One class of polymers recently developed consists of a hydrophobic gel-core with emanating linear polymer arms. This nanogel star polymer is a versatile platform to formulate well-defined sub-50 nm particles for encapsulation and delivery of hydrophobic cargo. However, structure-function relationships require an understanding of the spatial distribution of components within the nanogel star polymer. Contrast variant small-angle neutron scattering (SANS) allows one to probe how different chain architecture effects such as the number of star arms, star arm copolymer composition, and nanogel-core chemistry are related to independent assessed drug loading extent and particle stability. Three different nanogel star polymers with variations in chemical composition of the star arms were studied in aqueous solution. These different generation of materials exhibit improved levels of drug loading and solution stability. In order to reconcile the differences in drug loading and stability, SANS provides the segmental, solvent, and drug loading profiles within the sub-50 nm polymer particle. We demonstrate how the drug partitions within the particle hydrophobic gel core and core star-arm interface. The main results from a series of nanogel star polymers with arms of poly(ethylene glycol), poly(ethylene glycol)-<i>b</i>-poly(valerolactone) or poly(ethylene glycol)-poly(valerolactone)-<i>b</i>-poly(4-tert-butyl-caprolactone)) will be described.

Structure and spatial distribution of hydrophobic drugs in nanogel star polymers

254th National Meeting (2017)

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