Effects of charge and hydrophilicity on the anti-fouling properties of kidney-inspired, polyester membranes

Nature-inspired materials hold promise to tackle fouling experienced by membranes. Herein, a systematic approach is taken to explore the relative impact of charge and hydrophilicity on the anti-fouling properties of polyester membranes, both of which appear to play a role in the kidney's remarkable anti-fouling properties. Monofunctional and bifunctional polypropylene glycol (PPG) and polyethylene glycol (PEG) are used to modify polyester membranes. In both cases of hydrophilic modification and the addition of charge, a reduction in the adsorbed mass of lysozyme is experienced, as a rudimentary proxy for anti-fouling. Force spectroscopy measurements are used to quantify the change in adhesion force between the lysozyme functionalised tip and the modified PET surface. Adhesion forces decrease most between monofunctional and bifunctional PPG, which is supported by filtration results. This suggests that charge impacts the anti-fouling potential more significantly than hydrophilicity. This opens a new prospective avenue to modify membranes in order to improve their anti-fouling properties.