Browsing Theses and Dissertations by Subject "Nanodiamond"
Now showing items 1-2 of 2
Improvement Of Biodegradable Biomaterials For Use In Orthopedic Fixation DevicesCurrent orthopedic internal fixation devices, such as pins and screws, are typically made from metals and have a long list of complications associated with them. Most notably, complications such as infection or decreased wound healing arise from revisional surgeries needed to remove the used hardware. A new class of fixation devices is being produced from biodegradable biomaterials to eliminate the need for revisional surgery by being naturally broken down in the body. While currently available polymers lack the necessary mechanical properties to match bone strength, the incorporation of small amounts of hydroxylated nanodiamonds has been proven to increase the mechanical properties of the native polymer to better resemble native bone. Additionally, modern polymers used in biodegradable fixation devices have degradation rates that are too slow to match the growth of new bone. Poly-(D, L)-lactic-co-glycolic acid (PDLG) incorporated with hydroxylated nanodiamonds has not only been proven to start out stronger, but then also helps the polymer degrade faster when compared to the pure polymer in vivo and prevents effusion of the polymer into the surrounding environment. Nanodiamond incorporation is accomplished via solid state polycondensation of PDLG to create a uniform material with increased mechanical properties, faster degradation rates, and enhanced calcification when tested in simulated body fluid.
Improving Degradable Biomaterials for Orthopedic Fixation DevicesCurrent degradable orthopedic ﬁxation devices do not typically facilitate tissue integration during healing. Proposed here is a novel combination of processing methods to enhance the tissue integration capability of degradable thermoplastics used in temporary orthopedic ﬁxation devices. The provision of open pores in devices used to aﬃx reconstructed hard tissues would allow for local cells to inﬁltrate during the healing process. Any openly porous structure is inherently weakened in comparison to its monolithic peers (i.e. decreased relative bulk modulus), such that the matrix materials must be made more resilient in keep the device from becoming friable. These processing methods aim to improve degradable surgical ﬁxation devices at multiple levels of design: both through the inclusion of porous morphology, processing changes, and additives to regain mechanical integrity. Biomimetic pores are added for cellular inﬁltration by dissolving a porogen’s interpenetrating polymer network. The addition of open pores signiﬁcantly reduces the bulk stiﬀness. More uniform phase separation has led to better pores, but the objects still need more resilience. Carbon nanomaterials are used to improve on the mechanics and surface chemistry of the polymer matrix material, composites of polylactide/nanodiamond are produced through cryogenic milling and solid state polycondensation. The addition of minute amounts of functionalized nanodiamond has remedied the brittle failure of the material, by cryogenic milling and solid state polycondensation of poly((D,L)lactide-co-glycolide) and hydroxyl functionalized detonation nanodiamonds. This composite has also demonstrated increased cytocompatability with 7F2 osteoblasts, as analyzed by cellular adhesion through ﬂuorescence microscopy and alamar blue assay.