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[Display omitted] • A novel magnetic MXene@Fe 3 O 4 /Au/polydopamine (PDA) nanosheet is developed. • MXene provides more uniformly dispersed active sites for Au nanocrystals. • PDA-confined-Au-nanocrystals hybrid shell is achieved by a simple one-step method. • The MXene@Fe 3 O 4 /Au/PDA nanosheet has excellent photothermal conversion property. • The nanosheet exhibits magnetically-enhanced photothermal antibacterial activity. • The edge of the nanosheet cut the cytomembrane similar to a magnetic "hot nanoblade". Harmful bacteria are common substances in water that endanger human health, so it is urgent to establish a simple system that can tackle these hazardous substances simultaneously. In this work, a novel magnetic MXene@Fe 3 O 4 /Au/polydopamine (PDA) nanosheet with excellent photothermal-magnetolytic coupling antibacterial performance is developed. MXene, Au and polydopamine all have good photothermal properties, so the photothermal conversion efficiency of the MXene@Fe 3 O 4 /Au/PDA nanosheet reaches as high as 48.7%. After 6 min of 808 nm laser irradiation, the MXene@Fe 3 O 4 /Au/PDA nanosheets (120 μg·mL−1) can achieve nearly 100% antibacterial effect against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). In comparison to the sole photothermal treatment, the nanosheet at lower concentration (80 μg·mL−1) also exhibit stronger antibacterial properties against both Gram-negative and Gram-positive bacteria during the photothermal-magnetic coupling treatment. The result is mainly because the heat generated by the photothermal effect of the nanosheet is directly transferred to the cell membrane, and the edge of the nanosheet cuts the cytomembrane similar to a magnetic "hot nanoblade", resulting in subsequent shrinkage, deformation and even rupture. [ABSTRACT FROM AUTHOR]

Soft actuators with large deformation and high stability in response to multi-stimuli are highly demanded in biomimetic applications. However, most of the present actuators driven by a single stimulus often exhibit low performance and high energy consumption. In this work, a sandwich structural soft actuator (MPDMS/MXene/PTFE) which possesses electrothermal/magnetic coupling actuation is fabricated by combining magnetic NdFeB/Polydimethylsiloxane (MPDMS) composite layer, MXene film, and PTFE tape together. Due to the large difference of thermal expansion coefficient between MPDMS film and PTFE tape, the soft actuator shows a wonderful electrothermal actuation and the bending deformation can reach to as high as 353° under a 3 V power supply. The excellent electrical conductivity of MXene component endows the sandwich film with good thermal management performance, thus the soft MPDMS/MXene/PTFE sandwich films can be applied in the thermal treatment of body and thermal imaging. Most importantly, the soft actuator also exhibits a typical magnetic biomimetic actuation and the programmable actuation performance of the dragonfly actuator can be demonstrated by both experiments and finite element simulations. Eventually, the electrothermal/magnetic coupling actuation is successfully applied in an intelligent crawling robot to overcome the traditional inchworm movement simulation. A dual-mode biomimetic soft actuator based on MPDMS/MXene/PTFE with excellent electrothermal and magnetic drive performance is developed. The soft actuator enables to prepare grippers for transferring objects and assemble the wings of a biomimetic dragonfly in a magnetic field. Finally, a crawling robot is developed to demonstrate the electrothermal/magnetic coupling actuation. [Display omitted] • The highlight of this work is: • The MPDMS/MXene/PTFE soft actuator presents both electrothermal and magneto-actuated deformation behaviors. • The soft actuator shows a wonderful electrothermal actuation and the bending deformation can reach to as high as 353° under a 3 V power supply. • The finite element analysis model can provide design guidance for the deformation process of bionic actuator with complex structure. • The soft actuator strategy presented in this paper is expected to be useful for the development of bionic intelligent actuators with multi-stimulus response. [ABSTRACT FROM AUTHOR]

Local surface plasmon resonance (LSPR) of noble metal nanoparticles plays a significant role in nanocatalysis via directly harvesting optical energy from resonant light. However, the photothermally-assistant catalytic application is limited due to the narrow visible/infrared absorption range and low photothermal conversion efficiency. Herein, a sandwich-structured MXene@Au/Polydopamine (PDA) nanosheet with good hydrophilicity, large specific surface area and tri-photothermal components is developed for nanocatalysis. The Au/PDA hybrid shells are covered on the MXene nanosheets via a simple one-step redox-oxidize polymerization method. As a result, the catalytic dynamic of MXene@Au/PDA nanosheets on reducing 4-nitrophenol reaches to 0.28 min−1·mg−1, which is about 2 times larger than that of the nanocatalysts without NIR light irradiation. Owing to the well protection of PDA shell, after 10 cycles of reduction of 4-nitrophenol, MXene@Au/PDA nanosheets still maintain more than 90% activity. This work in depth insights into NIR light-assistant avenue to enhance the catalytic activity of noble metal nanocatalysts and highlights an easy synthetic model for heterogeneous catalysts based on MXene nanocomposites. An MXene@Au/PDA nanosheet with sandwiched nanostructure has been rationally fabricated by a simple in situ redox-oxidizing polymerization method. Under the irradiation of near-infrared light, the catalytic dynamic of the MXene@Au/PDA nanosheet is excitingly improved by 2 times, thus shows a typical photothermal-enhanced catalytic activity. [Display omitted] [ABSTRACT FROM AUTHOR]

Local surface plasmon resonance (LSPR) of noble metal nanoparticles plays a significant role in nanocatalysis via directly harvesting optical energy from resonant light. However, the photothermally-assistant catalytic application is limited due to the narrow visible/infrared absorption range and low photothermal conversion efficiency. Herein, a sandwich-structured MXene@Au/Polydopamine (PDA) nanosheet with good hydrophilicity, large specific surface area and tri-photothermal components is developed for nanocatalysis. The Au/PDA hybrid shells are covered on the MXene nanosheets via a simple one-step redox-oxidize polymerization method. As a result, the catalytic dynamic of MXene@Au/PDA nanosheets on reducing 4-nitrophenol reaches to 0.28 min−1·mg−1, which is about 2 times larger than that of the nanocatalysts without NIR light irradiation. Owing to the well protection of PDA shell, after 10 cycles of reduction of 4-nitrophenol, MXene@Au/PDA nanosheets still maintain more than 90% activity. This work in depth insights into NIR light-assistant avenue to enhance the catalytic activity of noble metal nanocatalysts and highlights an easy synthetic model for heterogeneous catalysts based on MXene nanocomposites. An MXene@Au/PDA nanosheet with sandwiched nanostructure has been rationally fabricated by a simple in situ redox-oxidizing polymerization method. Under the irradiation of near-infrared light, the catalytic dynamic of the MXene@Au/PDA nanosheet is excitingly improved by 2 times, thus shows a typical photothermal-enhanced catalytic activity. [Display omitted] [ABSTRACT FROM AUTHOR]