Design, fabrication, and analysis of spatially heterogeneous scaffold by melt electrospinning writing of poly(ε‐Caprolactone)

Abstract

Melt electrospinning writing (MEW) that processes molten polymers has emerged as a reliable method to fabricate high-fidelity fibrous tissue scaffolds for investigation of cell biological performance as a function of structural features. However, most of the current investigations have focused on the scaffolds with homogeneous features, which can yield homogeneous cell performance outcomes as expected. In contrast, spatially heterogeneous scaffolds with well-defined, nonuniform pore attributes can serve as biomimetic, multiplexed platforms for biological investigations. In this study, an analytically derived general heterogeneous toolpath design model is introduced. In addition to the traditional orthogonal fiber orientations, fiber placement along diagonal directions is introduced to generate semi-0-θ patterned or 0-θ patterned heterogeneous scaffolds. By specifying model parameters and hence tuning the relative location of the diagonal fibers to orthogonal fibers, the customized heterogeneous scaffolds produced can possess at most three different pore morphologies. The various distributions of different pore morphologies within one scaffold are subsequently mapped by an advanced mathematical matrix method for the first time. Moreover, the proportion of different pore morphologies of semi-0-θ patterned scaffolds can be obtained numerically. Finally, this proposed analytical design model is preliminarily validated by fabrication using a MEW printing process.

Engineering Heart Valve Interfaces Using Melt Electrowriting: Biomimetic Design Strategies from Multi‐Modal Imaging

“…[44,47] More recently, the ability to fabricate heterogeneous fibrous structures within a single layer using MEW has been demonstrated, marking a notable step forward in the field of fibrous scaffold fabrication. [20,[48][49][50][51] Despite this, the concept of heterogeneous MEW printing is still in its infancy, and as a result, the design of the interface between het-erogeneous regions has not been a primary focus of previous work. [48][49][50][51] Here we explore the potential for MEW to engineer complex, user-defined, interfaces between heterogeneous regions of heart valve scaffolds.…”

“…[20,[48][49][50][51] Despite this, the concept of heterogeneous MEW printing is still in its infancy, and as a result, the design of the interface between het-erogeneous regions has not been a primary focus of previous work. [48][49][50][51] Here we explore the potential for MEW to engineer complex, user-defined, interfaces between heterogeneous regions of heart valve scaffolds. The complexity and heterogeneity of the aortic valve make it a good showcase to examine the technical capabilities of MEW in complex scaffold fabrication for soft tissue interfaces.…”

“…[ 20,48–51 ] Despite this, the concept of heterogeneous MEW printing is still in its infancy, and as a result, the design of the interface between heterogeneous regions has not been a primary focus of previous work. [ 48–51 ]…”

Effects of Printing Sequence on the Printing Accuracy of Melt Electrowriting Scaffolds

“…Currently, extensive studies have been made to investigate the structure-function relationship between the seeded cells and the microarchitecture of the scaffolds such as the tympanic membrane regeneration, [11] periodontal tissue regeneration, [12] and bone tissue regeneration. [9,13] Furthermore, to expand the application categories of MEW scaffolds, different types of scaffolds are designed and fabricated including hollow fiber, [] heterogeneous scaffolds, [15,16] tubular scaffolds, [17] and multi-phasic scaffolds. [18] Although many efforts have been made to enrich the capability of MEW, one barrier is that printed fibers deviate from their prescribed locations, which hinders the application of MEW.…”

“…For example, to decrease the pore size of scaffolds or fabricate scaffolds with triangle pores, diagonal fibers are introduced to obtain the 0– θ pattern. [ 16 ] As a result, the inter‐fiber distances separating fibers along the diagonal directions are not identical to those separating fibers along the orthogonal directions. Thus, there is a need to decide the printing sequence of the printing directions, whose effects on printing accuracy are ignored.…”