Browsing by Subject "Encapsulation"

Now showing 1 - 6 of 6
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    Cell Response to Silica Gels with Varying Mechanical Properties
    (2013-07) Lefebvre, Molly
    Sol-gel encapsulation has a variety of applications in biotechnology and medicine: creating biosensors, biocatalysts, and bioartificial organs. However, encapsulated cell viability is a major challenge. Consequently, interactions between cells and their 3D microenvironment were studied through rheological, metabolic activity, and extraction studies to aid in the development of new gel protocols. The cells were encapsulated in variations of three silica sol-gels with varying stiffness. It was hypothesized that the cell viability and the amount of extracted cells would depend on gel stiffness. For two gels, there was no apparent correlation between the gel stiffness and the cell viability and extracted cell quantity. These gels did strongly depend on the varying gel ingredient, polyethylene glycol. The third gel appeared to follow the hypothesized correlation, but it was not statistically significant. Finally, one gel had a significantly longer period of cell viability and higher quantity of extracted cells than the other gels.
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    Encapsulation and real-time release characteristics of spray dried l-menthol
    (2008-11) Mortenson, Michael Alan
    The objective of this research was to understand the effects of octenyl succinic anhydride (OSAn) substitution level of carbohydrate encapsulation materials on the capsule characteristics and real-time release of l-menthol from spray dried powder. Spray dried l-menthol powder was prepared from modified dextrin and gum acacia of varying levels of OSAn substitution. Physical properties of the microcapsules and encapsulation matrices were determined by: constructing moisture sorption isotherms, particle sizing, density measurement via pycnometry, and by total and surface menthol content of the finished powders. Real-time menthol release and moisture uptake profiles were accomplished by using dynamic vapor sorption (DVS) coupled with either Tenax trapping and gas chromatography (GC) or proton transfer reaction mass spectrometry (PTR-MS). It was found that as OSAn substitution of carbohydrates increases, total and surface menthol appeared to increase and decrease, respectively. The particle size of the finished spray dried powder was influenced by spray dryer infeed solids concentration with higher solids leading to larger particle size. Microcapsule density did not appear to be affected by OSAn substitution or carrier type. Menthol release profiles varied greatly with carrier material used. Increased OSAn substitution (up to 3% treatment level) of the carrier material resulted in a significantly greater, but not earlier burst of menthol release. For most samples, the characteristic burst of menthol was followed by a decrease in release which was attributed to an observed matrix collapse. Moisture uptake rates of the powders were related to corresponding menthol release rates. As OSAn substitution increased for gum acacia (Acacia seyal), a trend of increased moisture uptake rate with menthol release rate was evident. However, for the dextrins, the moisture uptake rate had no influence on the rate of menthol release. The degree of OSAn substitution did not affect moisture sorption characteristics for dextrin samples. For gum acacia, increased levels of OSAn substitution resulted in a decreased affinity for moisture in the range of 0.3 to 0.7 aw.
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    Encapsulation of Orange oil using fluidized bed granulation
    (2019-05) Patil, Shardul
    The objective of this research was to determine if orange oil can be spray dried and agglomerated in a single step process called granulation and if so, to compare the products prepared using granulation to the traditional processes of spray drying and then agglomerating. The processes that were studied as a part of this research were spray drying (SD - A conventional process widely used in industry), agglomeration of spray dried Flavors (SDA) and fluidized bed granulation (FBG). The model system used to evaluate the two different processes was an orange oil emulsion. They were made by first preparing a slurry 55% in solids (carrier in water). The carrier was a blend of Maltodextrin (MD-150 as bulking agent) and Modified Starch (Capsul™, an Octenylsuccinate acid derivatized starch as emulsifier). Orange oil was added at 25% of the carrier solids level and emulsion was made using a high shear rotor-stator blender. The said emulsion was subjected to spray drying and the resultant spray dried emulsion was agglomerated. The emulsion with same composition was also used for fluidized bed granulation (FBG). The resultant product, orange oil encapsulates were analyzed for Limonene Oxide content under storage (Shelf life study), Particle Size, Density, Orange Oil retention and Moisture Content. It was observed that FBG samples had higher density than SD and SDA samples. Density was found to be proportional to run time of the process and SDA samples had higher density than SD samples. Under the study operating conditions, fluidized bed granulation produced larger particles compared to spray drying or SDA. As one would expect particle size was found to be proportional to run time of the process (FBG and SDA). In case of FBG, it can be explained by the continuous spraying of emulsion while processing, which results continuous drying and film formation on granules (particle growth). Under the study operating conditions, FBG products also had a lower moisture content compared to other products. FBG samples had the highest oil retention followed by spray drying and SDA; The SDA batch with shortest run time (about 30 mins) had the least oil retention. While conducting the shelf life study, it was observed that granulation samples had the lowest limonene oxide content, hence less oxidation after four weeks of storage followed by agglomerated samples. Spray dried samples were observed to have highest limonene oxide content and hence, the highest oxidation after four weeks of storage as smaller particle size contributes to a higher available surface area per unit volume for oxidation. Overall, it was observed during this study that fluidized bed granulation produced orange oil encapsulates that possessed better properties such as more resistance to oxidation, better retention of flavors and higher density than spray dried orange oil.
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    Encapsulation of proteins and cells in silica nanoporous materials
    (2011-11) Reategui, Eduardo
    My dissertation presents fundamental and practical scientific contributions. I demonstrated the versatility of the sol-gel processing technology for the study of the basic science behind water and protein structure under confinement, and for the development of novel biotechnology and biomedical engineering applications based on cell encapsulation in nanoporous silica gels.For the basic science studies of my dissertation, silica nanoporous gels were used to investigate the kinetic and thermodynamic transitions of water under confinement. I demonstrated a direct correlation between the structure of confined water and the secondary structure of proteins in a wide range of temperatures (- 196C to 95C). I showed qualitatively that the incorporation of a highly hydrogen bonding osmolyte contributed to improve the thermal stability of encapsulated proteins by a mechanism based on prevention of adsorption at the surface of the nanoporous silica material. For the practical contributions of my dissertation, I developed two novel applications relevant to the biotechnology and biomedical engineering fields. These applications were based on the encapsulation of prokaryotic and eukaryotic cells in silica nanoporous gels. First, I developed a highly selective and efficient biodegradation platform for the removal of an herbicide, atrazine, from contaminated water. In the second application, I invented a cell capture and isolation methodology that was successfully tested as a cancer cell isolation tool from mixed populations of eukaryotic cells (normal and cancer cells). Miscellaneous applications were also investigated such as encapsulation as a means of cryopreservation of mammalian and algae cells, and were incorporated in the Appendices of this thesis.
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    Influence of Molecular Mobility and Free Volume on the Oxidative Stability of Spray Dried Orange Oil
    (2017-05) Hohman, Abbie
    The objective of this research was to determine whether molecular mobility and/or free volume influences the oxidative stability of spray dried orange oil. Encapsulated orange oil was prepared by spray drying using maltodextrin, gum acacia and HiCAP® 100 as carrier materials. The physical properties of the spray dried orange oil were characterized by: viscosity, particle size, moisture content, volatile retention, and absolute density. The molecular mobility was determined by glass transition, free volume was measured positron annihilation lifetime spectroscopy (PALS) and orange oil oxidation was determined by gas chromatography. The infeed viscosity and resultant particle size of the unloaded powders decreased as the molecular weight of the carrier material decreased. Differences between the viscosity of the unloaded and loaded emulsions was due to the addition of orange oil as it is less viscous than water and does not hydrate carrier materials yet contributes to the total percent spray drier infeed solids. The reconstituted emulsion particle size was much smaller than the infeed emulsion particle size due to the high shear of the atomizer in the spray drier. The moisture content and absolute density were independent of carrier material type. The moisture content increased with increasing water activity however, the absolute density was unaffected by a change in water activity. The volatile retention of the spray dried powders improved greatly upon the addition of emulsifier to the carrier wall material. The size of the molecular voids and orange oil oxidation decreased while molecular mobility increased with decreasing molecular weight of the carrier material. As the relative humidity increased, the average size of the molecular voids and the molecular mobility increased. The effect of water activity on the oxidation of spray dried carrier systems appeared to increase to a certain point and then decrease with increasing water activity. Spray dried carrier systems that were formulated as a blend of carbohydrate and emulsifier provided a balance between molecular mobility and molecular free volume that provided the greatest protection against the oxidation of spray dried orange oil.
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    Polyethylene glycol as a robust, biocompatible encapsulant for two-stage treatment of food and beverage wastewater
    (2023-05) Gutenberger, Gretchen
    This research investigates encapsulation of microorganisms for two-stage anaerobic treatment of industrial food and beverage wastewater. Encapsulants were tested in batch reactors to determine the potential for biological inhibition during encapsulation. Flow through reactors were to test the leakage of microorganisms from the encapsulants over time. Five different reactor designs were explored to assess the effects of reactor conditions on encapsulant longevity and activity. It was found that polyethylene glycol (PEG) beads encapsulating biomass grown in suspension did not change in shape, activity, or protein concentration over one month in flow-through reactors. In reactors mixed by stir bars, PEG beads encapsulating suspended biomass lasted 6-10 months. PEG beads encapsulating PAC-supported biofilms improved methane production approximately 27 times compared to PEG beads encapsulating suspended biomass. This study provides information on encapsulant performance that will be used to select encapsulants for a future pilot demonstration of the pretreatment system at a brewery.