Fabrication and Degradation of Electrospun Scaffolds from L-Tyrosine-Based Polyurethane Blends for Tissue Engineering Applications

It is important to control the degradation rate of a tissue-engineered scaffold so that the scaffold will degrade in an appropriate matching rate as the tissue cells grow in. A set of potential tissue engineering scaffolds with controllable rates of degradation were fabricated from blends of two biocompatible, biodegradable L-tyrosine-based polyurethanes (PEG1000-HDI-DTH and PCL1250-HDI-DTH) using the electrospinning process. The scaffolds were characterized by mat morphology, fiber diameter, diameter distribution, pore size, and hydrolytic degradation behavior. The majority of the scaffolds, despite having radically different chemical compositions, possessed no statistical difference with pore sizes and fiber diameters. The degradation pattern observed indicated that scaffolds consisting of a greater mass percentage of PEG1000-HDI-DTH decayed to a greater extent than those containing higher concentrations of PCL1250-HDI-DTH. The degradation rates of the electrospun scaffolds were much higher than those of the thin cast films with same compositions. These patterns were consistent through all blends. The work demonstrates one practical method of controlling the degradation of biopolymer scaffolds without significantly affecting an intended morphology. 1. Introduction Biomaterials are a class of materials that interact in a desirable way with their intended living hosts. The source of such materials spans both naturally occurring and synthetic means of acquisition and each material, whether native or synthetic, presents its own set of challenges and benefits. Substances such as silk, collagen, metals, ceramics, and polymers, have all been used to solve a problem requiring a biomaterial solution. The two major concerns when choosing or designing a biomaterial for any specific application are: how the material functions in the body and how the body reacts to the presence and function of the material. Native materials, such as collagen, are advantageous in that the living host (i.e., human) has an evolutionary means of handling and eventually disposing of the substance through hydrolytic, oxidative, and enzymatic means. Additionally, the body is able to recognize the substance as “friendly” and limit the immune response. The frequent disadvantage is that collagen by itself, for example, is often unsuited for the mechanical stresses placed on the material for many applications [1]. Polymers present an interesting alternative solution to the aforementioned problems. Synthetic polymers possess the useful property of relative ease in functional changes.