Metal-binding polymesr as chelating agents

Abstract

Abstract Metal chelating polymers are functional polymers that bear specified chemical groups capable of selectively binding metals. Heavy metal contamination is considered a serious problem because these metals, even at relatively low concentration, could accumulate in the human body and cause damage to vital organs. Although, some of these metals like iron, zinc, and manganese participate in controlling various metabolic and signaling pathways, an excess amount of these metals could still lead to toxicity and detrimental side effects. Metal chelating polymers are frequently used as chelating agents when treating metal toxicity such as iron overload diseases. Siderophores are small, high-affinity iron chelators secreted by microorganisms such as bacteria. The objective of this thesis was to emulate the high affinity, siderophore-mediated iron uptake system of bacteria by mimicking the structure of naturally occurring siderophores, such as enterobactin. First, polyallylamine (PAAm) hydrogels containing 2,3 dihydroxybenzoic acid (2,3 DHBA), a portion of the metal chelating domain of enterobactin, were synthesized as a potential non-absorbed chelator for iron in the gastrointestinal tract. Next, a series of polymeric chelators with various hydrogel:DHBA ratios were prepared. PAAm hydrogels were also synthesized and further modified by conjugating thioglycolic acid (TGA) and DHBA. These hydrogels were utilized for the removal of toxic metal ions such as Pb, Cd and As from aqueous environments. The rapid, high affinity binding of toxic metals by these functionalized hydrogels offers potential applications in waste water treatment and may enable applications in acute metal poisoning. Finally, a unique synthetic methodology using similar metal chelating polymers for synthesizing magnetic nanoparticles offered potential for contrast-enhanced magnetic resonance imaging or drug delivery. In summary, polymers offer an attractive platform for mimicking siderophore structure which provides new approach for applications in medicine explored here.