Real-time electro-mechanical profiling of dynamically beating human cardiac organoids by coupling resistive skins with microelectrode arrays.

Cardiac organoids differentiated from induced pluripotent stem cells are emerging as a promising platform for pre-clinical drug screening, assessing cardiotoxicity, and disease modelling. However, it is challenging to simultaneously measure mechanical contractile forces and electrophysiological signals of cardiac organoids in real-time and in-situ with the existing methods. Here, we present a biting-inspired sensory system based on a resistive skin sensor and a microelectrode array.

Engineered anti-EGFRvIII targeted exosomes induce apoptosis in glioblastoma multiforme.

Background: The drug delivery for treatment of glioblastoma multiforme (GBM) has been unsatisfactory mainly due to the drug resistance and low targeting efficiency. The selective targeting of GBM cells and using a cocktail of therapeutic agents to synergistically induce apoptosis may help enhance the drug delivery.

Methods: In this study, mesenchymal stem cells (MSCs) were engineered to produce exosomes, i.

Depletable peroxidase-like activity of FeO nanozymes accompanied with separate migration of electrons and iron ions.

As pioneering FeO nanozymes, their explicit peroxidase (POD)-like catalytic mechanism remains elusive. Although many studies have proposed surface Fe-induced Fenton-like reactions accounting for their POD-like activity, few have focused on the internal atomic changes and their contribution to the catalytic reaction. Here we report that Fe within FeO can transfer electrons to the surface via the Fe-O-Fe chain, regenerating the surface Fe and enabling a sustained POD-like catalytic reaction.

Colorimetric Detection of Extracellular Hydrogen Peroxide Using an Integrated Microfluidic Device.

It is well known that hydrogen peroxide (HO) is a signaling molecule essential for vital physiological reactions in mammalian cells, such as cell survival, intercellular communication, and cancer metabolism. However, to fully understand the function of HO, it is critical to monitor its intracellular and/or extracellular concentrations. Current techniques implemented to address this need require large sample volumes, expensive instrumentation, and long sample preparation and analysis times, inapplicable to inline or online monitoring.

Three-dimensional imaging on a chip using optofluidics light-sheet fluorescence microscopy.

Volumetric, sub-micron to micron level resolution imaging is necessary to assay phenotypes or characteristics at the sub-cellular/organelle scale. However, three-dimensional fluorescence imaging of cells is typically low throughput or compromises on the achievable resolution in space and time. Here, we capitalise on the flow control capabilities of microfluidics and combine it with microoptics to integrate light-sheet based imaging directly into a microfluidic chip.

Stretchable gold fiber-based wearable textile electrochemical biosensor for lactate monitoring in sweat.

Past several years have witnessed growing interest in developing wearable biosensors for non-invasive monitoring vital signs of chemical/biological markers such as lactate. In this context, textiles can be seen as a promising platform for the integration of wearable chemical sensors due to their inherent breathability, flexibility, softness and comfortableness. Gold is regarded as a preferred active sensing material due to its excellent biocompatibility, chemical inertness and wide electrochemical window.

High-Aspect-Ratio SU-8-Based Optofluidic Device for Ammonia Detection in Cell Culture Media.

Miniaturization of sensing technology has led to the development of multifunctional micro total analysis systems (μTAS) that benefit from microfluidic technology. Optical sensing is one of the most commonly used sensing approaches integrated into μTAS devices and features high sensitivity and low detection limits. Different materials have been used for the fabrication of μTAS devices, each having their advantages and disadvantages.

Enzyme-like electrocatalysis from 2D gold nanograss-nanocube assemblies.

Nanotechnology's rapid development of nanostructured materials with disruptive material properties has inspired research for their use as electrocatalysts to potentially substitute enzymes. Herein, a novel electrocatalytic nanomaterial was constructed by growing gold nanograss (AuNG) on 2D nanoassemblies of gold nanocubes (AuNC). The resulting structure (NG@NC) was used for the detection of HOvia its electrochemical reduction.

Vertically Aligned Gold Nanowires as Stretchable and Wearable Epidermal Ion-Selective Electrode for Noninvasive Multiplexed Sweat Analysis.

The noninvasive continuous analysis of human sweat is of great significance for improved healthcare diagnostics and treatment in the future, for which a wearable potentiometry-based ion-selective electrode (ISE) has attracted increasing attention, particularly involving ion detection. Note that traditional solid-state ISE electrodes are rigid ion-to-electron transducers that are not conformal to soft human skin and cannot function under stretched states. Here, we demonstrated that vertically aligned mushroom-like gold nanowires (v-AuNW) could serve as stretchable and wearable ion-to-electron transducers for multiplexed, in situ potentiometric analysis of pH, Na, and K in sweat.

Cat-Tail-Like Mesostructured Silica Fibers Decorated with Gold Nanowires: Synthesis, Characterization, and Application as Stretchable Sensors.

Invited for this month's cover are the collaborating groups of Prof. Xiaojun Han from Harbin Institute of Technology, China and Prof. Wenlong Cheng from Monash University, Australia.

Cat-Tail-Like Mesostructured Silica Fibers Decorated with Gold Nanowires: Synthesis, Characterization, and Application as Stretchable Sensors.

Gold-nanowires (AuNWs)-coated mesostructured silica fibers that have the appearance of a cat's tail have been successfully designed and synthesized. The silica fibers had a Brunauer-Emmett-Teller (BET) surface area of 347 m  g and Barret-Joyner-Halenda (BJH) pore size of 3.8 nm.

Recent Progress in Lab-On-a-Chip Systems for the Monitoring of Metabolites for Mammalian and Microbial Cell Research.

Lab-on-a-chip sensing technologies have changed how cell biology research is conducted. This review summarises the progress in the lab-on-a-chip devices implemented for the detection of cellular metabolites. The review is divided into two subsections according to the methods used for the metabolite detection.

Disruptive, Soft, Wearable Sensors.

The wearable industry is on the rise, with a myriad of technical applications ranging from real-time health monitoring, the Internet of Things, and robotics, to name but a few. However, there is a saying "wearable is not wearable" because the current market-available wearable sensors are largely bulky and rigid, leading to uncomfortable wearing experience, motion artefacts, and poor data accuracy. This has aroused a world-wide intensive research quest for novel materials, with the aim of fabricating next-generation ultra-lightweight and soft wearable devices.

Real-Time and In-Situ Monitoring of HO Release from Living Cells by a Stretchable Electrochemical Biosensor Based on Vertically Aligned Gold Nanowires.

Traditional electrochemical biosensing electrodes (e.g., gold disk, glassy carbon electrode, etc.

Multiscale Soft-Hard Interface Design for Flexible Hybrid Electronics.

Emerging next-generation soft electronics will require versatile properties functioning under mechanical compliance, which will involve the use of different types of materials. As a result, control over material interfaces (particularly soft/hard interfaces) has become crucial and is now attracting intensive worldwide research efforts. A series of material and structural interface designs has been devised to improve interfacial adhesion, preventing failure of electromechanical properties under mechanical deformation.

Local Crack-Programmed Gold Nanowire Electronic Skin Tattoos for In-Plane Multisensor Integration.

Sensitive, specific, yet multifunctional tattoo-like electronics are ideal wearable systems for "any time, any where" health monitoring because they can virtually become parts of the human skin, offering a burdenless "unfeelable" wearing experience. A skin-like, multifunctional electronic tattoo made entirely from gold using a standing enokitake-mushroom-like vertically aligned nanowire membrane in conjunction with a programmable local cracking technology is reported. Unlike previous multifunctional systems, only a single material type is needed for the integrated gold circuits involved in interconnects and multiplexed specific sensors, thereby avoiding the use of complex multimaterials interfaces.

Self-assembly and characterization of 2D plasmene nanosheets.

Freestanding plasmonic nanoparticle (NP) superlattice sheets are novel 2D nanomaterials with tailorable properties that enable their use for broad applications in sensing, anticounterfeit measures, ionic gating, nanophotonics and flat lenses. We recently developed a robust, yet general, two-step drying-mediated approach to produce freestanding monolayer, plasmonic NP superlattice sheets, which are typically held together by holey grids with minimal solid support. Within these superlattices, NP building blocks are closely packed and have strong plasmonic coupling interactions; hence, we termed such freestanding materials 'plasmene nanosheets'.

Hierarchically Structured Vertical Gold Nanowire Array-Based Wearable Pressure Sensors for Wireless Health Monitoring.

We have recently demonstrated that vertically aligned gold nanowires (v-AuNWs) are outstanding material candidates for wearable biomedical sensors toward real-time and noninvasive health monitoring because of their excellent tunable electrical conductivity, biocompatibility, chemical inertness, and wide electrochemical window. Here, we show that v-AuNWs could also be used to design a high-performance wearable pressure sensor when combined with rational structural engineering such as pyramid microarray-based hierarchical structures. The as-fabricated pressure sensor featured a low operation voltage of 0.

Covalent-Cross-Linked Plasmene Nanosheets.

Thiol-polystyrene (SH-PS)-capped plasmonic nanoparticles can be fabricated into free-standing, one-nanoparticle-thick superlattice sheets (termed plasmene) based on physical entanglement between ligands, which, however, suffer from irreversible dissociation in organic solvents. To address this issue, we introduce coumarin-based photo-cross-linkable moieties to the SH-PS ligands to stabilize gold nanoparticles. Once cross-linked, the obtained plasmene nanosheets consisting of chemically locked nanoparticles can well maintain structural integrity in organic solvents.

2D Freestanding Janus Gold Nanocrystal Superlattices.

2D freestanding nanocrystal superlattices represent a new class of advanced metamaterials in that they can integrate mechanical flexibility with novel optical, electrical, plasmonic, and magnetic properties into one multifunctional system. The freestanding 2D superlattices reported to date are typically constructed from symmetrical constituent building blocks, which have identical structural and functional properties on both sides. Here, a general ligand symmetry-breaking strategy is reported to grow 2D Janus gold nanocrystal superlattice sheets with nanocube morphology on one side yet with nanostar on the opposite side.

Highly Stretchable and Strain-Insensitive Fiber-Based Wearable Electrochemical Biosensor to Monitor Glucose in the Sweat.

Development of high-performance fiber-shaped wearable sensors is of great significance for next-generation smart textiles for real-time and out-of-clinic health monitoring. The previous focus has been mainly on monitoring physical parameters such as pressure and strains associated with human activities. Development of an enzyme-based non-invasive wearable electrochemical sensor to monitor biochemical vital signs of health such as the glucose level in sweat has attracted increasing attention recently, due to the unmet clinical needs for the diabetic patients.

A General Approach to Free-Standing Nanoassemblies via Acoustic Levitation Self-Assembly.

Droplets suspended by acoustic levitation provide genuine substrate-free environments for understanding unconventional fluid dynamics, evaporation kinetics, and chemical reactions by circumventing solid surface and boundary effects. Using a fully levitated air-water interface by acoustic levitation in conjunction with drying-mediated nanoparticle self-assembly, here, we demonstrate a general approach to fabricating free-standing nanoassemblies, which can totally avoid solid surface effects during the entire process. This strategy has no limitation for the sizes or shapes of constituent metallic nanoparticle building blocks and can also be applied to fabricate free-standing bilayered and trilayered nanoassemblies or even three-dimensional hollow nanoassemblies.

Embedding Pinhole Vertical Gold Nanowire Electronic Skins for Braille Recognition.

Electronic skins (e-skins) have the potential to be conformally integrated with human body to revolutionize wearable electronics for a myriad of technical applications including healthcare, soft robotics, and the internet of things, to name a few. One of the challenges preventing the current proof of concept translating to real-world applications is the device durability, in which the strong adhesion between active materials and elastomeric substrate or human skin is required. Here, a new strategy is reported to embed vertically aligned standing gold nanowires (v-AuNWs) into polydimethylsiloxane, leading to a robust e-skin sensor.

Enokitake Mushroom-like Standing Gold Nanowires toward Wearable Noninvasive Bimodal Glucose and Strain Sensing.

We have recently demonstrated that Enokitake mushroom-like gold with nanoparticles as the "head" and nanowires as the "tail" could grow directly on elastomeric substrates, which are extremely stretchable electrodes that can be used as wearable sensors for detecting strain and pressure. In this work, we show that such electrodes can also be used as intrinsically stretchable glucose biosensors. By modifying the vertical gold nanowire electrodes with glucose oxidase and Prussian blue nanoparticles, a limit of detection of 10 μM, sensitivity of 23.