A simple and green method is developed for the preparation of nanostructured TiO supported on nitrogen-doped carbon foams (NCFs) as a free-standing and flexible electrode for lithium-ion batteries (LIBs), in which the TiO with 2.5-4 times higher loading than the conventional TiO -based flexible electrodes acts as the active material. In addition, the NCFs act as a flexible substrate and efficient conductive networks. The nanocrystalline TiO with a uniform size of ≈10 nm form a mesoporous layer covering the wall of the carbon foam. When used directly as a flexible electrode in a LIB, a capacity of 188 mA h g is achieved at a current density of 200 mA g for a potential window of 1.0-3.0 V, and a specific capacity of 149 mA h g after 100 cycles at a current density of 1000 mA g is maintained. The highly conductive NCF and flexible network, the mesoporous structure and nanocrystalline size of the TiO phase, the firm adhesion of TiO over the wall of the NCFs, the small volume change in the TiO during the charge/discharge processes, and the high cut-off potential contribute to the excellent capacity, rate capability, and cycling stability of the TiO /NCFs flexible electrode.

The vast majority of these gels, however, are isotropic in nature and therefore, fail to mimic the anisotropic organization of some biological ECMs, which are fundamental in guiding cell organization [11][12][13] and tissue function. [14,15] Additionally, in a pathological context, a progressive transition to ECM anisotropy occurs in many cancers. [16][17][18][19] Therefore, hydrogelbased anisotropic ECMs are needed for developing more physiologically relevant tissues and for disease modeling.Recently, many methods have been developed to fabricate anisotropic hydrogels, for instance, electrospinning, [13,20,21] strain-driving alignment, self-assembly, [21,22] microfluidics, [23,24] electric field, [25] and magnetic-induced alignment. [10,11] Among these, employing a magnetic field to generate oriented structures in the hydrogel matrix is attractive, because the application of a magnetic field is independent of the shape and size of the sample, is remotely controllable, nondestructive, and fully biocompatible. [10,26] In the case of directing neuronal regeneration, a high magnetic field of 9.4 T was needed, [27] and gels with limited anisotropy were formed [28] with complex fabrication processes. [10] At this moment, it is still an outstanding challenge to fabricate uniaxial or more complex tissue architectures with highly anisotropic functions and (mechanical) properties in a facile way.Here, we describe a novel biocompatible, tunable, anisotropic, and fully synthetic nanocomposite hydrogel, which we name AnisoPIC. The AnisoPICs are composed of a fibrous network of stress-responsive, biomimetic polyisocyanide (PIC) hydrogels and magnetically responsive iron oxide nanoparticles (FeNPs) (see Figure 1). When a PIC-FeNP suspension is gelled in the presence of a small external magnetic field (EMF), highly anisotropic gels are formed, which can be frozen in the network through a cross-linking reaction between the polymer and the FeNPs. The resulting gels formed are optically, architecturally, and mechanically anisotropic even after the removal of the EMF; the anisotropy is stable for at least a month, which is long enough for most biological applications. Interestingly, we observed more complex structure formation, also with alignment perpendicular to the magnetic field, as a result of the electronegativity of the FeNPs. In this manuscript, we thoroughly study the key parameters for optimal alignment in the AnisoPICs and demonstrate hierarchical adaptive alignment in a single hydrogel composite. Particularly, the facile single-step fabrication procedure makes the material very attractive to develop further advanced anisotropic cell culture matrices.In vivo, natural biomaterials are frequently anisotropic, exhibiting directional microstructures and mechanical properties. It remains challenging to develop such anisotropy in synthetic materials. Here, a facile one-step approach for in situ fabrication of hydrogels with hierarchically anisotropic architectures and direction-dependent mechanical properties is proposed. The ...

Interactions between different cell types are crucial for their behavior in tissues, but are rarely considered in 3D in vitro cell culture experiments. One reason is that such coculture experiments are sometimes difficult to perform in 3D or require specialized equipment or know‐how. Here, a new 3D cell coculture system is introduced, TempEasy, which is readily applied in any cell culture lab. The matrix material is based on polyisocyanide hydrogels, which closely resemble the mechanical characteristics of the natural extracellular matrix. Gels with different gelation temperatures, seeded with different cells, are placed on top of each other to form an indirect coculture. Cooling reverses gelation, allowing cell harvesting from each layer separately, which benefits downstream analysis. To demonstrate the potential of TempEasy , human adipose stem cells (hADSCs) with vaginal epithelial fibroblasts are cocultured. The analysis of a 7‐day coculture shows that hADSCs promote cell–cell interaction of fibroblasts, while fibroblasts promote proliferation and differentiation of hADSCs. TempEasy provides a straightforward operational platform for indirect cocultures of cells of different lineages in well‐defined microenvironments.

A self‐standing nonwoven flexible Li4Ti5O12/carbon nanofiber composite (denoted LTO/CNF) was synthesized by using a facile method involving the electrospinning fabrication of CNFs and chemical deposition of LTO over the CNF surface. Scanning electron microscopy and transmission electron microscopy analyses show that the LTO/CNF film is composed of 50±20 nm diameter LTO polycrystalline particles distributed over 300±50 nm diameter CNF nanofibers. The nitrogen sorption isotherm further reveals the existence of mesopores in the LTO/CNF film. The as‐prepared LTO/CNF composite exhibits attractive rate capability for lithium‐ion batteries (LIBs), delivering initial specific capacities of 158, 153, 146, 138, 131, 122, and 109 mA h g−1 at rates of 1, 5, 10, 20, 30, 40, and 50 C, respectively, and a very stable cycling performance during 500 charge and discharge cycles at 20 C, which superior to electrodes made of commercial coarse‐type LTO anodes. In addition, the electrochemical impedance is effectively reduced by fabricating the unique electrode architecture, which originates from the improved 3D conducting network and the nanocrystalline size of the LTO active phase. Electrospinning of CNFs and chemical deposition of a nanocrystalline LTO phase proves to be an effective and facile method to develop anodes for flexible LIBs with a wide range of potential applications.