Characterizing Microporous PCL Matrices for Application of Tissue ...

92

Journal of Medical and Biological Engineering, 29(2): 92-97

Characterizing Microporous PCL Matrices for Application of Tissue Engineering Chih-Chang Yeh1

Yun-Ting Li2 Yiwei Wang3

2

Pei Hsiu Chiang2

Chun-Hao Huang2

Hsin-I Chang2,*

1 Department of Orthopedics, Chia-Yi Veterans Hospital, Chiayi 600, Taiwan, ROC Department of Biochemical Science and Technology, National Chia Yi University, Chiayi 600, Taiwan, ROC 3 School of Pharmacy, The University of Queensland, Brisbane QLD 4072, Australia

Received 7 Oct 2008; Accepted 6 Apr 2009

Abstract Polycaprolactone (PCL) is a semicrystalline polymer and has been fabricated into various forms such as membranes, films, matrices, fibers, micro/nano particles, capsules and reservoir devices for drug delivery and tissue engineering due to its good biocompatibility. In this study, microporous PCL matrices (MPM) with 10–20 μm pores on the surface were produced using various PCL molecular weight from 40,000 to 80,000 by precipitation casting method. The tensile strength of MPM prepared using 12.5% w/v polymer solution tended to increase from 0.83 Mpa to 1.42 Mpa and the elongation rate was improved from 35.2% to 117.8% when increasing PCL molecular weight. In addition, there was also a significant increase in compression and bending strength. MPM exhibited high porosity up to 72.4%, and the porosity of MPM reduced with rising of PCL solution concentration and molecular weight. The crystallinity of MPM prepared using 12.5% CAPA6400 polymer solution was measured at approximately 67%, while molecular weight showed a minor effect on the crystallinity of MPM. In cytocompatibility studies, MPM prepared using CAPA 6500 and 6800 showed higher cell attachment than CAPA 6400. Three-point bending test also showed that MPM prepared with low molecular weight (CAPA 6400) had a higher fragility for easy breakdown of tissue scaffold. Therefore, MPM prepared using CAPA 6500 (or CAPA 6800) may be more suitable tissue scaffold for biomedical application. Herein, we report that processing parameters such as polymer solution concentrations and molecular weight could modify the porosity and stiffness of MPM and then influence cell/biomaterial interaction. Keywords: Polycaprolactone, Tissue engineering, Cytocompatibility, Fibroblast

1. Introduction Generally, tissue engineering strategies utilize combination of cells, biodegradable scaffolds, and bioactive molecules to develop the process of tissue regeneration. A rational design of biomaterials is required to meet particular biological and chemical requirements, e.g. biocompatibility, degradability, mediation of cell adhesion, etc. Characteristics of the microstructure and architecture of a biomaterial such as porosity, pore size and surface physiochemical properties are well known to stimulate cell attachment, alignment and proliferation. Therefore, porous, biodegradable materials are important for guided tissue repair or for support of seeded cells prior to implantation. Polycaprolactone (PCL) is a semicrystalline biodegradable * Corresponding author: Hsin-I Chang Tel: +886-5-2717923; Fax: +886-5-2717780 E-mail: [email protected]

polymer, with a melting point (Tm) in the range of 59–64°C and Tg of -60°C [1]. Due to its good biocompatibility, PCL has been fabricated into a variety of forms such as membranes, films, matrices, fibers, micro/nano particles, capsules and reservoir devices for drug delivery and tissue engineering. PCL films, disks and membranes are produced by melt processing or solvent casting of polymer solution or suspension (with drugs) followed by compression-molding at a certain temperature (100–130°C) [2-5]. PCL film provides a good surface chemistry for attachment of cells such as human dermal fibroblasts and myoblasts [4]. PCL matrices and PCL/hydroxyapatite (HA) composites prepared by solvent casting were reported to support osteoblast growth for bone repair [6]. In addition, PCL/HA composite scaffolds have also been studied for growth of rabbit bone marrow stromal cells over 8 weeks [7]. PCL/collagen biocomposite films produced by impregnation of freeze-dried, microporous collagen mats with PCL solution appears to be a favorable substitute for attachment of human osteoblasts and growth of mouse fibroblasts and human keratinocytes for skin repair [8-10].



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