The invasive nature and undesirable side-effects related to conventional cancer therapy, such as surgery and chemotherapy, have led to the development of novel drug delivery systems (DDS). A minimally invasive DDS using near-infrared (NIR) light as a trigger for drug release is investigated to reduce the adverse side-effects triggered by systemic delivery of chemotherapeutic drugs. The low tissue absorbance in the NIR region, λ = 650–2500 nm, allows the irradiation to penetrate through tissues to release cisplatin from a NIR-sensitive nanocomposite of Au-Au₂S. Our laboratory has recently shown that cisplatin can be effectively released from Au-Au₂S upon NIR irradiation. Cisplatin was loaded onto Au-Au₂S through its adsorption on COOH-functionalized alkanethiols coated on Au-Au₂S. The current work focuses on the development of methods to control the release of cisplatin. Drug release is controlled by either the irradiation parameters or the type of coatings. The effect of different coatings on NIR sensitivity and drug release is investigated. Molecular layers of HS-(CH₂)n-COOH and HS-CH₂-COO-CH₂(CH₂CH₂O)xCH₂-COOH have been successfully coated onto Au-Au₂S. The effect of different surface layers on drug adsorption is being examined. In addition, a mathematical model has been developed to describe the thermal effects of different irradiation parameters on soft tissues. / Singapore-MIT Alliance (SMA)

Thesis (Ph. D. in Biomedical Engineering)--Vanderbilt University, May 2007. / Title from title screen. Includes bibliographical references.

Novel intervention strategies such as food grade antimicrobials are used to enhance food safety. Nisin is a widely used naturally occurring antimicrobial effective against many pathogenic and spoilage microorganisms. However, its antimicrobial efficacy in food matrices is much reduced because of interactions with food components. Novel delivery systems may overcome this problem by protecting nisin in capsules and releasing it in a controlled manner. The overall goal of this research was to develop delivery systems of nisin to improve its long-term antimicrobial effectiveness. The first objective was to develop a low-cost method to extract nisin from a commercial preparation containing ~2.5% nisin. The best extraction yield was observed at 6 mg solids/mL 50% v/v ethanol. The nisin extract, after adjusting to 70% v/v ethanol, was dissolved with 2% zein (corn prolamins) and different amounts of Tween 20, glycerol, and thymol (another naturally occurring antimicrobial) for spray drying, a practical encapsulation method. Spray-dried capsules were characterized for release profiles of nisin at different pH conditions. Spray drying inlet temperature was first studied at 75 to 120°C, and the greatest sustained release of nisin was observed for capsules produced at 105°C, which was used in rest of this study. The impacts of Tween 20 and glycerol supplemented in spray-drying formulations were studied next. Addition of either 0.05% Tween 20 or glycerol in the spray-drying solution reduced the burst release of nisin at pH 6.0. Capsules with a higher amount of Tween 20 showed more complete release of nisin at pH 8.0, while glycerol had no apparent impact. The most sustained release of nisin at pH 6.0 was observed for capsules produced with both thymol and glycerol. Various capsules were then studied for their ability to inhibit the growth of Listeria monocytogenes at pH 6.0 during incubation at 30°C. Un-encapsulated nisin and thymol showed inhibition only for 12 h, while capsules with nisin and thymol containing either low or medium level of glycerol inhibited L. monocytogenes for >96 h. Our antimicrobial delivery systems, based on food grade ingredients and practical processes, have potential for practical application to enhance microbial safety and extend the shelf-life of foods.

Glioblastoma multiforme (GBM) is the most common malignant central nervous system tumor. The ability of glioma cells to rapidly disperse and invade healthy brain tissue, coupled with their high resistance to chemotherapy and radiation have resulted in extremely poor prognoses among patients. In recent years, nitric oxide (NO) has been discovered to play a ubiquitous of role in human physiology and studies have shown that, at sufficient concentrations, NO is able to induce apoptosis as well as chemosensitization in tumor cells. This thesis discusses the synthesis and characterization of targeted NO donors for the treatment of GBM. Two glioma targeting biomolecules, Chlorotoxin (CTX) and VTWTPQAWFQWVGGGSKKKKK (VTW) were reacted with NO gas to synthesize NO donors. These NO donors, CTX-NO and VTW-NO, released NO for over 3 days and were able to induce cytotoxicity in a dose dependent manner in glioma cells. The biggest advantage, a result of the targeted delivery of NO, was that the NO donors did not have toxic effects on astrocytes and endothelial cells. To characterize the chemosensitizing effects of CTX-NO, cells were incubated with CTX-NO prior to exposure to temozolomide (TMZ) or carmustine (BCNU). These drugs are the most popular chemotherapeutics used in the treatment of GBM, but have only shown modest improvements in patient survival. Viability studies showed that CTX-NO selectively elicited chemosensitivity in glioma cells, whereas the chemosensitivty of astrocytes and endothelial cells remained unaffected. Further investigation showed that CTX-NO pretreatment decreased O6-methylguanine DNA methyltransferase (MGMT) and p53 levels, suggesting that a decrease in DNA repair ability may be the mechanism by which chemosensitivity is induced. Lastly, the effects of CTX-NO on glioma cell invasion and migration were studied using Boyden chamber and modified scratch assays. Non-toxic doses of CTX-NO decreased glioma cell invasion in a dose dependent manner. Studies quantifying matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9) surface expression demonstrated that while MMP-2 expression was decreased by both CTX and CTX-NO, MMP-9 expression was decreased only by CTX-NO. Furthermore quantifying MMP-2 and MMP-9 activity levels showed that NO and CTX work synergistically to decrease the activity of the enzymes. These studies demonstrate that the decrease in glioma invasion resulting from CTX-NO treatment was partially a consequence of decreased levels of surface and activated MMP-2 and MMP-9. The work presented in this thesis describes a novel approach to treating GBM that can be modified to develop treatments for various other tumors. Furthermore this is the first study to develop glioma-targeting NO donors.

Targeted intracellular delivery is a goal of many novel drug delivery systems to treat site-specific diseases thereby increasing the effectiveness of drugs and reducing side effects associated with current drug administration. The development of ultrasound-enhanced delivery is aimed at providing a targeted means to deliver drugs and genes intracellularly by utilizing ultrasound s ability to non-invasively focus energy into the body and generate cavitation, which has been found to cause transient poration of cells. To address some of the current issues in this field, the goals of this study were (i) to develop a measurement of cavitation to correlate with cellular bioeffects and (ii) to evaluate the ability of ultrasound to target delivery into cells in viable tissue. In addition, this study sought to exploit the shear-based mechanism of cavitation by (iii) developing a simplified device to expose cells to shear stress and cause intracellular uptake of molecules. This study has shown that broadband noise levels of frequency spectra processed from cavitation sound emissions can be used to quantify the kinetic activity of cavitation and provide a unifying parameter to correlate with the cellular bioeffects. We further demonstrated that ultrasound can target delivery of molecules into endothelial and smooth muscle cells in viable arterial tissue and determined approximate acoustic energies relevant to drug delivery applications. Lastly, we developed a novel device to expose cells to high-magnitude shear stress for short durations by using microfluidics and demonstrated the ability of this method to cause delivery of small and macromolecules into cells. In conclusion, this work has advanced the field of ultrasound-enhanced delivery in two major areas: (i) developing a real-time non-invasive measurement to correlate with intracellular uptake and viability that can be used as means to predict and control bioeffects in the lab and potentially the clinic and (ii) quantitatively evaluating the intracellular uptake into viable cells in tissue due to ultrasound that suggest applications to treat cardiovascular diseases and dysfunctions. Finally, by using shear forces generated in microchannels, we have fabricated a simple and inexpensive device to cause intracellular uptake of small and large molecules, which may have applications in biotechnology.

Tissue engineering is an interdisciplinary field that seeks to address the needs by applying the principles of chemistry, biology and engineering for the development of viable substitutes that restore and maintain the function of human bone and cartilage tissues. In tissue engineering, scaffolds play an important role as temporary supports for the transplantation of specific cells and tissues. In this study, poly(ester-urethane)urea (PEUU) and poly(caprolactone) (PCL) scaffolds were fabricated. Scaffolds were characterized by SEM. Porosities of scaffolds vary from 67 % to 80 %. Controlled drug delivery systems release drugs at predetermined rates for extended periods. In this study / firstly poly(lactic-co-glycolicolide/tricalcium phosphate) (PLGA/TCP) and poly(L-lactide)/tricalcium phosphate (PLLA/TCP) composites loaded with Gentamicin or Vancomycin were prepared as controlled drug delivery systems for the local treatment of osteomyelitis. The release behavior of drugs were monitored by UV-VIS spectrometer. It was shown that, Vancomycin loaded samples released higher amounts of drug than the samples loaded with Gentamicin. Secondly, porous ceramic samples were coated with PLGA and PLLA and they were loaded with dexamethasone. The release behavior of samples were monitored by UV-VIS spectrometer.The cubic ceramics released higher amounts of dexamethasone than cylindrical ceramics. When the mechanical properties of porous ceramic samples were concerned, PLLA coated samples had better mechanical properties.

Controlled drug delivery systems are becoming increasingly interesting with the contribution of nanotechnology. In the case of transdermal applications the greatest limitation is the highly impermeable outermost layer of the skin, the stratum corneum. One promising method of controlled transdermal drug delivery of the skin therapeutics is the use of nanoparticles as carriers. Encapsulation of the drug, as opposed to classical topical application of creams or emulsions, allows the drug to diffuse into hair follicles where drug release can occur in the deeper layers of the skin. The aim of this study was to develop micro and nano sized carriers as drug delivery systems to achieve treatment for skin conditions like psoriasis, aging or UV damage, caused by radiation or health problems. Two different types of bioactive agents, retinyl palmitate (RP) and Dead Sea Water (DSW), were used by encapsulating in poly(3-hydroxybutyrate-co-3-hydroxyvalerate) carriers. In some tests MgCl2 was used as a substitute for DSW when quantification was needed. Bioactive agent loaded nanospheres and nanocapsules were prepared with o/w and w/o/w methods in low micron (1.9 &micro / m), mid nano (426 nm) and nano (166 nm) sizes. Loading, encapsulation efficiency and release kinetics were studied. The encapsulation efficiency and loading values are low especially for the water soluble agents, DSW and MgCl2. It was observed that the capsules loaded with hydrophilic agents released their content in the first 24 h in aqueous media. The encapsulation efficiency and loading values for RP were higher because of the insolubility of the agent in water. In the in vitro studies carried out with L929 mouse fibroblast cells, the nano sized PHBV capsules were detected in the cytoplasm of the cells. Cell viability assay (MTT) for L929 cells showed a growth trend indicating that the particles were not cytotoxic and the values were close to the controls. Hemolytic activity was examined using human erythrocytes and micro/nanoparticles of PHBV were found to be non hemolytic. In vivo testing with BALB/c mice, nanocapsule penetration revealed that a small amount of nano sized particles penetrated the mice skin, despite the highly impermeable outer skin layer. As a result, PHBV micro/nanoparticles have a significant potential for use as topical drug delivery systems in the treatment of skin diseases.

ABSTRACT OPPORTUNITIES AND BARRIERS OF ARCHITECT LED DESIGN-BUILD PROJECTS Deniz,Ay&ccedil / a M.Sc. in Building Science, Department of Architecture Supervisor: Assoc. Prof. Dr. Soofia Tahira Elias Ozkan September 2012, 77 pages From past to today, technological developments have resulted in new systems in parallel with digital age. Innovations have been started to be replaced with the traditional solutions. Standardizations have also started to be renewed in accordance with the high technology and complexity of the projects. Under these circumstances, design and construction activities have been separated in the construction industry. As a result, alternative project delivery systems have been developed and selecting the right delivery system has gained importance depending upon the complexity of the projects The main objective of this study was to propose a model that supports architect&rsquo / s leadership in design-build systems throughout an international airport project as a case study. Thus, construction industry will gain awareness for the organization structures in which architectural groups lead the other disciplines to achieve success in design-build systems considering time cost quality triangle. In this study, organization charts including project construction process and factors affecting design and construction activities were investigated. The matrix relationship in production level of the organization charts among the project disciplines has been analyzed. According to the evaluation of models reflecting the existing status, alternative models supporting architect&rsquo / s leadership are proposed.

The use of hydrogel nanoparticles, or nanogels, as targeted delivery vehicles to cancer cells was described. The nanogels were synthesized by free radical precipitation polymerization, with poly(N-isopropylmethacrylamide) as the main monomer, and have a core/shell architecture. The nanogels were near 50 nm in radius, contained fluorescein for visualization, and had an amine-containing shell for bioconjugation, making these particles ideal for delivery studies. The nanogels were conjugated with the YSA (YSAYPDSVPMMSC) peptide, which is an ephrin mimic, allowing for uptake by the EphA2 (erythropoietin-producing hepatocellular) receptor. We have delivered YSA-conjugated nanogels to Hey cells and BG-1 cells, as evidenced by fluorescence microscopy. We have shown that the nanogels can encapsulate siGLO Red Transfection Indicator (siGLO) and deliver the siGLO to Hey cells in vitro. After successful delivery of the non-targeting siGLO, we delivered siRNA for knockdown of epidermal growth factor receptor (EGFR). We have shown protein knockdown from 24-120 h after nanogel delivery, as well as knockdown with different siRNA concentrations delivered to the cells. Furthermore, addition of taxol following EGFR knockdown suggests that the chemosensitivity of the Hey cells is increased. Successful in vitro delivery of the nanogels prompted in vivo studies with the nanogels. The nanogels were used to encapsulate silver nanoclusters for potential bioimaging applications. Targeting of the nanogels to MatrigelTM plugs in mice suggest that the particles hold promise as in vivo delivery agents.

Regeneration of large bone defects presents a critical challenge to orthopaedic clinicians as the current treatment strategies are severely limited. Tissue engineering has therefore emerged as a promising alternative to bone grafting techniques. This approach features the delivery of bioactive agents such as stem cells, genes, or proteins using biomaterial delivery systems which together stimulate endogenous repair mechanisms to regenerate the tissue. Because bone is a highly mechanosensitive tissue which responds and adapts dynamically to its mechanical environment, application of mechanical stimuli may enhance endogenous tissue repair. While mechanical loading has been shown to stimulate bone fracture healing, the ability of loading to enhance large bone defect regeneration has not been evaluated. The goal of this thesis was to evaluate the ability of sustained osteogenic growth factor delivery and functional biomechanical loading to stimulate vascularized repair of large bone defects in a rat segmental defect model. First, we evaluated the hypothesis that the relationship between protein dose and regenerative efficacy depends on delivery system. We determined the dose-response relationship between dose of recombinant human bone morphogenetic protein-2 (rhBMP-2) and bone regeneration in a hybrid alginate-based protein delivery system and compared with the current clinically-used collagen sponge. The hybrid delivery system improved bone formation and reduced the effective dose due to its sustained delivery properties in vivo. Next, we tested the hypothesis that transfer of compressive ambulatory loads during segmental defect repair enhances bone formation and subsequent limb regeneration. We found that delayed application of axial loads enhanced bone regeneration by altering bone formation, tissue differentiation and remodeling, and local strain distribution. Finally, we evaluated the hypothesis that in vivo mechanical loading can enhance neovascular growth to influence bone formation. We found that early mechanical loading disrupted neovascular growth, resulting in impaired bone healing, while delayed loading induced vascular remodeling and enhanced bone formation. Together, this thesis presents the effects of dose and delivery system on BMP-mediated bone regeneration and demonstrates for the first time the effects of in vivo mechanical loading on vascularized regeneration of large bone defects.