Investigation of chromene-porphyrin derivatives for use in photodynamic therapy and photodynamic antimicrobial chemotherapy

This work focuses on the photophysical and photochemical properties of chromene-porphyrin derivatives (containing Zn, Ga and In as central metals) and their use as photosensitizers in photodynamic therapy (PDT) and photodynamic antimicrobial chemotherapy (PACT) in the presence and absence of carbon quantum dots (CQDs). PDT is being developed as an alternative non-invasive treatment option for cancer. PACT has been used to combat the growing challenge of antimicrobial resistance to the currently used anti-biotics. The biological activities were tested against the triple negative breast cancer cells against MDA-MB-231 (using PDT) and Escherichia coli (using PACT). Resazurin assay was used to monitor the toxicity of the complexes. The porphyrins were stacked ontoCQDs in order to enhance their water solubility and also improve their bio-availability. In general, the porphyrins did not show dark toxicity. Zinc tetrakis-(4‑bromo-chromene) porphyrin (ZnTBCP) and indium tetrakis-(4‑bromo-chromene) porphyrin (InTBCP) had good activities in PDT and PACT respectively, with cell viabilities as low as 23.43% (PDT) and 31.38% (PACT) at the highest concentrations. The results suggest that ZnTBCP and InBCTP are good candidates for use as photosensitizers. CQDs reduced the dark toxicity of the porphyrins.