Porous scaffolds of gelatin-hydroxyapatite nanocomposites obtained by biomimetic approach: Characterization and antibiotic drug release

Porous scaffolds of gelatin-hydroxyapatite nanocomposites obtained by biomimetic approach: Characterization and antibiotic drug release
Published Online: 29 Jun 2005
Received: 21 June 2004; Revised: 11 October 2004; Accepted: 21 October 2004
Hae-Won Kim 1 2 *, Jonathan C. Knowles 2, Hyoun-Ee Kim 1
Journal of Biomedical Materials Research Part B: Applied Biomaterials
Wiley InterScience
1School of Materials Science and Engineering, Seoul National University, Seoul, 151-742, Korea
2Division of Biomaterials and Tissue Engineering, Eastman Dental Institute, University College London, 256 Gray's Inn Road, London WC1X 8LD, United Kingdom

email: Hae-Won Kim (hwkim@snu.ac.kr)
*Correspondence to Hae-Won Kim, School of Materials Science and Engineering, Seoul National University, Seoul, 151-742, Korea
Funded by:
Korea Health 21 R&D Project, Ministry of Health & Welfare, Republic of Korea; Grant Number: 02-PJ3-PG6-EV11-0002
Keywords
gelatin ? hydroxyapatite (HA) ? nanocomposite ? porous scaffold ? biomimetic ? drug release
Abstract
Gelatin-hydroxyapatite (HA) nanocomposite porous scaffolds were fabricated biomimetically, and their feasibility as a drug-delivery carrier for tissue-regeneration and wound-healing treatments was addressed. The composite sols were prepared by the precipitation of HA up to 30 wt % within a gelatin solution with the use of calcium and phosphate precursors, and the porous scaffold was obtained by casting the sols and further freeze drying. The obtained bodies were crosslinked with carbodiimide derivatives to retain chemical and thermal integrity. The apatite precipitates were observed to be a poorly crystallized carbonate-substituted HA. The nanocomposite scaffolds had porosities of 89-92% and exhibited a bimodal pore distribution, that is, the macropores ( 300-500 m) of the framework structure, and micropores ( 0.5-1 m) formed on the framework surface. Transmission electron microscopy (TEM) observation revealed the precipitation of highly elongated HA nanocrystals on the gelatin network. The well-developed porous structure and organized nanocomposite configurations were in marked contrast to the directly mixed gelatin-HA powder conventional composites. For drug-release tests, tetracycline, an antibiotic drug, was entrapped within the scaffold, and the drug-release profile was examined with processing parameters, such as HA amount in gelatin, crosslinking degree, and initial drug addition. The drug entrapment decreased with increasing HA amount, but increased with increasing crosslinking degree and initial drug addition. The crosslinking of the gelatin was the prerequisite to sustaining and controlling the drug releases. Compared to pure gelatin, the gelatin-HA nanocomposites had lower drug releases, because of their lower water uptake and degradation. All the nanocomposite scaffolds released drugs in proportion to the initial drug addition, suggesting their capacity to deliver drugs in a controlled manner. Based on the findings of the well-developed morphological feature and controlled drug-release profile, the gelatin-HA nanocomposite porous scaffolds are suggested to be potentially useful for hard-tissue regeneration. ? 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2005
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