Persistent prolate polymersomes for enhanced co-delivery of hydrophilic and hydrophobic drugs

Self-assembled polymersomes encapsulate, protect, and deliver hydrophobic and hydrophilic drugs. Though spherical polymersomes are effective, early studies suggest that non-spherical structures may enhance specificity of delivery and uptake due to similarity to endogenous uptake targets. Here we describe a method to obtain persistent non-spherical shapes, prolates, via osmotic pressure and the effect of prolates on uptake behavior. Polyethylene glycol-b-poly(lactic acid) polymersomes change in diameter from 145 ± 6 nm to 191 ± 1 nm and increase in polydispersity from 0.05 ± 0.02 to 0.12 ± 0.01 nm after addition of 50 mM salt. Transmission and scanning electron microscopy confirm changes from spheres to prolates. Prolate-like polymersomes maintain their shape in 50 mM NaCl for seven days. Nile Red and bovine serum albumin-Fluorescein dyes are taken up in greater amounts by SH-SY5Y neural cells when encapsulated in polymersomes. Prolate polymersomes may be taken up more efficiently in neural cells than spherical polymersomes.