title: MoS₂ exhibits stronger toxicity with increased exfoliation.
abstract: MoS₂ belong to a class of inorganic 2D nanomaterials known as transition metal dichalcogenides (TMDs) which have recently attracted a renewed and growing interest due to their interesting electronic and catalytic properties when scaled down to single or few layer sheets. Although exfoliated MoS₂ nanosheets have been proposed for numerous energy-related and biosensing applications, little is known about the toxicological impacts of using MoS₂ nanosheets. Here, we report about the in vitro toxicity of MoS₂ nanosheets that have been chemically exfoliated with different lithium intercalating agents and compared their respective cytotoxic influence. Methyllithium (Me-Li), n-butyllithium (n-Bu-Li) and tert-butyllithium (t-Bu-Li) were used for the exfoliation of bulk MoS₂ and we found the t-Bu-Li and n-Bu-Li exfoliated MoS₂ nanosheets to be more cytotoxic than MoS₂ exfoliated by Me-Li. t-Bu-Li and n-Bu-Li provide more efficient exfoliation over Me-Li, and we establish that the extent of exfoliation that MoS₂ undergo is a factor influencing their toxicity. Specifically, the more exfoliated the MoS₂ nanosheets, the stronger its cytotoxic influence, which may be due to an increase in surface area and active edge sites. The potential toxicity of these MoS₂ nanosheets should be taken into account before their employment in real world applications and we have shown the effect the amount of exfoliation can have on the toxicity of MoS₂ nanosheets, representing the first step towards a better understanding of their toxicological properties.
authors.affiliation: Division of Chemistry & Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371. pumera@ntu.edu.sg pumera.research@gmail.com.
authors.forename: Elaine Lay Khim
authors.initials: EL
authors.lastname: Chng
authors.forename: Zdeněk
authors.initials: Z
authors.lastname: Sofer
authors.forename: Martin
authors.initials: M
authors.lastname: Pumera
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology; D045744:Cell Line, Tumor; D004220:Disulfides / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D008982:Molybdenum / Q000737:chemistry / Q000494:pharmacology; D053758:Nanoparticles / Q000737:chemistry*; D009369:Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology
chemical_list: D000970:Antineoplastic Agents; D004220:Disulfides; D008982:Molybdenum; C082964:molybdenum disulfide