Enhanced photodynamic therapy of porphyrin grafted Zn–Ag–In–S QDs/PMAO nanoparticles against melanoma cells and E. coli

Tetra-aminophenyl porphyrin (TAPP)-grafted Zn–Ag–In–S quantum dots (ZAIS QDs)/poly(maleic anhydride-alt-1-octadecene) (PMAO) nanoparticles were synthesized and their photoluminescence properties as well as photodynamic properties were studied. ZAIS QDs showed the brightest photoluminescence and highest quantum yield at an optimized Zn feeding molar ratio of 20%. Those TAPP-grafted nanoparticles (i.e., ZAIS/PMAO-g-TAPP) were able to produce ¹O₂ in aqueous solution under light irradiation as indicated by the ¹O₂ indicator, 9,10-anthracenediyl-bis(methylene) dimalonic acid (ADMA). ZAIS/PMAO-g-TAPP nanoparticles also demonstrate good biocompatibility and low dark toxicity even at a concentration as high as 2.8 mg·mL⁻¹, whith can be applied as both a fluorescence probe and a photodynamic therapy (PDT) agent. The PDT treatment showed that the viability of melanoma A2058 cells was less than 10% after treatment with the 420 nm light irradiation for 15 min at a photosensitizer concentration of 1.7 mg·mL⁻¹. During the PDT treatment with Escherichia coli, the survival rate of the bacteria decreased by −95% after light irradiation at the same concentration. Such dual-functional ZAIS/PMAO-g-TAPP nanoparticles researched in this study demonstrate promising potential for fluorescence labeling as well as effective PDT treatment against cancer cells and bacteria.