Conjugation of Quaternary Zn-Cu-In-S/ZnS Quantum Dots to Porphyrins and Their Photodynamic Therapy and Antibacterial Activities

Photodynamic therapy (PDT) is a non-invasive treatment modality that uses photosensitizing drugs (PS) to generate reactive oxygen species for the destruction of abnormally growing cells or microorganisms. Porphyrins are the most widely used PS in PDT, their clinical application is limited by poor water solubility, which often results in aggregation and their low quantum yield of ROS generation after light absorption in the near infra-red region (NIR. To overcome these limitations and improve PDT efficacy, we herein report the conjugation of Zn-Cu-In-S/ZnS (ZCIS/ZnS) quantum dots (QDs) to porphyrins and evaluated their PDT efficiency and antibacterial potency. The ZCIS/ZnS QDs and porphrins were evaluated to determine the optimized reaction conditions for the formation of QDs-porphyrin conjugates. The PDT efficiency of ZCIS/ZnS QDs, porphyrin and NIR emitting QDs- Porphyrin conjugates was evaluated against murine metastatic melanoma (B16 F10 Nex 2) cell line in the absence of light and under LED irradiation. B16 F10 Nex 2 exhibited the highest reduction in cell viabilities following exposure to the conjugate under LED light irradiation compared to the bare QDs and porphyrins (1%). The antimicrobial therapy studies were tested by exposing Escherichia coli (ATCC 25922) to ZCIS/ZnS QDs, porphyrin and the conjugate. The conjugate showed greater antibacterial effects compared to the bare ZCIS/ZnS QDs even in the absence of light. The results of this study show that the as-synthesized conjugate is a suitable and promising class of material for dual anticancer and antimicrobial PDT.