Dependence of EviTag™ T1 CdSe QD toxicity in Caco-2 cell culture on QD concentration. (A) Caco-2 viability assessed by MTT assay. (B) Caco-2 cell attachment, including both live and dead cells as well as total attached cells, assessed by Live/Dead fluorescent labelling. Data represent the mean ± SE of three separate experiments from cells of different cultures. Statistically significant differences in attached live cell number between a QD dosage and all other QD doses are indicated by an asterisk (*) (p < 0.05). Statistically significant differences in attached dead cells between a QD dosage and all other doses are indicated by a pound symbol (#) (p < 0.05).