(419f) Structurally pH Responsive Nangel Star Polymers for Use in Drug Delivery Applications

Biomedical applications of diblock star polymers, globular nanoparticle architectures in which linear polymer “arms” are connected to a central polymer core, as a drug delivery system rely on the design of its polymer block chemistries and architectures to be thermosensitive and biocompatible, with the additional ability to be biodegradable over suitable time scales. Smart polymers that exhibit a pH induced structural response are important since different tissue environments and cell compartments exhibit a wide variation in pH, and thus offer the potential for a more targeted delivery of therapeutic drugs. The highly combinatorial nature of the star, e.g. variations in monomer chemistry combined with variations in arm length and arm loading, provide a vast landscape to characterize for drug-delivery applications, most of which remains unexplored. Here, we present a Small Angle X-ray scattering (SAXS) study of polyelectrolyte stars whose hydrophilic blocks consist of acidic, basic and neutral chemistries. Examining the structure of these stars over a range of pH has lead to interesting insights with respect to these polymer's linear analogues, and indicate that they undergo structural transitions over a narrow range of pHs, depending on the chemical composition of the arms.