Recently, ultrathin 2D photocatalysts have attracted people’s attention due to their performances in the area of solar energy conversion. However, the synthesis of ultrathin 2D photocatalysts with a nonlayered crystal structure is still full of challenges. Herein, ultrathin 2D BiVO4 nanosheets (NSs) with monoclinic crystal structure are synthesized through a convenient colloidal two-phase method. The as-prepared BiVO4 NSs possess a thickness of less than 3 nm but a diameter larger than 1.2 μm. Furthermore, the presence of HNO3 facilitates the growth of BiVO4 NSs with nearly naked surfaces, largely exposed {010} planes, and widely distributed oxygen vacancies (V O) inside the crystalline structure, which are of great benefit to their photocatalytic activity under visible light irradiation. As a result, our ultrathin 2D BiVO4 NSs exhibit an impressive photocatalytic performance for water oxidation. The O2 evolution rate is 107.4 μmol h–1, and the apparent quantum yield (AQY) is as high as 26.1% (420 nm). Furthermore, by employing our ultrathin 2D BiVO4 NSs as the O2-evolving photocatalyst, Ru-SrTiO3:Rh and Fe3+/Fe2+ as the H2-evolving photocatalyst, and the redox mediator, respectively, a Z-scheme overall water splitting system is successfully constructed. Under visible light irradiation, our Z-scheme photocatalytic system presents high H2 and O2 evolution rates (16.7 and 8.0 μmol h–1) with an AQY of 1.88% (420 nm) and good photocatalytic stability.

Cancer multimodal treatment by combining the effects of different theranostics agents can efficiently improve treatment efficacy and reduce side effects. In this work, we demonstrate the theranostics nanodevices on the basis of Cu-loaded polydopamine nanoparticles (CuPDA NPs), which are able to offer magnetic resonance imaging (MRI)-guided thermochemotherapy (TCT). Systematical studies reveal that after Cu ions loading, the molar extinction coefficient of PDA NPs is greatly enhanced by 4 times, thus improving the performance in photothermal therapy. Despite Cu ions being toxic, the release of Cu is mainly stimulated in acidic environment. Once the NPs deposit in the slightly acidic tumor microenvironment (pH ≈ 6.5-6.8), the release rate boosts ∼30%, which effectively avoids the systematic toxicity during chemotherapy. Meanwhile, due to the increment of the electron-proton dipole-dipole interaction correlation time τ, the spin-lattice relaxation time (T) for PDA NPs is found to be shortened by Cu loading, which boosts the longitudinal relaxivity (r). Hence, CuPDA NPs can be used as T-weighted contrast agent in MRI. In addition, due to the naturally existing DA in the human body with stealth effect, CuPDA NPs have an outstanding tumor retention rate as high as 8.2% ID/g. Further in vitro and in vivo tests indicate that CuPDA NPs possess long blood circulation time, good photothermal and physiological stability, and biocompatibility, which are potential nanodevices for MRI-guided TCT with minimal side effects.

Iron oxide (Fe3O4), polydopamine (PDA), and in particular their composites are examples of the safest nanomaterials for developing multifunctional nanodevices to perform noninvasive tumor diagnosis and therapy. However, the structures and performances of Fe3O4-PDA nanocomposites should be further perfected to enhance the theranostic efficiency. In this work, we demonstrate the fabrication of PDA-capped Fe3O4 (Fe3O4@PDA) superparticles (SPs) employing preassembled Fe3O4 nanoparticles (NPs) as the cores. Owing to the collective effect of preassembled Fe3O4 NPs, the superparamagnetism and photothermal performance of Fe3O4@PDA SPs are greatly enhanced, thus producing nanodevices with improved magnetic resonance imaging (MRI)-guided photothermal efficiency. Systematical studies reveal that the molar extinction coefficient of the as-assembled Fe3O4 SPs is 3 orders of magnitude higher than that of individual Fe3O4 NPs. Also due to the high aggregation degree of Fe3O4 NPs, the T2-weighted MRI contrast is greatly enhanced for the SPs with r2 relaxivity of 230.5 mM(-1) s(-1), which is ∼2.5 times larger than that of individual Fe3O4 NPs. The photothermal stability, physiological stability, and biocompatibility, as well as the photothermal performance of Fe3O4 SPs, are further improved by enveloping with PDA shell.

A Rh(I)-catalyzed formal carbene insertion into C-C bond of benzocyclobutenols has been realized by employing diazoesters as carbene precursors. The product indanol derivatives were obtained in good yields and in diastereoselective manner under mild reaction conditions. All-carbon quaternary center is constructed at the carbenic carbon. This catalytic reaction involves selective cleavage of C-C bond, Rh(I) carbene insertion, and intramolecular aldol reaction.