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MXenes, an emerging family of graphene-analogues two-dimensional (2D) materials, have attracted continuous and tremendous attentions in many application fields because of their intrinsic physiochemical properties and high performance in versatile applications. In this work, we report on the construction of tantalum carbide (Ta4C3) MXene-based composite nanosheets for multiple imaging-guided photothermal tumor ablation, which has been achieved by rational choice of the composition of MXenes and their surface functionalization. A redox reaction was activated on the surface of tantalum carbide (Ta4C3) MXene for in-situ growth of manganese oxide nanoparticles (MnOx/Ta4C3) based on the reducing surface of the nanosheets. The tantalum components of MnOx/Ta4C3 acted as the high-performance contrast agents for contrast-enhanced computed tomography, and the integrated MnOx component functionalized as the tumor microenvironment-responsive contrast agents for T1-weighted magnetic resonance imaging. The photothermal-conversion performance of MnOx/Ta4C3 composite nanosheets not only has achieved contrast-enhanced photoacoustic imaging, but also realized the significant tumor-growth suppression by photothermal hyperthermia. This work broadens the biomedical applications of MXenes, not only by the fabrication of family members of biocompatible MXenes, but also by the development of functionalization strategies of MXenes for cancer-theranostic applications.

Biochar amendment offers a chance for sustainable agriculture. However, the effectiveness of biochar relies on its physical and chemical properties, which are heavily affected by biochar production conditions and management practices. Therefore, substantial uncertainties regarding the use of biochar exist in agricultural systems globally. This study provides the first quantitative evaluation of the impacts of biochar characteristics and management practices on key ecosystem services by performing a second-order meta-analysis based on 34,628 paired observations in biochar-amended and unamended systems. Overall, biochar enhances phytotoxicity alleviation, physiology regulation, soil remediation and carbon sequestration, and microbial functional gene abundance. However, some prominent trade-offs exist between crop productivity and ecosystem service deliveries including for nutrient cycling, microbial function, climate change mitigation, and the soil microbial community). The adoption of low C:N biochar produced at high pyrolysis temperatures from sewage sludge-derived feedstock, in combination with a moderate application rate and inorganic fertilizer input, shows potential for achieving synergistic promotion of crop productivity and ecosystem services. These outcomes highlight the need for judicious implementation of biochar-based solutions to site-specific soil constraints. The quantified synergy and tradeoff relationships will aid the establishment of a sustainable biochar development framework that strengthens necessary ecosystem services commensurate with food security assurance.