Cytotoxicity of Exfoliated Transition-Metal Dichalcogenides (MoS2, WS2, and WSe2) is Lower Than That of Graphene and its Analogues Wei Zhe Teo, Elaine Lay Khim Chng, Zdeněk Sofer, Martin Pumera* Chemistry-A European Journal 2014, 20(31), 9627-9632