Polyphosphonates and their Complexes with Metal Oxides and Multi-Functional Cations

Virginia Polytechnic Institute And State University, Blacksburg VA

Investigators

Abstract

DMR 0805179: Polyphosphonates and their Complexes with Metal Oxides and Multifunctional Cations TECHNICAL SUMMARY: Molecules containing phosphonic acid or phosphate groups are well-known to bind strongly with electropositive substrates including metals and metal oxides and cations. Thus, research thrusts in this project are aimed toward gaining fundamental knowledge of 1) synthesis and properties of phosphonate copolymers, and 2) properties of complexes of those polymers with magnetite nanoparticles and polycationic antibiotics (aminoglycosides). The characteristics of the phosphonate/bisphosphonate functional groups could enable the use of many such materials in physiological media by enhancing stabilities of their complexes. Our approach will be to investigate the synthesis and properties of homopolyphosphonic acids and their statistical copolymers with water-soluble comonomers such as vinylamides and vinyl acetate (post-hydrolyzed to vinyl alcohol), and to explore controlled radical polymerizations that could lead to functional oligomers with targeted MWs. Tailored endgroups will be reacted with functionally-compatible polyether blocks to produce polyphosphonate-nonionic block copolymers with systematically varied compositions and MWs. This research will lead to new statistical and block copolymers, as well as modified polyether oligomers with strongly-adhesive properties. To our knowledge, this is the first study of polyphosphonates with different architectures. Effects of phosphonate/bisphosphonate moieties in these random, block and modified-polymer architectures on complexation with metal oxide nanoparticles (i.e., magnetite) and polycations such as the aminoglycosides will be elucidated. Structures of the complexes in aqueous media will be measured and modeled, guided by DLVO theory and our previous work, to relate polymer MW and composition to the solution sizes and properties of the complexes. It is also anticipated that the stability of magnetite complexes with the phosphonate binding groups will enable assembly of controlled clusters, and this will contribute to an understanding of how to prepare polymer-metal oxide assemblies in solution. NON-TECHNICAL SUMMARY: There is overwhelming evidence that phosphonic acid and phosphate groups bind strongly to a myriad of substrates. Important examples include metals (to impart corrosion resistance), metal oxide nanoparticles, tooth enamel, hydroxyapetite (bone) and cationic antibiotics for intracellular drug delivery. Moreover, many potential drug delivery systems based on polymers complexed with drugs are destroyed in biological media and the binding characteristics of phosphorus-oxygen bonds may avoid this problem. Thus, it is hypothesized that polymers containing multiple phosphonate groups could enable many biomaterial complexes that could be effective in physiological conditions. This project will investigate the synthesis and properties of new polymers containing phosphorus-oxygen bonds and methods for complexing these polymers to magnetic nanoparticles and key antibiotics. Structure-property relationships of the new macromolecular materials could lead to intracellular drug carriers for antibiotics, responsive magnetic complexes for hyperthermia treatments for cancer, improved materials for magnetic cell and protein separations, new actuator materials, new materials for treating bone diseases, new dental materials, and materials with unprecedented biological imaging capabilities. The project is broadly interdisciplinary, and requires collaboration among chemists, physicists, engineers and microbiologists. Students will be educated in this multi-disciplinary environment, and will gain insight into the importance of a teamed approach. They will outreach to the public through science demonstrations and middle school programs, and to the industrial workforce by teaching laboratory sessions in industrial short courses.