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Here we report the preparation of water-dispersible glycosylated poly(2,5'-thienylene)porphyrin based nanoparticles by a nanoprecipitation method and demonstrate the application of these nanoparticles in antibacterial photodynamic therapy. The diameter of the nanoparticles is in the range of 50-80 nm and the resulting nanoparticles are stable in water without precipitation at least for a month. They have high singlet oxygen efficiency and display light-triggered biocidal activity against both Gram negative bacteria (Escherichia coli, E. coli) and Gram positive bacteria (Bacillus subtilis, B. subtilis). Upon white light irradiation for 10 min with a flux of 22 mW cm-2 of the E. coli suspension incubated with NPs (18 μg mL-1), a killing efficiency of 99% is achieved, whereas in the dark the effect is recorded as only around 8%.

We report here the synthesis and characterization of a water dispersible conjugated polymer nanoparticle‐based photosensitizer and its application in the antibacterial and anticancer phototherapies. Nanoparticles (CPPN) were synthesized in one‐pot by nanoprecipitation method, in which a hydrophobic azide functionalized, red‐emitting thiophene‐benzothiodiazole based conjugated polymer (CP‐AZ) was cross‐linked with a hydrophilic, propargylamine functionalized porphyrin (TPP‐4AL) through cucurbit[6]uril (CB6) catalyzed azide‐alkyne cycloaddition (CB6‐AAC) reaction. CPPN demonstrated high stability in aqueous medium for more than a month without any visible aggregation and appeared to be a good photosensitizer with high light‐triggered reactive oxygen species (ROS) generation ability. Consequently, CPPN displayed photo‐induced biocidal activity against Gram‐negative (Escherichia coli, E. coli) and Gram‐positive (Bacillus subtilis, B. subtilis and Staphylococcus aureus, S. aureus) bacteria. When bacteria suspension was incubated with CPPN (20 μg ml−1) and irradiated with white light (22 mW cm−2) for 10 min, more than 3.5‐log reduction in colony‐forming units (CFUs) was recorded for the three model bacteria. CPPN demonstrated minimal dark cytotoxicity against the bacteria. Moreover, the cytotoxicity of CPPN on mammalian cell was studied using MCF‐7 breast cancer cell line. The results demonstrated that CPPN is non‐toxic to mammalian cells in the dark even at a high concentration of 112.5 μg ml−1 and this feature makes CPPN an ideal photosensitizer. [ABSTRACT FROM AUTHOR]