Browsing by Author "Milthorpe, Bruce"

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    Development and dissolution studies of bisphosphonate (clodronate)-containing hydroxyapatite–polylactic acid biocomposites for slow drug delivery
    (2015-07-15) Macha, Innocent J; Cazalbou, Sophie; Shimmon, Ronald; Ben-Nissan, Besim; Milthorpe, Bruce
    An increase in clinical demand on the controlled release of bisphosphonates (BPs) due to complications associated with systemic administration, has been the current driving force on the development of BP drug-release systems. Bisphosphonates have the ability to bind to divalent metal ions, such as Ca2+, in bone mineral and prevent bone resorption by influencing the apoptosis of osteoclasts. Localized delivery using biodegradable materials, such as polylactic acid (PLA) and hydroxyapatite (HAp), which are ideal in this approach, have been used in this study to investigate the dissolution of clodronate (non-nitrogen-containing bisphosphonate) in a new release system. The effects of coral structure-derived HAp and the release kinetics of the composites were evaluated. The release kinetics of clodronate from PLA–BP and PLA–HAp–BP systems seemed to follow the power law model described by Korsmeyer–Peppas. Drug release was quantified by 31P-NMR with detection and quantification limits of 9.2 and 30.7 mM, respectively. The results suggest that these biocomposite systems could be tuned to release clodronate for both relatively short and prolonged period of time. In addition to drug delivery, the degradation of HAp supplies both Ca2+ and phosphate ions that can help in bone mineralization.
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    Improvement of Elongation in Nanosurface Modified Bioglass/PLA Thin Film Composites
    (Bentham Science, 2014-01) Macha, Innocent J; Ben-Nissan, Besim; Milthorpe, Bruce
    One of the major challenges in the development of biomaterials is the adaptation of the complex elastic nature and elongation of human tissues during biomechanical functional loading. Composite materials present the most appropriate means of attempting to match the mechanical and biocompatibility requirements. Composite films from polylactic acid (PLA) and sol-gel derived bioglass (BG) powders with particle size ranging from 50-100 nm were produced by solution casting method. Three different bioglass mixtures of 0.1, 0.5 and 1% bioglass were prepared. Physico-chemical and morphological properties of bioglass, pure PLA and PLA composites were investigated using XRD, SEM and FTIR. Bioglass particles were further treated by nanolayer coating of 3-aminopropyltriethoxysilane (APTES) to improve its mechanical properties. The effects of surface treated bioglass on the fracture of the PLA/bioglass composites were investigated under tensile loading conditions. The results suggest by nano-surface treating the bioglass with 1% APTES significantly influences the percentage elongation of the PLA/bioglass composite at fracture. SEM shows more agglomeration of untreated bioglass within the composite. In the treated samples, a better distribution of nanosized bioglass within PLA matrix was observed. Nanolayer modified bioglass /PLA thin film composites may have a wide range of biomedical applications in tissue engineering with improved elastic properties.
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    Multifunctional-Dual Drug Delivery Poly-Lactic Acid Biocomposite Coating with Hydroxyapatite for Bone Implants
    (Trans Tech Publications Inc, 2018-10) Karacan, Ipek; Chou, Joshua; Macha, Innocent J; Cazalbou, Sophie; Milthorpe, Bruce
    The new novel implant designs include the functionality of advanced drug delivery systems in order to improve osteointegration and to inhibit the implant-related post-operative infections. In this research, Ti6Al4V metallic implants were coated with the multifunctional-dual slow drug delivery coating which includes a polymeric matrix system based on a poly-lactic acid thin film and a bioactive ceramic hydroxyapatite. This system consists of two different kinds of pharmaceuticals, which are gentamicin and simvastatin. It is reported in this paper that the simvastatin and gentamicin containing poly-lactic acid coating which was applied uniformly and successfully with and without hydroxyapatite microspheres. Most importantly, the release rate of drugs was controlled with PLA matrix and HAp microspheres which have different dissolution rates in order to prevent the high dosages causing adverse side-effects of drugs.