Ulticomponent Transitio Metal Dichalcogenide Nanosheets For Imaging-guided Photothermal And Chemodynamic Therapy

Cancer,as one of the deadliest diseases worldwide,remains a serious health concern.Humans have made much effort towards overcoming this difficult problem based on all the methods that can be considered.Due to the advances in nanotechnology and the development of society,many advanced nanomaterials have been applied to address cancer.Transition metal dichalcogenides(TMDs)have become one of the most promising inorganic nanomaterials for nanocatalysis,biomedicine,electronic devices,and field effect tubes due to their distinctive structures and properties.Benefitting from their intrinsic near-infrared absorbance properties and extremely large specific surface areas,many efforts are devoted to fabricating 2D TMDs-based nanomaterials for photothermal therapy(PTT)and photoaustic imaging(PA).Nevertheless,it is still difficult to completely eradicate deep tumors and prevent metastasis by PTT alone,due to the fact that heat dispersion within the solid tumor is inhomogeneous and depth-dependent decline of laser intensity upon external irradiation.Therefore,modulating composition and structure to increase PTT effectiveness,and combining PTT with other therapeutic modalities,are vital to fulfill their potential in cancer theranostics.In this paper,the ultrathin LDH precursors are prepared by the"bottom-up" method.Based on the "topological transformation" characteristic,the metal composition and conversion conditions of LDH precursors are adjusted to achieve the controllable preparation and performance optimization of TMDs.The prepared TMDs have excellent treatments(PTT/chemodynamic therapy)and imagings(photoacoustic/magnetic resonance imaging),realizing the integration of tumor imaging and treatment.The main research contents and related results are as follows:1.Lamellar CoFeMn-LDH precursor was first prepared by a "bottom-up"synthesis route,followed by a facile vulcanization process to obtain ultrathin CFMS NSs.The surface of the CFMS was functionalized with PVP to enhance dispersion stability and biocompatibility for further experimental studies.XRD,TEM,zeta potential and other characteristics prove that CFMS-PVP with regular shape and uniform size distribution,can be stably dispersed in different solvents.AFM images reveal ultrathin structures with a thickness of～1.2 nm.The photothermal conversion efficiency(η)of the CFMS-PVP NSs can achieve 89.0%through modulation of the Co/Fe/Mn ratio in the LDH precursor,the highest photothermal conversion efficiency ever reported among 2D TMDs.2.Prior to investigating the anticancer effect of CFMS-PVP,a biocompatibility evaluation was conducted on HepG2,HeLa,and U87mg cell lines.HepG2 cells were incubated with CFMS-PVP to investigate PTT and the generation of OH,which responsive to pH and heat,can be used for CDT.All of which demonstrate the substantiate remarkable PTT/CDT efficacy of CFMS-PVP.Furthermore,the PA/MRI performance of CFMS-PVP in the HepG2 tumor-bearing model were investigated,a distinct PA/MRI signal was clearly distinguishable from the background and reached a peak at 8 h after i.v.injection.Finally,the biocompatibility and metabolic pathways of CFMS-PVP in vivo were studied,the results indicated good in vivo biocompatibility and further metabolized in the form of urine and feces.In situ tumor models substantiate remarkable PTT/CDT efficacy.These results all confirm that the CFMS-PVP have excellent and synergistic PA/MRI guided PTT/CDT performance,and thus potential clinical applications.In summary,a highly tunable CFMS-PVP platform was fabricated based on the vulcanization of lamellar CoFeMn-LDH precursor.The work provides a new and facile approach for the synthesis of high-quality ultrathin TMD nanosheets with precise process control,mass production and outstanding performance,which holds great promises in cancer theranostics.