2.4.1. Cell Culture HCT116 Human Colorectal Carcinoma

The HCT116 human colorectal carcinoma cells were cultured in McCoy’s 5A medium (a medium rich in folic acid) with 10% FBS. To study cell viability, HCT116 cells were seeded in 96-well plates at a density of 5500 cells/well in 200 µL of McCoy 5A medium. After 24 h of incubation at 37 °C, the cells were treated for 24, 48, 72, and 96 h with free RTX (2000, 1000, and 250 nM); AuNP-Cys-RTX (quantity equivalent to 2000, 1000 and 250 nM RTX); or AuNP-Cys (amounts equivalent to AuNP-Cys-RTX). Due to low solubility, the samples were re-suspended in a H₂O:DMSO (10:1) mixture, where the DMSO had a final concentration per well of 0.12% (v/v).