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Nanoparticles that catalyze biochemically relevant reactions are promoted as alternative enzymes. The application of such artificial enzymes is severely restricted by poor selectivity in biological fluids; mainly because the reactions occur at active sites on the exterior surface of the nanoparticle. Enzymes in contrast typically have their active sites down a nanoconfined substrate channel where the reaction occurs in different solution conditions to bulk solution which aids in achieving selectivity for the substrate. Herein the same 3D structure of enzymes is mimicked in nanoparticles to allow selective reactions in biological fluids. This is achieved using a gold nanoparticle coated in a conducting mesoporous carbon shell where isolated nanochannels lead to the gold surface. It can detect glucose in whole blood with no interference from other species. This is achieved by electrochemically pulsing the artificial enzymes to generate the locally required alkalinity for an effective electrocatalytic reaction in the nanochannels, as well as expelling fouling agents that will otherwise passivate the electrocatalytic reaction. The artificial enzymes are shown to be capable of detecting glucose in biological fluids, without loss of signal, for several months. This study shows how nanoconfinement in nanoparticles can be exploited to potentially allow a broad range of species to be selectively detected in biological fluids with stability that can exceed that of enzymes. [ABSTRACT FROM AUTHOR]

This study presents the combination of electrochemical cell based biosensor and fluorescence microscopy on a single platform to track biomolecular processes contributing to the morphology changes of the cells. Initial experiments demonstrate that using interdigitated electrodes where the gold microfingers were comparable in width and spacing to a single cell have the optimal sensitivity in the final electrochemical cell based‐sensing device. This was determined by measuring the cell index, based on the impedance analysis of bare and cell‐covered microelectrodes. The fabrication of the electrodes on a glass substrate enabled the capture of high‐resolution fluorescence microscopy images of single cells and related intracellular calcium release inside the HeLa cells via a window incorporated into the gold microelectrode design. As an illustration of the enhanced capability of the combined approach over traditional impedance cellular assay, the opto‐electric assay was utilized as a functional readout for G protein couple receptor activation. The simultaneous examinations of cells stimulated with histamine demonstrated an association between time courses of changes in cytosolic calcium concentration and reductions in cell‐cell adhesions. [ABSTRACT FROM AUTHOR]

Background: Superparamagnetic iron core iron oxide shell nanocubes have previously shown superior performance in magnetic resonance imaging T2 contrast enhancement compared with spherical nanoparticles. Methods: Iron core iron oxide shell nanocubes were synthesized, stabilized with dimercaptosuccinic acid (DMSA-NC) and physicochemically characterized. MRI contrast enhancement and biocompatibility were assessed in vitro. Results: DMSA-NC showed a transverse relaxivity of 122.59 mM-1·s-1 Fe. Treatment with DMSA-NC did not induce cytotoxicity or oxidative stress in U-251 cells, and electron microscopy demonstrated DMSA-NC localization within endosomes and lysosomes in cells following internalization. Global proteomics revealed dysregulation of iron storage, transport, transcription and mRNA processing proteins. Conclusion: DMSA-NC is a promising T2 MRI contrast agent which, in this preliminary investigation, demonstrates favorable biocompatibility with an astrocyte cell model. MRI is a powerful tool used in the diagnosis of cancer, strokes and other injuries. An MRI scan can be improved with the use of iron oxide nanoparticles, which enhance the contrast of the image. In this study we have developed cube-shaped iron nanoparticles (nanocubes), which have been previously shown to be more effective at inducing contrast. We demonstrated that iron-based nanocubes do not damage or induce stress in cells and work effectively as an MRI contrast agent. We further analyzed how the nanocubes may affect cell functioning by investigating changes to protein levels in the cells. The results of this study are promising steps towards using iron-based nanocubes as a tool to improve the clarity of MRI scans for medical imaging and diagnosis. Future work must determine whether these nanocubes work effectively and safely in an animal model, which is a critical step in progressing to their use in clinical settings. [ABSTRACT FROM AUTHOR]

Herein the development of cellular impedance biosensors, electrochemical impedance spectroscopy, and the general principles and terms associated with the cell–electrode interface is reviewed. This family of techniques provides quantitative and sensitive information into cell responses to stimuli in real-time with high temporal resolution. The applications of cell-based impedance biosensors as a readout in cell biology is illustrated with a diverse range of examples. The current state of the field, its limitations, the possible available solutions, and the potential benefits of developing biosensors are discussed. [ABSTRACT FROM AUTHOR]

Synthetic extracellular matrix (ECM) mimics that can recapitulate the complex biochemical and mechanical nature of native tissues are needed for advanced models of development and disease. Biomedical research has heavily relied on the use of animal-derived biomaterials, which is now impeding their translational potential and convoluting the biological insights gleaned from in vitro tissue models. Natural hydrogels have long served as a convenient and effective cell culture tool, but advances in materials chemistry and fabrication techniques now present promising new avenues for creating xenogenic-free ECM substitutes appropriate for organotypic models and microphysiological systems. However, significant challenges remain in creating synthetic matrices that can approximate the structural sophistication, biochemical complexity, and dynamic functionality of native tissues. This review summarizes key properties of the native ECM, and discusses recent approaches used to systematically decouple and tune these properties in synthetic matrices. The importance of dynamic ECM mechanics, such as viscoelasticity and matrix plasticity, is also discussed, particularly within the context of organoid and engineered tissue matrices. Emerging design strategies to mimic these dynamic mechanical properties are reviewed, such as multi-network hydrogels, supramolecular chemistry, and hydrogels assembled from biological monomers., (© 2024 The Author(s). Advanced Materials published by Wiley‐VCH GmbH.)

Single-atom electrocatalysts (SACs) are a class of promising materials for driving electrochemical energy conversion reactions due to their intrinsic advantages, including maximum metal utilization, well-defined active structures, and strong interface effects. However, SACs have not reached full commercialization for broad industrial applications. This review summarizes recent research achievements in the design of SACs for crucial electrocatalytic reactions on their active sites, coordination, and substrates, as well as the synthesis methods. The key challenges facing SACs in activity, selectivity, stability, and scalability, are highlighted. Furthermore, it is pointed out the new strategies to address these challenges including increasing intrinsic activity of metal sites, enhancing the utilization of metal sites, improving the stability, optimizing the local environment, developing new fabrication techniques, leveraging insights from theoretical studies, and expanding potential applications. Finally, the views are offered on the future direction of single-atom electrocatalysis toward commercialization., (© 2024 The Author(s). Advanced Materials published by Wiley‐VCH GmbH.)

It has been acknowledged that thousands of drugs that passed two-dimensional (2D) cell culture models and animal studies often fail when entering human clinical trials. Despite the significant development of three-dimensional (3D) models, developing a high-throughput model that can be reproducible on a scale remains challenging. One of the main challenges is precise cell deposition and the formation of a controllable number of spheroids to achieve more reproducible results for drug discovery and treatment applications. Furthermore, when transitioning from manually generated structures to 3D bioprinted structures, the choice of material is limited due to restrictions on materials that are applicable with bioprinters. Herein, we have shown the capability of a fast-cross-linking bioink that can be used to create a single spheroid with varying diameters (660, 1100, and 1340 μm) in a high-throughput manner using a commercialized drop-on-demand bioprinter. Throughout this work, we evaluate the physical properties of printable ink with and without cells, printing optimization, cytocompatibility, cell sedimentation, and homogeneity in ink during the printing process. This work showcases the importance of ink characterization to determine printability and precise cell deposition. The knowledge gained from this work will accelerate the development of next-generation inks compatible with a drop-on-demand 3D bioprinter for various applications such as precision models to mimic diseases, toxicity tests, and the drug development process.