Thesis (Ph. D.)--Drexel University, 2006. / Includes abstract and vita. Includes bibliographical references.

Thesis (Ph. D.)--School of Pharmacy. University of Missouri--Kansas City, 2005. / "A dissertation in pharmaceutical sciences and pharmacology." Advisor: Ashim K. Mitra. Typescript. Vita. Title from "catalog record" of the print edition Description based on contents viewed June 26, 2006. Includes bibliographical references (leaves 174-192). Online version of the print edition.

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: Nicholas A. Peppas. Vita. Includes bibliographical references. Also available from UMI.

Thesis (Ph.D. in Pharmaceutical Sciences) -- University of Colorado at Denver and Health Sciences Center, 2005. / Typescript. Includes bibliographical references (leaves 86-92). Free to UCDHSC affiliates. Online version available via ProQuest Digital Dissertations;

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

<p>Osteoarthritis (OA) is a degenerative disease of articular joints characterized by progressive deterioration of the cartilage lining, subchondral bone destruction and thickening of the joint capsule. These tissue changes lead to symptomatic joint pain and joint dysfunction, leading to restrictions on daily life activities. Intra-articular injections of corticosteroids or anti-inflammatory compounds are commonly given to relieve symptoms associated with OA; however, rapid clearance of these compounds from the joint space and into draining synovial lymphatics necessitates the use of drug carriers to increase drug residence and efficacy. </p><p>Silk fibroin, a protein polymer from the mulberry silkworm (Bombyx mori) and of slow biodegradation in vivo, has a long history of clinical use. Silk fibroin can be fabricated into nano- and micro-particles capable of entrapping small-molecule drugs to provide for sustained release. For this work, silk microparticles were fabricated entrapping the near-infrared fluorescent dye, Cy7, as a model small-molecule drug. The release kinetics of the Cy7 from the silk microparticles were characterized in vitro and fluorescence in vivo imaging was used to study the clearance of silk microparticles following intra-articular injection in healthy rat knee joints.</p><p>Furthermore, a surgically-induced model of OA was used in rat knee joints to study the effect of OA pathology on intra-articular clearance. Fluorescently-labeled dextrans of varying size (10 and 500 kDa molecular weight) were intra-articularly injected in the knee joints of healthy and OA rats, and fluorescence in vivo imaging was employed to detect changes in the intra-articular clearance. Additionally, a new method to characterize the trans-synovial clearance of the fluorescent dextrans was developed using the confocal microscopy of joint tissue sections from healthy and OA joints.</p> / Dissertation

Since its isolation in 2004, the research landscape around graphene and other 2D materials has expanded rapidly and now encompasses fields as diverse as electronic engineering and drug delivery. For biomedical applications, one of the most desirable properties of the graphene family of nanomaterials (GFNs) is their 2D geometry; the high surface area to volume ratio that is characteristic of nanomaterials is taken to its extreme in a material that can be viewed as being entirely surface. This particular property alongside the versatility with which they may be functionalised both makes GFNs well positioned to function as the foundation of highly tailored and multifunctional therapeutics platforms. In this project, two GFN types, namely pristine graphene and graphene oxide, were prepared to form suspensions suitable for application to therapeutics delivery. Firstly, experiments using four essential amino acids with pristine graphitic material were undertaken to assess whether graphene flakes could be suitably exfoliated and suspended using sonication in the presence of aqueous solutions of these biocompatible molecules. A positive correlation was found between the hydrophobicity of the amino acid and the presence of one or more aromatic rings in the amino acid, and the efficacy of exfoliation both in terms of concentration achieved in suspension and flake thinness. However, the system itself was found to be highly complex, both with regards to the sonication used to exfoliate the graphitic flakes, and the interactions between the amino acids and the flakes. These considerations limited the wider applicability of this form of graphene preparation for therapeutics delivery applications. Secondly, work was performed on graphene oxide (GO), a GFN far more studied in the literature, but notoriously heterogeneous. Therefore much of the work completed focused on its characterisation. A combination of established and novel fluorescence-based characterisation methods were used to fully characterise three preparations of GO, before preliminary experiments were undertaken to test their interactions with cell components. The work showed that the inherent fluorescence of GO can be exploited to improve suspension characterisation; raster image correlation spectroscopy (RICS) was used to measure the apparent hydrodynamic radii of the flakes and flow cytometry was used to provide insight into the interactions between GO flakes and serum components. Preliminary cellular experiments confirmed that flow cytometry could be also employed to assess particular graphene characteristics in the context of cell culture, demonstrating the relatively low toxicity of PEGylated GO compared to unfunctionalised GO. Finally, as the therapeutics target for this project was leukaemia, a targeting ligand was designed and synthesised that could bind to CXCR4 - a receptor that is overexpressed on CLL B-cells, as well as many other cancer types. The ligand was synthesised such that it could easily be attached to GO, however its molecular structure is flexible enough that it can be attached to a number of different therapeutics materials. It was confirmed using both competition and functional assays that the molecule was antagonistic, and was able to deliver a conjugated fluorescent molecule specifically to the CXCR4 receptors on primary CLL B-cells. The work presented in this thesis illustrates the complexity that affects the use of GFNs in biomedicine, but also confirms the potential for their future development. The field is still young, and therapeutics delivery is likely to benefit from advances in the preparation of pristine graphene, and from methods to minimise the heterogeneity of GO. These steps will support a route towards clinical application. In addition, as the field of 2D materials expands, other materials with enviable surface area to volume ratios may come to the fore. Furthermore, this thesis has shown the value of exploring novel approaches to the characterisation of GFNs, and has identified approaches that may be exploited to improve applications of GFNs in biomedicine. Additionally, the aim of using GFNs as a platform for a multifunctional therapeutics delivery vehicle was developed with regards to the attractive CXCL12/CXCR4 axis, which is relevant in a large number of disease states including over 20 cancers, by demonstrating a flexible targeting ligand that could be used to exploit the CXCR4 receptor as a drug delivery target.

No description available.

Drugs can be made up of nucleic acids, sugars, small organic and inorganic compounds, peptides, and large macromolecules. Drug therapy can be optimized by controlled delivery systems that release an appropriate dose to the site of action, extend the duration of delivery, reduce administration sessions, and can target a precise site of activity. An advanced method of controlled drug delivery is through injectable polymeric biomaterial microparticles that entrap drugs within their matrix for slow release (1-6 months). Surface morphology of polymer microparticles is known to affect drug release; however, it is often reported in qualitative terms only. In this thesis, a mastery over the controlled fabrication of biodegradable poly (ε-caprolactone) (PCL) microspheres is shown, as well as their characterization using different imaging conditions/techniques of the scanning electron microscope (SEM). Retinoic acid (RA), a morphogenic molecule, is encapsulated to create RA/PCL microspheres that are used to successfully deliver drug to human induced pluripotent stem cell aggregates. Furthermore, this works reports the creation of variable surface morphology PCL microspheres and their characterization via size analysis and stereo-microscopy. A rough morphology candidate is identified and selected for 3D SEM surface model reconstruction via a computer vision technique. Surface studies via SEM have a lot of potential to advance the development of these particles. The 3D model first reported here serves as foundation for quantitative surface morphology measurements. / Graduate

Doctor of Philosophy / Department of Chemistry / Stefan H. Bossmann / The therapeutic peptide sequence D-K₆L₉: LKLLKKLLKKLLKLL-NH₂ was developed for treating bacterial infections and solid tumors. It is effective against both conditions, because it is capable of targeting negatively charged surface domains due to its positive charge and the presence of hydrophobic units. Here, the peptide was modified with two extra amino acids (Serine and Alanine) at both, C and N terminals, resulting in SA-D-K₆L₉-AS. The sequence and structure of the modified peptide were determined by means of 2D ¹H-¹H -COSY, NOESY, and TOCSY-NMR spectroscopy. The 3D structure of the peptide in the solution phase was generated by CNS software utilizing data generated by NOE spectroscopy. This peptide was tested on the following mouse cancer cell lines: GL 26 (glioma), 4T1 (metastasizing breast cancer), NSC (neural stem cells), and pig monocytes. The LC50 values of the modified peptide were found to be 5- 10 times more active than of the original D-K₆L₉. To gain insight into its biochemical mode of action, SA-D-K₆L₉-AS tagged with a Rhodamine dye was incubated with GL 26 cancer cells. Sequential confocal imaging (every 30 seconds) revealed that the peptide interacts with cell membranes according to the carpet mechanism, and then becomes internalized into the cytoplasm in less than 5 min. and localizes in the mitochondria. This peptide is found to be toxic to neuronal stem cells and monocytes as well, showing the same mechanisms of interaction. To avoid the non-specific toxicity of the peptide for in-vivo applications, highly mesoporous silica nanoparticles (MSN) were synthesized, which served as a “container” for drug delivery. The peptide was then loaded into the MSN. MSN were further coated with a polysilazane as “gift wrap” (gatekeeper) after loading the peptide. This gatekeeper forms a shell that contains the peptide inside the MSN. While inside the MSN, the peptide shows no toxicity at 24 hours and subsequent slow release of its payload into the cytoplasm within 72 hours. This technology could be very useful for in-vivo cancer therapy by means of targeted delivery to the cancer site with appropriate surface modification of MSNs.