scaffold layers and GelMA hydrogel concentration). In vitro cell tests on bioartificial scaffolds using HCF-embedded GelMA hydrogels under static conditions displayed increasing cell viability, spreading, and cytoskeleton organization with decreasing GelMA hydrogel concentration. Moreover, α-smooth muscle actin (α-SMA)-positive cells were detected after 7 days of culture in static conditions followed by another 7 days of culture in dynamic conditions and not in HCF-loaded scaffolds cultured in static conditions for 14 days. These results suggested that in vitro culture under cyclic mechanical stimulations could induce an HCF phenotypic switch into myofibroblasts.

Nacre-like carbon fiber-reinforced biomimetic ceramic composites: Fabrication, microstructure, and mechanical performance

The unique structure of nacre is composed of 'bricks' and ‘mortar,’ which gives it excellent damage resistance. In this study, nacre-like bionic ceramic scaffolds were 3D-printed using vat photopolymerization (VPP) technology, filled with polymer, and reinforced with carbon fiber to create high-strength and high-toughness carbon fiber-reinforced bionic composites. This approach leverages additive manufacturing technology to easily overcome the challenges of fabricating complex bionic structures with a simple and flexible production process. It offers a practical method for developing other lightweight, high-strength, and tough bionic materials. The microstructure of the composites was observed using scanning electron microscopy and energy dispersive spectroscopy. Additionally, finite element method and molecular dynamics simulations were performed on the composites. The results indicate that the composite material increased the flexural strength by 293.52 % and the fracture toughness by 109.36 % compared to solid ceramic parts. The primary toughening mechanisms of carbon fiber include crack deflection, fiber “pull-out,” and “debonding” within the composite.

Polythiophene-wrapped Chitosan Nanofibrils with a Bouligand Structure toward Electrochemical Macroscopic Membranes.

Exploring structural biomimicry is a great opportunity to replicate hierarchical frameworks inspired by nature in advanced functional materials for boosting new applications. In this work, we present the biomimetic integration of polythiophene into chitosan nanofibrils in a twisted Bouligand structure to afford free-standing macroscopic composite membranes with electrochemical functionality. By considering the integrity of the Bouligand structure in crab shells, we can produce large, free-standing chitosan nanofibril membranes with iridescent colors and flexible toughness. These unique structured features lead the chitosan membranes to host functional additives to mimic hierarchically layered composites. We used the iridescent chitosan nanofibrils as a photonic platform to investigate the host-guest combination between thiophene and chitosan through oxidative polymerization to fabricate homogeneous polythiophene-wrapped chitosan composites. This biomimetic incorporation fully retains the twisted Bouligand organization of nanofibrils in the polymerized assemblies, thus giving rise to free-standing macroscopic electrochemical membranes. Our further experiments are the modification of the biomimetic polythiophene-wrapped chitosan composites on a glassy carbon electrode to design a three-electrode system for simultaneous electrochemical detection of uric acid, xanthine, hypoxanthine, and caffeine at trace concentrations.