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Generally, electrospun silk fibroin scaffolds collected by traditional plates present limited pore size and mechanical properties, which may restrict their biomedical applications. Herein, regenerated Antheraea pernyi silk fibroin (RASF) with excellent inherent cell adhesion property was chosen as a raw material and the conductive metal meshes were used as collectors to prepare modified RASF scaffolds by electrospinning from its aqueous solution. A traditional intact plate was used as a control. The morphology and mechanical properties of the obtained scaffolds were investigated. Schwann cells were further used to assess the cytocompatibility and cell migration ability of the typical scaffolds. Interestingly, compared with the traditional intact plate, the mesh collector with an appropriate gap size (circa 7 mm) could significantly improve the pore size, porosity and mechanical properties of the RASF scaffolds simultaneously. In addition, the scaffold collected under this condition (RASF-7mmG) showed higher cell viability, deeper cell permeation and faster cell migration of Schwann cells. Combined with the excellent inherent properties of ASF and the obviously enhanced scaffold cytocompatibility and mechanical properties, the RASF-7mmG scaffold is expected to be a candidate with great potential for biomedical applications.

Strong nonspecific protein/cell adhesion on conducting polymer (CP)-based bioelectronic devices can cause an increase in the impedance or the malfunction of the devices. Incorporating oligo(ethylene glycol) or zwitterionic functionalities with CPs has demonstrated superior performance in the reduction of nonspecific adhesion. However, there is no report on the evaluation of the antifouling stability of oligo(ethylene glycol) and zwitterion-functionalized CPs under electrical stimulation as a simulation of the real situation of device operation. Moreover, there is a lack of understanding of the correlation between the molecular structure of antifouling CPs and the antifouling and electrochemical stabilities of the CP-based electrodes. To address the aforementioned issue, we fabricated a platform with antifouling poly(3,4-ethylenedioxythiophene) (PEDOT) featuring tri(ethylene glycol), tetra(ethylene glycol), sulfobetaine, or phosphorylcholine (PEDOT-PC) to evaluate the stability of the antifouling/electrochemical properties of antifouling PEDOTs before and after electrical stimulation. The results reveal that the PEDOT-PC electrode not only exhibits good electrochemical stability, low impedance, and small voltage excursion, but also shows excellent resistance toward proteins and HAPI microglial cells, as a cell model of inflammation, after the electrical stimulation. The stable antifouling/electrochemical properties of zwitterionic PEDOT-PC may aid its diverse applications in bioelectronic devices in the future.

Bio-memristors constitute candidates for the next generation of non-volatile storage and bionic synapses due to their biocompatibility, environmental benignity, sustainability, flexibility, degradability, and impressive memristive performance. Silk fibroin (SF), a natural and abundant biomaterial with excellent mechanical, optical, electrical, and structure-adjustable properties as well as being easy to process, has been utilized and shown to have potential in the construction of bio-memristors. Here, we first summarize the fundamental mechanisms of bio-memristors based on SF. Then, the latest achievements and developments of pristine and composited SF-based memristors are highlighted, followed by the integration of memristive devices. Finally, the challenges and insights associated with SF-based bio-memristors are presented. Advances in SF-based bio-memristors will open new avenues in the design and integration of high-performance bio-integrated systems and facilitate their application in logic operations, complex circuits, and neural networks.

Biodegradable/bioabsorbable electrically conducting wires have an important role in the development of next-generation wearable microelectronics and implantable devices. The implantable devices, including conducting wires, must be biocompatible and biodegradable to avoid an inflammatory response and a second surgery. However, most conducting wires used in biomedicine are still conventional metallic wires. Herein, a new conducting wire with excellent conductivity, bioabsorbability, biocompatibility, and low weight was prepared from natural polymer and chromium/aurum (10/140 nm), providing the possibility to construct a fully bioabsorbable implantable device. The conducting wire substrate prepared from silk nanoribbons and konjac glucomannan has excellent mechanical properties. The wire resistance was approximately 8 Ω cm−1. The conducting wire exhibits an impedance of 140 Ω at 1000 Hz, which remains largely unchanged when the wire was immersed in buffer solution for ten days. Connection with a biodegradable triboelectric nanogenerator provides an integrated fully bioabsorbable energy generation device with a maximum output power density of 314.3 mW m−2. Compared with conventional metallic wires, this conducting wire has a higher transmission efficiency and biodegradability, better biocompatibility, and is more lightweight. This conducting wire and the integrated fully bioabsorbable energy generation device may be used in the fields of wearable electronics and implantable bioelectronics.

Graphene oxide (GO) with outstanding mechanical properties is a satisfactory filler to reinforce artificial silk. To prepare tough regenerated silk fibroin/graphene oxide (RSF/GO) hybrid fibers, it is important to understand the structural evolution of the hybrid fibers with external deformation. The morphology and microstructural changes of the hybrid fibers at different tensile strains were investigated by SEM, Raman spectra and synchrotron radiation wide angle X-ray diffraction (SR-WAXD). Longer and deeper stripes were found on the surface of RSF/GO fibers with the increase of strain as revealed by SEM. SR-WAXD results revealed that the fraction and orientation of crystals and the mesophase had slight changes in the elastic deformation zone of the fiber. However, in the plastic deformation zone of the fiber with a strain from 5 to 18%, the fraction of crystals gradually increased while the fraction of the mesophase decreased. During this deformation, the orientation of crystals (fc) firstly increased significantly and then increased slightly, while the orientation of the mesophase (fm) increased steadily beyond the yield point. When the strain exceeded 18%, the fraction of crystals decreased while the fraction of mesophase increased. The fc had a rapid increase again at a strain above 18%. A model was proposed to explain how the tensile deformation affects the molecular orientation of the hybrid fibers.

To improve the therapeutic effect of a damaged peripheral nerve, aligned scaffolds based on regenerated silk fibroin (RSF) were fabricated by electrospinning, and were simultaneously loaded with dual factors of brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF). An ELISA assay measurement in vitro demonstrated that the release of dual factors from the scaffolds was well maintained up to 2 weeks. Schwann cell (SC) morphologies on the RSF scaffolds were obtained using scanning electron microscopy (SEM) and laser scanning confocal microscopy (LSCM) after cell seeding. Cell viability and proliferation on the scaffolds were investigated using an MTT assay. Furthermore, the scaffolds were implanted in a mouse model to support nerve regeneration and angiogenesis in vivo, which was evaluated by histological and immunohistochemical (IHC) analyses at 4 and 8 weeks after implantation. In all retrieved scaffolds, de novo innervation and vascularization, indicated by a positive endothelial marker (von Willebrand factor, vWF) and an innervation marker (S-100 protein), were evident without chronic inflammatory responses. Compared to the control group, the dual-factor loaded scaffolds significantly promoted nerve regeneration and possessed great potential in peripheral nerve repair and regeneration, and for the repair of other tissues.

In this work, hydrogel photonic crystal beads with inverse opal structure are generated on a well-controlled microfluidic chip device. An online droplet drying method and templating technique are integrated into the producing process. This process results in the silica nanoparticles in the droplets self-assembled into spherical photonic crystals with narrow stop bands and identical structural colours, which is the ideal template for fabricating inverse opal hydrogel beads. The effects of acrylic acid (AA) concentration, water dosage and buffer pH on the equilibrium swelling of inverse opal hydrogel are discussed. In the concentration of AA (3%) and water (31%), the inverse opal hydrogel beads show wide sensing range and rapid response (less than 30 s) to pH variation. Overall, the inverse opal hydrogels as pH sensors show homogeneous structural colour changes due to the spherical 3D structure. The present characterization of quite mechanically robust and good reproducibility for the spherical pH sensor may have promise application in advanced optical devices.

Regenerated silk fibroin (RSF) scaffolds electrospun from aqueous solutions have great potential for tissue engineering. However, the traditional RSF mats are weak and limit the applications. A bladder acellular matrix graft (BAMG), a tough natural material, was used as an electrospinning substrate to toughen the RSF scaffolds. Compared with bare RSF scaffolds, the composite scaffolds with breaking energies ranging from 458 to 970 J kg−1 show significantly improved tensile properties and suture retention strength, which may satisfy the requirements for implantation. Vascular endothelial growth factor (VEGF) was encapsulated in the RSF/BAMG composite scaffolds by means of blend and coaxially electrospinning to promote the ability of vasculogenesis and angiogenesis. Transmission electron microscope (TEM) images show that the coaxially electrospun fibers had a core–sheath structure. An ELISA assay measurement indicates that VEGF can be released for more than 16 days. The samples annealed in water vapor exhibit higher release profiles than those immersed in ethanol. An in vitro assay indicates that VEGF loaded scaffolds evidently induced the attachment and proliferation of porcine iliac endothelial cells (PIECs) compared with those without VEGF. Moreover, the VEGF remained bioactive for up to 7 days. Thus the VEGF loaded composite scaffolds could be a promising candidate for tissue engineering applications.

In this paper, the structures and properties of regenerated silk fibroin (RSF) aqueous solutions under shear were investigated by using a polarizing microscope, an optical shearing instrument, a rotational rheometer, a Raman spectrometer and a synchrotron radiation small angle X-ray scattering facility. It was found that after being sheared at a constant shear rate for a suitable time, the RSF aqueous solution showed gradually decreased viscosity and enhanced birefringence before protein denaturation. Meantime, rod-like structures were formed and conformational transition happened in the solution. These results indicated that the RSF molecules in the solution might gradually form rod-like liquid crystal structures after applying sufficient shear. Moreover, it was also found that the increase of the shear rate could reduce the critical shear time for the solution to begin to form the liquid crystal structure.

Silk-based materials have great potentials in medical applications because of the proper mechanical properties and outstanding biocompatibility. This paper reports a novel method to prepare multi-layered silk fibroin (SF) tissue engineering scaffolds with well-aligned fibers oriented in different angles by an electrospinning process. The resulted aligned fibers construct the scaffolds with a grill-like structure, large area and improved mechanical properties, which have been demonstrated by scanning electron microscopy and tensile test. Biocompatibility analysis proves that the grill-like structure well guides the adhesion, proliferation and differentiation of porcine iliac endothelial cells along the aligned SF fibers in different directions.

Regenerated silk fibroin (RSF) fibers were dry-spun from RSF aqueous solution and then post-treated in ethanol aqueous solution. In order to prepare artificial silk which are tougher and stronger than their natural counterpart, the structure–property relationships of the RSF fibers and natural silkworm silks were investigated by using synchrotron radiation X-ray microdiffraction technology, birefringence measurements and Raman spectroscopy. The as-spun RSF fibers with poor mechanical properties exhibited a strong diffraction peak of the [021] lattice plane and a weak diffraction peak of the [020]/[200] lattice plane. However, both the natural silk and the post-treated RSF fibers with exceptional mechanical properties showed weak diffraction peaks of the [021] lattice plane and strong diffraction peaks of the [020]/[200] lattice plane. Nevertheless, the two crystalline peaks are attributed to the silk II structure of silk fibroin. By deconvoluting the one-dimensional wide-angle X-ray microdiffraction pattern, the crystallinity and the degree of crystalline orientation were obtained. The as-spun fibers showed low crystallinity and low crystalline orientation, but the microstructure of the RSF fibers could be improved greatly and even become similar to that of degummed cocoon silk by post-treatment. When the as-spun RSF fibers were first drawn 3 to 4 times with a draw rate of 0.9 mm s−1 in ethanol aqueous solution and then immersed in the same solution for another hour, the breaking strain and breaking energy of the post-treated fibers were significantly greater than those of degummed cocoon silk.

A multilayered microfluidic chip used for vacuum membrane distillation is designed, fabricated and tested by rectification of a water-methanol mixture.