Bottom-up synthesis of ultra-small molybdenum disulfide-polyvinylpyrrolidone nanosheets for imaging-guided tumor regression.

// Jiulong Zhao 1, * , Chunhua Zhou 1, 2, * , Mao Li 1, * , Jialing Li 1 , Guixiang Li 1 , Dan Ma 1 , Zhaoshen Li 1 and Duowu Zou 1 1 Department of Gastroenterology, Changhai Hospital, Second Military Medical University, Shanghai 200433, China 2 Department of Gastroenterology, The Second Affiliated Hospital of Soochow University, Suzhou 215004, China * These authors have contributed equally to this work Correspondence to: Duowu Zou, email: zdw_pi@163.com Keywords: molybdenum disulfide; ultra-small; bottom-up; cell nucleus; photothermal therapy Received: June 27, 2017     Accepted: August 27, 2017     Published: November 08, 2017 ABSTRACT The two-dimensional molybdenum disulfide (MoS 2 ) nanosheet has been extensively studied as a novel photothermal transducing agent. However, top-down exfoliation to produce MoS 2 nanosheets is inefficient, and MoS 2 nanosheet surface modification procedures are complex. Here, we report the synchronous synthesis and surface modification of 2D MoS 2 nanosheets with a polyvinylpyrrolidone (PVP)-assisted one-pot hydrothermal method. Due to the chelating-coordinating effect between the lone-pair electrons of the PVP carbonyl oxygen and the unoccupied 4d orbitals of molybdenum, the PVP chains could graft onto the surface of MoS 2 and guide the growth of the nanosheets. The resultant MoS 2 -PVP nanosheets were ultra-small (21.4 ± 4.4 nm) and exhibited excellent colloidal stability. Moreover, the strong near-infrared absorption of the MoS 2 -PVP nanosheets enabled sensitive photothermal conversion performance (with a mass extinction coefficient of 23.33 L g −1 cm −1 ) and in vitro / in vivo photoacoustic imaging. The MoS 2 -PVP nanosheets had excellent in vitro and in vivo compatibility and were used for highly efficient tumor photothermal therapy in xenograft tumor-bearing mice. The findings in this report will facilitate the rational design of stable colloidal 2D transition-metal dichalcogenides for effective photothermal cancer therapy.