Browsing by Author "Turasan H."

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    Thermodynamic mechanism of particulation of sodium alginate and chitosan polyelectrolyte complexes as a function of charge ratio and order of addition
    (Elsevier Ltd, 2019) Yilmaz T.; Maldonado L.; Turasan H.; Kokini J.
    This study focused on mechanistic understanding of the effect of charge ratio, order of addition and resulting thermodynamics of interaction on the formation and properties of polyelectrolyte complexes (PECs) from sodium alginate and chitosan at a constant tightly controlled pH 4 where the zeta potential difference was maximum for the formation of PECs. The morphology, particle size and particle size distribution as well as the stability of PECs were investigated as a function of molar charge ratio, and the order of addition. The association binding constant K a and the stoichiometry of interaction between the two electrolytes, evaluated using Isothermal titration calorimetry, showed that the stoichiometry and enthalpy of reactions were strongly affected by the order of addition and influenced the average particle size and zeta potential of PECs. The addition of alginate (-) into chitosan (+) gave positively charged particles and resulted in stronger interactions characterized by larger enthalpy and entropy of complexation which led to smaller particles. Reversing the order of addition gave negatively charged particles that were larger. Morphologies of complexes studied using scanning electron microscopy (SEM) showed distorted spherical particles for both orders of addition and at most charge ratios. Stability during 8 weeks was found to depend on the order of addition and charge ratio. Alginate in chitosan gave more stable PECs consistent with the thermodynamics of interaction which showed stronger interactions for this order of addition. The particle sizes and size distributions rapidly increased near electrical neutrality during storage at 4 °C where aggregation was facilitated because of electrical neutrality but particles were stable when the net charge was either strongly positive or strongly negative. © 2019 Elsevier Ltd
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    Comparison of the fabrication methods, formation dynamics, structure, and delivery performance of solid nanoparticles and hollow layer-by-layer edible/biodegradable nanodelivery systems
    (Blackwell Publishing Inc., 2020) Turasan H.; Bonilla J.; Bozkurt F.; Maldonado L.; Li X.; Yilmaz T.; Sadeghi R.; Kokini J.
    Aim: This article summarizes and reviews recent studies on nanoparticulation of solid and hollow nanoparticles using edible proteins and carbohydrates from plant and animal origin and shares new research conducted in our laboratory on fabrication of biopolymer-based nanodelivery systems. Methods: We compare the properties of nanoparticles fabricated using desolvation, coacervation, and layer-by-layer assembly. The parameters affecting the morphological and physical states of the nanodelivery systems as well as their abilities to encapsulate bioactive compounds, and the mechanisms of the nanoparticulation process are discussed in detail. Results: The article offers methods that need to be used with each nanoparticulation technique along with key characterization data obtained. The effect of varying a wide range of parameters on particle size, size distribution, morphology, effect of solvents and non-solvents, effect of surface charge of polyelectrolytes, effect of fabrication conditions are presented. Conclusions: We believe the article gives enough detail to give the reader useful information related to the performance of all the different nanoparticles studied in our laboratory over the last 6 years. Practical applications: Biopolymer based nanodelivery systems presented in this article, have great potential to be used in the nutraceutical, food, pharmaceutical industries as well as agriculture. The biodegradable and edible nature of these nanodelivery systems make them safe for incorporating into food and nutraceutical materials, because, the biopolymers used in their fabrication are biocompatible polymers of food origin that are generally recognized as safe (GRAS) (Food and Drug Administration, The Daily Journal of the United States Government, 2016). Therefore, use of edible polymer-based nanoparticles would be safer and less toxic and consequently better for all these industries. For example, in the food industry, antioxidant compounds can be encapsulated which would then be incorporated into packaging materials and that would help maintain freshness and good quality and would prevent oxidative deterioration of foods to increase shelf life. Pesticides and insecticides can also be encapsulated in these nanodelivery systems for agricultural applications. Because they are biodegradable and originated from natural biopolymers, their impact on the environment and the quality of the soil would be minimized compared to current applications that use some burdensome chemicals. Biopolymer based nanodelivery systems would also be of high interest for the pharmaceutical industry. Through the efficacy and extra stability gained with encapsulation, drugs and bioactives would be better protected from the acidic environment of the stomach and be released more controllably in the intestines. Further functionalization of nanodelivery systems with recognition elements, such as antibodies or aptamers, would enable more specifically targeted delivery. © 2020 Wiley Periodicals, Inc.