No description available.

No description available.

<p>  </p> <p>Conventional clinical therapies for head and neck squamous cell carcinomas (HNSCC) include surgical resection, chemotherapy (CT), and radiotherapy (RT). For locally advanced HNSCC, the CT-RT combination (“chemoradiation”) has been shown to be more effective than CT or RT alone and is the current standard of care. A novel radiation-controlled drug release nanoparticle formulation has been developed to realize the maximum benefits of intratumoral CT-RT. Under the application of low-dose X-ray, the formulation is capable of releasing PTX and providing localized, controlled, and sustained drug release for improvements in therapeutic efficacies.</p>

Liposomes are self-assembled lipid vesicles made from phospholipids that are safe and suitable for drug encapsulation and localized drug delivery. Liposomal formulations are characterized by low toxicity and improved therapeutic index (by changing drug biodistribution) and liposomes encapsulating antifungal or anticancer drugs have already been approvedby regulatory agencies.One area of application for liposomes is localized antibiotic delivery. Antibiotics target bacteria, but specific types of infections(namely biofilms or intracellular infections)that required high or prolonged antibiotic administration have long been a challenge for antibiotic treatments. Liposomal delivery of antibiotics can improve their therapeutic index while minimizing their adverse effects. When it comes to methods of antibiotic encapsulation, however,most reports to date follow the methods developed for anticancer drugs for encapsulating antibiotics. This oversight causes discrepancies in the literature, mainly because of the significantly different chemical structures of antibiotics and cancer drugs. Furthermore, most antibiotics are highly sensitive to temperature fluctuations, which is concerning, given most liposomal preparation methods involve extreme temperature fluctuations. The aim of my thesis was to explore these missing links in the literature by answering these questions: (1) will liposome preparation method affect encapsulation efficiency of antibiotics?And (2) does liposomal preparation method adversely affect the efficacy of antibiotics?Investigating these questions led to further insight into the optimal process for achieving high encapsulation efficiencies for different antibiotics and for further avoiding damage due to harsh processing conditions. We found that different preparation methods are better for different types of antibiotics, being the one that promotes a large aqueous space better for hydrophilic drugs and the one that creates oligolamellar and large unilamellar vesicles better for more hydrophobic drugs. The steps in liposome preparation methods such as heating and sonication can affect the stability of the antibiotics. / Thesis / Master of Applied Science (MASc) / When antibiotics are administered, orally or intravenously, they should pass through different tissues to arrive to the site of infection; this can cause dilution and/or intoxication. To overcome these problems, drug delivery vehicles have been used to encapsulate and deliver antibiotics, improving their therapeutic index while minimizing their adverse effects. Liposomes are vesicles composed of at least one lipid bilayer, with an inner aqueous compartment. Liposomes are an attractive vehicle to deliver antibiotics because they can encapsulate both hydrophobic and hydrophilic antibiotics, they have low toxicity, and they can change the bio-distribution of the drug. In mythesis, I addressedtwo main questions regarding liposomal antibiotic encapsulation:(1) will liposome preparation method affect encapsulation efficiency of antibiotics, and(2) does liposome preparation method adversely affect the efficacy of antibiotics. While investigating these questions,I also identified certain outstanding biases in the liposomal characterization methods.

Nanomaterials are defined as any material with at least one external dimension less than 100 nm. Recently, nanomaterials have become more common in medicine, technology, and engineering. One reason for their increased interest is due to nanomaterials having unique properties that allow them to interact effectively with biological systems. In terms of drug delivery, the lungs are a highly desirable site to administer therapeutic nanoparticles. Indeed, inflammatory diseases such as asthma and emphysema could potentially benefit from nanoparticle-mediated delivery. However, the lungs are also in constant contact with airborne particulate matter. Thus, harmful nanoparticles can enter the lungs and cause or even exacerbate inflammatory diseases. Our work focused on characterization of both therapeutic and potentially harmful nanoparticles in the lungs. We found that fluorescently-labeled nanoparticles were phagocytosed by macrophages and did not induce apoptosis or inflammation in the lungs, making them potentially useful as a therapeutic for inflammatory diseases. We also characterized a rare form of titanium-based particles called Magnéli phases, which have been shown to be produced via coal burning. We found that while these particles are non-inflammatory in the lungs of mice, they lead to apoptosis of macrophages as well as a change in gene expression associated with increased fibrosis. Ultimately, this was shown to lead to a decrease in lung function parameters and airway hyperresponsiveness, indicating increased lung stiffness after long-term nanoparticle exposure. Our data adds significant contributions to the field by assessing two nanoparticles with vastly different compositions in the lungs. Overall, we found that the unique properties of both particle types allows for interactions with cells and tissues. These interactions can have important outcomes on health, both in terms of disease treatment and exacerbation. / Ph. D. / Over the years, nanoparticles have become more common in medicine, technology, and engineering due to their unique properties. Many of these properties allow for increased interactions with biological materials. Organs such as the lungs are at increased risk of exposure because they naturally encounter microorganisms and airborne particles on a daily basis. However, the lungs are also a highly desirable site for drug delivery using nanoparticles, due to ease of access. Inflammatory diseases such as asthma and emphysema could potentially benefit from nanoparticle-mediated delivery. Additionally, harmful nanoparticles can enter the lungs and cause or even exacerbate these diseases. Unfortunately, there is a lack of knowledge pertaining to this subject. Our work focused on assessing the interactions of nanoparticles in the lungs. First, we looked at nanoparticles that could be used for drug delivery. We found that fluorescentlylabeled nanoparticles were taken up by phagocytic white blood cells called macrophages. Furthermore, these particles did not induce cell death or inflammation in the lungs. Therefore, we found that these particles could be useful for drug delivery in the lungs. Secondly, we investigated potentially harmful nanoparticles and their effects on the lungs. The titanium-based particles called Magnéli phases, have been shown to be produced through coal burning. We found that while these particles are non-inflammatory in the lungs, they do lead to programmed death of macrophages as well as the increase in genes associated with fibrosis. Ultimately these particles led to a decrease in lung function after long-term exposure.

Proper cell division is a fundamental process for the development and sustainability of healthy living organisms. Defective cell division can have deleterious effects on tissue homeostasis and can represent the first step towards disease development. The overall goal of this work was to develop and validate a new, mitosis-based, single-cell toxicity approach. This contributes to the current need of toxicology research to replace animal testing with predictive in vitro models. Cell division-based assays would be better at predicting risk than other commonly used in vitro measurements, such as persistent cell cycle arrest or cell death. Finally, single-cell microscopic analysis provides far deeper insight into the underlying toxicity mechanism(s) than bulk cell population measurements. To meet our goal, we investigated the toxicity of silver nanoparticles (AgNPs) on immortalized human retinal pigmented epithelial (RPE-1) cells. AgNPs are a major nanomaterial employed in product manufacturing due to desirable antimicrobial properties, yet toxicity reports are still confounding. RPE-1 cells were cultured in the presence of low and high doses of polyvinylpyrrolidone (PVP)-coated AgNPs for a single 24-hour treatment (acute treatment), for six 24-hour treatments administered over a period of 3 weeks (moderate treatment), or for twelve 24-hour treatments administered over a period of 6 weeks (chronic treatment). Time-lapse, phase-contrast microscopy of acutely treated cells showed that 100% of cells engulfed AgNPs, which was further confirmed by electron microscopy. Moreover, we found that higher concentrations of AgNPs resulted in large numbers of acutely treated cells becoming arrested in mitosis, dying, or dividing abnormally. In contrast, untreated cells displayed normal mitotic behavior. High-resolution fluorescence microscopy performed in treated cell populations identified an increased percentage of abnormal nuclear morphologies compared to the untreated cells. Further live-cell analysis indicated that treated cells failed cytokinesis or slipped out of mitosis more often than untreated cells. Overall, our results indicate that AgNPs impair cell division, not only further confirming toxicity to human cells, but also revealing previously unreported toxicity mechanisms and highlighting the propagation of adverse phenotypes within the cell population after exposure. Furthermore, this work illustrates that cell division-based single-cell analysis could provide an alternative to animal experimentation in the future. / Master of Science / Multiple agencies, including the U.S. Environmental Protection Agency and the National Academy of Science, are urging for a radical paradigm shift from standard, whole-animal testing to alternative and novel technologies. To meet this urgent need, we aimed to develop a new, cell division-focused toxicity assay by investigating the mechanism of toxicity from silver nanoparticles (AgNPs) on human retinal pigment epithelial (RPE-1) cells. Cultured RPE-1 cells were treated with varying concentrations of AgNPs and live-cell microscopy was used to analyze the behavior of cells undergoing cell division over a 24 hour time period. Physical interaction between cells and particles was visually observed and 100% of treated cells appeared to engulf particles. We found that higher concentrations of AgNPs resulted in large numbers of cells stalling in mitosis and/or dying. In contrast, untreated cells displayed normal mitotic behavior. High-resolution fluorescence microscopy performed in chronically treated cell populations identified an increased percentage of binucleated cells. Further live-cell analysis indicated that one major cell division defect could explain the binucleated cell phenotype. Indeed, treated cells failed cytokinesis (cytoplasmic division following mitotic chromosome segregation) more often than control cells. Overall, our results indicate that AgNPs specifically impair cell division, not only further confirming toxicity to human cells, but also revealing specific, previously unreported toxicity mechanisms and highlighting the propagation of adverse phenotypes within the cell population after exposure. Furthermore, this work illustrates that cell division-based assays and ingle-cell analysis could greatly benefit chemical safety experimentation in the future.

Brain inflammation has been implicated with the pathogenesis of neurodegenerative diseases. Activated microglia and endothelial cells induce production of reactive oxygen species (ROS) and overexpress pro-inflammatory mediators that perpetuate tissue damage. Current treatments are not effective against progressive stages of neurodegenerative diseases and more advanced therapies need to be developed. Recently, nanomaterials have been investigated for therapeutic applications. Nanoparticles can increase efficiency of drug delivery due to increased tissue distribution and the ability to modify surface chemistry to increase biocompatibility and incorporate targeting moieties. In the present study, we established in vitro and in vivo brain inflammation models by administering lipopolysaccharide to mouse brain endothelial cells, microglia, macrophage cells and C57BL/6 male mice. Changes in mRNA expression of pro-inflammatory mediators were analyzed by real-time reverse transcriptase-polymerase chain reaction (RT-PCR). Tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), monocyte chemotactic protein-1 (MCP-1), E-selectin, and intercellular adhesion molecule-1 (ICAM-1) displayed significant overexpression when compared to the control. Additionally, folate receptor-α (FR-α) was also overexpressed, confirming that our model will function appropriately for specific targeting experiments. Cellulose nanocrystals are rod-like particles, approximately 5 nm wide and 100-150 nm long. The surface area consists of extended hydroxyl groups and the structure is hydrophilic in nature. These characteristics make cellulose nanocrystals ideal for surface modification and ensuring long blood circulation half-life. Cell viability was determined using the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] conversion assay and a Lactate Dehydrogenase (LDH) Cytotoxicity Detection Kit. At each concentration of cellulose nanocrystals (10, 25, 50 μg/mL), both assays showed the nanoparticles to be non-toxic. Binding/uptake experiments utilizing a fluorescence plate reader and fluorescence microscope showed no non-specific uptake of untargeted cellulose nanocrystals. In contrast, when conjugated to folic acid, cellulose nanocrystals were selectively incorporated to folate receptor-overexpressing cells. These results indicate that both in vitro and in vivo brain inflammation models can be utilized to assess therapeutic efficacy of folate receptor-targeted bioconjugated nanoparticles. / Master of Science

No description available.

An aqueous nanoparticle dispersion is a complex fluid whose mobility in porous media is controlled by four key factors: the conditions necessary for the stability of nanoparticle dispersions, the kinetics of nanoparticle aggregation in an unstable suspension, the rheology of stable or unstable suspensions, and the interactions between the nanoparticles and oil/water interface and mineral surfaces. The challenges in controlling nanoparticle transport come from the variations of pH and ionic strength of brine, the presence of stationary and mobile phases (minerals, oil, water and gas), the geochemical complexity of reservoir rocks, and pore-network. The overall objective of this work is to achieve a better understanding of nanoparticle transport in porous media based on a systematic experimental and theoretical study of above factors. For this purpose, the critical conditions for the aqueous stability of nanoparticles are identified and fit by a theoretical model, which describes the interaction energy between silica nanoparticles. Above critical conditions nanoparticle aggregation becomes significant. A model for the aggregation kinetics is developed and validated by experiments. A mechanistic model for predicting the viscosity of stable and unstable silica nanoparticle dispersions over a wide range of solid volume fraction is developed. This model is based on the concept of effective maximum packing fraction. Adsorption experiments with silica nanoparticles onto quartz, calcite and clay surfaces and interfacial tension measurements provide insightful information on the interaction of the nanoparticles with minerals and decane/water interface. The extent of nanoparticle adsorption on mineral/water and decane/water interfaces is evaluated based on DLVO theory and Gibbs’ equation. Visual observations and analytical methods are used to understand the interaction of nanoparticles with clay. The characterization of nanoparticle behavior in bulk phases is built into an understanding of nanoparticle transport in porous media. In particular, the rheology of nanoparticle dispersions flowing through permeable media is compared with those determined using a rheometer. In the presence of residual oil, the retention of silica nanoparticles at water/oil interface during steady flow is investigated. The results from batch experiments of nanoparticle adsorption are used to explain the flow behavior of these nanoparticles in a glass bead pack at residual oil saturation. / text

The present thesis deals with synthesis of free alloy nanoparticles in immiscible alloy systems by the process of laser ablation under a liquid. In this process the alloy target is submerged in a liquid and the plume formed by the laser beam interaction with the target is confined in the liquid. The nanoparticles formed inside this plume and get quenched by the surrounding liquid yielding suspension of nanoparticles in the liquid. By the addition of suitable surfactants, these nanoparticles can be protected from other reactions and their size can be controlled by preventing further growth. We have selected immiscible alloys for the present study. These alloys tend to phase separate in melt as well as in solid depending on the value of the positive heat of mixing. We have used two binary alloys for the present study. These are alloys in Ag-Cu system and Fe-Cu system. In both these systems, there are reports of formation of extended solid solution due to kinetic factors during nonequilibrium processing like rapid solidification and mechanical alloying. In the present thesis we report synthesis of alloy nanoparticles of different compositions and sizes in these two systems and explore the nature of the phases that form in the small (nano) particles and their evolutionary pathways leading to the final microstructure. Microscopic techniques, especially transmission electron microscope, were used for characterization of these nanoparticles. The phase evolution was further studied using in situ microscopic techniques. After introducing the thesis in the Chapter 1, we describe briefly the relevant literatures in Chapter 2. The experimental details, in particular the experimental set up for laser ablation with targets under liquid are described in chapter 3. This chapter also includes the experimental details of the characterization. Transmission electron microscopy was used as primary characterization tool in the present study. The Chapter 4 presents the result of our study of alloy nanoparticles in Fe-Cu system. This system exhibits a submerged liquid miscibility gap. Although we have studied alloy targets of different compositions, the results of alloy nanoparticles obtained from targets with compositions Cu-40at.%Fe and Cu-60at.%Fe were primarily presented in this chapter. The nanoparticles that were synthesized had a size range of approximately 40nm to more than 100 nm. These particles have spherical morphology. The measurements of local compositions of different locations in the particle indicate the presence of a layer of Fe3O4 oxide at the spherical surface. This layer is devoid of copper. Most of the copper exist in the core of the particle. Fe rich spherical particles of much smaller size (~15 nm) are found to be embedded in the copper rich core. The copper formed solid solution with Fe and a copper concentration gradient exists in the particle below oxide layer due to oxidation of Fe. In contrast the nanoparticles obtained from alloy target with composition Fe-40at.% Cu have a spherical morphology. These have a composite structure with a Fe core in addition to Fe3O4 oxide layer at the surface. We have attempted to explain the phase evolution taking into account under cooling of the melt condensate that forms in the plume and their subsequent solidification through submerged miscibility gap. The chapters 5-7 deals with alloys of Ag-Cu system. In Chapter 5, we have carried out a detailed study of morphological evolution of the nanoparticles of Ag-Cu system. After optimizing the ablation parameters using pure Ag and Cu targets, we have synthesized alloy nanoparticles using different target compositions over the entire range of compositions with sizes having a mode of 25 nm. The evolution of the two phase structure is shown to be composition dependent with particles near equiatomic composition exhibit solid solution with uniformly distributed segregations of composition (Cu & Ag rich) while copper rich alloys exhibit a core shell structure with outer layer being Ag rich. The isothermal experiments again reveal emergence of core-shell morphology at intermediate time for particles with equiatomic composition. In order to compare the results of Ag-Cu nanoparticles with particles produced by other techniques we have synthesized Ag-Cu nanoparticles of near equiatomic composition by chemical route using nitrate salts and NaBH4 as reducing agent. PVP was used as capping agent. The results are presented in chapter 6. Depending on time of reaction, it is possible to synthesis free alloy particles from 2-3 nm to a network of chains. The nanoparticles contain Ag rich and Ag deficient region with Ag tends to segregate near surface. We have also presented mechanism for the formation of chain structure with prolonged reaction. The thermodynamic basis of phase formation in the immiscible system and evolution of phases under nonequilibrium situation have been discussed in chapter 7. This also includes a model to estimate size dependent surface energy. The analysis presented allows a discussion of possible pathways for phase evolution observed in the present work. The thesis ends with a final chapter that discussed the critical issues remains to be addressed and possible future work.