ACS Applied Materials & Interfaces最新文献

The controllable regulation of immune and osteogenic processes plays a critical role in the modification of biocompatible materials for tissue regeneration. In this study, titanium dioxide-europium coatings (MAO/Eu) were prepared on the surface of a titanium alloy (Ti-6Al-4V) via a one-step process combining microarc oxidation (MAO) and in situ doping. The incorporation of Eu significantly improved the hydrophilic and mechanical properties of the TiO₂ coatings without altering their morphology. The presence of Eu effectively stimulated calcium influx in macrophages and activated β-catenin through the wnt/β-catenin signaling pathway. Consequently, macrophage M2 polarization was accelerated through the overexpression of prostaglandin E2 (PGE2). Additionally, Ca²⁺ promoted the osteogenic differentiation of MC3T3-E1 cells through the synergistic upregulation of transcription factors (e.g., AP-1, BMP-2). In vivo studies demonstrated that MAO/Eu coatings significantly enhanced osseointegration compared with the titanium alloy group. Therefore, MAO/Eu shows promising potential as an ideal coating for implants that offers effective immunomodulatory strategies and improves bone integration.

Various glassy hydrogels are developed by forming dense physical associations within the matrices, which exhibit forced elastic deformation and possess high stiffness, strength, and toughness. Here, the viscoplastic behaviors of the glassy hydrogel of poly(methacrylamide-co-methacrylic acid) are investigated by stress relaxation and creep measurements. We found that the characteristic time of stress relaxation of the glassy gel is much smaller than that of amorphous polymers. The varying hydrogen bond strength leads to a broad distribution of structural activation energies, which in turn affects the range of characteristic time. In the presence of water, the weak hydrogen bond associations are easily disrupted under applied strain, enhancing segmental mobility and reducing relaxation time in the preyield regime, while in the postyield regime, the relaxation time increases slightly since the chain stretching increases the energy barrier. In creep tests, the creep strain rate accelerates at the initial stage due to stress-activated segments and then decelerates as chains are extensively stretched. The stress required for structural activation during creep is much lower than the Young's modulus of the gel, reflecting the poor structural stability. To further analyze the underlying mechanism of the glassy gel, a micromechanical model is established based on an extension on shear transformation zone theory. By incorporating a state variable for hydrogen bond density, this model can capture the intricate mechanical responses of glassy gels. Our findings reveal that glassy hydrogels are far from the thermodynamic equilibrium state, exhibiting rapid segment activation under external loading. This work provides insights to the dynamics and structural stability of glassy materials and can promote the design and applications of tough hydrogels.

Due to the critical importance of carbon neutrality for the survival of humanity, passive thermal management, which manages thermal energy without additional energy consumption, has become increasingly attractive. Camouflage materials offer a promising solution for passive thermal management, as they can dissipate heat through thermal radiation, reducing the need for energy-intensive cooling systems. However, developing effective infrared (IR) camouflage solutions for low-temperature environments and small-sized applications remains a challenge because the low temperatures limit the ability to dissipate radiative energy from the surface. Moreover, conventional IR camouflage materials, typically optimized for single band (5-8 μm), face significant limitations in energy dissipation at lower temperatures, which requires a novel way to increase the energy dissipation without the additional energy consumption. Herein, we present a novel low-temperature IR camouflage material (LICM) designed to address these challenges by employing dual-band resonances in the nondetection bands, 5-8 and 14-20 μm based on the atmospheric transmittance. LICM demonstrated an increase in energy dissipation of 273 and 167% at 250 and 350 K, respectively than the conventional IR camouflage materials. Despite the enhanced dissipation, the LICM maintained an IR signature reduction of around 10% of blackbody radiation, ensuring effective IR camouflage. Thermographic measurements using an LWIR camera (7.5-14 μm) further demonstrated the LICM's superior IR camouflage performance. This dual-band resonance design not only extends IR camouflage to low-temperature environments but also facilitates significant energy savings, making it a key ingredient for broad-scale deployment in areas such as energy conversion, aerospace, and sustainable thermal management technologies.

Si nanowire transistors are ideal for the sensitive detection of atmospheric species due to their enhanced sensitivity to changes in the electrostatic potential at the channel surface. In this study, we present unique ambipolar Si junctionless nanowire transistors (Si-JNTs) that incorporate both n- and p-type conduction within a single device. These transistors enable scalable detection of nitrogen dioxide (NO₂), a critical atmospheric oxidative pollutant, across a broad concentration range, from high levels (25-50 ppm) to low levels (250 ppb-2 ppm). Acting as an electron acceptor, NO₂ generates holes and functions as a pseudodopant for Si-JNTs, altering the conductance and other device parameters. Consequently, ambipolar Si-JNTs exhibit a dual response at room temperature, reacting on both p- and n-conduction channels when exposed to gaseous NO₂, thereby offering a larger parameter space compared to a unipolar device. Key characteristics of the Si-JNTs, including on-current (I_on), threshold voltage (V_th) and mobility (μ), were observed to dynamically change on both the p- and n-channels when exposed to NO₂. The p-conduction channel showed superior performance across all parameters when compared to the device's n-channel. For example, within the NO₂ concentration range of 250 ppb to 2 ppm, the p-channel achieved a responsivity of 37%, significantly surpassing the n-channel's 12.5%. Additionally, the simultaneous evolution of multiple parameters in this dual response space enhances the selectivity of Si-JNTs toward NO₂ and improves their ability to distinguish between different pollutant gases, such as NO₂, ammonia, sulfur dioxide and methane.

We introduce the proof of concept of a new methodology to produce robust hollow nanovesicles stable in water or mixtures of water and organic solvents. The bottom-up produced nanovesicles are formed by the self-assembly of depsipeptide chains of natural origin combined with new aggregation-induced emission luminogens that function as constitutional vesicle-forming moieties and fluorescent indicators of the structure of the nanovesicle. The newly formed nanovesicles are robust enough to be used to carry large molecules such as physiological peptides without losing their structural characteristics, acting as programmable nanocarrier systems within living cells as Trojan horse systems, constituting a new approach to active transport and nanoencapsulation.

Neutrophil extracellular traps (NETs) are networks of decondensed chromatin, histones, and antimicrobial proteins released by neutrophils in response to an infection. NET overproduction can cause an exacerbated hyperinflammatory response in a variety of diseases and can lead to host tissue damage without clearance of infection. Nanoparticle drug delivery is a promising avenue for creating materials that can both target NETs and deliver sustained amounts of NET-degrading drugs to alleviate hyperinflammation. Here, we study how particle physicochemical properties can influence NET interaction and leverage our findings to create NET-interfacing and NET-degrading particles. We fabricated a panel of particles of varying sizes (200 to 1000 nm) and charges (positive, neutral, negative) and found that positive charge is the main driver of NET-particle interaction, with smaller 200 nm positive particles having a 10-fold increase in binding compared to larger 1000 nm positive particles. Negative and neutral particles were mostly noninteracting, except for small negatively charged particles that exhibited very low levels of NET localization. Interaction strength of particles with NETs was quantified via shear flow assays and atomic force microscopy. This information was leveraged to create DNase-loaded particles that could adhere to NETs at varying degrees and therefore degrade NETs at different rates in vitro. Positively charged, 200 nm DNase-loaded particles showed the highest degree of interaction with NETs and therefore led to faster degradation compared with larger sizes, underscoring the importance of physicochemical design for NET-targeting drug delivery. Overall, this work provides fundamental knowledge of the drivers of particle-NET interaction and a basis for designing NET-targeting particles for various disease states.

Polyimide (PI)-based gas separation membranes are of great interest in the field of H₂ purification owing to their good thermal stability, chemical stability, and mechanical properties. Among polyimide-based membranes, intrinsically microporous polyimides are easily soluble in common organic solvents, showing great potential for fabricating hollow fiber gas separation membranes. However, based on the solution-diffusion model, improving the free volume or the movability of polymer chains can improve gas permeability, but would result in poor thermal stability. Herein, we develop a carbazole-alkyl-based diamine monomer that endows PI chains with a "rigid-soft" structure to balance the trade-off between them. Soft units enhance the movability of polymer chains during the film-forming process, ensuring that rigid units achieve tight chain packing and strong intermolecular interactions. Meanwhile, bulky carbazole groups could further restrict the motion of soft units in the solid state. On the one hand, it restricts the movability of the polymer chains below T_g, enhancing the small gas selectivity for H₂ and He. On the other hand, it ensures good thermal stability. Moreover, extending the length of the alkyl chains helps improve the free volume and intermolecular interactions simultaneously, thereby further optimizing the gas permeability/selectivity trade-off. As a result, the as-prepared PI shows H₂ permeability of 89.61 Barrer, H₂/CH₄ selectivity of 87.85, and H₂/N₂ selectivity of 45.03 in contrast to the reference FPI TFMB-6FDA exhibiting H₂ permeability of 92.95 Barrer, H₂/CH₄ selectivity of 72.62, and H₂/N₂ selectivity of 38.57. Meanwhile, a high T_g value of 334 °C is also achieved.

Superhydrophobic surfaces are considered to be an effective method for anti-icing, but passive anti-icing alone is not as effective as it should be, so it is crucial to develop effective anti-icing techniques. In this study, a photothermal anti-icing structure with multienergy barriers was designed by combining active and passive anti-icing technologies and prepared by a three-step method of laser etching, hydrothermal growth of nanostructures, and chemical modification based on the Cassie-Baxter-Wenzel transition theory. The experimental results show that the static water contact angle of the prepared surface is up to 160°, the sliding angle is less than 3.6°, and the surface temperature is 25 °C higher than that of the original control group over 100 s under standard solar irradiation. The multienergy barrier design greatly prolongs the time of the anti-icing, and the durability test shows that the surface maintains superhydrophobicity even after the abrasion of sandpaper and the impact of sand. This superhydrophobic photothermal coating has great potential for anti-icing and deicing applications.