PEGylated WS_2 Nanosheets as a Multifunctional Theranostic Agent for in vivo Dual-Modal CT/Photoacoustic Imaging Guided Photothermal Therapy

摘要

Two-dimensional (2D) nanomaterials have been receiving great attention in recent years because of their fascinating physical properties, which are the result of a quantum size effect associated to their ultra-thin structure. Graphene, which is the 2D sp~2-bonded nanocarbon with excellent electronic, optical, thermal, and mechanical properties, as a typical example, has been extensively studied in the past decade. It would thus seem natural to explore the graphene analogues such as layered inorganic materials. Transition-metal dichalcogenides (TMDCs), such as MoS_2, MoSe_2, WS_2 and WSe_2, all consist of a hexagonal layer of metal atoms (M) sandwiched between two layers of chalcogen atoms (X) within stoichiometry MX_2. The common feature of these materials is the layered structure with strong covalent bonding within each layer and weak Van der Waals forces between different MX_2 sheets. For their special characteristics, TMDCs have become the rising star in recent years, offering great opportunities in physics, chemistry and materials science. Single- and few-layered 2D TMDC nanosheets have been successfully prepared, via either mechanical or chemical exfoliation methods. In the respect of their applications, TMDCs have shown great promise in various different areas including field-effect transistors, lithium-ion batteries, integrated circuits, gas sensors, hydrogen evolution, and phototransistors. However, the exploration of this new class of 2D nanomaterials in the area of biomedicine is still at its infant stage.