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With the development and application of thermoelectric (TE) devices, it requires not only high-performance of TE materials but also high mechanical properties. Here, we report a medium-temperature liquid material, AgCuTe, with high mechanical properties. The results demonstrate that AgCuTe possesses a multiphase structure characterized by abundant grain boundaries, resulting in reduced lattice thermal conductivity and inherently high mechanical strength. Furthermore, nano-SiC was alloyed into the AgCuTe material to further improve its mechanical and TE properties. Nano-SiC exhibited a button-like distribution within the grain boundaries, introducing a pinning effect that significantly elevated the Vickers hardness of the samples. Additionally, nano-SiC induced strong lattice distortion energy in the vicinity, which promotes Ag/Cu ions to escape from the lattice and enhances the liquid-like behavior of Ag/Cu ions. Finally, these enhancements led to a 21% improvement in the mechanical properties and a 40% improvement in the TE properties for AgCuTe. Notably, AgCuTe achieved its peak TE performance, with a latest peak ZT value of 1.32 at 723 K. This research expands the potential applications of AgCuTe.

With the rapid development of triboelectric nanogenerators (TENGs) for flexible wearable devices and electronic skins, challenges have gradually emerged related to the electrification surface, such as pollutant contamination and sophisticated surface adaptability. Hence, we report a simple spraying method to produce a shape-adaptive photocatalytic (SAP) triboelectric material with both self-cleaning and shape-adaptive functions. By spraying the polyvinyl alcohol solution with TiO 2 photocatalysts and pre-drying cyclic, the SAP film can be adapted to a varied and intricate substrate. The highest transferred charge density of the SAP film reaches 197.5 μC/m 2 , when it contacts with the PTFE film. At the same time, it can degrade 74.4% of simulated pollutants under sunlight illumination, and 97% of the transferred charge density can be maintained after the degradation process, indicating good self-cleaning function and stable electrical output. Moreover, the spraying method of this allows it to have shape-adaptive functions. Accordingly, the SAP film can be deposited on the rectangular pyramid and hemispherical surface for fabricating TENGs with special shapes. This low-cost and simple spraying method further promotes the commercialized application of TENGs in the field of wearable devices and skin sensors.

Intelligent actuating materials with vapor-stimulated mechanical response usually require complicated synthesizing processes or have a high cost. Here, we found that the UV/O 3 -modified poly(dimethylsiloxane) PDMS) film can show spontaneous curling deformation when it encounters small alcohol molecules such as ethanol vapor. Based on the coupling of the vapor-responsive PDMS film and triboelectric nanogenerator (TENG), a flexible actuator for object transport and a double-finger gripper for loading small objects are designed. The deformation and size change induced by vapor stimulation help these devices to adapt to the target objects of different sizes, while the electrostatic force provided by TENG can move or control the target object, for instance, the double-finger gripper can clamp an object of a weight of 6 g.

Gold nanorods (AuNRs) are potentially useful in tumor theranostics, but the poor stability, high toxicity, and rapid removal by the immune system seriously limit their theranostic applications. In our study, we demonstrate the fabrication of Cu(II)-doped polydopamine-coated AuNR (AuNR@CuPDA), which significantly improves the potentials in tumor theranostics. Besides the improvement of physiological stability and biocompatibility, the PDA shell increases the photothermal performance and prolongs the blood circulation time of AuNRs. The half-life of AuNRs during blood circulation increases from 0.7 to 4.5 h after PDA coating, and the injected dose per gram of tumor tissue is 4.6% ID g -1 for AuNR@CuPDA. In addition to computer tomography imaging, the loading of Cu(II) in PDA shell endows AuNR@CuPDA with magnetic resonance imaging function. Cu(II) doped in PDA shell also exhibits chemotherapeutic behavior, and the tumor inhibitor rate is 31.2%. Further combining 808 nm laser-driven photothermal therapy, tumors were completely ablated, and no recurrence was observed. Liver and renal functions tests and histological analysis of major organs confirm that AuNR@CuPDA is in good safety.

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 2+ -loaded polydopamine nanoparticles (CuPDA NPs), which are able to offer magnetic resonance imaging (MRI)-guided thermochemotherapy (TCT). Systematical studies reveal that after Cu 2+ ions loading, the molar extinction coefficient of PDA NPs is greatly enhanced by 4 times, thus improving the performance in photothermal therapy. Despite Cu 2+ ions being toxic, the release of Cu 2+ 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 C , the spin-lattice relaxation time (T 1 ) for PDA NPs is found to be shortened by Cu 2+ loading, which boosts the longitudinal relaxivity (r 1 ). Hence, CuPDA NPs can be used as T 1 -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.