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Description
Cerebral aneurysms, also known as intracranial aneurysms, are sac-like lesions in the arteries of the brain that can rupture to cause subarachnoid hemorrhaging, damaging and killing brain cells. Metal coil embolization has been traditionally used to occlude and treat cerebral aneurysms to limited success, but polymer embolization has been suggested,

Cerebral aneurysms, also known as intracranial aneurysms, are sac-like lesions in the arteries of the brain that can rupture to cause subarachnoid hemorrhaging, damaging and killing brain cells. Metal coil embolization has been traditionally used to occlude and treat cerebral aneurysms to limited success, but polymer embolization has been suggested, because it can provide a greater fraction of occlusion. One such polymer with low cytotoxicity is poly(propylene glycol)diacrylate (PPODA) crosslinked via Michael-type addition with pentaerythritol tetrakis(3-mercaptopropionate) (QT). This study was performed to examine the behavior of PPODA-QT gel in vitro under pulsatile flow emulating physiological conditions. An idealized cerebral aneurysm flow model was designed based on geometries associated with an increase in rupture risk. Pressure was monitored at the apex of the aneurysm dome for varied flow rates and polymer filling fractions of 32.4, 78.2, and 100%. The results indicate that the amount of PPODA-QT deployed into the aneurysm decreases the peak-to-peak oscillation in pressure at the aneurysm wall by an inverse proportion. The 32.4 and 78.2% treatments did not significantly decrease the mean pressure applied to the aneurysm dome, but the 100% treatment greatly reduced it by diverting flow. This study indicates that the maximum filling fraction after swelling of PPODA-QT polymer should be deployed into the aneurysmal sac for treatment.
ContributorsWorkman, Christopher David (Author) / Vernon, Brent (Thesis director) / Frakes, David (Committee member) / Barrett, The Honors College (Contributor) / Department of Chemistry and Biochemistry (Contributor) / Harrington Bioengineering Program (Contributor)
Created2014-05
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Description
Rupture of intracranial aneurysms causes a subarachnoid hemorrhage, which is often lethal health event. A minimally invasive method of solving this problem may involve a material, which can be administered as a liquid and then becomes a strong solid within minutes preventing flow of blood in the aneurysm. Here we

Rupture of intracranial aneurysms causes a subarachnoid hemorrhage, which is often lethal health event. A minimally invasive method of solving this problem may involve a material, which can be administered as a liquid and then becomes a strong solid within minutes preventing flow of blood in the aneurysm. Here we report on the development of temperature responsive copolymers, which are deliverable through a microcatheter at body temperature and then rapidly cure to form a highly elastic hydrogel. To our knowledge, this is the first physical-and chemical-crosslinked hydrogel capable of rapid crosslinking at temperatures above the gel transition temperature. The polymer system, poly(N-isopropylacrylamide-co-cysteamine-co-Jeffamine® M-1000 acrylamide) and poly(ethylene glycol) diacrylate, was evaluated in wide-neck aneurysm flow models to evaluate the stability of the hydrogels. Investigation of this polymer system indicates that the Jeffamine® M-1000 causes the gels to retain water, resulting in gels that are initially weak and viscous, but become stronger and more elastic after chemical crosslinking.
ContributorsLee, Elizabeth Jean (Author) / Vernon, Brent (Thesis director) / Brennecka, Celeste (Committee member) / Overstreet, Derek (Committee member) / Barrett, The Honors College (Contributor) / School of Mathematical and Statistical Sciences (Contributor)
Created2013-05
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Description

Polymer drug delivery system offers a key to a glaring issue in modern administration routes of drugs and biologics. Poly(lactic-co-glycolic acid) (PLGA) can be used to encapsulate drugs and biologics and deliver them into the patient, which allows high local concentration (compared to current treatment methods), protection of the cargo

Polymer drug delivery system offers a key to a glaring issue in modern administration routes of drugs and biologics. Poly(lactic-co-glycolic acid) (PLGA) can be used to encapsulate drugs and biologics and deliver them into the patient, which allows high local concentration (compared to current treatment methods), protection of the cargo from the bodily environment, and reduction in systemic side effects. This experiment used a single emulsion technique to encapsulate L-tyrosine in PLGA microparticles and UV spectrophotometry to analyze the drug release over a period of one week. The release assay found that for the tested samples, the released amount is distinct initially, but is about the same after 4 days, and they generally follow the same normalized percent released pattern. The experiment could continue with testing more samples, test the same samples for a longer duration, and look into higher w/w concentrations such as 20% or 50%.

ContributorsSeo, Jinpyo (Author) / Vernon, Brent (Thesis director) / Pal, Amrita (Committee member) / Dean, W.P. Carey School of Business (Contributor) / Harrington Bioengineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
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Description
In an embolization therapy, a material is injected into a vessel to block blood flow. While this therapy is useful in starving cancerous cells it can be dangerous, with some blockades in the brain dislodging and causing strokes or blindness. Currently, embolic materials on the market such as metal coils,

In an embolization therapy, a material is injected into a vessel to block blood flow. While this therapy is useful in starving cancerous cells it can be dangerous, with some blockades in the brain dislodging and causing strokes or blindness. Currently, embolic materials on the market such as metal coils, balloons, and liquid embolic agents do not have a quick removal procedure. An ultrasound cleavable material could be removed in an emergency situation without invasive surgery. The primary goal of this research is to design and synthesize a polymer that can be broken down by high intensity focused ultrasound (HIFU). Initially, we have tested the ultrasound sensitive qualities on PPODA-QT hydrogel, a common embolic agent, but the gel showed no physical change after HIFU exposure. It is theorized that PNIPAAm combined with HIFU sensitive monomers can develop a temperature and ultrasound sensitive embolic agent. In our studies, poly(NIPAAm-co-tBa) had a slight lower critical solution temperature (LCST) change of about 2˚C from before to after HIFU while the study with poly(NIPAAm-co-ACL-BME) and PPODA-QT showed no change in LCST.
ContributorsLein, Karolena (Author) / Vernon, Brent (Thesis director) / Pal, Amrita (Committee member) / Harrington Bioengineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2020-05