Hydrogel Fibers Research Articles

Recent advances in systemic and local delivery of ginsenosides using nanoparticles and nanofibers

Ginsenosides are the main pharmacologically active constituents of ginseng which have been used in East Asian countries for centuries to modulate blood pressure, metabolism and immune function. Following the technological advances in isolation, purification and mass production, their mechanisms of action are gradually elucidated, providing solid basis for clinical applications. Ginseng extracts (total ginsenosides) and ginsenoside Rg3, CK, Rd have been marketed or entered clinical trials as drugs or dietary supplements. Despite the proven safety and efficacy of some ginsenosides, their applications are hindered by inferior pharmacokinetics such as low solubility, poor membrane permeability and metabolic instability. Nanoparticle formulation of drugs and implantable drug depots are effective strategies to improve the pharmacokinetics of therapeutic agents by enhancing solubility, providing protection, facilitating intracellular transport, and enabling sustained and controlled release. This mini-review summarizes the recent advances in systemic delivery of ginsenosides using liposomes, micelles, albumin-based nanoparticles, and inorganic nanoparticles, as well as local delivery of ginsenosides by electronspun fibrous membranes and hydrogels.

UV-initiated crosslinking of electrospun chitosan/poly(ethylene oxide) nanofibers doped with ZnO-nanoparticles: development of antibacterial nanofibrous hydrogel.

UV-initiated crosslinking of electrospun poly(ethylene) oxide (PEO)/chitosan (CS) nanofibers doped with zinc oxide nanoparticles (ZnO-NPs) was performed using pentaerythritol triaclyrate (PETA) as the photoinitiator and crosslinker agent. The influence of the addition of PETA to the PEO/CS diameter and crosslinking of nanofibers was evaluated. The effect of irradiation time on the morphology and swelling properties of the crosslinked nanofibers were investigated. For ZnO-NPs, the minimum inhibitory concentrations were found at 1 mg/mL, and the minimum bactericidal concentrations at 2 mg/mL for all the strains tested. The nanofibrous hydrogel antibacterial effect was tested. This material enters the realm of fibrous hydrogels which have potential use in several applications as in the biomedical area.Supplementary materialThe supplementary material for this article can be found at 10.1557/mrc.2020.74.

A Self-Healing Hierarchical Fiber Hydrogel That Mimics ECM Structure.

Although there have been many studies on using hydrogels as substitutes for natural extracellular matrices (ECMs), hydrogels that mimic the structure and properties of ECM remain a contentious topic in current research. Herein, a hierarchical biomimetic fiber hydrogel was prepared using a simple strategy, with a structure highly similar to that of the ECM. Cell viability experiments showed that the hydrogel not only has good biocompatibility but also promotes cell proliferation and growth. It was also observed that cells adhere to the fibers in the hydrogel, mimicking the state of cells in the ECM. Lastly, through a rat skin wound repair experiment, we demonstrated that this hydrogel has a good effect on promoting rat skin healing. Its high structural similarity to the ECM and good biocompatibility make this hydrogel a good candidate for prospective applications in the field of tissue engineering.

Joule Heating-Induced Carbon Fibers for Flexible Fiber Supercapacitor Electrodes.

Microscale fiber-based supercapacitors have become increasingly important for the needs of flexible, wearable, and lightweight portable electronics. Fiber electrodes without pre-existing cores enable a wider selection of materials and geometries than is possible through core-containing electrodes. The carbonization of fibrous precursors using an electrically driven route, different from a conventional high-temperature process, is particularly promising for achieving this structure. Here, we present a facile and low-cost process for producing high-performance microfiber supercapacitor electrodes based on carbonaceous materials without cores. Fibrous carbon nanotubes-agarose composite hydrogels, formed by an extrusion process, are converted to a composite fiber consisting of carbon nanotubes (CNTs) surrounded by an amorphous carbon (aC) matrix via Joule heating. When assembled into symmetrical two-electrode cells, the composite fiber (aC-CNTs) supercapacitor electrodes deliver a volumetric capacitance of 5.1 F cm−3 even at a high current density of 118 mA cm−3. Based on electrochemical impedance spectroscopy analysis, it is revealed that high electrochemical properties are attributed to fast response kinetics with a characteristic time constant of 2.5 s. The aC-CNTs fiber electrodes exhibit a 94% capacitance retention at 14 mA cm−3 for at least 10,000 charge-discharge cycles even when deformed (90° bend), which is essentially the same as that (96%) when not deformed. The aC-CNTs fiber electrodes also demonstrate excellent storage performance under mechanical deformation—for example, 1000 bending-straightening cycles.

Coaxial 3D bioprinting of organ prototyps from nutrients delivery to vascularization

Vascular networks inside organs provide the means for metabolic exchange and adequate nutrition. Similarly, vascular or nutrient networks are needed when building tissue constructs >500 µm in vitro due to the hydrogel compact pore size of bioinks. As the hydrogel used in bioinks is rather soft, it is a great challenge to reconstruct effective vascular networks. Recently, coaxial 3D bioprinting was developed to print tissue constructs directly using hollow hydrogel fibers, which can be treated as built-in microchannels for nutrient delivery. Furthermore, vascular networks could be printed directly through coaxial 3D bioprinting. This review summarizes recent advances in coaxial bioprinting for the fabrication of complex vascularized tissue constructs including methods, the effectiveness of varying strategies, and the use of sacrificial bioink. The limitations and challenges of coaxial 3D bioprinting are also summarized.

Anisotropic hygro-expansion in hydrogel fibers owing to uniting 3D electrowriting and supramolecular polymer assembly

Melt electrowriting (MEW) is mostly applied to print complex three-dimensional (3D) structures using traditional, relatively hydrophobic polymers, such as polycaprolactone. Here, we 3D printed a supramolecular hydrophilic polymer into a solid micrometer-sized fiber structure, solely held together via non-covalent interactions. Interestingly, the solid fibers showed anisotropic swelling in a humid environment as demonstrated by the longitudinal and transverse surface strain determined using a novel global digital height correlation algorithm. This anisotropy in swelling is proposed to originate from a shear-induced orientation of crystals packed into lamellae as shown with small-angle x-ray scattering measurements. The MEW fibers were dried after swelling to study structural differences. Remarkably, no differences in nano-structural conformation in the micrometer-sized fibers was observed after swelling and subsequent drying. In conclusion, a free-standing supramolecular polymer-based hydrogel scaffold, displaying anisotropic hygro-expansion, is shown to be produced using MEW. This unique combination of 3D printing, via a top-down approach, and supramolecular polymer chemistry, via a bottom-up approach, provides new ways to introduce anisotropy and hierarchy in aqueous supramolecular systems. This will open the door towards even more complex hierarchical structures with unprecedented properties.

Large-Scale Spinning Approach to Engineering Knittable Hydrogel Fiber for Soft Robots.

Efforts to impart responsiveness to environmental stimuli in artificial hydrogel fibers are crucial to intelligent, shape-memory electronics and weavable soft robots. However, owing to the vulnerable mechanical property, poor processability, and the dearth of scalable assembly protocols, such functional hydrogel fibers are still far from practical usage. Herein, we demonstrate an approach toward the continuous fabrication of an electro-responsive hydrogel fiber by using the self-lubricated spinning (SLS) strategy. The polyelectrolyte inside the hydrogel fiber endows it with a fast electro-response property. After solvent exchange with triethylene glycol (TEG), the maximum tensile strength of the hydrogel fiber increases from 114 kPa to 5.6 MPa, far superior to those hydrogel fiber-based actuators reported previously. Consequently, the flexible and mechanical stable hydrogel fiber is knitted into various complex geometries on demand such as a crochet flower, triple knot, thread tube, pentagram, and hollow cage. Additionally, the electrochemical-responsive ionic hydrogel fiber is capable of acting as soft robots underwater to mimic biological motions, such as Mobula-like flapping, jellyfish-mimicking grabbing, sea worm-mimicking multi-degree of freedom movements, and human finger-like smart gesturing. This work not only demonstrates an example for the large-scale production of previous infeasible hydrogel fibers, but also provides a solution for the rational design and fabrication of hydrogel woven intelligent devices.

3D printed high-resolution scaffold with hydrogel microfibers for providing excellent biocompatibility.

Melt electrowriting (MEW) can print high-resolution scaffolds with the ultrafine fibers from 800 nm to 20 µm. However, the cell seeding efficiency relatively low due to the large pore size of the MEW scaffold. Here, we reported a method to solve this dilemma by electrospinning a gelatin methacrylate (GelMA) hydrogel fibers membrane (HFM) on the MEW scaffold. This composite scaffold can own the controlled structures and porosity and excellent cell seeding performance. We systematically investigate the fabrication, morphology, and biocompatibility of composite scaffolds. The implanting of human umbilical vein endothelial cells(HUVES) showed excellent adhesion and biocompatibility on the composite scaffold. Moreover, the cells migrated gradually into the MEW scaffold along the GelMA HFM to form the cell sheet. We hold the opinion that the composite scaffolds have potential applications in the field of tissue engineering repair.

Stretchable, self-healing, conductive hydrogel fibers for strain sensing and triboelectric energy-harvesting smart textiles

Abstract Stretchable conductive fibers are essential for smart electronic textiles (E-textiles). Here, we develop a continuous dry-wet spinning approach to fabricate stretchable, conductive and self-healing hydrogel fibers. By tuning the contents of acrylamide (AAm) and N-acryloylglycinamide (NAGA), the physically cross-linked poly (NAGA-co-AAm) (PNA) hydrogel precursor exhibits thermally reversible sol-gel transition, which ensures the success of the spinning process. The obtained PNA hydrogel fiber achieves excellent tensile strength (2.27 Mpa), stretchability (900%), high conductivity (0.69 S m−1), and self-healing capability. With an elastomeric poly (methyl acrylate) (PMA) coating, the PNA/PMA core-sheath fiber shows excellent resistance to water evaporation and absorption. The strain sensing capability of the PNA/PMA fiber is demonstrated for monitoring human body motions. Furthermore, a triboelectric nanogenerator (TENG) textile woven from the PNA/PMA fibers is fabricated to convert mechanical motion energy into electric power. Our stretchable conductive hydrogel fibers suggest great potentials for next-generation multifunctional smart textiles and wearable electronics.

Fiber Crimp Confers Matrix Mechanical Nonlinearity, Regulates Endothelial Cell Mechanosensing, and Promotes Microvascular Network Formation.

Mechanical interactions between cells and their surrounding extracellular matrix (ECM) guide many fundamental cell behaviors. Native connective tissue consists of highly organized, 3D networks of ECM fibers with complex, nonlinear mechanical properties. The most abundant stromal matrix component is fibrillar type I collagen, which often possesses a wavy, crimped morphology that confers strain- and load-dependent nonlinear mechanical behavior. Here, we established a new and simple method for engineering electrospun fibrous matrices composed of dextran vinyl sulfone (DexVS) with controllable crimped structure. A hydrophilic peptide was functionalized to DexVS matrices to trigger swelling of individual hydrogel fibers, resulting in crimped microstructure due to the fixed anchorage of fibers. Mechanical characterization of these matrices under tension confirmed orthogonal control over nonlinear stress-strain responses and matrix stiffness. We next examined ECM mechanosensing of individual endothelial cells (ECs) and found that fiber crimp promoted physical matrix remodeling alongside decreases in cell spreading, focal adhesion area, and nuclear localization of Yes-associated protein (YAP). These changes corresponded to an increase in migration speed, along with evidence for long-range interactions between neighboring cells in crimped matrices. Interestingly, when ECs were seeded at high density in crimped matrices, capillary-like networks rapidly assembled and contained tube-like cellular structures wrapped around bundles of synthetic matrix fibers due to increased physical reorganization of matrix fibers. Our work provides an additional level of mechanical and architectural tunability to synthetic fibrous matrices and implicates a critical role for mechanical nonlinearity in EC mechanosensing and network formation.

Antifreezing and stretchable all-gel-state supercapacitor with enhanced capacitances established by graphene/PEDOT-polyvinyl alcohol hydrogel fibers with dual networks

Although aqueous fibrous supercapacitor is one of the most advantageous energy storage devices for powering wearable electronics due to its excellent flexibility, outstanding cycling stability and high safety, it is still a challenge for its electroactive components to be cold-tolerant and stretchable for adapting fluctuating climate environments. Herein, a graphene/PEDOT:PSS hydrogel fiber with a continuous rose flower-like network is firstly constructed, and an antifreezing polyvinyl alcohol (PVA) network is subsequently taken into the hydrogel fiber via solvent replacement to generate an antifreezing and stretchable graphene/PEDOT-PVA hydrogel fiber with dual networks. Benefiting from superior interface compatibility of the hydrogel fiber with a PVA electrolyte, the assembled all-gel-state supercapacitor delivers a high capacitance of 281.2 F g−1 (0.1 A g−1) at 25 °C, more than twice higher than that of an aerogel fiber-based supercapacitor. Furthermore, this supercapacitor exhibits stable subzero-temperature electrochemical performances due to the smooth ion-transport channels and good conductivity of the antifreezing hydrogel fiber electrode, evidenced by the high specific capacitance of 212.6 F g−1 and the excellent capacitance retention of 91% after 5000 charge/discharge cycles at −20 °C. Finally, a highly stretchable spring-like supercapacitor exhibits an excellent capacitance retention of 92% after 5000 stretching cycles at a strain of 500%.

Enzyme-Crosslinked Electrospun Fibrous Gelatin Hydrogel for Potential Soft Tissue Engineering.

Soft tissue engineering has been seeking ways to mimic the natural extracellular microenvironment that allows cells to migrate and proliferate to regenerate new tissue. Therefore, the reconstruction of soft tissue requires a scaffold possessing the extracellular matrix (ECM)-mimicking fibrous structure and elastic property, which affect the cell functions and tissue regeneration. Herein, an effective method for fabricating nanofibrous hydrogel for soft tissue engineering is demonstrated using gelatin–hydroxyphenylpropionic acid (Gel–HPA) by electrospinning and enzymatic crosslinking. Gel–HPA fibrous hydrogel was prepared by crosslinking the electrospun fibers in ethanol-water solution with an optimized concentration of horseradish peroxidase (HRP) and H2O2. The prepared fibrous hydrogel held the soft and elastic mechanical property of hydrogels and the three-dimensional (3D) fibrous structure of electrospun fibers. It was proven that the hydrogel scaffolds were biocompatible, improving the cellular adhesion, spreading, and proliferation. Moreover, the fibrous hydrogel showed rapid biodegradability and promoted angiogenesis in vivo. Overall, this study represents a novel biomimetic approach to generate Gel–HPA fibrous hydrogel scaffolds which have excellent potential in soft tissue regeneration applications.

Integrated dynamic wet spinning of core-sheath hydrogel fibers for optical-to-brain/tissue communications.

Hydrogel optical light-guides have received substantial interest for applications such as deep-tissue biosensors, optogenetic stimulation and photomedicine due to their biocompatibility, (micro)structure control and tissue-like Young's modulus. However, despite recent developments, large-scale fabrication with a continuous synthetic methodology, which could produce core-sheath hydrogel fibers with the desired optical and mechanical properties suitable for deep-tissue applications, has yet to be achieved. In this study, we report a versatile concept of integrated light-triggered dynamic wet spinning capable of continuously producing core-sheath hydrogel optical fibers with tunable fiber diameters, and mechanical and optical propagation properties. Furthermore, this concept also exhibited versatility for various kinds of core-sheath functional fibers. The wet spinning synthetic procedure and fabrication process were optimized with the rational design of the core/sheath material interface compatibility [core = poly(ethylene glycol diacrylate-co-acrylamide); sheath = Ca-alginate], optical transparency, refractive index and spinning solution viscosity. The resulting hydrogel optical fibers exhibited desirable low optical attenuation (0.18 ± 0.01 dB cm−1 with 650 nm laser light), excellent biocompatibility and tissue-like Young's modulus (<2.60 MPa). The optical waveguide hydrogel fibers were successfully employed for deep-tissue cancer therapy and brain optogenetic stimulation, confirming that they could serve as an efficient versatile tool for diverse deep-tissue therapy and brain optogenetic applications.

Polylactic acid-based electrospun fiber and hyaluronic acid-valsartan hydrogel scaffold for chronic wound healing

BackgroundIn this study, the chronic wound healing ability of PLA-based electrospun nanofibers loaded with hyaluronic acid, valsartan, and ascorbic acid is explored. PLA-based scaffolds were fabricated by electrospinning, followed by loading the scaffolds with different concentrations of hyaluronic acid, valsartan, and ascorbic acid hydrogels. The produced formulations were characterized by scanning electron microscopy imaging (SEM), tensile strength testing, Fourier-transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). An in vitro drug release study was conducted to monitor the release of valsartan from the different formulations. This was followed by exploring the wound healing effects of the scaffolds in alloxan-induced diabetic rats and comparing the wound healing effects with positive and negative controls.ResultsThe average diameter of the fibers was in the range of 300 to 490 nm with high porosity in the range of 63.90 to 79.44%, offering a large surface area-to-volume ratio, enhanced drug solubility, oxygen permeability, and fluid uptake. The presence of valsartan significantly impacted on the re-epithelization rate. Percentage re-epithelization rate was 31.2% ± 1.77% in the absence of treatment. Histologic section of tissue showed skin with underlying loose fibro-collagenous stroma (dermis) containing sebaceous glands and hair follicles for animals treated with VA, VB, VC, and VD. All the scaffolds reduced the number of inflammatory cell infiltrates at the wound site compared to the no treatment and conventionally treated groups. Conventional antibiotic treatment and VD (electrospun biomimetic scaffolds containing ascorbic acid) had % re-epithelization rates of 59.45% ± 1.69% and 62.01% ± 1.68% which were significantly lower than the PLA/HA-valsartan hydrogel scaffolds with VB having the highest % re-epithelization rate of 85.5% ± 1.7% (Figure 4B & 5C).ConclusionThis study explored the use of biomimetic polylactic acid-based electrospun fiber and HA-valsartan hydrogel scaffold incorporating topical angiotensin receptor blockers to successfully accelerate wound healing. The novel PLA-based electrospun fibers loaded with hyaluronic acid-valsartan hydrogels were stable and possessed proven diabetic wound healing property. This was as a result of the known biomimetic effect of the fibers and increased re-epithelization facilitated by the hydrogels containing valsartan.Graphical abstract

Strong and tough PVA/PAA hydrogel fiber with highly strain sensitivity enabled by coating MWCNTs

A super strong poly (vinyl alcohol)/poly (acrylic acid) (PVA/PAA) anti-freezing hydrogel fiber has been successfully constructed and studied. The introduction of PVA chains significantly improves tensile strength and toughness to 3.8 MPa and 13.7 MJ/m3, respectively. In addition, glycerol in the hydrogel fiber ensures its good flexibility even in −15 °C. We coat hydrogel fiber with multi-walled carbon nanotubes (MWCNTs) and study their strain sensing properties. The composite hydrogel fiber has a high gauge factor of 25 at the strain of 40%, which is superior to those common hydrogel-based strain sensors. Notably, the composite hydrogel fiber shows a high stability and repeatability of 5000 cycles, and a fast response time of 225 ms. Besides, the composite hydrogel fiber can detect the large and subtle body movements accurately and timely. Therefore, this composite hydrogel fiber may be a very hopeful candidate for wearable sensing devices.

Spidroin-Inspired, High-Strength, Loofah-Shaped Protein Fiber for Capturing Uranium from Seawater.

The unique three-dimensional structure of spidrion determines the outstanding mechanical properties of the spider silk fiber. Inspired by the similarity of the three-dimensional structure of superb-uranyl binding protein (SUP) to that of spidroin, a dual-SUP (DSUP) chimeric protein fiber with high tensile strength is designed. The DSUP hydrogel fiber exhibits a loofah-shape structure by the cross-interaction of the protein nanofiber. Full exposure of abundant functional uranyl-binding sites in the stretchable loofah-shape hydrogel protein fiber give the DSUP fiber a groundbreaking uranium extraction capacity of 17.45 mg g-1 with an ultrashort saturation time of 3 days in natural seawater. This work reports the design of an adsorbent with ultrahigh uranium extraction capacity and explores a strategy for fabricating artificial high-strength functional non-spidroin protein fiber.

Additive batch electrospinning patterning of tethered gelatin hydrogel fibres with swelling-induced fibre curling

Limited methods exist to integrate patterning of free-spanning hydrogel microfibres as part of an additive manufacturing strategy. We demonstrate 3D additive batch electrospinning (3D-abES) workflow to efficiently produce layered hydrogel gelatin microfibres, tethered to 3D printed thermoplastic structures of various shapes. Enabled by the digital-design approach, multiple 3D printed fibre devices can be fabricated in a batch efficiently with minimised sample-to-sample variance. Customised fibre patterns and device geometries can be rapidly altered to fit with potential applications in 6- to 24- well plate formats. The diameter of as-produced dry fibres is in a range of ∼2−4 μm. With the intended device applications in aqueous environments, we investigate the effect of combinations of processing parameters on the gelatin fibre integrity, and its swelling behaviour when immersed in water. Aided by the parametric study, patterns of swelling-induced fibre curling, from straight to wavy, can be tuned. Our findings could serve as a guide to optimise the 3D fabrication and patterning of electrospun hydrogel-like fibres made of crosslinked hydrophilic polymers and oligomers, for cell culture or bio-sensing applications.

Fabrication and extrusion of the PAAm-SAlg hydrogels with magnetic particles

Magnetic hydrogels have received extensive attention in various research fields due to their excellent controllability and responsiveness. In this work, we constructed a magnetic biocompatible hydrogel based on PAAm-SAlg (polyacrylamide and sodium alginate) system. The crosslinking network of this magnetic hydrogel is constructed by two kinds of chemical bonds. Magnetic particles with cores of Fe3O4 are embedded in hydrogel networks by physical and chemical bindings. The addition of magnetic particles has different effects on the properties of hydrogels. Firstly, compared to hydrogels without magnetic particles, the tensile strength of magnetic hydrogels increases by 40 % from 0.035 MPa to 0.049 MPa, however, the swelling property is slightly reduced. In addition, magnetic hydrogels retain the characteristics of shear thinning and excellent superparamagnetism, and the magnetic response is slightly weakened than pure magnetic particles. The printed hydrogel fiber has a diameter of 100 μm and the magnetic particles are evenly distributed in the fiber. Moreover, increasing the air pressure of printing will cause irregular bumps on the surface of the printed hydrogel.

Highly stretchable CNT Fiber/PAAm hydrogel composite simultaneously serving as strain sensor and supercapacitor

The integration of different functional components into one device is attracting increasing attention. In this work, a high strength carbon nanotube (CNT) fiber/polyacrylamide (PAAm) hydrogel composite is developed by embedding quasi-sinusoidal shaped CNT fibers in PAAm hydrogel. Combination of ionic conductive hydrogel and wavy CNT fibers yields a highly stretchable and wearable device with integration of strain sensing component and electrochemical energy storage component. On the one hand, the CNT fiber/PAAm hydrogel (CFPH) composite shows an excellent strain sensing performance with a stretch-ability up to 100% in a wide frequency of 0.1–10 Hz. As a result, it is effective as stretchable and wearable strain sensor to monitor a range of small to large scale human activities. On the other hand, with two parallel quasi-sinusoidal shaped CNT fibers as electrodes and one ionic conductive PAAm hydrogel as electrolyte and separator simultaneously, the CFPH composite serves as a stretchable all-solid-state supercapacitor with an areal capacitance of 10.6 mF cm−2. The electrochemical performance of the CFPH composite under both static and dynamic loading is very stable, exhibiting a capacitance retention of 90.0% after 3000 charge-discharge cycles with dynamic stretching applied simultaneously. The developed dual-mode CNT fiber/PAAm hydrogel composite is promising to serve as two functional components in one device.

Iodine ions sensing based on fluorescence quenching method and hydrogel fiber doped with fluorescein

This paper presents an iodine ions fluorescence quenching sensor based on hydrogel fiber doped with fluorescein. The hydrogel fiber was made by photo-crosslinking with core-cladding structure made from PEGDA precursor solutions with different concentration. Compared with calcium alginate cladding material, this structure is less susceptible to damage and the thickness of the cladding is controllable, which significantly reduces the loss of the hydrogel fiber. Experimental results show that the loss of the cladding-free hydrogel is 1.669 dB/cm ± 0.4 dB/cm, and the loss of the core-cladding hydrogel fiber is 0.597 dB/cm ± 0.2 dB/cm. By analyzing the properties of different hydrogel precursor solutions before and after photo-crosslinking, a functional hydrogel fiber doped with fluorescein for measuring iodine ions with numerical aperture of 0.3932 and mode number about 17 was fabricated. The hydrogel fiber shows high coupling efficiency with PMMA plastic optical fiber. The sensor of iodine ions exhibited a linear range of 0 ∼36 mM and the detection limit was calculated to be 26nM. The system also shows good stability and repeatability. Hydrogel fibers shows good biocompatibility and flexibility, which will have broad application prospects in biological area in the future.