A Novel Method to Precisely Assemble Loose Nanofiber Structures for Regenerative Medicine Applications

Abstract

Polymer nanofibers are favorable for tissue engineering scaffolds because of their high surface-to-volume ratio and biomimicry of the extracellular matrix. Random and uniaxially oriented polymer nanofibers are easily fabricated by conventional electrospinning techniques; however, control over fiber organization within nanofiber structures is limited when they are collected directly from an electrospinning jet. The regenerative medicine applications of electrospun scaffolds could be expanded by developing assembly methods that allow better control of fiber organization. Here, a novel technique is presented that utilizes parallel automated tracks to orient and collect nanofibers from an electrospinning jet. The stabilized fibers are then subsequently assembled into desirable structures. It is difficult to assemble complex structures directly from an electrospinning jet because of high electrical charge and velocities, so this technology adds an intermediate step where nanofibers are immobilized on automated tracks. The result is a continuous steady-state delivery of static stabilized nanofibers that provides a unique and promising platform for automated post processing into useful nanofiber structures. This technique also allows for an indefinite amount of time, as determined by design parameters, for fibers to dry or cool before they contact other nanofibers in the collection site, thus eliminating potential for fiber-to-fiber adhesions even with slow evaporating solvents or high-temperature melts. To demonstrate potential in regenerative medicine applications, several nanofiber structures were fabricated, including: 2D structures with well-controlled fiber density; 3D loosely assembled aligned nanofiber structures with good cell penetration properties; and, complex layer-by-layer 3D aligned fiber structures assembled by integration with post-processing techniques.

Layer-by-layer nanofiber-enabled engineering of biomimetic periosteum for bone repair and reconstruction

“…The versatility of electrospun fiber sheets in mimicking extracellular matrix (ECM) [20-23] and the benefits of high surface-to-volume ratio fibrous matrices for cell attachment, drug loading, and mass transport [24, 25] enable the construction of a flexible tissue membrane that can fit bone of any size and shape. To overcome the limitations of nanofibrous sheets in cellular infiltration and vascular ingrowth, we further adopted a layer-by-layer assembly strategy [26], which has been successfully used in a number of tissue engineering applications to facilitate uniform cell seeding and complex tissue construction [27-32]. …”

Making Nonwoven Fibrous Poly(ε‐caprolactone) Constructs for Antimicrobial and Tissue Engineering Applications by Pressurized Melt Gyration

“…Generally, nonwoven polymer fibrous scaffolds are made with spinning techniques either using polymer solutions or melts . The primary focus of the spinning technique is the production of fibers in a scale range from nano‐ to microrange that resembles the native extracellular matrix (ECM) . Although there has been much research on solution spinning to form fibrous polymer scaffolds for tissue engineering and wound healing applications, little has been reported on melt spinning to fabricate nonwoven scaffolds .…”

Nanotechnologies in tissue engineering

“…The author emphasizes, that the successful fabrication of the electrospun nanofibrous scaffolds starts with the selection of proper polymers, whereas the combination of multiple polymers as well as various postmodification techniques may provide desirable properties [12] . Beachley and coworkers addressed the limited control over fiber organization within nanofiber structures when they are collected directly from an electrospinning jet [13] . Furthermore, a novel assembly technique that utilizes parallel automated tracks to orient and collect nanofibers from the electrospinning jet has been established in order to allow a better control of the fiber organization, resulting in a continuous steady-state delivery of static stabilized nanofibers [13] .…”

“…Beachley and coworkers addressed the limited control over fiber organization within nanofiber structures when they are collected directly from an electrospinning jet [13] . Furthermore, a novel assembly technique that utilizes parallel automated tracks to orient and collect nanofibers from the electrospinning jet has been established in order to allow a better control of the fiber organization, resulting in a continuous steady-state delivery of static stabilized nanofibers [13] . Another study by Leverson and colleagues demonstrated the feasibility of fabrication of electrospun scaffolds containing two differently scaled fibers as well as scaffolds containing fibers of the two different materials fibrin and PCL using a dual extrusion electrospinning setup.…”