Polystyrene-block-poly(ethylene oxide) Thin Films Fabricated from a Solvent Mixture for the Co-Assembly of Polymers and Proteins

Abstract

The co-assembly of peptides and proteins in poly(styrene- block -ethylene oxide) (PS- b -PEO) thin films has proven to be a promising method to fabricate polymer–biomolecule functional materials. Contrary to the covalent immobilization of biomolecules on surfaces, co-assembly presents the opportunity to arrange cargo within thin films, which can be released upon exposure to an aqueous environment. The use of a mixed solvent system ensures the solubilization of hydrophobic polymer as well as the solubilization and protection of the biomolecule cargo. However, to produce largely defect-free films of PS- b -PEO from a solvent mixture containing water is challenging due to the narrow range of solvent miscibility and polymer/protein solubility. This work explores the limits of using a benzene/methanol/water solvent mixture for the production of thin PS- b -PEO films and provides a template for the fabrication optimization of block copolymer thin films in different complex solvent systems. The film quality is analyzed using optical microscopy and atomic force microscopy and correlated to the solvent composition. By adjusting the solvent composition to 80/18.8/1.2 vol % benzene/methanol/water, it was possible to reliably fabricate thin films with less than 1% macroscopic defect surface coverage. Using the optimized solvent composition, we also demonstrate the fabrication of ordered PS- b -PEO films containing lysozyme. Furthermore, we show the release of lysozyme into aqueous media, which highlights the potential use of such films for drug delivery applications.

Styrenic block copolymer‐based thermoplastic elastomers in smart applications: Advances in synthesis, microstructure, and structure–property relationships—A review

“…Amphiphilic block copolymers like PS-b-PMMA and PS-b-PEO in nanoscale orders have attracted great interest in this field. [18][19][20] Selectively removing one block leads to nanoporous template which can be useful in an emerging class of applications ranging from microelectronic devices, masks for lithographic application, and semiconductors to filtration. 21,22 In general, Controlling the domain spacing is a current primary focus for these applications.…”

“…Self‐assembly of block copolymers can produce orderly structures with atomic or molecular level precisions. Amphiphilic block copolymers like PS‐ b ‐PMMA and PS‐ b ‐PEO in nanoscale orders have attracted great interest in this field 18–20 . Selectively removing one block leads to nanoporous template which can be useful in an emerging class of applications ranging from microelectronic devices, masks for lithographic application, and semiconductors to filtration 21,22 .…”

Quantitative analysis of biomolecule release from polystyrene-block-polyethylene oxide thin films

“…Our research group has previously studied and optimised the solvent composition of PS- b -PEO in a benzene/methanol/water (BMW) solvent mixture. 48 In short, the ideal solvent composition was 81/17.9/1.1 vol% BMW, with ratios further from this point either phase separating or producing films with defects. Additionally, our research group has also confirmed the ability of these films to remain microscopically undisturbed with the incorporation of moderate concentrations of biomolecules.…”

“…Polystyrene-block-poly-(ethylene oxide) (PS-b-PEO) has been utilized extensively for this biomolecule co-assembly. [46][47][48] Our research group has previously demonstrated the biocompatibility of PS-b-PEO thin films within cell culture in vitro. 49 Further, we have explicitly demonstrated the ability for proteins to localise within the PEO domains of PS-b-PEO.…”

“…Additionally, our research group has also confirmed the ability of these films to remain microscopically undisturbed with the incorporation of moderate concentrations of biomolecules. 47,48 The biomolecules chosen for co-assembly in this study were lysozyme (LZ) and FITC-TAT. LZ was chosen as a model protein for GFs due to its commercial availability, stability, and enzymatic activity.…”