Tumor microenvironment-activated theranostic nanozymes for trimodal imaging-guided combined therapy.

Synergistic therapy is expected to be a promising strategy for highly effective cancer treatment. However, the rational design of a simple and multifunctional nanoplatform still remains a grand challenge. Considering the nature of weak acidic, hypoxic, and H2O2 abundant tumor microenvironment, we constructed an indocyanine green (ICG) modified platinum nanoclusters (Pt NCs) decorated gold nanobipyramids (Au NBPs) to form the multifunctional nanocomposites (Au NBPs@Pt NCs-ICG) for multimodal imaging mediated phototherapy and chemodynamic cancer therapy. The photosensitizer ICG was covalently linked to Au NBPs@Pt NCs by bridging molecules of SH-PEG-NH2 for both photodynamic therapy (PDT) and fluorescence imaging. Besides, Au NBPs@Pt NCs-ICG nanocomposites exhibited catalase- and peroxidase-like activities to generate O2 and ·OH, which relieved the tumor hypoxia and upregulated antitumoral ROS level. Moreover, the combination of Au NBPs and ICG endowed the Au NBPs@Pt NCs-ICG with super photothermal conversion for effective photothermal imaging and therapy. In addition, the Au NBPs@Pt NCs-ICG nanoplatform displayed excellent X-ray computed tomography (CT) imaging ability due to the presence of high-Z elements (Au and Pt). Overall, our results demonstrated that Au NBPs@Pt NCs-ICG nanoplatform exhibited a multimodal imaging guided synergistic PTT/PDT/CDT therapeutic manners and held great potential as an efficient treatment for breast cancer.

Biogenic Copper Selenide Nanoparticles for Near-Infrared Photothermal Therapy Application.

Near-infrared (NIR) photothermal therapy (PTT) is attractive for cancer treatment but is currently restricted by limited availability and insufficient NIR-II photoactivity of photothermal agents, for which artificial nanomaterials are usually used. Here, we report the first use of biogenic nanomaterials for PTT application. A fine-controlled extracellular biosynthesis of copper selenide nanoparticles (bio-Cu2-xSe) by Shewanella oneidensis MR-1 was realized. The resulting bio-Cu2-xSe, with fine sizes (∼35.5 nm) and high product purity, exhibited 76.9% photothermal conversion efficiency under 1064 nm laser irradiation, outperforming almost all the existing counterparts. The protein capping also imparted good biocompatibility to bio-Cu2-xSe to favor a safe PTT application. The in vivo PTT with injected bio-Cu2-xSe in mice (without extraction nor further modification) showed 87% tumor ablation without impairing the normal organisms. Our work not only opens a green route to synthesize the NIR-II photothermal nanomaterial but may also lay a basis for the development of bacteria-nanomaterial hybrid therapy technologies.

AQDS Activates Extracellular Synergistic Biodetoxification of Copper and Selenite via Altering the Coordination Environment of Outer-Membrane Proteins.

The biotransformation of heavy metals in the environment is usually affected by co-existing pollutants like selenium (Se), which may lower the ecotoxicity of heavy metals, but the underlying mechanisms remain unclear. Here, we shed light on the pathways of copper (Cu2+) and selenite (SeO32-) synergistic biodetoxification by Shewanella oneidensis MR-1 and illustrate how such processes are affected by anthraquinone-2,6-disulfonate (AQDS), an analogue of humic substances. We observed the formation of copper selenide nanoparticles (Cu2-xSe) from synergistic detoxification of Cu2+ and SeO32- in the periplasm. Interestingly, adding AQDS triggered a fundamental transition from periplasmic to extracellular reaction, enabling 14.7-fold faster Cu2+ biodetoxification (via mediated electron transfer) and 11.4-fold faster SeO32- detoxification (via direct electron transfer). This is mainly attributed to the slightly raised redox potential of the heme center of AQDS-coordinated outer-membrane proteins that accelerates electron efflux from the cells. Our work offers a fundamental understanding of the synergistic detoxification of heavy metals and Se in a complicated environmental matrix and unveils an unexpected role of AQDS beyond electron mediation, which may guide the development of more efficient environmental remediation and resource recovery biotechnologies.