Issue 24, 2022

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

Abstract

Block copolymers have garnered recent attention due to their ability to contain molecular cargo within nanoscale domains and release said cargo in aqueous environments. However, the release kinetics of cargo from these thin-films has not yet been reported. Knowledge of the release quantities and release profiles of these systems is paramount for applications of these systems. Here, Polystyrene-block-poly(ethylene oxide) (PS-b-PEO) was co-assembled with fluorescein isothiocyanate isomer I-lysozyme (FITC–LZ) and fluorescein isothiocyanate isomer I–TAT (FITC–TAT), such that these molecular cargos arrange within the PEO domains of the thin films. We show that high loading ratios of cargo/PS-b-PEO do not significantly impact the nanostructure of the films; however, a loading limit appears to be present with aggregates of protein forming at the microscale with higher loading ratios. The presence of lysozyme (LZ) within the films was confirmed qualitatively after aqueous exposure through photo-induced force microscopy (PiFM) imaging at the Amide I characteristic peak (∼1650 cm−1). Furthermore, we demonstrate that LZ maintains activity and structure after exposure to the polymer solvent (benzene/methanol/water mix). Finally, we demonstrate quantitatively 20–80 ng cm−2 of cargo is released from these films, depending on the cargo incorporated. We show that the larger molecule lysozyme is released over a longer time than the smaller TAT peptide. Finally, we demonstrate the ability to tune the quantity of cargo released by altering the thickness of the PS-b-PEO thin-films during fabrication.

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

Supplementary files

Article information

Article type
Paper
Submitted
28 Meur. 2022
Accepted
26 Mae 2022
First published
01 Mezh. 2022

Soft Matter, 2022,18, 4513-4526

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

M. S. Horrocks, T. Kollmetz, P. O’Reilly, D. Nowak and J. Malmström, Soft Matter, 2022, 18, 4513 DOI: 10.1039/D2SM00383J

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