Electrospinning is a process in which polymer solutions are sprayed and stretched using a static electric field to create nanoscale fibers. The fibers typically have diameters ranging from approximately 100 nm to 1 µm and can reach lengths of several kilometers. These fibers exhibit properties such as a high surface area-to-volume ratio, fine porosity, and a lightweight structure.1
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The electrospinning process has recently attracted attention for its advantages over other nanofiber production methods. Compared to techniques such as melt fibrillation and gas jet methods, electrospinning provides higher production rates at lower costs, expanding the use of electrospun membranes across various fields.2
Principle of Electrospinning
Electrospinning is an electrohydrodynamic process in which a liquid droplet is electrified to produce a jet that stretches and elongates into fibers. The setup is simple, typically consisting of a high-voltage power source, syringe pump, spinneret (often a blunt-tipped needle), and conductive collector, making it feasible for use in laboratories and industry.3
The process begins with a liquid droplet extruded from the spinneret, which, upon electrification, deforms into a Taylor cone. The cone emits a charged jet that initially follows a straight path but then undergoes whipping caused by bending instabilities. As the jet thins, it solidifies and deposits onto a collector plate.3
The electrospinning process consists of four main stages: (i) the liquid droplet becomes charged under an applied voltage, forming a cone-shaped jet called the Taylor cone; (ii) the jet extends in a straight line; (iii) as it moves within the electric field, the jet thins and develops bending instabilities (whipping instability); and (iv) the jet solidifies and is collected as nano- or microfibers on a grounded drum or flat collector.2
Characteristics of Electrospun Nanofibers
Electrospun nanofibers possess a large surface area-to-volume ratio due to their interconnected network, as well as adjustable surface properties, versatile functionalities, mechanical resilience, and high permeability.4
Several parameters influence the quality and morphology of electrospun fibers. Increasing the conductivity of the electrospinning solution, often achieved by adding salts or conductive polymers, improves jet stability and reduces defects.1
Reducing surface tension, achieved by adding surfactants or using low-tension solvents such as ethanol, helps prevent liquid bead formation and decreases fiber diameter. This results in smoother, more uniform fibers, improving the overall quality of electrospun fibers.5
Concentration and viscosity are also critical factors in electrospinning. Low polymer concentrations can result in unstable jets and beaded fibers, while excessively high viscosity from higher polymer concentrations may block the nozzle, disrupting the spinning process.5
Applications of Electrospun Nanofibers
Biomedical Applications
Drug Delivery
Electrospun nanofibers are used in drug delivery applications due to their biodegradability, scalability, controlled drug release, and high surface-area-to-volume ratio. Controlled-release drugs such as Avandia, eprosartan, carvedilol, hydrochlorothiazide, aspirin, and naproxen are often incorporated into these nanofibers.6
A study by L. Contreras et al. (2021) demonstrated that nanofibers composed of carbon nanotubes (CNTs) form a hybrid structure that can be used for the delivery of doxorubicin (dox).7 Dox was chemically incorporated into CNT nanofibers with an encapsulation efficiency of 83.7 %.
To optimize the nanofiber structure, poly lactide-co-glycolide (PLGA) polymer was combined with dox in three different ratios and electrospun into fibers. Encapsulating CNTs within PLGA nanofibers did not alter the fiber structure but significantly enhanced their mechanical strength. Moreover, CNT nanofibers prevented the initial burst release of dox, enabling controlled delivery over 42 days.6
Tissue Engineering
In tissue engineering, nanofibrous structures that mimic the extracellular matrix and support the electrical conductivity of native myocardium are beneficial.
Ling Wang and colleagues (2017) developed conductive nanofiber sheets for 3D bioactuators based on cardiomyocytes, with potential applications in cardiac tissue engineering and electrically conductive biomaterials.8 These sheets also support the formation of 3D bioactuators in tubular and folding shapes, making them a promising material for cardiac tissue engineering and cardiomyocyte-based bioactuators.
Wound Dressings
A modified type of nanofiber, known as multilayered nanofibers, is created by coating polysaccharides onto polycaprolactone-based fibers and is well-suited for use in wound dressing applications.9
These nanofibers are produced through a combination of electrospinning and layer-by-layer deposition, where positively charged chitosan is alternated with negatively charged polyelectrolytes to form charged fiber layers.
Filtration
Filters are widely used across households, healthcare, and industry to remove unwanted particles and protect against pollutants in air and water.
A study by J. Cao (2020) compared a nylon-6 electrospun membrane (100 μm thick, 0.24 μm pore size) with a commercial HEPA filter (500 μm thick, 1.7 μm pore size) using 300 nm test particles. The nanofiber membrane demonstrated slightly higher filtration efficiency (99.993 %) compared to the HEPA filter (99.97 %).10
Nanofibers are also effective in cabin air filtration for mining vehicles. Cellulose-nanofiber filters, which replace traditional cellulosic filters, improve dust reduction from 68 % to 92 % by circulating fresh air and expelling contaminated air.11
Textiles
Traditional fiber-based yarns have been used in the textile industry for thousands of years. Electrospun nanoyarns, however, offer the potential to develop nanotextiles with enhanced optical, electrical, mechanical, and biological properties, due to their unique size and surface characteristics.6
Nanoyarn-based nanotextiles further present opportunities to enhance traditional microfibrous textiles with precise, multi-dimensional patterns. Electrospun fibers enable the production of lightweight, mechanically strong fabrics suitable for applications such as sportswear, protective clothing, and other functional textile.6
Wu et al. developed woven nanotextiles with varying yarn densities using high-strength poly(L-lactic acid) (PLLA) electrospun fibers. Their work demonstrated control over structure, pore size, and mechanical properties. They also observed that yarn density significantly affected cell adhesion, growth, and proliferation.12
The Electrospinning Technology
Recent Advances in Electrospinning
Recent developments in electrospinning have expanded the versatility and applications of nanofibers through innovations in materials and functionalization. The use of biocompatible and biodegradable polymers, such as polyvinyl alcohol (PVA) and polyethylene oxide, alongside solvent-soluble options like polyimide and polystyrene, has enabled the production of nanofibers designed for biomedical, energy storage, and environmental applications.1
Functionalized nanofibers represent another advancement. By incorporating materials such as metal oxides, metal-organic frameworks, and other additives, composite nanofibers with specific structures, morphologies, and functionalities can be created, broadening the applicability of electrospun fibers.2
For example, Xu et al. (2021) developed a novel aptamer@AuNPs@UiO-66-NH2 nanofiber sensor for detecting microcystin (MC-LR). This sensor achieved a high loading of metal-organic frameworks (MOFs) and aptamers on nanofibers.13
When combined with solid-phase microextraction and liquid chromatography-mass spectrometry (LC–MS), the sensor demonstrated highly specific detection of MC-LR with a low limit of detection (LOD) of 0.004 ng/mL and high precision (CV% <11.0 %). These advancements highlight the growing capabilities of electrospinning to address the requirements of diverse, high-performance applications.
More from AZoNano: How Emulsion Electrospinning is Transforming Materials
References and Further Reading
1. Song, J., Lin, X., Ee, LY., Li, SFY., Huang, M. (2023). A Review on Electrospinning as Versatile Supports for Diverse Nanofibers and Their Applications in Environmental Sensing. Advanced Fiber Materials. https://link.springer.com/article/10.1007/s42765-022-00237-5
2. Bavatharani, C., Muthusankar, E., Wabaidur, SM., Alothman, ZA., Alsheetan, KM., mana AL-Anazy, M., Ragupathy, D. (2021). Electrospinning Technique for Production of Polyaniline Nanocomposites/Nanofibres for Multi-Functional Applications: A Review. Synthetic Metals. https://www.sciencedirect.com/science/article/abs/pii/S0379677920308614?via%3Dihub
3. Xue, J., Wu, T., Dai, Y., Xia, Y. (2019). Electrospinning and Electrospun Nanofibers: Methods, Materials, and Applications. Chemical reviews. https://pubs.acs.org/doi/10.1021/acs.chemrev.8b00593
4. Patil, JV., Mali, SS., Kamble, AS., Hong, CK., Kim, JH., Patil, PS. (2017). Electrospinning: A Versatile Technique for Making of 1d Growth of Nanostructured Nanofibers and Its Applications: An Experimental Approach. Applied Surface Science. https://www.sciencedirect.com/science/article/abs/pii/S0169433217317725
5. Vasconcelos, F., et al. (2022). Biomedical Applications of Fibers Produced by Electrospinning, Microfluidic Spinning and Combinations of Both. Electrospun Nanofibers: Principles, Technology and Novel Applications. https://link.springer.com/chapter/10.1007/978-3-030-99958-2_10
6. Nadaf, A., Gupta, A., Hasan, N., Ahmad, S., Kesharwani, P., Ahmad, FJ. (2022). Recent Update on Electrospinning and Electrospun Nanofibers: Current Trends and Their Applications. RSC advances. https://www.sciencedirect.com/org/science/article/pii/S2046206922015881
7. Contreras, L., Villarroel, I., Torres, C., Rozas, R. (2021). Doxorubicin Encapsulation in Carbon Nanotubes Having Haeckelite or Stone–Wales Defects as Drug Carriers: A Molecular Dynamics Approach. Molecules. https://pubmed.ncbi.nlm.nih.gov/33805628/
8. Wang, L., Wu, Y., Hu, T., Guo, B., Ma, PX. (2017). Electrospun Conductive Nanofibrous Scaffolds for Engineering Cardiac Tissue and 3d Bioactuators. Acta biomaterialia. https://pubmed.ncbi.nlm https://pubmed.ncbi.nlm.nih.gov/28663141/.nih.gov/28663141/
9. Tan, G., Wang, L., Pan, W., Chen, K. (2022). Polysaccharide Electrospun Nanofibers for Wound Healing Applications. International Journal of Nanomedicine. https://pubmed.ncbi.nlm.nih.gov/36097445/
10. Cao, J., Cheng, Z., Kang, L., Lin, M., Han, L. (2022). Patterned Nanofiber Air Filters with High Optical Transparency, Robust Mechanical Strength, and Effective Pm 2.5 Capture Capability. RSC advances. https://pubs.rsc.org/en/content/articlelanding/2020/ra/d0ra01967d
11. Qin, X., Subianto, S. (2017). Electrospun Nanofibers for Filtration Applications. Electrospun Nanofibers. https://www.sciencedirect.com/science/article/abs/pii/B9780081009079000179
12. Wu, S., Liu, J., Cai, J.; Zhao, J., Duan, B., Chen, S. (2021). Combining Electrospinning with Hot Drawing Process to Fabricate High Performance Poly (L-Lactic Acid) Nanofiber Yarns for Advanced Nanostructured Bio-Textiles. Biofabrication. https://pubmed.ncbi.nlm.nih.gov/34450602/
13. Xu, Z., et al. (2021). Aptamer-Functionalized Metal-Organic Framework-Based Electrospun Nanofibrous Composite Coating Fiber for Specific Recognition of Ultratrace Microcystin in Water. Journal of Chromatography A. https://www.sciencedirect.com/science/article/abs/pii/S002196732100666X
