Conductive Scaffold Research Articles

Electrical stimulation enhances the neuronal differentiation of neural stem cells in three-dimensional conductive scaffolds through the voltage-gated calcium ion channel

Electrical stimulation (ES) or electroconductive scaffold has been proved to have the positive effects on the behavior of neural stem cells (NSCs). We previously developed a novel three-dimensional conductive composite scaffold of poly (3, 4-ethylenedioxythiophen)/chitosan/gelatin (PEDOT/Cs/Gel) for neural tissue engineering. In the present study, we further studied the effect of three-dimensional conductive scaffolds combined with ES on the neuronal differentiation of NSCs. The sandwiched ES device was designed to apply single-phase pulse voltage on NSCs cultured in conductive scaffold for 7 days (4 h/day). Proliferation and differentiation related proteins and genes were analyzed by immunofluorescence staining and RT-qPCR. The role of voltage-gated ion channels (VGICs) in regulating NSCs’ neuronal differentiation by ES was investigated in presence of ion channels blockers. The results of protein and gene expression indicated that ES not only promoted the proliferation of NSCs cultured in the conductive scaffold, but also enhanced the differentiation of NSCs into neurons. Especially, the voltage-gated calcium channel (Cav2+) played an important role in the neuronal differentiation of NSCs under ES. Our findings demonstrated that ES combined with three-dimensional conductive scaffolds would be a promising strategy to regulate the neuronal differentiation of NSCs for neural regeneration.

MXene-Boosted Imine Cathodes with Extended Conjugated Structure for Aqueous Zinc-Ion Batteries.

Organic molecules have been considered promising energy-storage materials in aqueous zinc-ion batteries (ZIBs), but are plagued by poor conductivity and structural instability because of the short-range conjugated structure and low molecular weight. Herein, an imine-based tris(aza)pentacene (TAP) with extended conjugated effects along the CN backbones is proposed, which is in situ injected into layered MXene to form a TAP/Ti3 C2 Tx cathode. Theoretical and electrochemical analyses reveal a selective H+ /Zn2+ co-insertion/extraction mechanism in TAP, which is ascribed to the steric effect on the availability of active CN sites. Moreover, Ti3 C2 Tx , as a conductive scaffold, favors fast Zn2+ diffusion to boost the electrode kinetics of TAP. Close electronic interactions between TAP and Ti3 C2 Tx preserve the structural integrity of TAP/Ti3 C2 Tx during the repeated charge/discharge. Accordingly, the TAP/Ti3 C2 Tx cathode delivers a high reversible capacity of 303 mAh g-1 at 0.04 A g-1 in aqueous ZIBs, which also realizes an ultralong lifetime over 10000 cycles with a capacity retention of 81.6%. Furthermore, flexible Zn||TAP/Ti3 C2 Tx batteries with a quasi-solid-state electrolyte demonstrate potential application in wearable electronic devices. This work offers pivotal guidance to create highly stable organic electrodes for advanced ZIBs.

Influence of rGO on the Crystallization Kinetics, Cytoxicity, and Electrical and Mechanical Properties of Poly (L-lactide-co-ε-caprolactone) Scaffolds.

Biodegradable scaffolds of poly (L-lactide-co-ε-caprolactone) (PLCL) and reduced graphene oxide (rGO) were prepared by TIPS (thermally induced phase separation). The nonisothermal cold crystallization kinetics were investigated by differential scanning calorimetry (DSC) with various cooling rates. The experimental values indicate that nonisothermal crystallization improves with cooling rate, but the increasing rGO concentration delays crystallization at higher temperatures. The activation energies were calculated by the Kissinger equation; the values were very similar for PLCL and for its compounds with rGO. The electrical conductivity measurements show that the addition of rGO leads to a rapid transition from insulating to conductive scaffolds with a percolation value of ≈0.4 w/w. Mechanical compression tests show that the addition of rGO improves the mechanical properties of porous substrates. In addition, it is an anisotropic material, especially at compositions of 1% w/w of rGO. All of the samples with different rGO content up to 1% are cytotoxic for C2C12 myoblast cells.

TEGylated Double-Walled Carbon Nanotubes as Platforms to Engineer Neuronal Networks.

In the past two decades, important results have been obtained on the application of carbon nanotubes (CNTs) as components of smart interfaces promoting neuronal growth and differentiation. Different forms of CNTs have been employed as scaffolds, including raw CNTs and functionalized CNTs, characterized by a different number of walls, mainly single-walled CNTs (SWCNTs) or multiwalled CNTs (MWCNTs). However, double-walled carbon nanotubes (DWCNTs), which present interesting electronic and transport properties, have barely been studied in the field. Apart from the electrical conductivity, the morphology, shape, porosity, and corresponding mechanical properties of the scaffold material are important parameters when dealing with neuronal cells. Thus, the presence of open porous and interconnected networks is essential for cell growth and differentiation. Here, we present an easy methodology to prepare porous self-standing and electrically conductive DWCNT-based scaffolds and study the growth of neuro/glial networks and their synaptic activity. A cross-linking approach with triethylene glycol (TEG) derivatives is applied to improve the tensile performance of the scaffolds while neuronal growth and differentiation are promoted. By testing different DWCNT-based constructs, we confirm that the manufactured structures guarantee a biocompatible scaffold, while favoring the design of artificial networks with high complexity.

All 3D printing lithium metal batteries with hierarchically and conductively porous skeleton for ultrahigh areal energy density

The revival of Li metal batteries (LMBs) is revolutionizing current Li-ion battery technology. However, their practical applications are prevented by the bottlenecks like Li dendrite growth, low Coulombic efficiency, and mismatched cathodes with limited mass loading and sluggish kinetics, resulting in poor cyclability and low energy density. Here, 3D printed conductive Ti3C2Tx MXene scaffolds and porous LiFePO4 lattices are proposed to construct high-mass-loading LMBs with prolonged lifespan and high energy density. The exceptional lithiophilic feature of Ti3C2Tx regulates the uniform deposition of metallic Li, allowing the stable MXene scaffold to achieve an outstanding areal capacity of 30 mAh/cm2 at 30 mA/cm2 and ultralong cycle lifespan of 4800 h. The full battery is assembled by rationally matching this dendrite-free MXene based Li anode with a hierarchically conductive LiFePO4 framework at an ultrahigh mass loading of 171 mg/cm2. The as-assembled LMBs deliver unprecedented areal capacity of 25.3 mAh/cm2, record-high areal energy density of 81.6 mWh/cm2 and improved cycling stability of 500 cycles, breaking through the limitation of thick-film cathodes. Thereby, this work offers a viable strategy for the reasonable fabrication of advanced LMBs.

A Conductive Bioengineered Cardiac Patch for Myocardial Infarction Treatment by Improving Tissue Electrical Integrity.

Conductive scaffolds are of great value for constructing functional myocardial tissues and promoting tissue reconstruction in the treatment of myocardial infarction (MI). Here, a novel scaffold composed of silk fibroin and polypyrrole (SP50) with a typical sponge-like porous structure and electrical conductivity similar to the native myocardium is developed. An electroactive engineered cardiac patch (SP50 ECP) with a certain thickness is constructed by applying electrical stimulation (ES) to the cardiomyocytes (CMs) on the scaffold. SP50 ECP can significantly express cardiac marker protein (α-actinin, Cx-43, and cTnT) and has better contractility and electrical coupling performance. Following in vivo transplantation, SP50 ECP shows a notable therapeutic effect in repairing infarcted myocardium. Not only can SP50 ECP effectively improves left ventricular remodeling and restore cardiac functions, such as ejection function (EF), but more importantly, improves the propagation of electrical pulses and promote the synchronous contraction of CMs in the scar area with normal myocardium, effectively reducing the susceptibility of MI rats to arrhythmias. In conclusion, this study demonstrates a facile approach to constructing electroactive ECPs based on porous conductive scaffolds and proves the therapeutic effects of ECPs in repairing the infarcted heart, which may represent a promising strategy for MI treatment.

Compact Sulfurized-Polyacrylonitrile/Graphene Composite Cathode for High-Energy and Long-Life Li-S Batteries

Next-generation batteries have been in the spotlight to meet the demand for batteries with higher energy densities than commercial lithium-ion batteries. Among them, lithium-sulfur batteries have been actively investigated owing to their attractive features; 1) Ultrahigh energy density, 2) Low cost of sulfur. Herein, we propose a compact, high-performance, 2D sulfurized-polyacrylonitrile/graphene (2D-SPAN/G) cathode for practical Li–S batteries. A 2D-SPAN/G cathode with a high active-mass (sulfur) loading of 10 mg cm−2 is successfully prepared via high-pressure pelletization. In the 2D-SPAN/G cathode, graphene nanosheets function as a robust and conductive scaffold, which uniformly encapsulates SPAN nanoparticles, providing structural integrity and enabling the high electrochemical utilization of sulfur. Combined with the stabilized lithium metal anode by using a modified electrolyte (consisting of 1 M LiPF6 and 0.05 M LiDFOB in EMC:FEC (3:1 (v/v))), and a 2D-SPAN/G cathode delivers a high areal capacity of 11 mAh cm−2 and demonstrats outstanding cycling stability over 300 cycles at a high current density of 4 mA cm−2. Moreover, the excellent electrochemical performance of a scaled-up, pouch-type Li–S battery featuring a 2D-SPAN/G cathode demonstrats the viability of the proposed cathode. The reversibility of the Li+-ion storage mechanism of the 2D-SPAN/G cathode is confirmed using operando Raman spectroscopy. Reference s : [1] J.-Y. Hwang, S.-J. Park, C. S. Yoon and Y.-K. Sun, Energy Environ. Sci., 2019, 12, 2174–2184.[2] H. Kim, S. Bang, K.-J. Min, Y.-G. Ham, S.-J. Park and Y.-K. Sun, ACS Appl. Mater. Interfaces, 2021, 13, 39435–39445.[3] H. M. Kim, J.-Y. Hwang, D. Aurbach and Y.-K. Sun, J. Phys. Chem. Lett., 2017, 8, 5331–5337.

Low-Cost Processing of Highly Durable (>1000 cycles) Sulfur Cathodes for Li-S Batteries

Lithium-sulfur (Li-S) batteries are one of the promising alternatives to modern Lithium-ion Battery (LIB) technology due to their superior specific energy density, which can satisfy the emerging needs of advanced energy storage applications such as electric vehicles and grid-scale energy storage and delivery. However, achieving this high specific energy density is hampered by several challenges inherent to the properties of sulfur and its discharge products.One major issue is related to the insulating nature of S and its fully discharged product (Li2S), which often leads to low utilization of the active material and poor rate capability. The poor electronic conductivity of these species can be overcome by utilizing conductive hosts, though they are dilutive and decrease the energy density, meaning that their mass ratio to the active material should be as low as possible [1]. Another crucial issue relates to the undesired solubility of certain sulfur discharge products, so-called long-chain Li polysulfides (LiPSs), in the conventional ether-based liquid electrolyte. The solubility of long-chain LiPSs promotes their free back-and-forth transport between the positive and negative electrodes, which results in poor cyclability and capacity decay [2, 3]. Despite the efforts to engineer and control the undesired LiPSs shuttling effect, advances have been mostly limited to a small number of cycles (100-200), or the need for complex and often expensive synthesis that has limited the rational development of new sulfur cathodes.At present, a large majority of the sulfur cathode research has focused on nano-architectured electrodes using 2D and 3D host materials for sulfur, such as carbon nanotubes, graphene, conductive scaffolds, yolk-shell structures, and the like, to increase the conductivity and alleviate the LiPSs shuttling [4]. Although these approaches have helped to increase the achievable capacity, and sometimes the cyclability, their synthesis methods have been highly complex, meaning that their manufacturing cost will be high. Also, in operating cells, it is highly unlikely that these complex structures can be effectively reproduced upon many charge-discharge cycles – meaning that capacity loss is essentially inevitable. Thus, developing novel, yet affordable and scalable, cathode architectures that can enhance the rapid transport of Li-ions to active sites for electrode reactions, accommodate discharge-induced volume expansion, and minimize the shuttling mechanism by sulfur encapsulation are still in great need.In this work, we present a low-cost and scalable processing method for highly durable sulfur cathodes containing commercial sulfur, carbon black, and polyvinylidene fluoride (PVDF). The sulfur cathode slurry was prepared through a simple and scalable recipe where the degree of binder dissolution into the solvent was controlled before electrode deposition. Variables such as the solvent:binder ratio, dissolution time, and agitation will be discussed. The microstructure of the sulfur cathodes was characterized using scanning electron microscopy. Through controlled dissolution of binder, a porous, swollen network of binder was achieved that adhered the sulfur and carbon particles while providing a highly porous structure that can accommodate the sulfur volume expansion during discharge and impede dissolution of the discharge products into the electrolyte by physically trapping them. The cycling performance of the sulfur cathodes prepared through the present novel processing was tested at C/10 and compared with those prepared through the conventional production techniques. The sulfur cathodes prepared with this novel electrode processing offered impressive capacity retention of 80% after 1000 cycles suggesting a considerable improvement in the shuttling effect and active material preservation. These results are expected to help move the production and manufacturing of Li-S batteries forward.References -J. Lee, T.-H. Kang, H.-Y. Lee, J. S. Samdani, Y. Jung, C. Zhang, Z. Yu, G.-L. Xu, L. Cheng, S. Byun et al., Advanced Energy Materials, vol. 10, no. 22, p. 1903934, 2020.Yang, G. Zheng, and Y. Cui, Chemical Society Reviews, vol. 42, no. 7, pp. 3018–3032, 2013.She, Y. Sun, Q. Zhang, and Y. Cui., Chemical society reviews, vol. 45, no. 20, pp. 5605-5634, 2016.Zhou, D. L. Danilov, R.-A. Eichel, and P. H. L. Notten, Advanced Energy Materials, vol. 1, p. 2001304, 2020.

Thermal Percolation of Antiperovskite Superionic Conductor into Porous MXene Scaffold for High-Capacity and Stable Lithium Metal Battery.

Lithium metal battery is considered an emerging energy storage technology due to its high theoretical capacity and low electrochemical potential. However, the practical exploitations of lithium metal batteries are not realized because of uncontrollable lithium deposition and severe dendrite formation. Herein, a thermal percolation strategy is developed to fabricate a dual-conductive framework using electronically conductive Ti3 C2 Tx MXene aerogels (MXAs) and Li2 OHCl antiperovskite superionic conductor. By melting Li2 OHCl at a low temperature, the molten antiperovskite phase can penetrate the MXA scaffold, resulting in percolative electron/ion pathways. Through density functional theory calculations and electrochemical characterizations, the hybridized lithiophilic (MXA)-lithiophobic (antiperovskite) interfaces can spatially guide the deposition of lithium metals and suppress the growth of lithium dendrites. The symmetric cell with MXA-antiperovskite electrodes exhibits superior cycling stability at high areal capacities of 4 mAh cm-2 over 1000 h. Moreover, the full cell with MXA-antiperovskite anode and high-loading LiFePO4 cathode demonstrates high energy and power densities (415.7Wh kgcell -1 and 231.0W kgcell -1 ) with ultralong lifespans. The thermal percolation of lithium superionic conductor into electronically conductive scaffolds promises an efficient strategy to fabricate dual-conductive electrodes, which benefits the development of dendrite-free lithium metal anodes with high energy/power densities.

Hierarchical hybrid architectures assembled from carbon coated Li3VO4 and in-situ generated N-doped graphene framework towards superior lithium storage

Owing to high specific capacity (394 mA h g −1 based on a two-electron reaction), good ionic conductivity and suitable working potential (~ 0.8 V), Li 3 VO 4 (LVO) has been recently considered as a promising intercalation anode material for lithium-ion batteries (LIBs). Such material, however, suffers from poor electronic conductivity, thus limiting its practical applications. Herein, we develop a facile self-template strategy for constructing 3D hierarchical LVO/C hybrids assembled from carbon-coated LVO and in-situ generated N-doped graphene framework. Such hybrids not only offer an interconnected 3D conductive network, but also afford intimate contact between active components and conductive scaffolds, thus realizing a high-efficiency electron/ion transport system. When employed as anode for LIBs, the resulting product exhibits reversible capacities of 347.6 mA h g −1 at 0.5 A g −1 and 206.8 mA h g −1 at 4 A g −1 , and a capacity retention of 75.3 % after 1000 cycles at 1 A g −1 . This work provides a facile and green strategy for building 3D multiscale hierarchical hybrids, which could be extended to prepare other nanocomposites for energy-related applications. • Develop N-doped graphene framework encapsulated Li 3 VO 4 by a self-template strategy. • Such hybrids provide a 3D electron/ion conductive network. • Such hybrid can well accommodate the structural strain during cycles. • Realize superior high-rate capability and long-term cyclability.

Piezoelectric conduit combined with multi-channel conductive scaffold for peripheral nerve regeneration

Due to the complex structural hierarchy and regenerative microenvironment of peripheral nerves, developing a nerve guidance conduit (NGC) that can replace autografts for repairing long-distance nerve defects remains a challenge. To overcome this limitation, a multi-channel NGC with dual electrical activity of piezoelectricity and conductivity was constructed to enhance peripheral nerve regeneration. Silk fibroin (SF) was adopted to prepare a multi-channel cryogel scaffold by gradient freezing method, and then poly(3,4-ethylenedioxythiophene) (PEDOT) in situ polymerization based on the porous structure of the cryogel was carried out to achieve good conductivity. Meanwhile, a polyvinylidene fluoride (PVDF)/poly (l-lactic acid-co-caprolactone) (PLCL) film with spontaneous electrical properties and high mechanical strength was constructed and wrapped in the outer layer of SF/PEDOT cryogel to construct an NGC with spontaneous electrical stimulation properties and surgical suture resistance, providing a biomimetic electrophysiological microenvironment for peripheral nerve regeneration. In vitro cell experiments indicated that the multi-channel electroactive NGC not only promoted the proliferation, maturation and myelination of Schwann cells (SCs), but also effectively promoted neuronal differentiation and axonal regeneration of Pheochromocytoma 12 (PC12) cells. Furthermore, a rat sciatic nerve defect model was constructed to evaluate the effect of multi-channel electroactive NGC on peripheral nerve repair and the results showed that electroactive NGC could significantly promote peripheral nerve regeneration and functional recovery after 12 weeks, achieving the repair effect of autografts through the positive synergistic effect of piezoelectric and conductive properties of NGC. These results demonstrated the great potential of multi-channel electroactive NGCs in repairing peripheral nerve injury (PNI).

Biofabrication of a flexible and conductive 3D polymeric scaffold for neural tissue engineering applications; physical, chemical, mechanical, and biological evaluations

AbstractTissue engineering approach aims to overcome the transplant drawbacks and facilitate tissue repair and regeneration. Here, a new conductive, highly porous, and flexible polycaprolactone/gelatin/polypyrrole/graphene 3D scaffolds for nerve tissue repair is presented. A simple and efficient porogen leaching fabrication method is applied to create a 3D network with a pore radius of 3.8 ± 0.7 to 4.2 ± 0.8 μm with an exceptional uniform circular porous structure. The conductivity of the polymeric scaffold without graphene, in wet conditions, was found to be 0.78 ± 0.1 S.m−1 and it increased to 3.3 ± 0.2 S.m−1 for the optimized sample containing 3wt% graphene (G3). Tensile strength was measured at 163 KPa for the base sample (without graphene) and improved to 526 KPa for G3 sample. Following 42 days of incubation in PBS, 32.5% degradation for the base sample (without graphene) was observed. The cell study demonstrated a non‐cytotoxic nature of all scaffolds tested and the cells had mostly stretched and covered the surface. Overall, the sum of results presented in this study demonstrate a simple fabrication platform with extraordinary aspects that can be utilized to mimic the native conductive tissue properties, and also because of its flexibility it can easily be rolled into a nerve conduit to fill gaps in nerve tissue regeneration.

Interface engineering to regulate hollow one-dimensional N-doped Carbon@ZnO nanocomposite for boosting electromagnetic wave absorption

Hollow composite structure has attracted much attention due to its great design space for adjusting impedance matching and enhancing interfacial polarization. Heterogeneous interface as well as improve the polarization relaxation and enhance the dielectric loss ability of material. However, the precise control of heterogeneous interface and hollow structure is a complex issue, which hiders the development of hollow composite structure for practical application. Herein, a mild sacrificial template method is proposed to construct a hollow nanocomposite comprised of N-doped carbon and ZnO (ZnO@HNCR), where self-assembled nanostructure (9,10-dibromoanthracene, DBA), polydopamine (PDA) and ZIF-8 were used as a sacrificial template, conductive scaffold and the ZnO precursor, respectively. During the calcination treatment, ZIF-8 and PDA were in situ converted into ZnO and N-doped carbon. In addition, self-assembled nanostructure sublimated away, leaving hollow structure behind, which overcomes the shortcoming of using corrosive agents. The large specific surface area and unique hollow structure optimize the impedance matching, and the abundant heterogeneous interfaces between HNCR and ZnO improve interfacial polarization. By virtue of joint efforts of conduction loss, multiple scattering and polarization relaxation, ZnO@HNCR exhibits outstanding performance, including minimum reflection loss value (RLmin) of − 57.4 dB at 2.6 mm and effective absorption bandwidth (EAB) of 6.04 GHz at 2.2 mm. This work proposes a feasible method to synthesize hollow heterogeneous electromagnetic absorbent.

Polypyrrole‐Assisted Nitrogen Doping Strategy to Boost Vanadium Dioxide Performance for Wearable Nonpolarity Supercapacitor and Aqueous Zinc‐Ion Battery

AbstractFiber‐shaped energy‐storage devices with high energy and power density are crucial for powering wearable electronics. However, the improvement of their energy and power density is limited by the low mass loading of active materials and slow diffusion of ions, which further hinders the application as flexible energy‐storage devices. Herein, a facile and cost‐effective strategy is proposed to fabricate polypyrrole (PPy)‐assisted nitrogen‐doped vanadium dioxide/nitrogen‐doped carbon (N–VO2@NC) heterostructures by the pyrolyzation of vanadium oxide (VOx)/PPy supported on carbon nanotube fiber (CNTF). The carbonization of PPy nanowire not only forms nitrogen‐doped carbon 3D conductive scaffold for enhancing ion transport pathways and mass loading of N–VO2 but also provides source of nitrogen in situ doping into VOx to produce N–VO2 for improving electronic conductivity and energy‐storage capacity. Consequently, the well‐designed N–VO2@NC@CNTF electrode delivers impressive electrochemical performance and extraordinary mechanical flexibility both applied in all‐solid‐state fiber‐shaped nonpolarity supercapacitors and aqueous zinc‐ion batteries. Furthermore, the results of theoretical calculations discovered that the band gap of PPy‐assisted N–VO2 can be significantly reduced from 0.55 to 0.23 eV and thus its conductivity is greatly enhanced. This work sheds light on the construction of high‐performance free‐standing electrodes for next‐generation wearable aqueous energy‐storage devices.

Electrified nanohybrid filter for enhanced phosphorus removal from water.

Phosphorus (P) has been identified as a major cause of eutrophication. One feasible way to deal with P-containing wastewater is to employ advanced adsorbents with high P affinity. Towards this end, the loading of these sorbents onto a conductive scaffold would facilitate the introduction of an electric field into the reaction system thereby permitting a continuous-flow operation and improved P sorption kinetics. Here, the preparation and evaluation of an electroactive carbon nanotube (CNT) filter functionalized with cerium-based metal organic frameworks (Ce-MOF) is reported. Various advanced characterization techniques confirmed the successful fabrication of the Ce-MOF/CNT nanohybrid filter. The results suggested that the nanohybrid filter had a maximum P adsorption capacity of 22.41mgg-1, which compared favorably with other state-of-the-art P sorbents. Ce-MOF loading, applied voltage and flow rate each increased the rate constants for phosphate removal by factors of 1.6, 2.1 and 5.8 times relative to the absent states. The underlying P sorption mechanisms involved outer-sphere surface complexation (electrostatic attraction), inner-sphere surface complexation (Ce-O-P) and diffusion. The performance was tolerant of a wide operational pH range and different water matrices. The Ce-MOF/CNT electrochemical filter described in this study provides a viable strategy to address the challenging issues associated with aqueous P pollution.

3D bioprinted conductive spinal cord biomimetic scaffolds for promoting neuronal differentiation of neural stem cells and repairing of spinal cord injury

Spinal cord injury (SCI) is a terrible injury of the central nervous system for which there is no ideal treatment in clinic so far. The spinal cord biomimetic scaffolds which mimic the shape and structure of native spinal cord tissue, could effectively promote the repair of SCI. However, current biomimetic scaffolds do not mimic the biological functions, especially the electrical conductivity, of spinal cord tissue, which largely limits the therapeutic effect of SCI. In this study, we have developed novel conductive hydrogels based on gelatin methacrylate (GelMA), hyaluronic acid methacrylate (HAMA) and poly(3,4-ethylenedioxythiophene): sulfonated lignin (PEDOT:LS). The incorporation of PEDOT:LS into GelMA/HAMA hydrogel matrix significantly improved the conductivity of the hydrogels. By precisely regulating the light curing time, the conductive hydrogels showed mechanical properties similar to native spinal cord tissues. Then, the conductive biomimetic scaffolds were fabricated by 3D bioprinting, and the neural stem cells (NSCs) encapsulated in the scaffolds exhibited good survival rate (higher than 90%). Compared to the non-conductive scaffolds reported, the conductive scaffolds remarkably promoted neuronal differentiation of NSCs in vitro. In a rat spinal cord complete transection model, the conductive biomimetic scaffold dramatically promoted the recovery of hindlimb motor function. Immunofluorescence staining results further showed that the conductive biomimetic scaffold effectively promoted the regeneration of neurons at the injury site, reduced the deposition of glial scar, and promoted nerve axon regeneration and myelination. Overall, the 3D bioprinting of the conductive spinal cord biomimetic scaffolds developed in this work represents a promising approach for the stem cell-based treatment of SCI.

Cascade scaffold of porous carbon-coated carbon derivates from a bimetallic zeolitic imidazolate framework for use as an efficient sulfur host in high-performance Li-S batteries

Currently, there is increasing concern about meeting energy demands, and a lithium-sulfur (Li-S) battery is a promising candidate for use in next-generation energy storage systems. However, some problems still limit the practical implementation of Li-S batteries. Herein, we present a conductive cascade scaffold developed by depositing a porous carbon over a nanoporous carbon layer derived from bimetallic zeolitic imidazolate (BMZIF) as an efficient sulfur host for use in Li-S batteries. Due to the increased conductivity, abundant active sites and large surface area of this prepared material, the assembled Li-S batterie exhibits excellent rate and long cycling performances. Results show an outstanding reversible cycling capacity above 1004.1 mAh/g at 0.2 C for over 100 cycles. This work is designed to effectively address the problems of sulfur electrodes and proposes a new scheme of hosting sulfur in Li-S batteries.

Electrical Stimulation-Mediated Differentiation of Neural Cells on Conductive Carbon Nanofiller-Based Scaffold

An important strategy in neural tissue engineering involves imparting electrical properties to the regenerative template to encourage cell proliferation and differentiation. Several clinical studies have confirmed that direct or indirect electrical stimulation therapy greatly impacts the treatment of peripheral and central nerve injury. Nerve regeneration can be accelerated by the application of electrical stimulations of different methods and with varying parameters. For a long period, electrical stimulation along with conventional conductive polymers have played an important role in nerve tissue regeneration, due to their conductivity. However, the low biocompatibility of these materials has brought attention toward the need for the alternative of the conductive polymers. Carbon nanofillers (graphene, nanotubes, and their derivatives) have been showing promising results in bioimaging, biosensing, and composites, simultaneously, proving themselves as a prospective biomaterial in neural tissue repair and regeneration due to their excellent electrical and mechanical properties, alongside, biocompatibility. Therefore, carbon nanofiller-based scaffolds synchronized with electrical stimulation may lead to a breakthrough in the treatment of nerve injury. This review article focuses on the influence of the electrical properties of carbon-based material on nerve tissue engineering. In this article, we explicitly focus on the different methods to deliver electrical stimulation and the pathways involved in the differentiation of neuronal cells. Emphasis is given to the analysis of the suitable fabrication strategies of carbon-based neural scaffold and the way its interfaces interact with neurons for promoting neuronal differentiation. Furthermore, this review summarizes the ongoing advancements to augment the conductivity and biological activities (cell adhesion, proliferation, neural differentiation, neurite outgrowth), as well as to reduce the potential toxicity in conductive carbon nanofiller-based scaffolds.

Retraction Note to: Polyanizidine and Polycaprolactone Nanofibers for Designing the Conductive Scaffolds

Retraction Note to: Polyanizidine and Polycaprolactone Nanofibers for Designing the Conductive Scaffolds

A novel flexible, conductive, and three-dimensional reduced graphene oxide/polyurethane scaffold for cell attachment and bone regeneration

Development of conductive and three-dimensional scaffolds with elastic properties and shape-recovery capability for bone regeneration within irregular bone cavities has been challenging. Polyurethanes (PUs) are intrinsically elastic polymers; however, their mechanical performance, biocompatibility, and functionality need to be improved for application as implants and biomedical devices. Herein, application of a novel flexible, conductive, and three-dimensional polyurethane scaffold (3DPU), fabricated through coating a commercial PU foam with graphene oxide (GO) and its subsequent reduction with ascorbic acid, described as 3DrGO/PU, is investigated for bone regeneration. The 3DrGO/PU scaffold supported the growth and proliferation of mouse osteoblast cells (MG-63) with strong mineralization and cell attachment. It is likely that the electrically conductive macro-porous 3DrGO/PU scaffold, provides bioactivity and promote nucleation and growth of hydroxyapatite (HA) in the simulated body fluid. Experiments assessing in vivo bone formation in rat calvarial skull defects provided clear evidence for efficacy of the 3D scaffold for treatment of irregular bone defects. The results of this study are promising, as they present easy production of a cost-effective green fabricated scaffold. It also offers a potential for cell attachment and capture, to be used in future tissue engineering and even biosensing applications.