A Liquid Metal-Based Temperature-Responsive Low-Toxic Smart Coating for Anti-Biofouling Applications in Marine Engineering.

Titanium alloys have been widely used in marine engineering fields. However, because of high biocompatibility, they are vulnerable to biofouling. In this work, based on the micro-arc oxidation technology and spontaneous galvanic replacement reaction, a temperature-responsive low-toxic smart coating consisting of liquid metal particles is designed to control the release of Ga3+, Cu2+, and Cu1+ ions in different temperatures. This technology can ensure the full release of active ingredients within the target temperature range, intelligently maintaining the excellent anti-biofouling performance, while saving active ingredients. After being immersed in culture media with Sulfate-Reducing Bacteria (SRB) for 14 days at 10, 20, and 30 °C, at the optimal activity temperature of 30 °C for SRB, the best sample releases the highest amounts of Ga3+, Cu2+, and Cu1+ ions, demonstrating a 99.9% bactericidal rate. When the temperature decreases to 10 °C, the activity level of SRB is very low, and the smart coating can also reduce the released ions correspondingly, still with a 97.3% bactericidal rate. The remarkable anti-biofouling performance is attributed to the physical damage and lethal ions interaction. Furthermore, the best sample exhibits good corrosion resistance. This work presents a design route for smart anti-biofouling coatings for temperature-responsive.

In Situ Fabrication of Heterogeneous Co/Nanoporous Carbon Nano-Islands for Excellent Electromagnetic Wave Absorption.

High-performance electromagnetic wave (EMW) absorbers are essential for addressing electromagnetic pollution and military security. However, challenges remain in realizing cost-effectiveness and modulating absorbing properties. In this study, heterogeneous Co/nanoporous carbon (NPC) nano-islands are prepared by efficient method co-precipitation combined with in situ pyrolysis. The multi-regulation strategy of morphology, graphitization, and defect density is achieved by modulating the pyrolysis temperature. Adjusting the pyrolysis temperature can effectively balance the conductivity and defect density, optimizing the impedance matching and enhancing the attenuation. Furthermore, it facilitates obtaining the appropriate shape and size of Co magnetic nanoparticles (Co-MNPs), triggering strong surface plasmon resonance. This resonance, in turn, bolsters the synergy of dielectric and magnetic loss. The incorporation of porous nanostructures not only optimizes impedance matching and enhances multiple reflections but also improves interfacial polarization. Additionally, the presence of enriched defects and heteroatom doping significantly enhances dipole polarization. Notably, the absorber exhibits an impressive minimum reflection loss (RLmin ) of -73.87 dB and a maximum effective absorption bandwidth (EABmax ) of 6.64 GHz. The combination of efficient fabrication methods, a performance regulation strategy through pyrolysis temperature modulation, and radar cross section (RCS) simulation provides a high-performance EMW absorber and can pave the way for large-scale applications.

Spongy ternary nano-composites with optimized impedance matching and synergistic effect for broadband and strong microwave absorption.

To counter the negative effects of electromagnetic radiation on the immunity of precision instruments, the stealthiness of military equipment, and human health, the preparation of porous multi-component nano-composites is considered an effective strategy to obtain efficient microwave absorption. In this work, the spongy ternary nano-composites (STC) with large specific surface area (SSA) and pore volume obtained by adjusting the calcination temperature, the porous effectively improves the impedance matching. The ternary composition of FeCo/Fe0.45Ni0.55/C, large SSA and pore volume provide abundant specific surface/interface for polarization and magnetization, the continuous conductive network is established, the strong dielectric and magnetic loss achieve a synergistic effect, realizing strong absorption in the low-frequency, greatly reducing the minimum reflection loss (RLmin, -56.37 dB) and broadening the effective absorption bandwidth (EAB, 7.45 GHz). The microwave absorption mechanism has been analyzed in detail and its great potential for practical applications has been verified by RCS signal simulations. This research provides an effective method for fabricating high-performance ternary nano-composite microwave absorbers.

A disposable impedance-based sensor for in-line cell growth monitoring in CAR-T cell manufacturing.

This paper presents the development of low-cost, disposable impedance-based sensors for real-time, in-line monitoring of suspension cell culture. The sensors consist of electrical discharge machining (EDM) cut aluminum electrodes and polydimethylsiloxane (PDMS) spacers, both of which are low-cost materials that can be safely disposed of. Our research demonstrates the capability of these low-cost sensors for in-line, non-invasive monitoring of suspension cell growth in cell manufacturing. We use a hybrid equivalent circuit model to extract key features/parameters from intertwined impedance signals, which are then fed to a novel physics-inspired (gray-box) model designed for α-relaxation. This model determines viable cell count (VCC), a critical quality attribute (CQA) in cell manufacturing. Predicted VCC trends are then compared with image-based cell count data to verify their accuracy.

An efficient metal-organic framework-based drug delivery platform for synergistic antibacterial activity and osteogenesis.

Bone implants for clinical application should be endowed with antibacterial activity, biocompatibility, and even osteogenesis-promoting properties. In this work, metal-organic framework (MOF) based drug delivery platform was used to modify titanium implants for improved clinical applicability. Methyl Vanillate@Zeolitic Imidazolate Framework-8 (MV@ZIF-8) was immobilized on the polydopamine (PDA) modified titanium. The sustainable release of the Zn2+ and MV causes substantial oxidative damage to Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The increased reactive oxygen species (ROS) significantly up-regulates the expression of oxidative stress and DNA damage response genes. Meanwhile, the structural disruption of lipid membranes caused by the ROS, the damage caused by Zinc active sites and the damage accelerated by the MV are both involved in inhibiting bacterial proliferation. The up-regulated expression of the osteogenic-related genes and proteins indicated that the MV@ZIF-8 could effectively promote the osteogenic differentiation of the human bone mesenchymal stem cells (hBMSCs). RNA sequencing and Western blotting analysis revealed that the MV@ZIF-8 coating activates the canonical Wnt/ß-catenin signaling pathway through the regulation of tumor necrosis factor (TNF) pathway, thereby promoting the osteogenic differentiation of the hBMSCs. This work demonstrates a promising application of the MOF-based drug delivery platform in bone tissue engineering.

MOF-derived CuO@ZnO modified titanium implant for synergistic antibacterial ability, osteogenesis and angiogenesis.

Surface modification of titanium implants with antibacterial, osteogenic and even angiogenic capabilities are essential to enhance their clinical applicability. Herein, metal-organic framework (MOF) derived CuO@ZnO composite was grafted onto the polydopamine (PDA) modified titanium alloy to achieve vascularized bone regeneration. The CuO@ZnO-coated titanium effectively inhibits the formation of bacterial biofilms and the sterilization rate of Staphylococcus aureus (S. aureus) reaches 99%. Benefitting from the intrinsic porous architecture of MOFs, the Zn2+ and Cu2+ could be controllably released to facilitate the production of excess intracellular reactive oxygen species (ROS) inside the bacteria, which ensures the excellent antibacterial performance of the composite coating. The CuO@ZnO-coated titanium also exhibits good cytocompatibility, effectively promotes the adhesion and proliferation of the human bone marrow mesenchymal stem cells (hBMSCs) and reduces the level of the cell apoptosis. The up-regulated expression of the osteogenesis-related genes and the superior extracellular matrix mineralization reveals that the CuO@ZnO coating possesses fantastic osteoinductive properties. In addition, the transwell and tube formation assays of the human umbilical vein endothelial cells (HUVECs) suggest the superior angiogenesis ability of the CuO@ZnO-coated titanium. The released Cu2+ stimulated the angiogenesis of the HUVECs in vitro by up-regulating the expression of the vascular endothelial growth factor (VEGF). These findings will provide new insight into the development of multifunctional titanium implants for clinical applications.

Quantitative Investigation of the Process Parameters of Electrohydrodynamic Direct-Writing and Their Effects on Fiber Surface Roughness and Cell Adhesion.

Electrohydrodynamic (EHD) direct-writing has been widely used to fabricate micro/nanofibers that can serve as a building block in tissue engineering scaffolds. However, the application of EHD direct-writing in tissue engineering is limited by the lack of fundamental knowledge in the correlations among the process parameters, the fiber surface roughness, and the cell adhesion performance. Without a standardized experimental setting and the quantitative database, inconsistent results have been reported. Here, we quantitatively investigate the process-structure-property relationships as the first step towards a better understanding of the EHD direct-writing technology for tissue engineering. Polycaprolactone (PCL) solution is used as a model ink material, and human mesenchymal stem cells (hMSCs) are used to study cell adhesion on PCL fibers. We investigate the different jetting modes defined by the applied voltage, the feed rate, and the nozzle-collector distance. The quantitative effects of process parameters on the fiber surface roughness and the cell adhesion performance are experimentally determined. The quantitative process-structure-property relationships revealed in this study provide guidelines for controlling the surface roughness and the cell adhesion performance of EHD direct-written fibers. This study will facilitate the application of EHD direct-writing in tissue engineering.

Rapid Fabrication of Ready-to-Use Gelatin Scaffolds with Prevascular Networks Using Alginate Hollow Fibers as Sacrificial Templates.

In this study, we developed a facile manufacturing method for interconnected prevascular networks using calcium chloride (CaCl2) cross-linked alginate hollow fibers as sacrificial templates. The resulting network can be used to deliver oxygen and nutrients and remove waste for embedded cells in large-volume gelatin scaffolds during in vitro culturing. The sacrificial templates were printed by customized coaxial nozzles and embedded in scaffolds made of a mixture of gelatin, microbial transglutaminase (mTG), and sodium citrate. During the cross-linking of gelatin and mTG, the sacrificial templates started to dissolve from the scaffold-template interface due to the presence of the sodium citrate in the gelatin. The embedded sacrificial templates were completely dissolved without any postprocessing, and the designed prevascular networks successfully retained their geometries and dimensions. No residue of the template was observed at the scaffold-template interface after dissolution, which promoted cell adhesion. This manufacturing method has a high degree of freedom in templates' geometry, which was demonstrated by fabricating prevascular networks with various designs, including grid, branched, and dendritic networks. The effects of hollow fiber size and sodium citrate concentration on the dissolution time were analyzed. Human umbilical vein endothelial cells were injected into the aforementioned networks and formed a confluent endothelial cell monolayer with high viability during the culture process. The results suggest great promise to rapidly build large-scale ready-to-use gelatin scaffolds with prevascular networks for the applications in tissue engineering.

Integrated Flexible, Waterproof, Transparent, and Self-Powered Tactile Sensing Panel.

Portable and wearable electronic devices are human-centered devices; therefore, many unique attributes are highly desirable, such as flexibility, being self-powered, and waterproof. These properties render devices excellent adaptivity in harsh operation environments. In this work, we report an integrated triboelectric tactile sensor array with flexible, transparent, self-powered, and waterproof features. Each tactile sensor is a surface nano/microtexture enhanced triboelectric nanogenerator. The sensor array can serve as a touch panel for electronic devices. Owing to a unique design of a built-in triboelectric contact pair and an electrical shielding layer, an individual pixel of the fabricated tactile sensor array can generate an open circuit voltage up to 1.613 V and a short circuit current density of 47.308 mA/m(2) under 612.5 kPa. The tactile sensors can produce stable voltage signals regardless of the materials of the touching objects, and work stably both in ambient and aqueous environments. To examine the touch panel function of a sensor array, a matrix of 10 × 10 individually addressable 4 mm × 4 mm triboelectric sensors has been integrated into a thin, transparent, and flexible film, and the 2-D touch mapping has been successfully demonstrated. The unique triboelectric tactile sensor array reported here is robust and highly versatile, and it may find broad applications in display, wearable electronics, artificial skins, Internet of Things (IoT), etc.