Cryogenic Exfoliation of 2D Stanene Nanosheets for Cancer Theranostics

Stanene(Sn)-based materials have been extensively applied in industrial production and daily life,but their potential biomedical application remains largely unexplored,which is due to the absence of the appropriate and effective methods for fabricating Sn-based biomaterials.Herein,we explored a new approach combining cryogenic exfoliation and liquid-phase exfoliation to successfully manufacture two-dimensional(2D)Sn nanosheets(SnNSs).The obtained SnNSs exhibited a typical sheet-like structure with an average size of~100 nm and a thickness of~5.1 nm.After PEGylation,the resulting PEGylated SnNSs(SnNSs@PEG)exhibited good stability,superior biocompatibility,and excellent photothermal performance,which could serve as robust photothermal agents for multi-modal imaging(fluorescence/photoacoustic/photothermal imaging)-guided photothermal elimination of cancer.Furthermore,we also used first-principles density functional theory calculations to investigate the photothermal mechanism of SnNSs,revealing that the free electrons in upper and lower layers of SnNSs contribute to the conversion of the photo to thermal.This work not only introduces a new approach to fabricate 2D SnNSs but also establishes the SnNSs-based nanomedicines for photonic cancer theranostics.This new type of SnNSs with great potential in the field of nanomedicines may spur a wave of developing Sn-based biological materials to benefit biomedical applications.

Multifunctional core/satellite polydopamine@Nd^3＋- sensitized upconversion nanocomposite： A single 808 nm near-infrared light-triggered theranostic platform for in vivo imaging-guided photothermal therapy

Significant attenuation and overheating, caused by the absorption of the excitation band （980 nm） in water, are the major obstacles in the in vivo application of lanthanide-doped upconversion nanoparticles （UCNPs）. Therefore, appropriately- structured Nd3^＋-doped UCNPs with 808 nm excitation could be a promising alternative. Herein, we developed core-shell-shell structured Nd3^＋-sensitized UCNPs as imaging agents, and decorated them onto the surface of polydopamine （PDA） to construct a novel multifunctional core/satellite nanotheranostic （PDA@UCNPs） for in vivo imaging guidance photothermal therapy using single 808 nm laser irradiation. The core-shell-shell structured design enabled outstanding upconversion luminescence properties and strong X-ray attenuation, thereby making the nanocomposites potential candidates for excellent upconversion luminescence/computed tomography dual modal imaging. In addition, the PDA core not only provides high photothermal conversion efficiency and outstanding antitumor effect, but also endows the platform with robust biocompatibility owing to its natural features. Therefore, this multifunctional nanocomposite could be a promising theranostic in future oncotherapy, with high therapeutic effectiveness but low side effects. This study would stimulate interest in designing bio- application-compatible multifunctional nanocomposites, especially for cancer diagnosis and treatment in vivo.

Ultrathin tellurium nanosheets for simultaneous cancer thermo-chemotherapy

The emerging two-dimensional monoelemental materials(2D Xenes)have been commonly supposed as promising drug delivery carriers,photothermal and photodynamic therapeutic agents,biosensors,theranostics,and some other candidates for biomedical applications.Here,high-performance and bioactive ultrathin 2D Tellurium nanosheets(Te NSs)are prepared by a simple but efficient liquid-phase exfoliation approach.The as-obtained Te NSs possess a mean size of~90 nm and a mean thickness of~5.43 nm.The pegylation Te NSs(Te-PEG NSs)possess excellent biocompatibility and stability.The Te-PEG NSs could generate local hyperthermia with a remarkable photothermal conversion efficiency of about 55%under 808 nm laser irradiation.Additionally,Te-PEG NSs exhibit an extremely high loading capacity of chemo drug(~162%)owing to their ultra-high surface area and tumor microenvironment-triggered drug release superiority.The results of in vivo experiments show that the Te-PEG NSs have higher tumor elimination efficiency via the combination of photothermal and chemotherapy,comparing to any other single therapeutic modalities.Therefore,our work not only highlights the promising potentials of tellurene as an ideal anti-cancer platform but also expands the application of 2D Te for cancer nanomedicine.