Highly concentrated MoS2 nanosheets in water achieved by thioglycolic acid as stabilizer and used as biomarkers

Abstract

In this work, we reported the synthesis of water soluble MoS₂ quantum dots from the monolayer nanosheets of MoS₂, using thioglycolic acid (TGA) with a sonication method. The gaps between the MoS₂ layers were enlarged by the stirring process. Meanwhile TGA molecules strongly binding to the defect sites of MoS₂ would reduce the van der Waals force between the MoS₂ layers through sonication. This led to the improved dispersion of MoS₂ monolayers in water. The addition of TGA molecules not only exfoliated the bulk of MoS₂, but also modified the surface of MoS₂ with carboxylic acid groups. As a result, highly concentrated MoS₂ nanosheets were produced in water. Subsequently, heavy metal-free MoS₂ quantum dots with sustained fluorescence emission, which were fabricated from hydrothermal treatment of MoS₂ monolayers, can be utilized as cell biomarkers.