Degradation Behaviors of Electrospun Resorbable Polyester Nanofibers Yixiang Dong, B.Sc., 1 Susan Liao, Ph.D., 2 Michelle Ngiam, B.Sc., 3 Casey K. Chan, M.D., 1,4 and Seeram Ramakrishna, Ph.D. 2,5 Biodegradable materials are widely used in the biomedical field because there is no postoperative surgery after implantation. Widely used synthetic biodegradable materials are polyesters, especially those used in tissue engineering. Advances in the tissue engineering field have brought much attention in terms of scaffold fabri- cation, such as with biodegradable polyester nanofibers. The rationale for using nanofibers for tissue engineering is that the nonwoven polymeric meshwork is a close representation of the nanoscale protein fiber meshwork in native extracellular matrix (ECM). Electrospinning technique is a promising way to fabricate controllable con- tinuous nanofiber scaffold mimicking the ECM structure. Electrospun nanofibers provide high surface-to-volume ratio and high porosity as a promising scaffold for tissue engineering. Because the degradation behaviors of scaffolds significantly affect new tissue regeneration, the degradation of the material becomes one of the crucial factors when considering using polyester nanofibers as scaffolds in tissue engineering. In this review paper, we focus on the degradation studies of several bioresorbable polyester nanofibrous scaffolds used in tissue engi- neering. The degradable properties of nanofibers were compared with the corresponding degradable materials in macroscale. The factors that might affect the degradation behaviors were analyzed. Introduction of Electrospinning and Its Application in Tissue Engineering Tissue engineering and nanofiber T issue engineering is emerging as a potential solution to the high demand for tissue and organ transplantations. 1 General strategies for tissue engineering therapies involve using synthetic and natural functional scaffolds cultured with or without appropriate cells harvested from the patient or donor and then implanting the cell–scaffold construct in the patient’s body where tissue replacement is required. The basic promise of in vitro tissue engineering is to integrate the specific cells with scaffolds under appropriate conditions that lead to tissue formation. Essentials of tissue scaffolds include biocompatibility, physical properties, and biode- gradability, which should be individually tailored to meet the requirements of targeting tissues. They could also be subdivided into detailed characteristics, as shown in Table 1. Different engineered tissues have specific requirements for scaffolds. For example, bone tissue engineering requires the scaffold to be mechanically strong and osteoconductive, whereas liver tissue engineering needs angiogenic and a highly porous three-dimensional scaffold. The nanotopographic environment is believed to be con- ducive to cell and tissue growth because the in vivo micro- environment where cells and tissue reside is a nanofeatured environment composed of a porous and nanofibrous extra- cellular matrix (ECM). 2,3 It has also been suggested that the proper phenotypic cell expression may not be achieved within the cellular matrix if the scaffold’s fiber diameter is equivalent to the size of the cell or of an order of magnitude greater than the cell size. 4,5 In addition, the nanofibrous structure has a high surface-to-volume ratio (SVR), which may enhance cell attachment. Therefore, one strategy for scaffold fabrication is to construct an ECM-like nanofibrous structure. Electrospun nanofibers as a tissue-engineered scaffold Although tissue scaffolds can be manufactured using various methods, only some methods have the ability to 1 Division of Bioengineering, Faculty of Engineering, National University of Singapore, Singapore. 2 Department of Mechanical Engineering, Faculty of Engineering, National University of Singapore, Singapore. 3 Graduate Programme in Bioengineering Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore. 4 Department of Orthopedic Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore. 5 Nanoscience and Nanotechnology Initiative, National University of Singapore, Singapore. TISSUE ENGINEERING: Part B Volume 15, Number 3, 2009 ª Mary Ann Liebert, Inc. DOI: 10.1089=ten.teb.2008.0619 333