In vitro characterization of bioresorbable polymers and composites for drug delivery and bone replacement

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en
dc.contributor.author Rich, Jaana
dc.date.accessioned 2012-02-10T09:33:14Z
dc.date.available 2012-02-10T09:33:14Z
dc.date.issued 2002-09-26
dc.identifier.isbn 951-22-6083-2
dc.identifier.issn 1239-0518
dc.identifier.uri https://aaltodoc.aalto.fi/handle/123456789/2218
dc.description.abstract A biodegradable device for controlled release of toremifene citrate was studied based upon ε-caprolactone and DL-lactide copolymers (P(CL/DL-LA)) and silica xerogel. The effect of copolymer composition, molecular weight of a copolymer, and drug loading on the release rate of toremifene citrate were investigated and thus it was possible to adjust the release period from 3 months to 1 year. The applicability of the P(CL/DL-LA) copolymers for matrix type controlled release devices was further studied by characterizing the interactions between copolymers and model compounds, theophylline, propranolol hydrochloride and lidocaine by differential scanning calorimetry (DSC) and molecular modelling. The hydrophilicity of the copolymers as well as the level of average molecular weight was modified using different co-initiators i.e. glycerol and polyethylene glycols. Hydrolytic degradation of the copolymers was recorded and the comparison between degradation and release profiles was obtained. The results clearly demonstrated that the desired release rates of these model compounds could be tailored by varying the compound loading, by modifying the hydrophilicity of the matrix copolymer from matrices with low lactide content and by choosing the appropriate comonomer ratio between ε-caprolactone and DL-lactide. Two different composite materials for bone replacement were studied and their properties evaluated in vitro. The first material combined the P(CL/DL-LA) copolymer with bioactive glass S53P4 and the second was a composite consisting of amorphous lactic acid based poly(ester-urethane) (PEU-BDI) with hydroxyapatite (HA) or biphasic calcium phosphate (BCP). The formation of a biologically active Ca-P layer on the surfaces of the composites in hydrolysis indicates in vitro bioactivity and it was found to be dependent on the weight fraction and granule size range of the bioactive glass used. PEU-BDI and its composites with 20 and 40 vol.% bioceramic filler, were characterized prior to their use as biocompatible and bioabsorbable artificial bone materials. The rigidity of the materials was increased with fillers, due to good compatibility with the matrix. Processing by melt blending and sterilization by gamma-irradiation caused some chemical degradation, i.e. loss of molecular weight, but did not affect dynamic mechanical properties. The storage modulus values of all the composite materials remained within ranges that were mechanically compatible with bone over the whole five weeks of hydrolysis. The correlation of in vitro and in vivo bioactivity of the composites needs to be established, but based on the in vitro evaluation, the glass composites have the potential for a variety of applications as implant materials in orthopaedics and dentistry and the PEU-BDI composites have potential for application as fracture fixation materials. en
dc.format.extent 47, [61]
dc.format.mimetype application/pdf
dc.language.iso en en
dc.publisher Helsinki University of Technology en
dc.publisher Teknillinen korkeakoulu fi
dc.relation.ispartofseries Acta polytechnica Scandinavica. Ch, Chemical technology series en
dc.relation.ispartofseries 289 en
dc.relation.haspart Ahola, M., Rich, J., Kortesuo, P., Kiesvaara, J., Seppälä, J., and Yli-Urpo, A., In vitro evaluation of biodegradable poly(ε-caprolactone-co-DL-lactide)/silica xerogel composites containing toremifene citrate, Int. J. Pharm. 181 (1999) 181-191.
dc.relation.haspart Rich, J., Kortesuo, P., Ahola, M., Yli-Urpo, Kiesvaara, J., and Seppälä, J., Effect of the molecular weight of poly(ε-caprolactone-co-DL-lactide) on toremifene citrate release from copolymer/silica xerogel composites, Int. J. Pharm. 212 (2001) 121-130.
dc.relation.haspart Karjalainen, T., Rich, J., and Seppälä, J., Release of model compounds from modified lactone copolymers, J. Appl. Polym. Sci. 81 (2001) 2118-2126.
dc.relation.haspart Rich, J., Karjalainen, T., Ahjopalo, L., and Seppälä, J., Model compound release from DL-lactide/ε-caprolactone copolymers and evaluation of specific interactions by molecular modelling, accepted in J. Appl. Polym. Sci. 86 (2002) 1-9.
dc.relation.haspart Rich, J., Jaakkola, T., Tirri, T., Närhi, T., Yli-Urpo, A., and Seppälä, J., In vitro evaluation of poly(ε-caprolactone-co-DL-lactide)/bioactive glass composites, Biomaterials 23 (2002) 2143-2150.
dc.relation.haspart Rich, J., Tuominen, J., Kylmä, J., Seppälä, J., Nazhat, S., and Tanner, K.E., Lactic acid based PEU/HA and PEU/BCP composites: dynamic mechanical characterization of hydrolysis, J. Biomed. Mat. Res. Appl. Biomater. 63 (2002) 346-353.
dc.subject.other Chemistry en
dc.subject.other Medical sciences en
dc.title In vitro characterization of bioresorbable polymers and composites for drug delivery and bone replacement en
dc.type G5 Artikkeliväitöskirja fi
dc.description.version reviewed en
dc.contributor.department Department of Chemical Technology en
dc.contributor.department Kemian tekniikan osasto fi
dc.subject.keyword bioresorbable polymers en
dc.subject.keyword ε-caprolactone en
dc.subject.keyword lactic acid en
dc.subject.keyword lactide en
dc.subject.keyword copolymer en
dc.subject.keyword poly(ester-urethane) en
dc.subject.keyword drug release en
dc.subject.keyword bioactive composite en
dc.subject.keyword hydrolysis en
dc.identifier.urn urn:nbn:fi:tkk-001884
dc.type.dcmitype text en
dc.type.ontasot Väitöskirja (artikkeli) fi
dc.type.ontasot Doctoral dissertation (article-based) en
dc.contributor.lab Laboratory of Polymer Technology en
dc.contributor.lab Polymeeriteknologian laboratorio fi


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