Block Copolymers: from Nanopatterning to Cell Membrane Integrity Modulation

Jiayu Wang (University of Chicago)

Block copolymers (BCPs) have great potential in advanced technology applications, arising from the ability to self-assemble into a variety of nanostructures. One of the challenges for the use of BCPs in practice is to control their self-assemblies. Our studies show that the introduction of lithium ions into polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) copolymers is able to significantly enhance the alignment of BCP microdomains in thin films under an electric field. Such an enhanced alignment is attributed to the enhancement of dielectric contrast, the mediation of surface interactions, and the increase in the segmental interaction between two blocks. On the other hand, clinic studies have revealed that the family of PEO-PPO-PEO triblock copolymers has the opposite effects on the integrity of biological cell membranes--they behave either as membrane sealants in the sealing of structurally compromised cell membranes or as permeabilizers to promote drug intake for multidrug-resistant cancer cells. Our studies demonstrate that such opposite effects originate from the distinct interactions between these BCPs and lipid membranes; the key factor determining these interactions is the overall hydrophobicity of the BCP. In light of this interaction mechanism, a new series of triblock copolymers were developed as promising polymer therapeutics.

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