Fabrication of Bio-composite Drug Delivery System Using Rapid Prototyping Technology

The rapid prototyping (RP) technology has advanced in various fields such as verification of design, and functional test. Recently, researchers have studied bio-materials to fabricate functional bio-RP parts. In this research, a nano composite deposition system (NCDS) was developed to fabricate three-dimensional functional parts for bio-applications. In the hybrid process, the material removal process by mechanical micro machining and/or the deposition process are combined. NCDS uses biocompatible or biodegradable polymer resin as matrix and various bioceramics to form bio-composite materials. To test drug release rate in vivo environment, two different types of drug delivery system (DDS) were fabricated using the bio-composite materials. 1) Container type DDS used poly(DL-lactide-co-glycolide acid)(50:50) and 5-fluorouracil as the drug composite while polycaprolactone(PCL) served as the container of the drug. 2) Scaffold type DDS formed porous microstructure with poly(DL-lactide-co-glycolide acid)(50:50) and 5-fluorouracil composite. The effect of geometry of the DDS on release rate of drug is under investigation. Introduction The Rapid Prototyping technology has advanced in product development cycle since 1980s. One of the new approaches in recent RP technology is application to micro parts [1, 2]. Other new fields of RP research include bio and medical applications where simulation of operation is performed using RP models, and artificial bones made by RP process are implanted into human body [3-8]. As an example, an implantable drug delivery system (DDS) was developed using micro fabrication and RP technique [9]. Such devices would permanently remain in the biological tissue if not removed surgically. Because of inherent difficulty associated with retrieving small-scale devices from tissues, it is advantageous to apply biodegradable polymers, such that the micro-devices would naturally degrade and disappear in tissues over a desired period of time. On the material issue, wide acceptability of the biodegradable system can be appreciated from the fact that biodegradability can be manipulated. Biodegradation can be enzymatic, chemical or of microbial origin or simply by hydrolysis [10]. An attractive approach for the delivery of pharmacologically active compound is the controlled and sustained release of active agents from a resorbable polymeric delivery system that is implanted next to the diseased tissue [11]. Among biodegradable polymers, polylactic acid and poly(lactic/glycolic) acid (PLGA) have been the most commonly used in sustained-release drug delivery, as they degrade by simple hydrolysis of the ester bonds into natural metabolites, glycolic and lactic acid. These polymers are therefore biocompatible, biodegradable and considered safe [12, 13]. Polycaprolactone (PCL), aliphatic Key Engineering Materials Vols. 342-343 (2007) pp 497-500 online at http://www.scientific.net © (2007) Trans Tech Publications, Switzerland Online available since 2007/Jul/15 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of the publisher: Trans Tech Publications Ltd, Switzerland, www.ttp.net. (ID: 130.203.133.33-17/04/08,19:10:03) polyester, is one of the important biodegradable polymers in medicine. Some of the applications of PCL are sutures and biocompatible medical devices [14]. In the emerging field of tissue engineering, biodegradable polymers are used for realizing polymer scaffolds to assist tissue and cell growth during formation of artificial organs [15]. In this research, a nano composite deposition system (NCDS) was developed to fabricate DDS. As a drug material, 5-fluorouracil was used to form a polymer-drug composite. Nano Composite Deposition System (NCDS) NCDS was constructed to fabricate bio-composite with various applications. Hardware system NCDS consists of two main parts (Fig. 1 (a)), one is deposition system and the other is machining system. The detailed specification of NCDS is listed in Table 1. The 3-axis stage had linear encoder at each axis, which provided 1μm resolution, and the stage was controlled by PMAC control board. Fig. 1 (b) shows the deposition needle and a magnified view of the micro endmill. Fig. 1. Hardware system of (a) nano composite deposition system(NCDS), and (b) deposition and cutting tools of NCDS. Table 1 Hardware specifications of NCDS