Biocidal activity of a light-absorbing fluorescent conjugated polyelectrolyte

Synthesis, self-assembly, and photophysical behavior of oligo phenylene ethynylenes: from molecular to supramolecular properties

A pair of cationic phenylene ethynylene oligomers (OPEs) have been synthesized, and their optical properties have been studied in solution with and without added scaffold materials, including carboxymethylcellulose, carboxymethylamylose, and Laponite. The OPEs are strongly fluorescent in methanol solution, but in water, the fluorescence yield is suppressed. The addition of scaffolds to aqueous solutions of OPEs leads to a red shift in the absorption and in most cases a significant increase in the fluorescence quantum yield. The effects most likely arise because of template-induced formation of linear J-dimers or possibly because of planarization, which give rise to an effective increase in the conjugation length of OPEs.

Light-induced biocidal action of conjugated polyelectrolytes supported on colloids

A series of water soluble, cationic conjugated polyelectrolytes (CPEs) with backbones based on a poly(phenylene ethynylene) repeat unit structure and tetraakylammonium side groups exhibit a profound light-induced biocidal effect. The present study examines the biocidal activity of the CPEs, correlating this activity with the photophysical properties of the polymers. The photophysical properties of the CPEs are studied in solution, and the results demonstrate that direct excitation produces a triplet excited-state in moderate yield, and the triplet is shown to be effective at sensitizing the production of singlet oxygen. Using the polymers in a format where they are physisorbed or covalently grafted to the surface of colloidal silica particles (5 and 30 microm diameter), we demonstrate that they exhibit light-activated biocidal activity, effectively killing Cobetia marina and Pseudomonas aeruginosa. The light-induced biocidal activity is also correlated with a requirement for oxygen suggesting that interfacial generation of singlet oxygen is the crucial step in the light-induced biocidal activity.