Recent advances in the chemical design and synthesis of fluorophores in the second near-infrared biological window (NIR-II) for multimodal imaging and theranostics are summarized and highlighted in this review article.

In this work, we designed a sensitivity-enhanced surface plasmon resonance biosensor structure based on silicon nanosheet and two-dimensional transition metal dichalcogenides. This configuration contains six components: SF10 triangular prism, gold thin film, silicon nanosheet, two-dimensional MoS₂/MoSe₂/WS₂/WSe₂ (defined as MX₂) layers, biomolecular analyte layer and sensing medium. The minimum reflectivity, sensitivity as well as the Full Width at Half Maximum of SPR curve are systematically examined by using Fresnel equations and the transfer matrix method in the visible and near infrared wavelength range (600 nm to 1024 nm). The variation of the minimum reflectivity and the change in resonance angle as the function of the number of MX₂ layers are presented respectively. The results show that silicon nanosheet and MX₂ layers can be served as effective light absorption medium. Under resonance conditions, the electrons in these additional dielectric layers can be transferred to the surface of gold thin film. All silicon-MX₂ enhanced sensing models show much better performance than that of the conventional sensing scheme where pure Au thin film is used, the highest sensitivity can be achieved by employing 600 nm excitation light wavelength with 35 nm gold thin film and 7 nm thickness silicon nanosheet coated with monolayer WS₂.

Combined phototherapy and immunotherapy demonstrates strong potential in the treatment of metastatic cancers. An upconversion nanoparticle (UCNP) based antigen‐capturing nanoplatform is designed to synergize phototherapies and immunotherapy. In particular, this nanoplatform is constructed via self‐assembly of DSPE‐PEG‐maleimide and indocyanine green (ICG) onto UCNPs, followed by loading of the photosensitizer rose bengal (RB). ICG significantly enhances the RB‐based photodynamic therapy efficiency of UCNP/ICG/RB‐mal upon activation by a near‐infrared (NIR) laser, simultaneously achieving selective photothermal therapy. Most importantly, tumor‐derived protein antigens, arising from phototherapy‐treated tumor cells, can be captured and retained in situ, due to the functionality of maleimide, which further enhance the tumor antigen uptake and presentation by antigen‐presenting cells. The synergized photothermal, photodynamic, and immunological effects using light‐activated UCNP/ICG/RB‐mal induces a tumor‐specific immune response. In the experiments, intratumoral administration of UCNP/ICG/RB‐mal, followed by noninvasive irradiation with an NIR laser, destroys primary tumors and inhibits untreated distant tumors, using a poorly immunogenic, highly metastatic 4T1 mammary tumor model. With the simultaneous use of anti‐CTLA‐4, about 84% of the treated tumor‐bearing mice achieve long‐term survival and 34% of mice develop tumor‐specific immunity. Overall, this antigen‐capturing nanoplatform provides a promising approach for the treatment of metastatic cancers.