Fischell Department of Bioengineering
Permanent URI for this communityhttp://hdl.handle.net/1903/6626
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Item Polymeric Materials for Hemostatic and Surgical Sealant Applications(2015) Behrens, Adam Michael; Kofinas, Peter; Bioengineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Commercial hemostatic agents and surgical sealants do not meet the current clinical need. The available options suffer from a variety of shortcomings including high costs, short shelf lives, difficult preparations, and concerns over safety. This work aims to utilize synthetic polymers to develop alternative approaches that have the potential to improve outcomes from traumatic injuries and surgeries while minimizing risk and cost. The first aspect of this research focuses on the development of hemostatic hydrogel particles. These spherical hydrogels with a narrow size distribution were synthesized via inverse suspension polymerization. A cationic monomer was utilized in the hydrogel formulation to facilitate rapid swelling, leading to the formation a physical barrier to blood loss. Coagulation studies demonstrated the ability to cause localized aggregation through charge interactions with erythrocytes while reducing clotting activity in the bulk. This mechanism allows the hydrogel to quickly block blood flow and may mitigate thrombotic complications at distal sites. Hemostatic efficacy was exhibited by decreases in both the time to hemostasis and mass of blood loss in rat liver puncture and tail amputation injury models when compared to compression with gauze alone. The second aspect of this research focuses on the development of a synthetic surgical sealant. This work is centered on the investigation of a polymer fiber mat deposition method called solution blow spinning. This fabrication technique allows for the rapid in situ generation of polymer fibers, offering the ability to conformally deposit polymeric materials directly on the surgical site of interest. Solution blow spinning was utilized to deposit a body temperature responsive, biodegradable polymer blend. Above a critical temperature, the two phase fibrous polymer mat transitioned into a one phase polymer film. This transition resulted in plasticization and promoted polymer-substrate interaction, leading to increased adhesion. Sealant efficacy was demonstrated in a cecal intestinal anastomosis mouse model, where the polymer blend was used to supplement sutures. Both burst pressure and survival rate were significantly improved over the suture-only control.Item OPTICAL COHERENCE TOMOGRAPHY FOR NEUROSURGEY AND CANCER RESEARCH(2014) Liang, Chia-Pin; Chen, Yu; Bioengineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Optical Coherence Tomography (OCT) provides non-labeling, real-time and high resolution images, which has the potential to transform the paradigm of surgical guidance and preclinical animal studies. The design and development of OCT devices for neurosurgery guidance and novel imaging algorithms for monitoring anti-cancer therapy have been pursued in this work. A forward-imaging needle-type OCT probe was developed which can fit into minimally invasive tools (I.D. ~ 1mm), detect the at-risk blood vessels, and identify tissue micro-landmarks. This promising guidance tool improves the safety and the accuracy of needle-based procedures, which are currently performed without imaging feedback. Despite the great imaging capability, OCT is limited by the shallow imaging depth (1-2 mm). In order to address this issue, the first MRI compatible OCT system has been developed. The multi-scale and multi-contrast MRI/OCT imaging combination significantly improves the accuracy of intra-operative MRI by two orders (from 1mm to 0.01 mm). In contrast to imaging systems, a thin (0.125 mm), low-cost (1/10 cost of OCT system) and simple fiber sensor technology called coherence gated Doppler (CGD) was developed which can be integrated with many surgical tools and aid in the avoidance of intracranial hemorrhage. Furthermore, intra-vital OCT is a powerful tool to study the mechanism of anti-cancer therapy. Photo-immunotherapy (PIT) is a low-side-effect cancer therapy based on an armed antibody conjugate that induces highly selective cancer cell necrosis after exposure to near infrared light both in vitro and in vivo. With novel algorithms that remove the bulk motion and track the vessel lumen automatically, OCT reveals dramatic hemodynamic changes during PIT and helps to elucidate the mechanisms behind the PIT treatment. The transformative guidance tools and the novel image processing algorithms pave a new avenue to better clinical outcomes and preclinical animal studies.