Fig. 6: Potential associations of tested properties of commercial nominal graphene materials and cell viability and membrane damage.

a PCA-biplot (score and loading plot) from principal component analysis. Three apparent clusters can be seen from the PC scores of the samples. The solid scatter points are NGM^int and open scatter points are NGM^def. b HCA dendrogram. Vertical lines represent roots samples while horizontal lines represent similarities between samples. Two samples cannot be classified into either intact or defective graphene and are thus indicated with green/red circles. c Persistent inorganics; and d Fraction of sp³ bonded carbon r(sp³), as a proxy measure for the surface adsorbents in the samples, plotted against the cytotoxicity. The analysis was performed for a subset of NGMs with the most graphene-like properties. e + f Performance heptagrams representing the NGMs with the lowest and highest cytotoxic profile in d. The red line represents the linear fit (c and d). Deviation bars represent the upper and lower bound for PI.