Surface modification of 2D MXene and evaluation of cytotoxicity and photothermal therapy

The MXenes are a novel family of 2D materials with promising biomedical activity whereas their anticancer potential is largely unexplored. Polyethylene glycol (PEG) surface modified MXenes showed enhanced anticancer potential as compared to Bare MXenes, but, depending on the manufacturing process, PEGs may include ethylene oxide, a known human carcinogen and 1,4-dioxane, a possible human carcinogen. This study aims at investigating poly propylene glycol as a safer alternative to surface modify MXene as it photodegrades less compared to PEG and PPG has been labelled as a safe food additive by the FDA. In this study, a comparative cytotoxicity investigation for Ti3C2MXene, PPG,and PEG surface-modified Ti3C2MXene has been conducted towards normal and cancerous human cell lines. The chemical etching method was used to synthesize MXene followed by a simple chemical mixing method for surface modification of Ti3C2MXene with PPG and PEG molecules. SEM and XRD analyses were used to examine surface morphology and composition respectively. FTIR and Uv-vis spectroscopy was used to confirm surface modification and light absorption respectively. The cell lines used were normal (HaCaT and MCF-10A) and cancerous (MCF-7 and A375) human cells. The surface-modified MXenes exhibited a sharp reduction in cell viability towards both normal (HaCaT and MCF-10A) and cancerous (MCF-7 and A375) cells but it was more pronounced towards cancerous cell lines. The highest toxicity towards both normal and cancerous cell lines was observed with PEGylated MXenes followed by PPGylated and Bare MXenes. The normal cell’s viability is barely above 70% threshold with 250mg/L PEGylated MXene concentration whereas PPGylated and Bare MXene are less toxic towards normal cells even at 500mg/L concentration. Moreover, the toxicity was directly related to the type of cell lines. In general, the HaCaT cell line exhibited the lowest toxicity while toxicity was highest in the case of the A375 cell line. The photo-thermal studies revealed high photo-response for PEGylated MXenes followed by PPGylated and Bare MXenes. However, the PPGylated MXenes lower cytotoxicity towards normal cells while comparable toxicity towards malignant cells as compared to PEGylated MXenes makes the former a relatively safe and effective anticancer agent.