HYDROXYAPATITE - CHITOSAN BIOCOMPOSITES

Transcription

1 HYDROXYAPATITE - CHITOSAN BIOCOMPOSITES Maria Ratajska, K. Haberko*, Danuta Ciechańska, Antoni Niekraszewicz, Magdalena Kucharska Institute of Biopolymers and Chemical Fibres, Lodz, Poland ibwch@ibwch.lodz.pl *AGH University of Science and Technology, Kraków, Poland 1. Introduction Bone repair or regeneration is a common and complicated clinical problem in orthopedic surgery. Every year, millions of people are suffering from bone diseases arising from trauma, tumour or bone fractures and unfortunately some of them are dying due to insufficient of ideal bone substitute [1]. Metallic implants are widely used in many treatments and are fairly successful. However, they do not provide the optimum therapy due to their shortcomings such as stress shielding during post-healing, chronic inflammation caused by corrosion, and fatigue and loosening of implant [2]. As a result a second surgery is often required to remove the metallic implant. Even though authogenic bone performs better functions in terms of biocompatibility and other factors, it also needs secondary surgery to procure donor bone from the patient s own body. A desirable material for use in clinical orthopedics is a biodegradable biomimetic material that induces and promotes new bone formation by osteogenic cells at a required site. Ideally, these materials should be in form of scaffolds, which provide space for tissue development and offer temporary mechanical support [3, 4]. Potentially suitable biomaterials for use in bone tissue engineering include ceramics (e.g. hydroxyapatite (HAp)) and polymer. In presented paper as a polymer chitosan (Ch) was used. Chitosan is a biocopolymer comprising of glucosamine and N-acetyloglucosamine, obtained by deacetylation of chitin. Polish Chitin Society, Monograph XIII,

2 M. Ratajska, K. Haberko, D. Ciechańska, A. Niekraszewicz, M. Kucharska The aim of the paper was to elaborate a new, modern group of the products which could be used as an adhesive or implants in orthopedic surgery. The optimum composition and a method of production should be found. 2. Materials and methods HAp powder was extracted from the cortical part of long pig bones. Two kinds of HAp were studied: After standard technique of preparation [5], the material was heated at the temperature 450 and 700 C. The properties of the formed powders were studied using standard analytical methods: FTIR, DTA. TG, X-ray diffraction. Chemical analysis of both samples is comparable, and gives following results: Powder heated at 400 C: CaO 51.91%; P 2 O %; MgO 0.60%; Na 2 O 2.84%. Powder heated at 700 C: CaO 52.30%; P 2 O %; MgO 0.59%; Na 2 O 2.06%. Other parameters of both samples are very similar. As an example in Figure 1 an X-ray diffraction pattern of one kind of HAp is shown. The other HAp sample gives identical result. The size of crystallites counted with half breath of (002) reflex is: a = b = Å, c = Å. In Figure 2 is given SEM photo of of HAp sample heated at 700 C. In the figure can also be seen a distribution of grain size. Grain size fits mainly in the range µm. The individual grains of higher size form probably agglomera Figure 1. X-Ray diffraction pattern of the HAp calcinated at 700 C. 90

3 Hydroxyapatite - chiosan biocomposites Three kinds of initial chitosan were studied. Their properties are compared in Table 1. Above characterized chitosans were used to produce their s useful forms: - Microcrystaline chitosan [6] - Salts of chtosans - Salts of chitosans with increased ph. Chitosan was mixed with HAp in different weight proportions. As an example FTIR spectra of composites with HAp heated at 700 C are shown in Figure 3. As it can be observed both chitosan and HAp characteristic absorption bands can be observed. Their intensity is proportional to the component amount in the mixture. 3. Results and discussion HAp/chitosan composites were used to produce their useful, 3-dimencial forms. The best results were received for the compositions collected in Table 2. Figure 2. SEM micrograph of HAp 700 powder and its grain size distribution. 91

4 M. Ratajska, K. Haberko, D. Ciechańska, A. Niekraszewicz, M. Kucharska Table 1. Some properties of initial chitosan. Sample M v, kd SD, % Content of heavy metals, % Ash content, % WRV, % Chitosan 1 Vanson 01-ASSC-1604 Chitosan 2 Vanson 03- CISB Chitosan 3 Primex FG Table 2. Composition of 3-dimentional forms of HAp/MKCh. Sample MKCh properties M v, kd SD, % Composition HAp : MKCh Composit s WRV, % HAp / MKCh : HAp / MKCh : HAp / MKCh : HAp / MKCh : MKCh - refrence Figure 3. FTIR spectra of HAp/chitosan mixtures. 92

5 Hydroxyapatite - chiosan biocomposites In Figure 4. are given the chosen photos of sponges made of HAp / MKCh composites. MKCh - reference HAp/ MKCh-12 (25:75) HAp/ MKCh-14 (75:25) Figure 4. HAp/ MKCh sponges. The compositions HAp/ MKCh form well shaped 3-dimensional structures which can be used in future as a base for scaffolds production. Crystals of HAp form aggregates well seen in cross section of sponges. Similar 3-dimentional structures can be formed using chitosan lactate instead of MKCh as a component of the mixture. Photos of such structures are given in Figure 5. HAp400/ML 1/0.5 HAp 400/ML 1/1 HAp 400/ML 2/1 HAp700/ML 1/0.5 HAp 700/ML 1/1 HAp 700/ML 2/1 Figure 5. HAp/chitosan lactate sponges. 93

6 4. Conclusions M. Ratajska, K. Haberko, D. Ciechańska, A. Niekraszewicz, M. Kucharska 1. Both samples of HAp form with chitosan and it s useful forms (MKCh, chitosan lactate) well shaped 3-dimentional forms sponges. 2. The sponges can be used as implants in orthopedic surgery 3. 3-dimentional structures of HAp/chitosan composites are a good base for scaffolds productin. 5. Acknowledgment The studies realized within the research project No 3 T98E , supported by the Ministry of Science and Higher Education 6. References 1. Murugan R., Ramakrishna S.: Bioresorbable composite bone paste using polysaccharide based nano hydroxiapatite. Biomaterials 25 (2004) pp Qiaoling Hu and others: Preparation and characterization of biodegradable chitosan/ hydroxyapatite nanocomposite rods via in situ hybridization: a potential material as internal fixation of bone fracture. Biomaterials 25 (2004) pp Feng Zhao and others: Preparation and histological evaluation of biomimetic three-dimensional hydroxyapatite/chitosan-gelation network composite scaffolds. Biomaterials 23 (2002) pp Marciniak J.: Biomateriały, Wydawnictwo. Politechniki Śląskiej, Gliwice Haberko K. and others: Natural hydroxyapatite its behaviour during heat treatment. Journal of the European Ceramic Sociaty 26 (2006) pp Struszczyk H.: Progress on the Modification of Chitosan, Advances of Chitin Science vol. II Lyon, France, 1996 pp