Conjugation study of 5-aminolevulinic acid with microbial synthesized gold nanoparticles to evaluate its effect on skin melanoma and epidermoid carcinoma cell lines using photodynamic cancer therapy

Cancer therapy using minimal invasive technique has been a challenge since decades. In the present research, the concept of photodynamic cancer therapy (PDT) has been applied on biologically synthesized nanoparticles for the treatment of skin melanoma (B16F10) and epidermoid carcinoma (A431) cells. The biologically synthesized nanoparticles have been conjugated with a photosensitizer drug 5-aminolevulinic (5-ALA) acid to treat cancer cells by activating the protoporphyrin IX (PpIX) formation through irradiation. Bacterial strain Escherichia coli was used for the synthesis of gold nanoparticles. The size and characteristics of nanoparticles were studied with scanning electron microscope, dynamic light scattering and zeta potential analysis. The gold nanoparticles were encapsulated with polyethylene glycol (PEG) and tagged with 5-aminolevulinic acid, a photosensitizer drug. The drug was activated using a halogen lamp to enhance the production of reactive oxygen species (ROS) molecules. The cytotoxicity of pure nanoparticles and conjugated nanoparticles were assessed on skin melanoma and epidermoid carcinoma cell lines and compared against standard drug 5-ALA, and the production of ROS molecules was measured using a 2,7 dichlorofluorescein-diacetate (DCFH-DA) probe. The results indicated that pure gold nanoparticles had greater cytotoxicity on cells compared to 5-ALA and gold-5-ALA conjugate. But when the cells were subjected to irradiation, the gold-5-ALA conjugate showed higher cytotoxicity than 5-ALA and pure nanoparticles. The cytotoxic levels of gold-5-ALA conjugates were doubled which indicated greater reactive oxygen molecule production compared to other samples.