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Colloidal microswarms have attracted increasing attention in the last decade due to their unique capabilities in various complex tasks. Thousands or even millions of tiny active agents are gathered with distinctive features and emerging behaviors, demonstrating fascinating equilibrium and non-equilibrium collective states. In recent studies, with the development of materials design, remote control strategies, and the understanding of pair interactions between building blocks, microswarms have shown advantages in manipulation and targeted delivery tasks with high adaptability and on-demand pattern transformation. This review focuses on the recent progress in active micro/nanoparticles (MNPs) in colloidal microswarms under the input of an external field, including the response of MNPs to external fields, MNP–MNP interactions, and MNP–environment interactions. A fundamental understanding of how building blocks behave in a collective system provides the foundation for designing microswarm systems with autonomy and intelligence, aiming for practical application in diverse environments. It is envisioned that colloidal microswarms will significantly impact active delivery and manipulation applications on small scales. [ABSTRACT FROM AUTHOR]

Objective: Untethered microrobots hold great promise for applications in biomedical field including targeted delivery, biosensing, and microsurgery. A major challenge of using microrobots to perform in vivo tasks is the real-time localization and motion control using medical imaging technologies. Here we report real-time magnetic navigation of a paramagnetic nanoparticle-based microswarm under ultrasound guidance. Methods: A three-axis Helmholtz electromagnetic coil system integrated with an ultrasound imaging system is developed for generation, actuation, and closed-loop control of the microswarm. The magnetite nanoparticle-based microswarm is generated and navigated using rotating magnetic fields. In order to localize the microswarm in real time, the dynamic imaging contrast has been analyzed and exploited in image process to increase the signal-to-noise ratio. Moreover, imaging of the microswarm at different depths are experimentally studied and analyzed, and the minimal dose of nanoparticles for localizing a microswarm at different depths is ex vivo investigated. For real-time navigating the microswarm in a confined environment, a PI control scheme is designed. Results: Image differencing-based processing increases the signal-to-noise ratio, and the microswarm can be ex vivo localized at depth of 2.2–7.8 cm. Experimental results show that the microswarm is able to be real-time navigated along a planned path in a channel, and the average steady-state error is 0.27 mm ($\sim$ 33.7% of the body length). Significance: The colloidal microswarm is real-time localized and navigated using ultrasound feedback, which shows great potential for biomedical applications that require real-time noninvasive tracking. [ABSTRACT FROM AUTHOR]

Precise synthesis of well-controlled metal nanoparticles on various supports is one of the most challenging issues in their applications for the sustainable production of fuels and chemicals. We herein propose an effective method to generate small Ni nanoparticles at a high loading content of 20 wt% with homogeneous dispersion on Al2O3 regardless of low-temperature or high-temperature reduction. MIL-Al (110) was selected as the host for the fabrication of Ni nanoparticles with the size mainly at ∼5 nm after reduction at 600 or 800 °C. Conventional Al2O3 loaded Ni with the same amount shows a different behavior, that is, the particle size of Ni nanoparticles increases from 12.5 ± 1.8 nm after reduction at 600 °C to 20.0 ± 2.4 nm after reduction at 800 °C. The formation of a surface NiAl2O4 spinel structure on the Ni/Al2O3 sample and the inherent confinement effect from pristine MIL-110 (Al) contribute to the stabilization of small Ni nanoparticles with a high loading content under different reduction conditions. These results will open a possibility of rationally designing and fabricating highly dispersed metal nanoparticles on certain supports. [ABSTRACT FROM AUTHOR]

LaMnO3 and LaCoO3 perovskite nanoparticles have sprung up as the platinum group-metal (PGM)-free catalysts of NO oxidation to reduce NOX in the exhaust. In this paper, we present mesoporous LaMnO3 and LaCoO3 with rhombohedral structures prepared by a facile molten-salt synthesis method. LaMnO3 and LaCoO3 achieved NO oxidation performance with the highest NO conversions of 85% and 94% at 300 °C, which may be improved by K and Na introduced via flux. [ABSTRACT FROM AUTHOR]

Microalgae as the photosynthetic organisms offer enormous promise in a variety of industries, such as the generation of high-value byproducts, biofuels, pharmaceuticals, environmental remediation, and others. With the rapid advancement of gene editing technology, CRISPR/Cas system has evolved into an effective tool that revolutionised the genetic engineering of microalgae due to its robustness, high target specificity, and programmability. However, due to the lack of robust delivery system, the efficacy of gene editing is significantly impaired, limiting its application in microalgae. Nanomaterials have become a potential delivery platform for CRISPR/Cas systems due to their advantages of precise targeting, high stability, safety, and improved immune system. Notably, algal-mediated nanoparticles (AMNPs), especially the microalgae-derived nanoparticles, are appealing as a sustainable delivery platform because of their biocompatibility and low toxicity in a homologous relationship. In addition, living microalgae demonstrated effective and regulated distribution into specified areas as the biohybrid microrobots. This review extensively summarised the uses of CRISPR/Cas systems in microalgae and the recent developments of nanoparticle-based CRISPR/Cas delivery systems. A systematic description of the properties and uses of AMNPs, microalgae-derived nanoparticles, and microalgae microrobots has also been discussed. Finally, this review highlights the challenges and future research directions for the development of gene-edited microalgae. [ABSTRACT FROM AUTHOR]

Palladium-silver bimetallic nanoparticles loaded on reduced graphene oxide (Pd-Ag/RGO) were prepared by co-reduction of mixed metal salts and graphene oxide (GO) with urea-assisted ethylene glycol (EG). The as-obtained Pd-Ag/RGO nanocomposites were characterized by X-ray diffraction, transmission electronic microscopy, and UV-Vis absorption spectroscopy. The results show that the nanoparticles with an average particle size of 5 nm are dispersed on the surface of RGO highly uniformly, besides the Pd-Ag bimetallic nanoparticles are more helpful to promote the reduction of GO than monometal ones. The electrochemical activities of the as-prepared nanocomposites for ethanol oxidation were investigated by using cyclic voltammetry and chronoamperometry in alkaline solution. Compared to the Pd-Ag/E-tek carbon (Pd-Ag/C) and Pd-Ag/multi-walled carbon nanotubes (Pd-Ag/MWCNTs) which were fabricated by the same method, the Pd-Ag/RGO exhibit much higher electrocatalytic activity, stronger tolerance to CO and better stability during the ethanol electro-oxidation reaction in alkaline media. The electrocatalytic performances of Pd-Ag/RGO with different mass ratios of Pd-Ag toward ethanol oxidation in alkaline media were also studied. The results indicate that the electrocatalytic activity of Pd-Ag/RGO with 1:1 mass ratio of Pd-Ag is the best. [ABSTRACT FROM AUTHOR]

Abstract: This paper reported a novel label-free electrochemical impedimetric immunosensor for sensitive detection of metabolite of furaltadone, 5-morpholino-3-amino-2-oxazolidone (denoted as AMOZ), based on monoclonal antibody against AMOZ (denoted as AMOZ–McAb) immobilized on gold electrode modified with 1,4-benzenedithiol and gold nanoparticle self-assembled layers. The sensitive steps of surface modification have been characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The immunoreaction between AMOZ and AMOZ–McAb directly triggered a signal via electrochemical impedance spectroscopy measurement. Under the optimized conditions, the relative change in impedance was proportional to the logarithmic value of AMOZ concentrations in the range of 1.0 to 1.0 × 106 ng/mL (r = 0.9991) with the detection limit of 1.0 ng/mL. The advantages of the immunosensor are exhibited in its high sensitivity, wide linear range and better stability. The proposed impedimetric immunosensor was successfully applied to the determination of AMOZ in animal derived food with excellent recoveries. [Copyright &y& Elsevier]

• Homogeneous or non-homogeneous Ni-Co alloy was prepared on SiO 2. • Ni and Co strong interaction and the formation of CoO facilitate to uniform alloy. • The different alloy structures affect catalytic properties in CO methanation. • Homogeneous Ni-Co/SiO 2 exhibits superior catalytic performance. • CO dissociation, hydrogen spillover and CO 2 adsorption were enhanced on homogeneous alloy. Designing and tailoring the fine structure of bimetallic nanoparticles is an essential and effective way to boost the catalytic properties. Herein, two types of Ni-Co alloys are generated on SiO 2 including non-homogeneous or homogeneous form for CO methanation. The formation of homogeneous Ni-Co alloy originates from the strong interaction between Ni and Co and a small amount of CoO. Compared with non-homogeneous alloy, the homogeneous Ni-Co alloy exhibits superior CO conversion and CH 4 selectivity below 380 °C, and is stable for 100 h long-term test at 400 °C in CO methanation. The electron enrichment of Ni and Co of homogeneous alloy contributes to CO dissociation, hydrogen spillover, and CO 2 adsorption, which facilitates CH 4 formation and the removal of deposited carbon species. This work provides a new clue for fabricating bimetallic catalysts and revealing the relationship between the fine structure of Ni-Co alloy and their catalytic performances. [ABSTRACT FROM AUTHOR]

Coalescence and splitting of liquid marbles (LMs) are critical for the mixture of precise amount precursors and removal of the wastes in the microliter range. Here, the coalescence and splitting of LMs are realized by a simple gravity‐driven impact method and the two processes are systematically investigated to obtain the optimal parameters. The formation, coalescence, and splitting of LMs can be realized on‐demand with a designed channel box. By selecting the functional channels on the device, gravity‐based fusion and splitting of LMs are performed to mix medium/drugs and remove spent culture medium in a precise manner, thus ensuring that the microenvironment of the cells is maintained under optimal conditions. The LM‐based 3D stem cell spheroids are demonstrated to possess an approximately threefold of cell viability compared with the conventional spheroid obtained from nonadhesive plates. Delivery of the cell spheroid to a hydrophilic surface results in the in situ respreading of cells and gradual formation of typical 2D cell morphology, which offers the possibility for such spheroid‐based stem cell delivery in regenerative medicine. [ABSTRACT FROM AUTHOR]