Limited by their size, small-scale robots are usually simple in structure and unable to achieve various motions to adapt to changing environments with a single control method. The emergence of multi-motion transformable actuators based on one stimulus provides a solution to this problem. Here, we report novel photothermal bimorph actuators that generate deformation based on asymmetric thermal expansion of the bilayer structure combined with a shape memory material having heat shrinkage properties. These photothermal actuators can be transformed simply by heating or illumination to achieve different shapes and functions. Furthermore, an actuator was made into a light-driven transformable small-scale robot with the capacity of multiple types of motion. Driven by light alone, the robot can transform from a crawling robot moving at a speed up to 2.28 mm s−1 to one rolling at 6.9 mm s−1 and further to a spontaneously oscillating one with a frequency of 3 Hz. These results demonstrate a promising approach to realize multiple functions and motions in one actuator, as well as a small-scale robot using only one control method. Graphical abstract A transformable soft robot with the capacity of crawling, rolling, and oscillation was prepared by combining a shape memory material having heat shrinkage properties with bimorph actuators. Driven by light, the robot can transform from a crawling robot moving at a speed up to 2.28 mm s−1 to one rolling at 6.9 mm s−1 and further to a spontaneously oscillating one with a frequency of 3 Hz Download : Download high-res image (85KB) Download : Download full-size image .

A direct Z-scheme heterojunction coupling hierarchical nanosheet MoS2 nanotubes with CuInS2 quantum dots was successfully prepared to fabricate MoS2 NTs/CuInS2 QDs photoanodes for enhanced photoelectrocatalytic (PEC) activity. The MoS2 NTs with stacked nanosheets and tubular structure have high surface area and abundant basal edges, which can create more active reaction sites. Simultaneously, the continuous and broad photo-absorption range of MoS2 NTs improved the utilization of visible-light and increased the separation efficiency of photo-induced electron-hole pairs. The integration of MoS2 NTs with CuInS2 QDs onto Cu foil yielded direct Z-scheme heterojunction photoanode. The formation of Z-scheme heterojunction inhibited the recombination of photo-induced electron-hole pairs and produced more active electrons and holes to facilitate the generation of highly active species. Under visible light illumination, the prepared MoS2 NTs/CuInS2 QDs photoanode showed superior PEC activity by applying a suitable bias voltage. In PEC process, the generated holes, hydroxyl radicals and superoxide radicals with strong oxidative were employed to achieve highly efficient degradation of tetracycline. The prepared photoanode exhibited high stability, reusability, and broad application potential in PEC degradation of organic pollutants. Moreover, a possible mechanism of the transfer pathway of photo-induced electron-hole pairs on the MoS2 NTs/CuInS2 QDs photoanode was proposed based on a direct Z-scheme heterojunction. Graphical abstract Download : Download high-res image (115KB) Download : Download full-size image

Portable analytical systems are versatile tools for application in areas including biomedicine, biosecurity, food safety and environmental monitoring. This work contributes to the increasing demand for low-cost, environmentally friendly substrates for portable analytical systems by using natural Bombyx mori cocoons. Further, silk fibroin is also extracted from these cocoons and electrospun into oriented and randomly oriented fiber substrates. Oxygen plasma treatment is applied to improve their hydrophilicity. Fiber morphology, mechanical properties, porosity, thermal characteristics and surface contact angle are extensively characterized and the ability of the samples for passive capillary flows demonstrated. Plasma treated pressed cocoons show superhydrophilicity, capillary flow rates of 44.8 ± 3.75 mm.min-1, and high mechanical resistance with Young`s modulus values up to 592.13 ± 19.83 MPa. The developed materials are used as substrates for the colorimetric quantification of three commonly scrutinized clinical analytes. Hydrophobic barriers are first wax-printed on all samples with a proper design and albumin assays are performed on all substrates. Further assays for uric acid and glucose quantification are successfully accomplished on the pressed cocoons after a simple in between washing step, with overall high coefficient of determination, proving the suitability of the developed materials as low-cost, sustainable and reusable microfluidic substrates. Graphical abstract Download : Download high-res image (242KB) Download : Download full-size image

3D-printing technology has brought light to the large-scale and sustainable production of a wide range of low-cost electronic devices with custom forms on-demand. Despite the current availability of mainstream carbon-based nanocomposite filaments, 3D-printing of noble metals is nowadays a challenge. Herein, a one-step functionalization approach has been devised for the straightforward and cost-effective manufacturing of functional metal-based 3D-printed electronics by galvanically replacing Cu-based 3D-printed (3D-Cu) electrodes with nobler metal counterparts, viz. Ag and Au. As a first demonstration of applicability, two appealing bio-electroanalytical approaches, such as the chiral discrimination of amino acids and the supramolecular determination of uranium have been considered —by taking advantage of the capability of noble metals to physically/chemically accommodate several molecular components—, reaching enhanced performances when compared with the pristine 3D-Cu counterpart. Consequently, this alchemy-inspired approach, which combines (i) 3D-Cu electrodes as sacrificial platforms with (ii) noble metals via a galvanic exchange reaction, provides a robust pathway to harbor molecular components in order to exploit metal-based 3D-printed electronics in real tasks. Graphical abstract Download : Download high-res image (128KB) Download : Download full-size image

Nanoparticle clouds feature a unique evolution of the Seebeck coefficient under applied strain. At low strain, the Seebeck effect is very stable while, when a critical strain threshold is reached, it sharply decreases to zero. The evolution mechanism of this phenomenon that contributes to the development of various strain-insensitive sensors has yet to be documented. We elucidate here this evolution by proposing a phenomenological model supported by strong experimental evidence. We realize a full study of the Seebeck effect evolution for a network of nanoparticles under variable strain. We describe the evolution of this network as three subsequent stages: completely connected, partially connected, and disconnected. Based on the conductance-weighted formula, we theoretically analyze the evolution of the Seebeck coefficient in each stage. The Seebeck coefficient’s initial stability is attributed to the connected pathways that exist in the first two stages. We validated these theoretical results by constructing percolated networks with embedded silver nanowires in elastomers and calculating the Seebeck coefficient under various stretching conditions. Finally, using the theoretical results as a guide, we created a temperature sensor that is highly resistant to mechanical damage. Graphical abstract Download : Download high-res image (160KB) Download : Download full-size image

Increase extracellular adenosine triphosphate (ATP, a necessary eat me signal for ICD) is a facile way to amplify immunogenic cell death (ICD) cascade for cancer immunotherapy. However, it is still challenging for intratumoral delivery ATP due to complicated enzyme environment in the whole body. Furthermore, tumor immunosuppressive microenvironment (TIM) also hampers the function of mature DCs and limit the activation of immune response. To overcome these drawbacks, a tumor-permeated ATP-based immunogenic cell death amplifier (NABP@SNCs) is fabricated for the first time. (Phenylboronic acid-polyethylene glycol-phenylboronic acid) PBA-PEG-PBA stabilized ultrasmall platinum nanoparticles (ABP) is constructed and interacted with ATP through borate ester bond. Indoleamine 2, 3-dioxygenase 1 (IDO1) inhibitor NLG919 and ABP are co-wrapped with MMP-2 sensitive framework to form NABP@SNCs. NABP@SNCs can not only protect ATP degradation but also release small sized ABP under MMP-2 microenvironment for tumor penetration. Interestingly, ATP can also be released into extracellular regions in tumor acidic pH and act as ‘eat me signal’ for DCs maturation. Synergistically ICD activation by BP (PBA-PEG-PBA stabilized ultrasmall platinum nanoparticles) and TIM reversal by NLG919 can facilitate T lymphocyte cells infiltration for immune response. NABP@SNCs can significantly regress tumor growth and reduce pulmonary metastasis for improved cancer immunotherapy.

The limited solubility of electrolyte active materials has impeded the development of energy dense aqueous redox flow batteries. Here, we report on the solubilizing effect urea has on metal-organic complexes chelated by aminopolycarboxylate ligands. Upon addition of urea, solubility enhancements of up to 60% or 125% are observed for chromium ethylenediaminetetraacetate (CrEDTA) and chromium 1,3-propylenediaminetetraacetate (CrPDTA) salts, respectively, resulting in maximum solubilities of e.g., 1.5 м for KCrPDTA and 2.2 м for NaCrEDTA. We investigate the mechanism behind enhanced solubility of aminopolycarboxylate chelates, revealing strong hydrogen bonding between urea and anions, resulting in eutectic-like destabilization of the solid phase. We study the impact of urea on the electrochemical performance of near neutral pH flow batteries and demonstrate 50% higher anolyte capacities, up to 40 Ah L−1, than previously reported for this promising class of materials. In capacity balanced full cells, using ferrocyanide catholytes, we observe excellent Coulombic efficiencies >99.6% and voltage efficiencies >78% at average discharge voltages of ca. 1.5 V when cycling at 100 mA cm−2. Peak discharge power densities of >400 mW cm−2 further highlight the potential of our facile and cost-effective approach. Finally, we discuss avenues for future work to further exploit the solubilizing effect described herein. Graphical abstract Download : Download high-res image (61KB) Download : Download full-size image

Tumor hypoxic microenvironment is a crucial bottleneck limiting its clinical therapeutic efficacy. Therefore, how to design nano-drugs with clear structure and function based on the characteristics of the tumor microenvironment to overcome the hypoxia of tumors and achieve high-efficiency and low-toxicity treatment is an important strategy to solve the problem of tumor treatment. Herein, we design and synthesize a ternary nano-platform, Ce6-AuCeFe, with longan structure by a simple method to obtain Magnetic Resonance Imaging (MRI)-guided cascade reagent to enhance cancer Photodynamic therapy (PDT). The AuCeFe was synthesized via a one-pot reaction with controlled morphology and loaded with Ce6 to assist PDT. Ce6-AuCeFe was synthesized as a hybrid nanocatalyst model of glucose oxidase and peroxidase mimics because of its outstanding catalytic performance. As nontoxic glucose was continuously converted to abundant H2O2 by AuCeFe, the excess H2O2 was subsequently catalyzed by the peroxidase-like activity of AuCeFe to generate O2, which helped to alleviate the hypoxic tumor microenvironment. The mechanistic studies elucidate that the ternary nanoparticles facilitate triplet oxygen into singlet oxygen through energy transfer, which leads to highly toxic reactive oxygen species (ROS) production combined with PDT, achieving much desirable cancer cells killing effect under hypoxia conditions. Meanwhile, the degradation of Ce6-AuCeFe under tumor microenvironment also enhanced on T1 and T2-weighted MRI, indicating that Ce6-AuCeFe could be used as two-mode MRI contrast agents for precisely guiding in therapy. In summary, our study provides a novel strategy for tumor therapy by utilizing well-structured metal composites to achieve high-efficiency oxygen production, thereby overcoming the hypoxic tumor microenvironment. Graphical abstract Download : Download high-res image (297KB) Download : Download full-size image

The development of nanotheranostic agents is attracting attention as an innovative strategy to synergistically detect bacterial infection and eliminate bacteria. A novel MOF (ZIF-67)-armored zinc peroxide core–shell structure with a loaded organic NIR probe (ONP) is reported herein. These nanomaterials serve as “reactive oxygen species factories” that eradicate drug resistant bacteria with image guided and in situ activated photodynamic therapy (PDT). The up-regulated levels of ONOO− at infected sites can be detected by the ONP. ONP could react with ONOO− generating MB as an imaging agent and as a photosensitizer. The ZnO2@ZIF-67(ZZ) nanogenerator simultaneously generates O2 and H2O2 in an infected, weakened acidic microenvironment. The PDT can be applied on-demand to eliminate bacteria depending on illumination of the probe. The in situ activated PDT strategy can effectively exterminate drug-resistant bacteria, using small amounts of nanomaterials, with no obvious adverse effects in vitro and in vivo. The ONP@ZnO2@ZIF-67(ONP@ZZ) nanoagent simultaneously eliminates drug-resistant bacteria, reduces inflammation, and accelerates wound healing. This novel nanotheranostic agent can act as an effective antibacterial platform by integrating infection detection and bacterial eradication synergistically, and bring new light for the increasingly severe challenge of drug-resistant bacteria in clinic.