Ultrafast fabrication of Nanofiber-based 3D Macrostructures by 3D electrospinning

Fabrication of macroscopic three-dimensional (3D) structures made of nanofibers of widely used polymers is reported. 3D structures have several benefits over conventional flat two-dimensional (2D) structures by the added dimension. The structures have been fabricated by the 3D electrospinning technology that can build 3D structures rapidly due to certain additives in the solution and appropriate process conditions. The process parameters of 3D electrospinning have been identified and investigated to better understand the formation mechanism of the 3D build-up for polystyrene (PS), polyacrylonitrile (PAN), and polyvinylpyrrolidone (PVP). Different types of electrodes were inserted in the electrospinning chamber to alter the electric field and have better control over the shape of the 3D structure. The upscalability of this technology was investigated by using a standard electrospinner and a nozzle-free electrospinning setup. It was possible to manufacture 3D structures with these devices, highlighting the versatility of this technology. 3D electrospinning opens the pathway for the facile fabrication of macroscopic 3D structure with microfibrous features on a commercial scale

3D electrospinning used in medical materials

Electrospinning (ES) is an interesting and efficient technique for biomedical use. This is a method used for the fabrication of polymer fibers used in tissue engineering (TE). The electrospun nano- and microfibers biomaterial, called scaffolds, are also used for regenerative medicine. The aim of the present mini-review is to present methods used to fabricate 3D fibers by electrospinning and their applications in TE. Also, discussed here are issues regarding the electrospinning limitations and research challenges

Automated fabrication of 3D chondrocyte-laden anisotropic scaffolds for articular cartilage

Tissue engineering (TE) strategies for repairing and regenerating articular car-tilage face critical challenges to approximate the biochemical and biomechanical microen-vironment of native tissue, particularly regarding collagen fibril depth-orientation and chondrocyte distribution. Here, a recently developed electromechanically 3D electrospin-ning platform was employed to develop three-dimensional (3D) anisotropic electrospun scaffolds in a fully automated manner with simultaneous chondrocyte incorporation. As expected, the 3D scaffolds possessed an arcade-like fibrous configuration with a uniform chondrocyte distribution. Overall, the results suggest that this combined approach has potential for cartilage TE.publishe

Wearable high-performance pressure sensors based on three-dimensional electrospun conductive nanofibers

Polymer-based pressure sensors play a key role in realizing lightweight and inexpensive wearable devices for healthcare and environmental monitoring systems. Here, conductive core/shell polymer nanofibers composed of poly (vinylidene fluoride-co-hexafluoropropene) (PVDF-HFP)/poly(3,4-ethylenedioxythiophene) (PEDOT) are fabricated using three-dimensional (3D) electrospinning and vapor deposition polymerization methods, and the resulting sponge-like 3D membranes are used to create piezoresistive-type pressure sensors. Interestingly, the PEDOT shell consists of well-dispersed spherical bumps, leading to the formation of a hierarchical conductive surface that enhances the sensitivity to external pressure. The sponge-like 3D mats exhibit a much higher pressure sensitivity than the conventional electrospun 2D mats due to their enhanced porosity and pressure-tunable contact area. Furthermore, large-area, wireless, 16 x 10 multiarray pressure sensors for the spatiotemporal mapping of multiple pressure points and wearable bands for monitoring blood pressure have been fabricated from these 3D mats. To the best of our knowledge, this is the first report of the fabrication of electrospun 3D membranes with nanoscopically engineered fibers that can detect changes in external pressure with high sensitivity. The developed method opens a new route to the mass production of polymer-based pressure sensors with high mechanical durability, which creates additional possibilities for the development of human-machine interfaces.11Ysciescopu

3D silica-gelatin hybrid scaffolds for tissue regeneration

Cartilage defects affect millions of people worldwide however current treatment options do not provide the zonal organisation required to regenerate healthy hyaline cartilage. In particular, the regeneration of high density ECM and cells is required to provide the articular surface of the tissue. Developments in tissue scaffolds have typically focused on synthetic polymers with low bioactivity due to their ease of processing. Here, the silica-gelatin sol-gel hybrid system was further developed for 3D printing and electrospinning to generate a zonal, bioactive scaffold. GPTMS, (3-glycidyloxypropyl)trimethoxysilane, was used to couple the silicate network and gelatin molecules. A modified hybrid method was required to avoid rapid gelation but retain high levels of crosslinking and sol-gel network condensation. To produce the material, the gelatin and GPTMS were mixed for 3 h and 3D printed scaffolds were aged for 1 week at room temperature. The hybrid composition most compatible with the 3D printing process had a 78:22, gelatin to TEOS mass ratio, and C-factor of 500 (molar ratio of GPTMS to gelatin). When 3D printing the gels, a minimum strut separation of 1 mm was achievable. To dry the 3D printed scaffolds, freeze drying and critical point drying resulted in very different structures. Freeze drying produced very thin, <40 μm struts, and large ~700 μm channels. Critical point drying produced ~160 μm struts and ~200 μm channels which falls within the range hypothesised to be suitable for cartilage regeneration. Electrospinning required further adjustments to the hybrid method to improve the volatility of the solvent. Conformable cotton wool-like fibres with ~1.5 μm diameter were achieved using a 70:30 gelatin to TEOS mass ratio. The C-factors used: 250, 500, and 750, resulted in increasing silica network condensation: 64.3 %, 75.5 %, and 81.1 % respectively. To create the cotton wool-like fibre structure, hybrid solutions with 60-80 cP viscosity were electrospun in 55 % humidity and dried without contacting each other or the collector surface. Both 3D printed and electrospun fibres showed promising dissolution results. The structures were maintained as only ~3 % gelatin was released over a one month study (3D printed) and ~2 %gelatin over a one week study (fibres). The silicon release was ~25 % of the silica content for 3D printed scaffolds, and ~13 % for fibres (CF500 and CF750). The silica-gelatin hybrids were biocompatible and provided native attachment sites for both osteoblasts and chondrocytes. Over 28-days, chondrocytes appeared to regenerate uniform density hyaline cartilage throughout the 3D printed scaffolds in vitro.Open Acces