Antimicrobial Finish of Polyethersulfone Membranes: Sticking Photosensitizers‐Like Marine Mussels Would Do

• Published in: Advanced engineering materials 2023-03, Vol.25 (6), p.n/a
• Main Authors: Grafl, Anna, Müller, Alexander, Preuß, Annegret, Röder, Beate, Börner, Hans. G.
• Format: Article
• Language: English
• Subjects: antibacterial coatings; light-activated reactive oxygen species (ROS) disinfection; membrane finish; microbial control of water filtration membranes; photodynamic therapy; singlet oxygen production
• ISSN: 1438-1656; 1527-2648
• DOI: 10.1002/adem.202201279

Biofouling is one of the most serious problems in membrane filtration systems for water treatment. An easily applicable antimicrobial finish of polyethersulfone (PES) filter membranes is shown by derivatizing an approved chlorin photosensitizer drug with adhesive ortho‐catechol functionalities as known from l‐3,4‐dihydroxyphenylalanin (Dopa) residues of marine mussel glues. The chemical structure of the second‐generation photosensitizer 5,10,15,20‐tetrakis(3‐hydroxyphenyl)chlorin (m‐THPC) is modified by 2‐iodoxybenzoic acid (IBX) oxidation, transforming the peripheric meta‐phenols of m‐THPC into ortho‐catechols, and thus improving the adsorption properties of m‐THPC derivatives onto PES material. Stable coatings are formed that preserve chlorin's capability to generate singlet oxygen under visible light illumination. The modification of one or two phenol groups out of the four m‐THPC substituents leads to an optimum in the generation of active singlet oxygen, and thus the finish significantly reduces the bacterial growth of gram‐negative Escherichia coli and gram‐positive Micrococcus luteus on the PES membranes. A chlorin‐based photosensitizer, known from photodynamic therapy, is derivatized to realize antimicrobial finishes for water‐filtration membranes. The introduced catechol moieties known from adhesive systems of marine mussels, improve the coating and affect both positioning and packing of the photosensitizers, to retain singlet oxygen production. Irradiating coated membranes by visible light significantly reduces bacterial growth of both gram‐positive and gram‐negative strains.