Master of Science in Chemistry, Youngstown State University, 2018, Department of Chemistry

Enzyme immobilization refers to any technique by which an enzyme is restrained or localized to a support system. This can provide retention of catalytic activity and reusability of the enzyme, both of which are important in industrial processes. Enzyme supports can be made of organic materials, typically naturally occurring polysaccharides, such as cellulose, agarose, or chitosan. The objective of this study was to immobilize beta glycosidase BglX and its mutant E293Q on chitosan gel beads while retaining catalytic activity. The beads were fortified with activated charcoal or silica and cross-linked with glutaraldehyde to increase their mechanical stability and immobilization efficiency. Lactase was used as a model enzyme to determine which type of chitosan gel bead was the most suitable for immobilization. The chromogenic substrate ortho-nitrophenyl ß-D-galactopyranoside (oNPGal) and a lactose solution were used to test the catalytic activity of immobilized lactase. Upon successfully immobilizing lactase, BglX and E293Q were tested similarly. Since BglX showed higher percent conversion of substrate, it was used in a packed bed column and the ability of the immobilized enzyme to hydrolyze the lactose present in milk whey was tested in a small-scale continuous production system.

Committee: Nina Stourman PhD (Advisor); Michael Serra PhD (Committee Member); Clovis Linkous PhD (Committee Member) Subjects: Biochemistry; Chemistry; Food Science

Master of Science, The Ohio State University, 2024, Animal Sciences

Salmonellosis continues to be one of the major public health concerns worldwide causing a gastrointestinal disease. Poultry meat and eggs are recognised as one of the major sources of Salmonella food poisoning in humans. Our study evaluated the protective efficacy of mannose-conjugated chitosan-nanoparticle (mChitosan-NP) based oral subunit vaccine consisting of outer membrane proteins and flagella of Salmonella Enteritidis against Salmonella colonization in the intestines of broilers by incorporating two known mucosal adjuvants, c-di-GMP (stimulator of interferon gene agonist) and whole cell lysate (WCL) of Mycobacterium smegmatis. We try to identify the optimal dose of c-di-GMP and WCL adjuvants by using three different amounts (2.5µg, 10µg and 50µg/dose) in vivo to potentiate the efficacy of Salmonella subunit vaccine formulation. In vitro analysis revealed that mChitosan-NP Salmonella vaccine and mChitosan-NP adjuvant formulations were carrying high positive charge (Zeta potential +20-25mV), size 235-260nm, and polydispersity index 0.35-0.52, conducive for in vivo studies. Subsequently, the vaccine-adjuvant formulations were evaluated for efficacy in vivo in broiler chickens by challenging with Salmonella Enteritidis. Our data showed that mChitosan (OMP+FLA)/FLA-NP WCL 10µg/dose formulation reduced over 0.5 log10 reduction of challenge bacterial load comparable to a commercial live vaccine at both day post challenge 4 and 10. The systemic and mucosal antibody responses were found superior in adjuvanted mChitosan-NP Salmonella vaccine groups. Additionally, most of the vaccine groups had an increased frequency of B cells compared to mock group at day post-challenge 4, associated with upregulation of TGF-β mRNA at day post-challenge 10. Overall, mChitosan (OMP+FLA)/FLA-NP WCL 10 µg/dose and mChitosan (OMP+FLA)/FLA-NP GMP 50µg/dose performed well in inducing immune responses and efficacy.

Committee: Renukaradhya Gourapura (Advisor); Liesa Bielke (Committee Member); Gireesh Rajashekara (Committee Member) Subjects: Animal Sciences

Master of Science, The Ohio State University, 2023, Animal Sciences

Intranasal vaccination has important implications for generation of vaccine-induced cross protective immunity against mucosal infections, including influenza A virus (IAV). In this study, intranasal delivery of an adjuvanted nanoparticulate vaccine platform was developed and characterized. The whole inactivated swine influenza virus (OH10-H1N2) and STING-activating ADU-S100 adjuvant was either surface adsorbed or entrapped in mannose-chitosan nanoparticles (m-Chit-NPs). The m-Chit-NPs were optimized by studying NPs size distribution, zeta potential and cytotoxicity. A cross protective study was performed using a heterologous challenge infection in vaccinates using CA09-H1N1 IAV in specific-pathogen-free (SPF) pigs following prime-boost vaccination. Samples from animals were evaluated for viral loads in the nose, antibody as well as innate and adaptive cellular immune responses both at systemic and respiratory tract. Physical characterization of m-Chit NPs showed that these particles are suitable for mucosal vaccination with zeta potential ≥ +15 mV, polydispersity index of <0.5, size diameter of around 350nm and 1:9 antigen (Ag)/NPs mass ratio for both loading methods with 75% cell viability. Animal study results show that m-Chit-NP intranasal vaccination induced cross reactive secretory IgA antibodies in both upper and lower airways exceeding those in FluSureXP™ - a commercial swine influenza virus vaccine. Between mucosal vaccine groups, the Ag entrapped vaccine induced higher virus specific neutralizing activity in serum, whereas surface adsorbed vaccine induced high virus neutralization and hemagglutination inhibition (HAI) activity in bronchoalveolar lavage (BAL) fluid. Mucosal vaccination induced high gamma interferon and IL-17A secreting cytotoxic T lymphocytes and T-helper/memory cells both systematically and in tracheobronchial lymph nodes, especially pronounced in Ag and adjuvant entrapped vaccinates. Viral replication was reduced substantially in the nose (open full item for complete abstract)

Committee: Renukaradhya Gourapura Dr. (Advisor); Scott Kenney Dr. (Committee Member); Anastasia Vlasova Dr. (Committee Member) Subjects: Animal Diseases; Animal Sciences; Immunology

Doctor of Philosophy (Ph.D.), Bowling Green State University, 2022, Photochemical Sciences

Nature provides a wide range of biopolymers that have been used over the years to create different materials with different properties. Among these biopolymers, we used polysaccharides to develop sustainable materials with unique properties. To enhance their properties, we tried recreating the hierarchal assemblies found in nature between soft organic and hard inorganic components. In other words, our approach was to use metal coordination to ligand groups present in the polysaccharides to make materials with unique mechanical properties and water stability. We also wanted to be able to use light to modify the properties of these materials or degrade them. We chose to work with Fe(III) and V(V) metal ions because these two metals ions showed photoreactivity with different ligands such as carboxylate-containing polyuronates such as alginate and pectin, and other polysaccharides such as chitosan and cellulose and small hydroxy acids such as tartaric acid. First, we studied the photoreactivity of V(V) with two polysaccharides, alginate and chitosan in aqueous solution. In both solutions, a decrease in viscosity was observed with light irradiation accompanied by a change in color from an initial yellow color to a blue color corresponding to the photochemical reduction of V(V) to V(IV) according to previous studies. Second, we made solid films from pectin and chitosan and improved their properties using V(V) ion coordination. V(V)-coordinated films showed increased strength and water stability compared to V(V)-free films. The photochemical reaction observed in solution was also observed in solid state. Finally, to further understand the photochemical reaction in solid state, we made films by blending two of the three polysaccharides, either pectin and chitosan or pectin and ᴋ-carrageenan with different Fe-species. We learned that rheological properties and photochemical properties can be tuned by changing the blend of polysaccharide (open full item for complete abstract)

Committee: Alexis D. Ostrowski Ph.D. (Committee Chair); Xiangdong Xie Ph.D. (Other); Alexander Tarnovsky Ph.D. (Committee Member); Joseph C. Furgal Ph.D. (Committee Member) Subjects: Chemistry; Polymer Chemistry; Polymers

Master of Science (MS), University of Toledo, 2020, Pharmaceutical Sciences (Industrial Pharmacy)

In-situ forming depots for drug delivery are a remarkable emerging technology that offer many advantages compared to traditional injectables. The depot can act to slowly release therapeutics thus reducing administration rate and increasing patient compliance. These depots can be liquid when administered but then turn into a semi solid in the body. Chitosan-based hydrogels can fall under this category when combined with a gelling agent. These hydrogels behave as a solution at low temperatures and induce gelation when introduced to the higher temperature of the body. However, chitosan hydrogel lacks in its ability to gel quickly at body temperature and in its mechanical strength. The addition of co-polymers and additional gelling agents have showed positive effects. Chitosan was added with gelatin and sodium bicarbonate to analyze the effects produced. With a design of experiment software, unique formulations were created and subjected to rheological and mechanical testing. All hydrogels were thermoresponsive at a variety of temperatures. Analysis of the data produced a formulation with ideal characteristics and the effect of changing the ratio of gelling agents were analyzed.

Committee: Jerry Nesamony (Committee Chair); Gabriella Baki (Committee Member); Caren Steinmiller (Committee Member) Subjects: Pharmaceuticals; Pharmacy Sciences

Master of Science in Chemistry, Youngstown State University, 2020, Department of Chemistry

Immobilized multienzyme systems catalyzing cascade reactions have shown to be an effective industrial strategy. These systems reduce production cost by increasing both reusability and stability of enzymes under extreme conditions. Development of a stable support for enzyme immobilization further improves the process. The objective of this study was to improve lactose hydrolysis by designing a two-component system comprised of lactase and glucose oxidase immobilized independently on a modified chitosan support. The structural stability of chitosan was enhanced by addition of fortifying agents such as activated charcoal, silica, and magnetic particles followed by crosslinking beads with glutaraldehyde. Lactase was immobilized on chitosan-magnetic beads, chitosan-charcoal beads, and chitosan-silica beads. Glucose oxidase was immobilized on chitosan-charcoal beads and chitosan-silica beads. The physical properties, immobilization efficiency, and enzymatic activity were determined for each immobilized enzyme. Both enzymes, lactase and glucose oxidase, retained their activity after immobilization. Assays performed with the combinations of the chitosan beads indicated that the immobilized enzymes are capable of catalyzing two sequential reactions - lactose hydrolysis and glucose oxidation.

Committee: Nina Stourman PhD (Advisor); Michael Serra PhD (Committee Member); Douglas Genna PhD (Committee Member) Subjects: Biochemistry; Chemistry

Doctor of Philosophy, The Ohio State University, 2020, Animal Sciences

Salmonellosis causes around one million illness every year in the Unites States. The symptoms of the disease in human include diarrhea, fever and vomiting. Animal-origin foods especially Salmonella Enteritidis contaminated poultry-related produce, remain the most common source of Salmonella outbreaks, which is responsible for half of the total cases of food poisoning. With the huge consumer demand of chicken meat in the U.S., reducing Salmonella colonization in broilers can largely decrease the risk of foodborne salmonellosis. Current Salmonella vaccines in broiler have failed to provide protection and reduce food contamination. Therefore, our goal is to develop an innovative Salmonella oral vaccine which elicits robust immunity and reduces bacterial colonization and shedding in broilers. Our preliminary data showed gastric pH resistant biodegradable and mucoadhesive chitosan (CS) nanoparticles based vaccine containing entrapped immunogenic outer membrane proteins (OMP) and flagellin (FLA) of Salmonella Enteritidis (SE) with surface labeled flagella [CS(OMP+FLA)-F] was found targeted to intestinal immune sites and induced the expression of important Toll-like receptors in cecal tonsils of birds. In this study, we first prepared CS(OMP+FLA)-F and the temporal dynamic immune responses of the immunized broilers were examined after 1st dose to 3-day-old broilers and 2nd dose inoculated 2 weeks later. We observed increased mRNA expression level of Toll-like receptors (TLRs) 1, 4, 7 and 7 in the cecal tonsils of birds received CS(OMP+FLA)-F, especially at 7 days post 1st dose of vaccine delivery. The antigen specific splenocytes proliferation response was enhanced after 7 days post 1st and 2nd dose of vaccine. This study showed our candidate vaccine can induce both innate and adaptive immune responses. To determine the efficacy of candidate vaccine and investigate the ideal vaccination schedule for maximum protection, dose- and age-dependent study was carried out followed (open full item for complete abstract)

Committee: Renukaradhya Gourapura (Advisor); Ramesh Selvaraj (Advisor); Michael Lilburn (Committee Member); Sheila Jacobi (Committee Member); Thaddeus Ezeji (Committee Member) Subjects: Animal Sciences

Doctor of Philosophy, University of Akron, 2020, Integrated Bioscience

The World Health Organization (WHO) estimated the number of spinal cord injuries to be between 250,000 and 500,000 new cases every year, with an increasing incidence over the years. In the USA alone, about 282,000 persons are living with SCI. All these cases suffer from loss of sensory and motor functions to some degree, and there is no definitive treatment until now that can restore these functions. Moreover, one-third of these patients experience insidious damage to the neural tissues and a decline in the quality of their lives due to the development of post-traumatic intraspinal cystic lesions. The strategies for restoring neurological functions are long-term solutions, retrospective, and require the synergy of different therapeutic approaches. Along with these strategies, simple proactive strategies are required to prevent SCI complications. Molecular mechanisms involved in spinal cord development and disease seem very promising targets for both strategies, yet they are mostly unclear. Better exploitation of these molecular mechanisms can help researchers find definitive solutions for urgent and long-term problems, even without a full understanding of them. Therefore, the primary objective of this study was to prove the utility of some of the mechanisms involved in spinal cord development and disease while attempting to explain how they work, when possible. The overall hypothesis of this work is that molecular mechanisms involved in the spinal cord development and disease can be exploited for improving the outcome of SCI treatment. First, the focus was on utilizing the molecular signaling and cues retained in the subcutaneous environment throughout adulthood for priming aNSPCs encapsulated in chitosan-based hydrogel and helping nascent neurons acquire region-specific identity based on the region of implantation of the bioscaffold. To investigate this hypothesis, I implanted three bioscaffolds in the subcutaneous tissues in the back of rats in the cervical, thor (open full item for complete abstract)

Committee: Nic Leipzig (Advisor); Abraham Joy (Committee Member); Jordan Renna (Committee Member); Rebecca Willits (Committee Member); Ge Zhang (Committee Member) Subjects: Biology; Biomedical Engineering; Biomedical Research; Neurosciences

Doctor of Philosophy, University of Toledo, 0, Biomedical Engineering

Cellulose and chitosan (CS) are two of the most abundant biopolymers in nature. CS is highly explored in tissue engineering applications mainly because of its unique chemical structure of possessing cationic amine groups. This bestows it with the ability to have specific interaction with extracellular matrix components such as glycosaminoglycan and proteoglycans making it even more attractive in bone regeneration. This study focused on the application of these biopolymers towards the development of microparticles and hence robust injectable bone scaffolds. The current strategy of applying MPs for bone regeneration involves their direct injection to the defect site. This technique most of the time, however, leads to the improper localization of those MPs. This becomes more problematic when these MPs are loaded with therapeutic agents or growth factors as the intended localized delivery of those agents could not be achieved. Another strategy that has been implemented for the use of MPs in bone regeneration involves the development of preformed solid scaffolds created mostly through chemical agglomeration or sintering techniques. This technique, however, takes away the injectable property of MPs making them like the conventional solid scaffolds. To address this issue related to the applications of the MPs and to develop effective therapeutics releasing scaffolds, the concept of embedding microparticles into a thermosensitive gel was used. This MPs-gel composite was developed to stay as a liquid at a lower temperature enabling an easy injection, but it undergoes a temperature-induced transition to gel at physiological temperature (37 oC). This gel enables the proper localization of MPs at the target defect site enabling efficient therapeutic effects. The blend of methylcellulose (MC) and alginate (Alg) was used to develop thermosensitive gel. The gelation occurs primarily due to the physical interaction among the hydrophobic chains of MC and is further strengthened by (open full item for complete abstract)

Committee: A. Champa Jayasuriya (Committee Chair); Arunan Nadarajah (Committee Member); Sarit Bhaduri (Committee Member); Ahalapitiya H. Jayatissa (Committee Member); Jiayong Liu (Committee Member) Subjects: Biomedical Engineering

Master of Science in Engineering, University of Akron, 2019, Biomedical Engineering

Wound healing is a challenge not specific to a particular demographic. It affects all areas of the world and is the result of many different disease types and scenarios. There is a vast array of sources for disease initiation in wound healing and the field currently lacks simple and effective solutions for remedying the ailment. Oxygen is an essential component required in many of the biochemical processes occurring during the wound healing process and many chronic wounds lack oxygen resulting in wounds that do not heal or heal too slowly. A wound healing hydrogel, methacrylated fluorinated (Ali15) chitosan (MAC) also known as MAC(Ali15)F, was developed and characterized in an attempt to enhance local oxygen concentrations in oxygen-deficient skin. More specifically, this chitosan-based hydrogel used Schiff base nucleophilic substitution to attach perfluorocarbons (PFCs), which are known for their ability to capture oxygen from the surrounding atmosphere. Material characterization studies showed the MAC(Ali15)F hydrogel's ability to release oxygen, to sustain lysozyme concentrations of 1000 U/mL, and to retain the ability after degradation to sequester oxygen. The MAC(Ali15)F hydrogel showed evidence of biocompatibility when exposed to human dermal fibroblasts and in rodent studies. In vitro studies established that the hydrogels encouraged cell proliferation. In vivo studies indicated that the wounds being treated with hydrogels were able to progressively heal in a moist environment. Preliminary studies show that the hydrogels have the potential to provide specific levels of oxygen to the wound site while simultaneously providing moisture for wounds in a portable and customizable bandage size.

Committee: Nic Leipzig Ph.D. (Advisor); Brian Davis Ph.D. (Committee Member); Judith Fulton Ph.D. (Committee Member); Rebecca Kuntz-Willits Ph.D. (Committee Member) Subjects: Biomedical Engineering; Chemical Engineering

Doctor of Philosophy, The Ohio State University, 2018, Comparative and Veterinary Medicine

Swine influenza A virus (SwIAV) causes severe economic loss to the swine industry globally. Pigs are also regarded as mixing vessel for influenza A viruses (IAV) of human, avian and swine origin, generating viruses capable of human infections. Vaccination is one of the effective means to prevent influenza in pigs. Currently available SwIAV vaccines in pigs are predominantly monovalent or multivalent whole inactivated virus (WIV) vaccines administered by intramuscular (IM) route with potent adjuvants. IM WIV vaccines provide homologous protection, but limited heterologous protection against continuously evolving field viruses, attributable to the induction of inadequate levels of mucosal IgA and cellular immune responses in the respiratory tract. Additionally, IM WIV vaccines are not effective in the presence of maternally-derived antibodies (MDA) and often lead to vaccine-associated enhanced respiratory disease (VAERD) when vaccine virus antigenically mismatches with challenge virus. Therefore, an alternative vaccine delivery approach is required to develop efficient SwIAV vaccine. A novel vaccine delivery platform using biodegradable and biocompatible polymer-based nanoparticles (NPs) administered through intranasal (IN) route, has the potential to elicit strong mucosal and cellular immune responses in pigs and overcome the limitations of current IM WIV vaccines. In this study, we developed poly(lactic-co-glycolic acid) (PLGA), polyanhydride, chitosan and Nano-11 NPs-based SwIAV vaccine candidates. Inactivated/killed SwIAV H1N2 (delta-lineage) antigens (KAg) were either encapsulated within or adhered onto the surface of NPs. The vaccine candidates were administered twice IN as mist to nursery pigs. Vaccinates and controls were then challenged with a zoonotic and virulent heterologous SwIAV H1N1 (gamma-lineage) via IN and intratracheal routes. None of the nanovaccines enhanced respiratory disease after virus infection. The IN PLGA-based nanovaccine resulted in ro (open full item for complete abstract)

Committee: Renukaradhya Gourapura (Committee Chair); Chang-Won Lee (Committee Member); Prosper Boyaka (Committee Member); Jordi Torrelles (Committee Member); Scott Kenney (Committee Member) Subjects: Immunology; Microbiology; Nanotechnology; Veterinary Services; Virology

Master of Science, University of Toledo, 2018, Chemical Engineering

Commercial antibacterial formulations typically contain toxic biocidal compounds such as cationic surfactants, sodium hypochlorite or triclosan. To this end, recent studies have explored using biocidal biopolyelectrolyte-based particles as potential substitutes. In this thesis, we exploit the antibacterial activity of chitosan derivative, N-(2-hydroxyl)propyl-3-trimethyl ammonium chitosan chloride (HTCC), in preparing antibacterial colloidal particles. The particles are formed via self-assembly by complexing HTCC with either tripolyphosphate (TPP) or alginate. Each ingredient used to prepare these particles is non-toxic to mammalian cells and their physiochemical properties are easily tuned by varying the HTCC, TPP and alginate concentrations, as well as the solution pH. Since phosphates can lead to aquatic eutrophication upon their disposal into the environment, the use of alginate over TPP is desirable. Moreover, HTCC/alginate particles form over a broader range of compositions than HTCC/TPP particles and (at least at the compositions explored for the two particle types) remain stable for longer times. HTCC/alginate particles maintain their dispersed state over as long as 9 months of iv storage at both room temperature and refrigerated (4 °C) conditions, and particles mixed with non-ionic non-toxic surfactant Triton X-100 (TX-100) stayed stable over as many as 6 months under the same conditions. This particle/surfactant mixture was tested against several bacterial strains, both Gram-positive and Gram-negative. Though it exhibited biocidal activity against all tested strains, the particle/surfactant mixture was especially effective against highly resistant opportunistic pathogen P. aeruginosa (where complete bacterial reduction was achieved within 30 min of contact). Finally, the effect of this formulation on wastewater treatment was investigated with the Microtox Toxicity Test (MTT), which indicated that the particle/surfactant mixture have a negligible toxicit (open full item for complete abstract)

Committee: Yakov Lapitsky PhD (Committee Chair); Youngwoo Seo PhD (Committee Member); Dong-Shik Kim PhD (Committee Member) Subjects: Chemical Engineering; Environmental Engineering

MS, University of Cincinnati, 2018, Engineering and Applied Science: Environmental Engineering

This dissertation provides background information about dyes and different treatment technologies available for the removal of dyes from wastewater. The presence of dyes in wastewater is a serious environmental and health concern. Various treatment technologies have been studied for dye removal and adsorption is considered as one of the efficient methods for dye removal. Apart from conventional adsorbents such as activated carbon, adsorbents prepared from agricultural and industrial wastes have been studied. One such promising material is chitosan which is waste product from the seafood industry. This study focuses on the adsorptive removal of dyes. In this study, an adsorbent is prepared using chitosan and granular activated carbon (GAC- Filtrasorb 400) as raw materials. The adsorption potential of the prepared adsorbent and GAC were investigated by conducting equilibrium, kinetics and adsorbent characterization studies. GAC was modified by chitosan impregnation. Different samples were developed using different carbon to chitosan weight ratios. The adsorption capacity was determined by conducting equilibrium studies for the adsorption of three dyes, namely, Acid Blue 113 (AB 113), Basic Blue 3 (BB 3) and Direct Blue 71 (DB 71). Among the different adsorbent samples prepared, modified granular activated carbon sample containing carbon to chitosan in the ratio of 5 to 1 (MGAC (5:1)), produced comparatively better results for each dye. GAC and MGAC (5:1) were used for conducting further experimental investigations. The equilibrium data obtained was compared with the Langmuir and Freundlich adsorption isotherm models. There was an increase in the adsorption capacity in the chitosan impregnated activated carbon when compared to virgin activated carbon towards the adsorption of each dye, indicating its versatility. The adsorption of BB 3 on to MGAC (5:1) showed about 40% increase when compared to the adsorption capacity of GAC. The increase in adsorption capacity in t (open full item for complete abstract)

Committee: George Sorial Ph.D. (Committee Chair); Margaret Kupferle Ph.D. (Committee Member); Drew McAvoy Ph.D. (Committee Member) Subjects: Environmental Engineering

Doctor of Philosophy, University of Toledo, 2017, Chemical Engineering

Ionically crosslinked chitosan nanocarriers have attracted significant attention as potential drug delivery vehicles due to their biocompatibility, mucoadhesiveness, payload protection ability, and mild formation/payload encapsulation procedures. Despite these advantages, however, most studies on these materials have tuned their drug uptake and release properties by trial and error, and not infrequently reported conflicting results. This dissertation aimed to address some of these issues. To better understand drug uptake properties, we have shown that, besides increasing with the drug/particle binding affinity, protein drug association efficiency (i.e., the fraction of the added protein that was taken up) increased almost linearly with the particle yield (the fraction of the added chitosan that self-assembled into particles). This scaling was explained via a predictive equilibrium binding model and suggested that many of the (often conflicting) variations in protein uptake reported in the literature might stem from the largely ignored variability in particle yield. Because sustained drug release could be affected by particle dissolution stability, ionically crosslinked chitosan particle dissolution was also examined. This revealed hysteresis in the ionic crosslink formation/dissociation cycle (where particle dissolution occurred at lower ionic crosslinker concentrations than those required for particle formation). Also explored was whether drug/particle binding (where the drug molecules served as additional physical crosslinks between the chitosan chains) enhanced the dissolution stability of chitosan/tripolyphosphate (TPP) particles. This indicated that, while protein/chitosan binding was insufficiently strong to generate a stabilizing effect, chitosan/TPP particles could be stabilized against dissolution through the uptake of DNA. Further, it has long been ignored that the in vitro drug release profiles obtained for chitosan particles via the common “s (open full item for complete abstract)

Committee: Yakov Lapitsky (Committee Chair); Constance Schall (Committee Member); Sasidhar Varanasi (Committee Member); Matthew Liberatore (Committee Member); Eda Yildirim-Ayan (Committee Member) Subjects: Biomedical Engineering; Chemical Engineering; Pharmaceuticals; Polymers

Doctor of Philosophy, University of Akron, 2017, Chemical Engineering

Hundreds of thousands of people suffer from spinal cord injuries in the U.S.A. alone, with very few patients ever experiencing complete recovery. Complexity of the tissue and inflammatory response contribute to this lack of recovery, as the proper function of the central nervous system relies on its highly specific structural and spatial organization. The overall goal of this dissertation project is to study the central nervous system in the healthy and injured state so as to devise appropriate strategies to recover tissue homeostasis, and ultimately function, from an injured state. A specific spinal cord injury model, syringomyelia, was studied; this condition presents as a fluid filled cyst within the spinal cord. Molecular evaluation at three and six weeks post-injury revealed a large inflammatory response including leukocyte invasion, losses in neuronal transmission and signaling, and upregulation in important osmoregulators. These included osmotic stress regulating metabolites betaine and taurine, as well as the betaine/GABA transporter (BGT-1), potassium chlodride transporter (KCC4), and water transporter aquaporin 1 (AQP1). To study cellular behavior in native tissue, adult neural stem cells from the subventricular niche were differentiated in vitro. These cells were tested under various culture conditions for cell phenotype preferences. A mostly pure (>80%) population of neural stem cells could be specified using soft, hydrogel substrates with a laminin coating and interferon-¿ supplementation. To guide and possibly recruit native stem cells, as well as reduce injury in the spinal cord, an injectable delivery iv strategy is necessary. An in situ cross-linking hydrogel could increase latency and localization of treatments. In this project, a chitosan/PEG based hydrogel was tailored for CNS tissues with low swelling post-gelation, a low elastic modulus (0.37 kPa), and very low cytotoxicity. When injected into the spinal cord parenchyma, the hydrogel elicited (open full item for complete abstract)

Committee: Nic Leipzig (Advisor); George Chase (Committee Member); Gang Cheng (Committee Member); Chelsea Monty (Committee Member); Abraham Joy (Committee Member); Rebecca Willits (Committee Member) Subjects: Biomedical Research; Materials Science; Neurobiology

Master of Sciences (Engineering), Case Western Reserve University, 2017, Biomedical Engineering

Hydrogels allow chondrocytes to maintain their morphology and provides an ideal environment for the chondrocytes to produce cartilage. Hydrogels have been widely used in three- dimensional (3D) printing to create scaffold for tissue engineering. There are various methods in additive manufacturing however, for this study we have decided to use stereolithography because of its high accuracy. In this study, we created a new hybrid biocompatible resin using a combination of natural and synthetic polymers (chitosan and polyethylene glycol diacrylate (PEGDA), respectively) by varying feed-ratios and photo-initiator concentration. Ear-shaped hybrid scaffolds were fabricated by a stereolithographic method using a low cost commercially available 3D printer. Hybrid hydrogel mixture of chitosan (50–190 kDa) and PEGDA (575 Da) were mixed at different feed-ratios. The formulations that were made were ideal in terms of mechanical properties and cell viability. However, the lyophilizing the scaffold affected the porosity that resulted in uneven cell adhesion. Therefore, an alternative formulation of Chitosan and PEGDA mixture was created which subsequently improved the scaffold porosity by CAD printing of the scaffold. This is the first report of stereolithographic printing using a commercially available low cost 3D printer hybridizing cell adhesive properties of chitosan with mechanical robustness of PEGDA in scaffolds suitable for regenerative process of the cartilage.

Committee: Ozan Akkus (Committee Chair); Dominique Durand (Committee Member); Eben Alsberg (Committee Member) Subjects: Biomedical Engineering; Biomedical Research

Doctor of Philosophy, The Ohio State University, 1954, Graduate School

Committee: Not Provided (Other) Subjects: Chemistry

Master of Science, University of Toledo, 2016, Bioengineering

This study explored the possibility of fabricating bio-factionalized injectable scaffolds for craniofacial bone repair using biopolymers and bioceremics. Injectable porous spherical particles were fabricated using chitosan biopolymer (CS), sodium tripolyphosphate (TPP), nano-hydroxyapatite (nHA) and nano-calcium phosphate (nCaP). TPP was primarily used as an ionic crosslinker to crosslink nHA/CS and nCaP/CS droplets. The hypothesis of this study was that incorporating nHA or nCaP into CS could support the osteoconduction by emulating the mineralized cortical bone structure, and improve the ultimate compressive strength (UCS) of the particles. Chitosan solutions were prepared with 0-2% nHA and 0-1% nCaP concentrations and used simple coacervation and lyophilization techniques to obtain spherical particles. The lyophilized nHA/CS and nCaP/CS spherical particle groups had mean diameters of 1.33 mm and 1.404 mm (n = 25) respectively. Further, portion of 2% nHA/CS lyophilized particles were soaked and dried to obtain lyophilized soaked and dried (LSD) particles. LSD particles had a mean diameter of 0.93 mm (n = 25). Scanning electron microscopy images showed porous surface morphology and interconnected pore structures inside all particle groups. One-way ANOVA results showed a significant increase (p < 0.001) in UCS of 0.5% nCaP/CS lyophilized particles compared to all other nCaP/CS and nHA/CS lyophilized particle groups. Moreover, LSD particles had significantly increased (p < 0.005) their mean UCS by 120% compared to its corresponding lyophilized particle group. In a drawback, all particles have transformed to gel like beads and lost their mechanical properties by 95% on the 2nd day when fully immersed in phosphate buffered saline. The live and dead cell assay showed no cytotoxicity and excellent osteoblast attachment to lyophilized particle groups at the end of 14th day of in vitro studies. 2% nHA/CS particles showed higher osteoblast attachment than 0% nHA/CS particl (open full item for complete abstract)

Committee: Champa Jayasuriya PhD (Committee Co-Chair); Arunan Nadarajah PhD (Committee Co-Chair); Patricia Relue PhD (Committee Member); Kelly Marbaugh PhD (Committee Member) Subjects: Biomedical Engineering; Biomedical Research

MS, University of Cincinnati, 2016, Engineering and Applied Science: Materials Science

Toxicity of commercially available curing agents for epoxy resins pose a severe environmental threat. There is therefore a need for alternative non-toxic curing agents for epoxy resins. In this research, Chitosan, a biomaterial, was employed as an environmentally friendly curing agent for crosslinking Diglycidyl Ether of Bisphenol A (DGEBA) resins. Properties such as cross-linking behavior, viscoelastic behavior, and thermal stability were investigated. Curing behavior of diglycidyl ether of bisphenol A resin using chitosan was studied by Fourier Transform Infrared (FTIR) Spectroscopy. Degree of crosslinking, correlated with the epoxy fractional conversion (α), was determined by following the change in area of oxirane ring peak at 914 cm-1. Four molar ratios (Epoxy:Chitosan) 1:1, 1:2, 1:3, and 1:4 cured at three isothermal curing temperatures 160°C, 180°C, and 200°C for 5 hours, were used to determine the effect of temperature and concentration of chitosan on the epoxy fractional conversion (α). It was found that the value of `α' increased over curing time, curing temperature, and chitosan concentration. The maximum epoxy fractional conversion of 70% was obtained for molar ratio of 1:4 at 200°C. A four parameter kinetic model with two rate constants was employed to simulate the experimental data obtained from FTIR analysis. Total order of the reaction was found to be about 2.8 and the activation energy was in the range of 27-48 KJmol-1. Result obtained shows that cure reaction is autocatalytic in nature, and does not follow simple nth order cure kinetics. Avrami analysis was performed on the curing reaction and parameters such as Avrami exponent (n), rate constant (k) and activation energy (Ea) were determined. At 200°C, the value of n, k and Ea were 0.87, 8.88 and 24.21 KJmol-1 respectively for molar ratio of 1:4 (Epoxy:Chitosan). Dynamic Mechanical Analysis (DMA) was used to study the viscoelastic properties of the chitosan cured epoxy resin films. Glass transi (open full item for complete abstract)

Committee: Jude Iroh Ph.D. (Committee Chair); Relva Buchanan Sc.D. (Committee Member); Raj Manglik Ph.D. (Committee Member) Subjects: Materials Science

PhD, University of Cincinnati, 2016, Engineering and Applied Science: Materials Science

A drug delivery device (micro-implant) providing sustained release of hydrophilic drugs has the potential to improve the therapeutic outcome for treatment of vitreoretinal (VR) diseases such as primary intraocular lymphoma, uveitis and proliferative retinopathy. At present, the preferred treatment of VR diseases is intravitreal methotrexate (MTX) injection. Each intravitreal injection of MTX is associated with potentially toxic and sub-therapeutic MTX concentrations. Repetitive intravitreal injections are required to maintain therapeutic MTX concentration. A drug delivery system is desired for sustained therapeutic release (0.2-2.0 µg/day) of MTX for >1 month to achieve effective treatment of VR diseases. In an in vitro study, chitosan (CS) and polylactic acid (PLA)-based micro-implants were fab-ricated for different MTX loadings (10%, 25% and 40% w/w). The micro-implant structure was characterized using optical and scanning electron microscopy, time of flight-secondary ions mass spectroscopy and differential scanning calorimetry techniques. The MTX release rate studies were evaluated using a UV-Visible Spectrophotometer. It was observed that uncoated CS-MTX micro-implant released MTX rapidly (~1 day) because of the hydrophilic nature of both CS and MTX. However, the CS-MTX micro-implant with a lipophilic coating of PLA showed therapeu-tic MTX release (0.2–2 µg/day) for >50 days. The MTX release kinetics from the coated micro-implants is explained by a) the Korsmeyer Peppas and zero order model fit (R2~0.9) of the first 60% of MTX release which indicates the swelling of polymer and initial burst release of MTX; and b) the first order and Higuchi model fit (R2 ~ 0.9) from the 10th day to the end of drug release, implying the therapeutic MTX release depends on its concentration and follows diffusion kinetics. The pharmacokinetics and toxicity of the PLA-coated CS-MTX micro-implant (40% w/w MTX) was evaluated in rabbit eyes. High performance liq (open full item for complete abstract)

Committee: Rupak Banerjee Ph.D P.E. (Committee Chair); Zelia Correa M.D. Ph.D. (Committee Member); James Augsburger M.D. (Committee Member); Relva Buchanan Sc.D. (Committee Member); Jude Iroh Ph.D. (Committee Member) Subjects: Materials Science