High-water-content hydrogels that are both mechanically robust and conductive could have wide applications in fields ranging from bioengineering and electronic devices to medicine; however, creating such materials has proven to be extremely challenging. This study presents a scalable methodology to prepare superelastic, cellular-structured nanofibrous hydrogels (NFHs) by combining alginate and flexible SiO nanofibers. This approach causes naturally abundant and sustainable alginate to assemble into 3D elastic bulk NFHs with tunable water content and desirable shapes on a large scale. The resultant NFHs exhibit the integrated properties of ultrahigh water content (99.8 wt%), complete recovery from 80% strain, zero Poisson's ratio, shape-memory behavior, injectability, and elastic-responsive conductivity, which can detect dynamic pressure in a wide range (>50 Pa) with robust sensitivity (0.24 kPa ) and durability (100 cycles). The fabrication of such fascinating materials may provide new insights into the design and development of multifunctional hydrogels for various applications.

These authors contributed equally to this work. SUMMARYMany Actinidia cultivars are characterized by anthocyanin accumulation, specifically in the inner pericarp, but the underlying regulatory mechanism remains elusive. Here we report two interacting transcription factors, AcMYB123 and AcbHLH42, that regulate tissue-specific anthocyanin biosynthesis in the inner pericarp of Actinidia chinensis cv. Hongyang. Through transcriptome profiling analysis we identified five MYB and three bHLH transcription factors that were upregulated in the inner pericarp. We show that the combinatorial action of two of them, AcMYB123 and AcbHLH42, is required for activating promoters of AcANS and AcF3GT1 that encode the dedicated enzymes for anthocyanin biosynthesis. The presence of anthocyanin in the inner pericarp appears to be tightly associated with elevated expression of AcMYB123 and AcbHLH42. RNA interference repression of AcMYB123, AcbHLH42, AcF3GT1 and AcANS in 'Hongyang' fruits resulted in significantly reduced anthocyanin biosynthesis. Using both transient assays in Nicotiana tabacum leaves or Actinidia arguta fruits and stable transformation in Arabidopsis, we demonstrate that co-expression of AcMYB123 and AcbHLH42 is a prerequisite for anthocyanin production by activating transcription of AcF3GT1 and AcANS or the homologous genes. Phylogenetic analysis suggests that AcMYB123 or AcbHLH42 are closely related to TT2 or TT8, respectively, which determines proanthocyanidin biosynthesis in Arabidopsis, and to anthocyanin regulators in monocots rather than regulators in dicots. All these experimental results suggest that AcMYB123 and AcbHLH42 are the components involved in spatiotemporal regulation of anthocyanin biosynthesis specifically in the inner pericarp of kiwifruit.

Wound dressing materials which are capable of meeting the demands of accelerating wound closure and promoting wound healing process have being highly desired. Electrospun nanofibrous materials show great application potentials for wound healing owing to relatively large surface area, better mimicry of native extracellular matrix, adjustable waterproofness and breathability, and programmable drug delivery process. In this review article, we begin with a discussion of wound healing process and current commercial wound dressing materials. Then, we emphasize on electrospun nanofibrous materials for wound dressing, covering the efforts for controlling fiber alignment and morphology, constructing 3D scaffolds, developing waterproof-breathable membrane, governing drug delivery performance, and regulating stem cell behavior. Finally, we finish with challenges and future prospects of electrospun nanofibrous materials for wound dressings.

Repair of bone defects with irregular shapes or at soft tissue insertion sites faces a huge challenge. Scaffolds capable of adapting to bone cavities, generating stiffness gradients, and inducing osteogenesis are necessary. Herein, a superelastic 3D ceramic fibrous scaffold is developed by assembly of intrinsically rigid, structurally flexible electrospun SiO2 nanofibers with chitosan as bonding sites (SiO2 NF‐CS) via a lyophilization technique. SiO2 NF‐CS scaffolds exhibit excellent elasticity (full recovery from 80% compression), fast recovery rate (>500 mm min−1), and good fatigue resistance (>10 000 cycles of compression) in an aqueous medium. SiO2 NF‐CS scaffolds induce human mesenchymal stem cell (hMSC) elongation and differentiation into osteoblasts. In vivo self‐fitting capability is demonstrated by implanting compressed SiO2 NF‐CS scaffolds into different shaped mandibular defects in rabbits, with a spontaneous recovery and full filling of defects. Rat calvarial defect repair validates enhanced bone formation and vascularization by cell (hMSC) histomorphology analysis. Further, subchondral bone scaffolds with gradations in SiO2 nanofibers are developed, leading to a stiffness gradient and spatially chondrogenic and osteogenic differentiation of hMSCs. This work presents a type of 3D ceramic fibrous scaffold, which can closely match bone defects with irregular shapes or at different implant sites, and is promising for clinical translation.