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dc.contributor.authorBray, Joshua
dc.date.accessioned2010-12-21T16:17:21Z
dc.date.available2010-12-21T16:17:21Z
dc.date.issued2010-12-21
dc.identifier.urihttp://hdl.handle.net/10222/13174
dc.description.abstractA modern approach to the treatment of localized disease involves the use of advanced polymeric or ceramic implant materials for controlled-rate drug delivery. These implants are dynamic systems that maintain drug concentrations within the optimal therapeutic window via complex hydration, swelling, and degradation processes. To optimize the performance of these materials, however, requires a fundamental understanding of the mechanisms that govern drug release. Magnetic resonance imaging (MRI) provides a means of non-invasively characterizing the microstructure and transport properties in this type of material, and has proven to be an invaluable tool for their advancement. Calcium polyphosphate (CPP) is a biomaterial that has shown promise as a degradable matrix for drug delivery and bone defect repair. Release rates are potentially governed by hydrogelation, swelling, and polymer chain scission. CPP bioceramics have previously been studied using models for drug elution, but these tend to be simplistic and unable to explain the many interrelated mechanisms. Structural analysis techniques have also been applied, but these tend to be inherently destructive and unable to characterize the material in situ. With the aim of characterizing degradation/drug release mechanisms, a non-invasive approach based on MRI was developed and optimized for imaging two existing types of CPP device. Techniques included mapping of the T1 and T2 relaxation times and the apparent diffusion coefficient (ADC), which together provide sensitivity to local fluid transport parameters. The non-destructive nature of MRI permitted longitudinal observation, and structural degradation effects were investigated by correlation with concurrent drug elution measurements. Temporal variation in the release mechanisms was treated by analyzing elution in stages. Large variation between samples was found, but on average, drug elution that was controlled by a structural-relaxation mechanism appeared correlated with the gradual formation of a highly-mobile ``free'' water component within the disk. Other characteristics, such as swelling rate, did not appear to correlate with drug release at all. While the data did not implicate a singular, governing scheme for drug release from CPP bioceramics, the approach did yield an assessment of the relative importance of the various contributing mechanisms.en_US
dc.language.isoenen_US
dc.subjectbioceramicsen_US
dc.subjectMRIen_US
dc.subjectcalcium polyphosphateen_US
dc.subjectnon-destructive characterizationen_US
dc.subjectdrug deliveryen_US
dc.titleNon-Destructive Characterization of Degradation and Drug Release Processes in Calcium Polyphosphate Bioceramics Using MRIen_US
dc.date.defence2010-12-06
dc.contributor.departmentDepartment of Physics & Atmospheric Scienceen_US
dc.contributor.degreeDoctor of Philosophyen_US
dc.contributor.external-examinerBenedict Newlingen_US
dc.contributor.graduate-coordinatorTheodore Moncheskyen_US
dc.contributor.thesis-readerChris Bowenen_US
dc.contributor.thesis-readerGerhard Stroinken_US
dc.contributor.thesis-readerMark Filiaggien_US
dc.contributor.thesis-supervisorSteven Beyeaen_US
dc.contributor.ethics-approvalNot Applicableen_US
dc.contributor.manuscriptsNot Applicableen_US
dc.contributor.copyright-releaseNot Applicableen_US
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