Fabrication and characterization of air-impedance electrospun polydioxanone templates

Abstract

Electrospinning, a fabrication technique used to create non-woven, porous templates from natural and synthetic polymers, is commonly used in tissue engineering because it is highly tailorable. However, traditional electrospinning creates restrictive pore sizes that limit the required cell migration. Therefore, tissue engineering groups have sought to enhance and regulate porosity of tissue engineering templates. Air-impedance electrospinning generates templates with tailorable, patterned areas of low and high density fiber deposition. Here we demonstrate an improved air-impedance electrospinning system, consisting of a newly designed funnel equipped to hold changeable porous deposition plates and administer air flow in a confined and focused manner, with parameters that maintain template integrity. In this preliminary study, we quantify the increase in porosity of polydioxanone templates with use of traditional fiber and pore analysis as well as with mercury porosimetry. Additionally, we validate the system's significance in fabricating enhanced porosity templates that maintain their mechanical properties (i.e. elastic modulus, tensile strength, and suture retention strength) despite the deliberate increase in porosity. This is of exceptional value to the template's integrity and efficacy as these parameters can be further optimized to induce the desired template porosity, strength, and texture for a given application.

Mechanical Properties of Electrospun Fibers—A Critical Review

“…Electrospun fibers possess the potential for outstanding characteristics, such as very large surface area to volume ratios, advanced mechanical performance (e.g., stiffness and tensile strength), unique physical and chemical properties, fabricability with multiple polymers, tuning of fiber diameters and flexibility in surface functionalities, compared with any other known forms of the materials. These superior properties make electrospun fibers potential candidates for diverse fields of applications, [ 5 ] including food packaging, [ 6 ] pharmaceuticals, [ 7 ] biomedical applications such as drug delivery, [ 8 ] tissue engineering, [ 9 ] wound dressing and cosmetics, [ 10 ] functional materials and devices such as filters, [ 11 ] template fibers for nanotubes, [ 12 ] composite reinforcement, [ 13 ] actuators, [ 14 ] protective clothing and smart textiles, [ 15 ] aerogels and responsive gel fibers, [13c,16] sponges, [ 17 ] and energy and electronics such as batteries/cells, [ 18 ] thermal insulation, [ 19 ] supercapacitors, [ 20 ] and EMI shielding, [ 21 ] and sensors and catalysts. [ 22 ] In all these applications, the electrospun fibers are subjected to stresses from the surrounding environment during their service lifetime.…”

Bioengineering Vascular Networks to Study Angiogenesis and Vascularization of Physiologically Relevant Tissue Models in Vitro

“…DuRaine et al reported the suitability of their TE constructs with a suture retention strength of 1.45 MPa for in vivo implantation by suturing them in place . Selders et al demonstrated that the suture retention strength of the developed polymer templates was between 0.40 and 1.20 MPa under dry conditions . Similarly, Syedain et al.…”

Electrospun fibers/branched-clusters as building units for tissue engineering

“…Rather than using a cylindrical mandrel, this study utilized an air funnel system that passed air perpendicularly through a flat, porous metal deposition plate. Certain combinations of deposition plate pore size, air flow velocity, and fiber size were able to achieve increased template porosity without sacrificing the mechanical strength of the template [15]. However, this study did not investigate the effect on cellular infiltration, meaning that there remains work needed to fully validate this technique with regards to tissue engineering templates.…”

“…Because the fibers are deposited at a 90 ∘ angle to a flat surface, they create flat two-dimensional structures that pack together with fibers oriented parallel to the surface instead of vertically through the structure. This random packing precludes complete control of pore size and pore interconnectivity [12][13][14][15], and the lateral orientation of fibers fails to provide vertical fibrous pathways to facilitate cell movement into the template. A variety of techniques have been developed to improve cellular infiltration into electrospun templates.…”