Zeolites are nanoporous crystalline aluminosilicates that are tasteless, odorless and nontoxic to humans. They can be tailored into antibacterial agents that are more cost effective than other conventional alternatives. Considering the increasing demand for enduring antibacterial agents, the potential uses of antibacterial zeolites are numerous in medical applications and for everyday household products. To produce antibacterial zeolites, the extra framework cations in the zeolite structures can be exchanged with silver ion (Ag+), the most commonly used antibacterial heavy metal ion due to its high stability, strong activity and broad spectrum. Utilization of antibacterial zeolite powders can be diversified when they are used as fillers in a polymer matrix. Polyurethanes (PU) are a class of polymers which can be prepared in wide range of physical structures with excellent mechanical properties. Ag+ loaded zeolites used as fillers in the PU matrix would contribute to the diversity and efficiency of the PU utilization in many applications including biomedical uses and consumer products. In this study, three types of zeolites, namely / zeolite Beta, X and A with different pores sizes and SiO2/Al2O3 ratios were synthesized hydrothermally and treated with Ag+ containing solution for the exchange of cations. Composites were prepared by incorporation of sieved Ag+ exchanged zeolite particles into biomedical grade PU prepolymers which were prepared either in film or as sponge forms. Films were prepared by molding and foams were prepared in the presence of water as the blowing agent. Liquid media antibacterial tests showed that all of the Ag+-zeolite powders were effective against E. coli at a concentration of 500 ppm zeolite in deionized water. To assess the antibacterial effect of composites against E. coli, disc diffusion tests were carried out. Bacterial growth inhibition zones formed around the composite samples were the evidence of the antibacterial activity in the vicinity of the surface. All three kinds of zeolites successfully introduced the desired antibacterial property to the biomedical grade PU both in elastomeric film and in the foam form. Mechanical characterization of the composites yield higher ultimate tensile strength, modulus of elasticity and elongation at break values compared to control PU. No significant change in thermal properties of the composites was observed. Hence mechanical and thermal characterization of the composites showed that zeolites serve for the reinforcement of the mechanical properties of the polymer and did not cause any deterioration in thermal properties.

Master of Science / Department of Biology / Peter P. Wong / Abstract Water purification methods that remove pathogens and harmful or distasting molecules make water potable. Recently, silver loaded ion-exchange resins have demonstrated a strong role in removing microbes. The goal is to make an effective silver ion-based water purifier that is portable, environmentally stable, and cost efficient. The project was conducted as a collaborative effort with Safewater A/S, an up and coming entrepreneurial business located in Denmark that is interested in developing novel water purifiers for developing nations, adventurers and military personnel. Purolite, a prominent business in ion-exchange resins located in Whales, designed and provided Safewater A/S and our research team with experimental resins for water purification, which will be discussed in the body of this thesis. The data reveals critical issues that may render this tool unavailable for commercial production in some countries due to the mode of action for killing the bacteria and the amount of silver leaching. Tests were conducted using Escherichia coli K12 and Enterococcus faecalis OG1SSp as model fecal organisms using different silver ion-exchange resins. Surveillance of leached silver ions, pH changes, and total dissolved solids (TDS) were also monitored to find correlations with capacity (liters of purified water produced) and effectiveness of microbicidal action. Overall, one resin was found to contain properties consistent with the stated objectives; however its use in some countries as a water purifier for human consumption will be nullified due to extensive silver leaching. Although this resin could be used in the United States of America since it passes the Environmental Protection Agency (EPA) standards, Safewater A/S is interested in further developing it for countries with stricter regulatory constraints before mass production. The goal of the present thesis report is to address the stated objectives in the development of a water purifier.

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The presented dissertation encompasses three distinct investigations into novel complexes with diverse applications. Firstly, a Europium-based complex, K[Eu(hfa)4], exhibits remarkable potential for detecting dissolved CO2 in an ethylene glycol medium, offering a low limit of detection, rapid response times, and high signal-to-noise ratios. This complex demonstrates promise for quantifying CO2 concentrations and finds utility in sugar fermentation monitoring. Secondly, an innovative ratiometric optical sensor, Eu(tta)3([4,4'-(t-bu)2-2,2'-bpy)], showcases exceptional sensitivity and selectivity in detecting aluminum ions, making it suitable for environmental and biological applications. It exhibits reliable quantification in both methanol and aqueous samples, with remarkable accuracy validated by ICP-OES. Lastly, modifications to the Au3Pz3 complex synthesis enable the development of a silver ion sensor, paving the way for detecting silver ion leaching in real-life scenarios, such as silver nanoparticle-embedded bandages. The research extends to the synthesis of silver nanoparticles using various methods and foresees expanded in vitro and in vivo studies. These investigations collectively offer insights into the development of advanced sensing technologies with significant implications for a wide range of practical applications.