title: Water disinfection using photosensitizers immobilized on chitosan.
abstract: We have designed experiments to test the idea that the photodynamic effect can be used to lower microbial levels in a flow of water using a sensitizer incorporated into a polymeric membrane. We have selected a naturally derived, wettable polymer, chitosan, which can be reinforced with nylon. Photosensitizers of singlet oxygen formation were incorporated into translucent chitosan membranes by adsorption [5,10,15,20-tetrakis(p-hydroxyphenyl)porphyrin, p-THPP], by dissolution and casting [5,10,15,20-tetrakis(p-aminophenyl)porphyrin, p-TAPP], and by covalent attachment by reactive dyeing [zinc(II) phthalocyanine tetrasulfonic acid, ZnPcS]. Preliminary evaluation of photomicrobicidal activity in static systems against Escherichia coli revealed some activity in each case, and showed that the phthalocyanine/chitosan membrane was the most effective. A novel photodisinfection reactor was designed and constructed as a model for a large-scale water-flow system. Using the novel reinforced ZnPcS/chitosan membrane as the photosensitizing surface, a significant photokill of E. coli was observed, thus providing proof of concept.
authors.affiliation: Department of Chemistry, Queen Mary, University of London, Mile End Road, London EI 4NS, UK. r.bonnett@qmul.ac.uk
authors.forename: Raymond
authors.initials: R
authors.lastname: Bonnett
authors.forename: Milka A
authors.initials: MA
authors.lastname: Krysteva
authors.forename: Ivo G
authors.initials: IG
authors.lastname: Lalov
authors.forename: Spas V
authors.initials: SV
authors.lastname: Artarsky
mesh_terms: D048271:Chitosan / Q000737:chemistry*; D004202:Disinfectants / Q000737:chemistry / Q000494:pharmacology*; D004926:Escherichia coli / Q000187:drug effects; D017319:Photosensitizing Agents / Q000737:chemistry / Q000494:pharmacology*; D011166:Porphyrins / Q000737:chemistry / Q000494:pharmacology*; D014867:Water / Q000737:chemistry*
chemical_list: D004202:Disinfectants; D017319:Photosensitizing Agents; D011166:Porphyrins; D014867:Water; D048271:Chitosan