Gold nanoparticle-colocasia gigantean conjugates for enhancing cytotoxic effect against A375 melanoma cell line

Abstract

    Herbs are a prototype of traditional medicine for primary health care. Their knowledge is the basis of many modern medicinal discoveries. With the new invention of nanomaterials for biomedical applications, gold nanoparticles (AuNPs) have been proven to be a promising drug delivery agent, but their advantage for use with plant extracts has never been elucidated. This study aims to evaluate a combinatory effect of Colocasia gigantea extract (CGE) and AuNPs on cytotoxicity towards melanoma skin cancer cells. The CGE and AuNPs were evaluated, both separately and combined, for their cytotoxic effect against A375 melanoma cells via an MTT viability assay. Images were taken via light microscopes to ascertain the overall cell density following the respective treatments. The mechanism of cell death was investigated by annexin V and propidium iodide (PI) staining. The experiment results show that CGE, AuNPs and combined forms exhibit cytotoxic effects toward the melanoma cell line with statistical significance. The combination of AuNPs and CGE was found to be more effective than treatment with AuNPs or CGE of the same concentration alone. Following all treatments, the cells’ shape was also altered from a spindle-like form to a more rounded one. From analysis of flow cytometer results and confocal images, the major mechanism of cell death following all treatment conditions is by means of apoptosis. 

   CGE, AuNPs and their mixture effectively kill melanoma cells leading to apoptotic death. In results specific to only the cells treated with a combination of CGE and AuNPs, the nuclear degradation was distinctively observed. The results from this work would shed the insight whether gold nanoparticles can be applied as a carrier and synergistic agent for topical treatment, in conjunction with herbal medicine.