![]() 3, 22 The process is relatively simple and relies on the electrostatic repulsion of a polymer solution to form polymer fibers. 1, 3 The technique is capable of producing long, continuous fibers ranging from 3 nm to 10 μm in diameter. 15Įlectrospinning is a time- and cost-efficient technique to produce polymer fibers and is the most commonly used method to produce fiber meshes in tissue engineering. 21 These unique mechanical properties are useful for modulating cell behavior as well as providing adequate tension and strength to resist the forces from the cell cytoskeleton. 20 This might especially be true of electrospun fibers, where flow-induced crystallization is thought to occur during spinning. Although this occurrence is not fully understood, one explanation is that the decrease in fiber diameter leads to an increase in macromolecular chain alignment within the fibers, 17– 19 with nanofibers of a smaller diameter having a higher degree of crystallinity. Specifically, the tensile modulus, 13– 16 tensile strength, 15 and shear modulus 17 have been shown to increase as fiber diameter decreases. 12įurther, polymeric nanofibers have been shown to display unique mechanical properties. Additionally, the nanofibrous constructs were found to selectively enhance the adsorption of specific proteins, such as fibronectin and vitronectin, 11 which is significant as fibronectin is one protein known to mediate cell adhesion and to bind many growth factors. For example, poly( l-lactic acid) (PLLA) fibers with diameters ranging from 50 to 500 nm were shown to have four times higher rates of protein adsorption than porous PLLA constructs with macroscale features. 3, 10 Compared to macroscale surfaces, nanofibers have shown higher rates of protein adsorption, a key mediator in cell attachment to a biomaterial surface. 4 The small diameter of nanofibers closely matches the size scale of extracellular matrix (ECM) fibers, allowing them to be used as biomimetic scaffolds, 6– 8 and the high surface area-to-volume ratio is ideal for cell attachment 9 and drug loading. In this field, the term “nanofiber” is typically used to describe fibers with diameters ranging from 1 to 1000 nm. The unique properties of polymeric nanofibers make them a valuable tool to tissue engineers. Finally, bioactive factor loading and applications of polymeric nanofibers in the fields of bone, cartilage, ligament and tendon, cardiovascular, and neural tissue engineering will be presented to demonstrate the utility of nanofibers in tissue engineering. 5 This review discusses information not previously reviewed with regard to the fabrication of polymeric nanofibers in the context of its effect on the physical properties of nanofibrous scaffolds, relevant to tissue engineering, including fiber degradation and control of pore structure and cell infiltration. The popularity of nanofibers is demonstrated by the number of reviews focusing on their production, 1– 3 application, 1, 2, 4 and interaction with cells. Since polymeric nanofibers are well suited for such applications, they are gaining popularity in tissue engineering and have been used in attempts to regenerate a variety of tissues. Although a wide range of scaffold materials are available, polymeric scaffolds are commonly employed to support tissue growth and to serve as carriers for bioactive factor delivery. Scaffolds generally serve as the foundation for many strategies to promote tissue formation. T issue engineering approaches typically involve three key elements: scaffolds, cells, and biochemical and/or mechanical stimuli. ![]()
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