Effect of Needle Diameter on Scaffold Morphology and Strength in E-Jetted Polycaprolactone Scaffolds

Abstract

Electro-hydrodynamic Jetting or E-Jetting is a process in which a polymer, dissolved in a solvent and extruded through a needle onto a substrate. A potential difference is applied between the needle and the substrate to facilitate the homogeneous extrusion of the fiber. This process is used to fabricate two dimensional scaffolds with porous mesh surfaces which act as a template for cell growth. As cells are very minute and are required to attach to the surface of the scaffold, it is essential to for the scaffold to have an adequate pore size that allows for nutrient transfer while preventing the penetration of cells through the scaffold. The fiber dimensions of the scaffold may be modified by varying the diameter of the needle through which the fiber is extruded. The change in fiber diameter subsequently results in the change in the bulk mechanical characteristics of the scaffold. It also causes a change in the net porosity of the scaffold. This paper aims to study the effect of the needle diameter on the bulk mechanical properties of the scaffold such as Young’s modulus, Tensile strength and Breaking Strength as well as morphological properties (porosity and pore size) of the Scaffolds are dependent on the cell type, as each type of cell has a different set of requirements depending on the functionality. Bone cells are smaller than soft tissue cells, hence a common scaffold design may not be suit either of the applications. Thus, a one size fits all approach is not suitable for the scaffold [9]. As seen in Figure 1, the Red Blood Cells are a fraction of the size of the fibroblasts and bone marrow stem cells [20–22]. Similarly, the stiffness of the cells is also different. Electro Hydrodynamic Jetting (E-jetting) is a process that is used to fabricate such 2D scaffolds by extruding a polymer solution through a needle and forming a fiber by applying a scaffold. For this study, twelve scaffolds belonging to three study groups were synthesized using e-jetting. By studying the effect of needle diameter on scaffold morphology and strength, we aim to develop a co-relation between the scaffold parameters, which will ultimately help in the creation of a knowledge database. The purpose of creating this database is to choose a select needle for a selected biomedical application.