Chitosan was widely studied for applications in tissue regeneration, because of its biodegradability and biocompatibility. However, its insolubility in a neutral solution and long gelation time limit its wide application in tissue engineering. In this thesis, a new chitosan-based biomaterial was synthesized, and its chemical structure and solubility were characterized. Afterwards, the gelation properties (crosslinker, crosslink time, swelling ratio, drug release and biocompatibility) of TMC material was investigated. Results show that TMC has higher water solubility than chitosan. The TMC liquid solution can transform to a hydrogel quickly at body temperature. The formed hydrogel controlled the release of the model protein. Cytotoxicity result shows the cationic TMC hydrogel brings a toxic effect on stromal cells but it may have the potential to inhibit bacteria or cancer cells, although more studied are required to confirm its potential functions. In summary, this new TMC hydrogel has a promising potential in biomedical fields. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

M.Sc. (Nanoscience) / Ochratoxin A and Aflatoxin B1 are important food contaminates as they are known to be mutagenic, genotoxic, nephrotoxic, hepatotoxic, immunosuppressive and teratogenic to both animals and humans. These mycotoxins are associated with the contamination of food stuff such as grapes, maize, red pepper, meat, milk, beans and processed products from contaminated raw material. Current physical, biological and chemical methods employed to improve the safety of food often compromise the nutritional value and result in huge losses. The alternative to these treatments are addition of supplements with protective properties to reduce the toxicity of mycotoxins or prevent their formation. The work presented in this dissertation reports an attempt to develop such materials to prevent damage caused by ochratoxin A and aflatoxin B1. This was done through the synthesis; characterisation and cytotoxicity study of chitosan nanoparticles with methanolic plant extracts (L. leonurus, M. longifolia and A. montanus). Inhibition of cellular damage due to mycotoxins for possible application in prevention of cellular damage by mycotoxins also presented. Chitosan nanoparticles were synthesised using an ionic gelation method with sodium triphosphate as the cross linker. The methanolic medicinal plants extracts were incorporated into the chitosan solution before synthesising nanoparticles, and nanoparticle synthesis initiated by the addition of sodium triphosphate solution. The synthesised products were characterised using zetasizer, transmission electron microscopy, x-ray diffraction and Fourier-transform infrared spectroscopy. The extracts’ antioxidant ability was evaluated before incorporation into chitosan using 2, 2-diphenyl- 1-picrylhydrazy (DPPH) radical scavenging assay. This assay was performed using UVvis spectroscopy. The cytotoxicity of the synthesised nanoparticles was assessed using a Vero cell line and by evaluating the cell viability with an MTS assay. The nanoparticles were successfully synthesised and showed the presence of different functional groups as expected. Plain chitosan nanoparticles were roughly spherical shaped and had smooth surfaces, nanoparticles containing extracts similarly were spherical in shape as well but had rougher surfaces when visualised under TEM. All nanoparticles had positive zeta potentials between 26 – 28 mV. The average particle sizes ranged between 31 – 65 nm as measured using TEM and average particle sizes obtained using zetasiser was 78 – 190 nm. The cytotoxicity studies of plain nanoparticles and nanoparticles with extract showed that the synthesised nanomaterials were not toxic even at concentration of 500 μg/ml and less than 20% of the Vero cells were affected under these conditions.

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering September, 2017 / South Africa emits large amounts of carbon dioxide (CO2) due to its reliance on coal. The emission of CO2 needs to be reduced for clean sustainable energy generation. Research efforts have therefore been devoted to reducing CO2 emissions by developing cost-effective methods for capturing and storing it. Amine-based absorption using monoethanolamine solvent is the most mature technique for CO2 capture despite its huge energy consumption, corrosiveness and difficulty in solvent regeneration. However, CO2 removal by solid adsorbents is a promising alternative because it consumes less energy, and can be operated at moderate temperature and pressure. Metal organic frameworks have received attention as a CO2 adsorbent because they have large surface areas, open metal sites, high porosity and they require less energy for regeneration. This research was aimed at optimizing and scaling-up SOD-ZMOF through structural modification for enhanced CO2 adsorption by impregnating it with chitosan. Scaled-up SOD-ZMOF samples were prepared as described elsewhere and impregnated with Chitosan. Physiochemical properties obtained using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Nitrogen physisorption showed that SOD-ZMOF and SOD-ZMOF-chitosan were successfully synthesized. Qualitatively, the surface area of the SOD-ZMOF synthesized using the scaled up protocol is lower than the one prepared using the non-scaled-up protocol XRD pattern of SOD-ZMOF showed that it was crystalline and was in agreement with literature. The XRD peaks of the SOD-ZMOF decreased after chitosan impregnation showing that chitosan was impregnated on SOD-ZMOF. The FTIR spectrum of SOD-ZMOF showed functional groups present in organic linker used to synthesize SOD-ZMOF, and that of the SOD-ZMOF-chitosan revealed the same functional groups but with disappearance of carboxylic acid functional group. N2 physisorption showed a decrease in BET surface area and pore volume after chitosan impregnation on SOD-ZMOF as well. Performance evaluation of the material was carried out with a demonstration adsorption set-up using a 15%/85% CO2/N2 mixture and as a thermal gravimetric analysis (TGA) using 100% CO2. For both the packed-bed column and the TGA experiments, evaluation was conducted on SOD-ZMOF and SOD-ZMOF with chitosan for comparison. About 50 mg of the adsorbent was used at 25 oC, 1 bar and 25 ml/min for the packed-bed column. For the adsorption with the TGA, 11 mg of adsorbent was used at 25 ℃, 1 bar and 60 ml/min. SOD-ZMOF showed improved adsorption capacity after chitosan impregnation. CO2 adsorption capacity of SOD-ZMOF increased by 16% and 39% using packed-bed column and TGA, respectively, after chitosan impregnation. The increase in adsorption capacity was attributed to the impregnated chitosan that has amine groups that display a high affinity for CO2. A traditional approach was used to investigate the effect of adsorption temperature and inlet gas flowrate on the CO2 adsorption capacity of SOD-ZMOF-chitosan. This was done using both the parked bed column and the TGA. Temperature range of 25-80 ℃ and inlet gas flowrate range of 25-90 ml/min were investigated. Adsorption capacity increased with a decrease in temperature and inlet gas flowrate. For the packed-bed column, maximum of 781 mg CO2/ g adsorbent was obtained at 25℃, 1 bar, 25 ml/min and for the TGA a maximum CO2 adsorption capacity of 23 mg/ g adsorbent at 25 ℃, 1 bar, and 60 ml/min was obtained. / MT2018