Currently, biopharmaceuticals including vaccines, proteins, and DNA are delivered almost exclusively through the parenteral route using hypodermic needles. However, injection by hypodermic needles generates pain and causes bleeding. Disposal of these needles also produces biohazardous sharp waste. An alternative delivery tool called microneedles may solve these issues. Microneedles are micron-size needles that deliver drugs or biopharmaceuticals into skin by creating tiny channels in the skin. This thesis focuses on dissolving microneedles in which the needle tips dissolve and release the encapsulated drug or vaccine upon insertion. The project aimed to (i) design and optimize dissolving microneedles for efficient drug and vaccine delivery to the skin, (ii) maintain vaccine stability over long-term storage, and (iii) immunize animals using vaccine encapsulated microneedles. The results showed that influenza vaccine encapsulated in microneedles was more thermally stable than unprocessed vaccine solution over prolonged periods of storage time. In addition, mice immunized with microneedles containing influenza vaccine offered full protection against lethal influenza virus infection. As a result, we envision the newly developed dissolving microneedle system can be a safe, patient compliant, easy to-use and self-administered method for rapid drug and vaccine delivery to the skin.

We used megahertz pulsed ultrasound and studied gene transfection with a human prostate cancer cell line. We first studied the compromise of cell viability and uptake efficiency and found out that increasing sonication temperature or changing US contrast agents could improve drug/gene delivery mediated by US exposure. We also found that accounting for cell debris after sonication was important to correctly determine cell viability. Next, we verified the capability of US to deliver DNA into the cell nuclei, which is necessary for successful gene transfection. Under the optimal sonication conditions, ~ 30% of cells showed DNA uptake right after US exposure and most had a portion of DNA already localized in the cell nuclei. The maximum transfection efficiency was ~ 12% at 8 h post US exposure. From the DNA perspective, ~ 30% of DNA was localized in the cell nuclei immediately after US exposure and ~ 30% was in the autophagosomes/ autophagolysosomes with the rest ¡°free¡± in the cytoplasm. At later time up to 24 h, DNA continued to be distributed ~ 30% in the nuclei and most or all of the rest in autophagosomes/autophagolysosomes. Our results showed that US was able to deliver DNA into the cell nuclei shortly after the treatment and that the rest of DNA was mostly cleared by autophagosomes/autophagolysosomes. To further increase transfection efficiency, we then studied the differences between live cells with DNA uptake and those with successful gene transfection post US exposure using cell sorting, cell cycle and microarray analysis. Cells with gene transfection were found to accumulate at the G1 phase of cell cycle and associate with the up-regulation of 32 genes (e.g., GADD45¦Á) and the down-regulation of 46 genes (e.g., TOP2¦Á). Drugs that regulate the expression levels of GADD45¦Á and TOP2¦Á were found to further enhance the transfection mediated by US. A maximun increase of ~ 2 fold in transfection efficiency was observed when cells were sonicated with 0.6 mg/mL ethyl methanesulfonate to up-regulate GADD45¦Á. These results suggestted that using drugs that regulate certain introcellular processes could further enhance US-mediated gene transfection. Over a broad range of US conditions, the integrity of three common gene delivery vectors, plasmid DNA, siRNA and adeno-associated virus, were not affected by US exposure. This thesis verified that US was able to delivery DNA into the cell nuclei to facilitate rapid gene transfection, and provided a proof of princible that by modulating certain intracellular processes, the efficiency of US-mediated gene transfection could be further increased. US could potentially be a safe and efficient method for gene therapy.

Thesis (Ph. D.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains xviii, 279 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references.

Multiple dose regimens are frequently required to optimize therapy; however, such therapy is frequently undermined by poor patient adherence. In fact, patient adherence is inversely related to the number of doses a patient is asked to take each drug. Consequently, great efforts are under way to develop drug delivery systems that are able to release drugs over an extended time interval; this could offer considerable benefits including reducing administration frequency. This dissertation describes multiple dose platforms designed to deliver a variety of drugs as a single oral administration are described in this dissertation. We believe these drug delivery systems can be used to enhance patient compliance and achieve better therapeutic outcomes. We developed and tested a novel gastroretentive pulsatile drug delivery platform. This platform could deliver multiple unit doses of a drug in a pulsatile pattern and be controlled by dissolution/erosion of a lag-time interval layer. The platform was designed to be retained in the stomach whilst pulsing drug at various timed intervals. This would allow each dose of the drug to release above or within an optimized absorption window over an extended period of time. To assure the robustness and reproducibility of the platform, various in vitro dissolution studies and physical stability tests were performed and evaluated through drug release characteristics, buoyancy, and structural integrity evaluations. The applicability of the novel multiple dose platform was demonstrated by providing repeated release profiles of ciprofloxacin and verapamil in a single, once-daily delivery system. Ultimately, this dissertation demonstrates that a novel multiple dose platform could be a suitable alternative dosing strategy for a variety of drugs to improve patient adherence and treatment efficacy. / text

Polymeric biomaterials have become ubiquitous in modern medical devices. ‘Smart’ materials, materials that respond to external stimuli, have been of particular interest for biomedical applications such as drug delivery. Poly(n-isopropylacrylamide) (pNIPAAm) is the best studied thermally responsive, biocompatible, ‘smart’ polymer and has been integrated into many potential drug delivery devices; however, the architectural design of the polymer in these devices is often overlooked. My research focus was the exploration of pNIPAAm architecture for biological applications. Two new biomaterials were synthesized as a result. Architectural modification of linear pNIPAAm was used to synthesize a well-defined homopolymer pNIPAAm with a sharp transition slightly above normal body temperature under isotonic conditions. This polymer required a combination of polymerization and control techniques including controlled radical polymerization, hydrogen bond induced tacticity, and end-group manipulation. The synthesis of this polymer opened up a variety of biomedical possibilities, one of which is the use of these polymers in a novel hydrogel system. Through the use of the controlled linear pNIPAAm synthesized through chain architectural modification, hydrogels with physiological transition temperatures were also synthesized. These hydrogels showed greater shrinking properties than traditional hydrogels synthesized in the same manner and showed physiological mechanical properties. Highly branched pNIPAAm was also optimized for biological applications. In this case, the branching reduced the efficacy of end-groups in transition temperature modification but increased the efficacy of certain copolymers. The resulting biomaterial was incorporated into a nanoparticle drug delivery system. By combining gold nanoparticles with highly branched pNIPAAm, which was designed to entrap small molecule drugs, a hybrid system was synthesized where heating of the nanoparticle through surface plasmon resonance can trigger drug release from the pNIPAAm. This system proved to be easy to synthesize, effective in loading, and controlled in release. As shown from the applications, architectural control of pNIPAAm can open up new possibilities with this polymer for biomedical applications. Small structural changes can lead to significant changes in the bulk properties of the polymer and should be considered in future pNIPAAm based medical devices.

Introduction: Embolic agents are used to block blood flow of hypervascular tumours, ultimately resulting in target tissue necrosis. However, this therapy is limited by the formation of new blood vessels within the tumour, a process known as angiogenesis. Targeting angiogenesis led to the discovery of anti-angiogenic factors, large molecular weight proteins that can block the angiogenic process. The aim of this research is development of poly (vinyl alcohol) (PVA) aqueous solutions that cross-link in situ to form a hydrogel that functions as an embolic agent for delivery of macromolecular drugs. Methods: PVA (14 kDa, 83% hydrolysed), functionalised by 7 acrylamide groups per chain, was used to prepare 10, 15, and 20wt% non-degradable hydrogels, cured by UV or redox initiation. Structural properties were characterised and the release of FITCDextran (20kDa) was quantified. Degradable networks were then prepared by attaching to PVA (83% and 98 % hydrolysed) ester linkages with an acrylate end group. The effect on degradation profiles was assessed by varying parameters such as macromer concentration, cross-linking density, polymer backbone and curing method. To further enhance the technology, radiopaque degradable PVA was synthesised, and degradation profiles were determined. Cell growth inhibition of modified PVA and degradable products were also investigated. Results: Redox initiation resulted in non-degradable PVA networks of well-controlled structural properties. Increasing the solid content from 10 to 20wt% prolonged the release time from few hours to ~ 2 days but had no effect on the percent release, with only a maximum release of 65% achieved. Ester attachment to the PVA allowed flexibility in designing networks of variable swelling behaviors and degradation times allowing ease of tailoring for specific clinical requirements. Synthesis of radiopaque degradable PVA hydrogels was successful without affecting the polymer solubility in water or its ability to polymerize by redox. This suggested that this novel hydrogel is a potential liquid embolic with enhanced X-ray visibility. Degradable products had negligible cytotoxicity. Conclusion: Novel non-degradable and radiopaque degradable PVA hydrogels cured by redox initiation were developed in this research. The developed PVA hydrogels showed characteristics in vitro that are desirable for the in vivo application as release systems for anti-angiogenic factors.

Introduction: Embolic agents are used to block blood flow of hypervascular tumours, ultimately resulting in target tissue necrosis. However, this therapy is limited by the formation of new blood vessels within the tumour, a process known as angiogenesis. Targeting angiogenesis led to the discovery of anti-angiogenic factors, large molecular weight proteins that can block the angiogenic process. The aim of this research is development of poly (vinyl alcohol) (PVA) aqueous solutions that cross-link in situ to form a hydrogel that functions as an embolic agent for delivery of macromolecular drugs. Methods: PVA (14 kDa, 83% hydrolysed), functionalised by 7 acrylamide groups per chain, was used to prepare 10, 15, and 20wt% non-degradable hydrogels, cured by UV or redox initiation. Structural properties were characterised and the release of FITCDextran (20kDa) was quantified. Degradable networks were then prepared by attaching to PVA (83% and 98 % hydrolysed) ester linkages with an acrylate end group. The effect on degradation profiles was assessed by varying parameters such as macromer concentration, cross-linking density, polymer backbone and curing method. To further enhance the technology, radiopaque degradable PVA was synthesised, and degradation profiles were determined. Cell growth inhibition of modified PVA and degradable products were also investigated. Results: Redox initiation resulted in non-degradable PVA networks of well-controlled structural properties. Increasing the solid content from 10 to 20wt% prolonged the release time from few hours to ~ 2 days but had no effect on the percent release, with only a maximum release of 65% achieved. Ester attachment to the PVA allowed flexibility in designing networks of variable swelling behaviors and degradation times allowing ease of tailoring for specific clinical requirements. Synthesis of radiopaque degradable PVA hydrogels was successful without affecting the polymer solubility in water or its ability to polymerize by redox. This suggested that this novel hydrogel is a potential liquid embolic with enhanced X-ray visibility. Degradable products had negligible cytotoxicity. Conclusion: Novel non-degradable and radiopaque degradable PVA hydrogels cured by redox initiation were developed in this research. The developed PVA hydrogels showed characteristics in vitro that are desirable for the in vivo application as release systems for anti-angiogenic factors.

Thesis (Ph.D.)--University of Wollongong, 2008. / Typescript. Includes bibliographical references: leaf 190-205.

Thesis (Ph. D.)--Lund University.

Thesis (Ph. D.)--Lund University.