ACS Applied Nano Materials最新文献

The nanoscale surface of the substrate is crucial for the molecule detection in surface-enhanced Raman spectroscopy (SERS) technology. In this work, we propose a VO₂/Au composite nanoparticle structure as a high-performance SERS substrate, which was fabricated through a combination of evaporation coating, annealing, and spin coating. The Raman enhancement factor (EF) for rhodamine 6G (R6G) molecules reaches 4.4 × 10⁹ with a minimum detection concentration of 10^–10 M and the relative standard deviation (RSD) is only 12.9%. The results show that the nanoengineered substrate exhibits exceptional Raman activity at 20 °C, attributed to plasmonic hotspots and charge transfer mechanisms. When the temperature increases to 80 °C, the phase transition of VO₂ is induced, leading to a weakening of the charge transfer. This enables the in situ modulation of the SERS signal. The VO₂/Au composite nanoparticle structure prepared in this work exhibits strong Raman enhancement performance and in situ modulation of the SERS signal intensity, which shows great potential for applications in trace detection.

Metal–organic frameworks (MOFs), a class of porous materials, featuring high surface areas, chemical tunability and stability, have been extensively studied for their applications in gas adsorption and separation, particularly in carbon dioxide (CO₂) capture. However, their CO₂ capture capacities often decrease under humid conditions and cannot meet practical application requirements. Herein, we present a facile postsynthetic method to incorporate amino acids (AAs) into an ultrastable MIP-206-OH MOF to construct a series of MIP-206-OH-AA materials. Among these materials, MIP-206-OH-Gly exhibited superior CO₂ capture performance, achieving capacities of 48.4 cm³ g^–1 (1 bar, 273 K) and 317 cm³ g^–1 (30 bar, 273 K), which showed 92.8 and 71.9% enhancement compared to the pristine MIP-206-OH materials, respectively. Furthermore, MIP-206-OH-Gly and MIP-206-OH-Ala exhibited enhanced CO₂ capture performance under humid conditions and exhibited exceptional stability, maintaining their performance even after 10 cycles. This study provides a facile method to construct amino acid-functionalized nanoporous MOFs for boosting CO₂ capture and underscores the potential of this strategy as an effective and scalable solution for carbon capture under dry and humid conditions.

This study explored the influence of the pore size and channel length of mesoporous organosilicas containing pyridine-bis-imidazolium units toward the cycloaddition of CO₂ to epoxides. Utilizing the same organosilica precursor, we synthesized two distinct types of materials: mesoporous organosilica nanoparticles (BIm-MON) with smaller channel sizes and periodic mesoporous organosilica (BIm-PMO) with larger channel sizes. Following the modification of the parent materials with iodide or bromide ions, we prepared a library of catalysts denoted as the X-BIm-PMO and X-BIm-MON series, where X is Cl, Br, or I. It was observed that after modifying BIm-PMO with iodide ions, the entrance pore size was 5.4 nm, whereas the pore sizes for chloride and bromide ions were 8.1 nm. We then compared their catalytic activities in the coupling of CO₂ with styrene oxide as a substrate under two reaction conditions A (5 bar CO₂ at 80 °C) and B (1 bar at RT). Under both reaction conditions, the I-BIm-PMO catalyst demonstrated a higher activity than the other catalysts. The enhanced performance of the I-BIm-PMO catalyst, when compared to its chloride and bromide equivalents or I-BIm-MON, can be explained by the fact that it not only still has good mass transfer but also provides enrichment of CO₂ molecules within the channels through a confinement effect. This confinement effect may be caused by the coexistence of iodide ions and bis-imidazolium groups, leading to increased catalytic activity under ambient conditions. To elucidate the role of the bis-imidazolium groups in the observed activity, we also synthesized a monoimidazolium catalyst (I-MIm-PMO) and evaluated its performance under the same reaction conditions. Due to its effective confinement effect, we found that the I-BIm-PMO catalyst can adsorb CO₂ three times more than I-MIM-PMO. Furthermore, various terminal epoxides were selectively converted into their corresponding cyclic carbonates. The catalyst was also reused four times.

For the practical diagnosis of inflammatory respiratory diseases, achieving sensitive and rapid NO sensing at the parts per billion level, all at room temperature, is of great significance. Herein, we developed a chemiresistor gas sensor with a sheet-on-sheet structure composed of an amorphous Cu-hemin MOF with reduced graphene oxide (rGO) nanosheets. The SEM images show that the Cu-hemin MOF/rGO composite exhibits a two-dimensional sheet-like structure. Due to its nanosized architecture, the Cu-hemin MOF exhibits a significant number of active sites for efficient NO detection. The Cu-hemin MOF/rGO composite material exhibited excellent NO sensing performance, including high sensitivity (R_a/R_g = 1.06, 50 ppb), reliable repeatability, high selectivity, and fast response/recovery (43 s/367 s, 10 ppm). The mechanism study revealed that the formation of the MOF altered the hemin dimer’s structure, resulting in the release of additional Fe(III)–N₄ active sites and improved sensitivity. Moreover, the incorporation of rGO significantly boosted the conductivity of Cu-hemin MOFs. Using this two-dimensional sheet-like material, a mask-type sensor was also prepared and verified to be effective as a flexible and wearable sensing device for parts per billion level exhaled NO detection.

The development of advanced conductive polymer matrix composites is crucial for technological innovation in sectors demanding materials with enhanced multifunctional properties. This study reports the synthesis and characterization of a polycaprolactone (PCL) membrane coated with reduced graphene oxide (rGO), combining the electrical conductivity of the rGO with the biocompatibility, flexibility, and mechanical integrity of the PCL membranes. We employed a rotary jet spinning technique to fabricate uniform PCL fibers, followed by dip-coating with graphene oxide and thermal reduction of the graphene oxide on a hot plate. The reduction process was systematically investigated to optimize the electrical conductivity and establish correlations between electrical performance, chemical composition, and structural transformations. The crystalline structure, morphology, chemical composition, and thermal stability of the nanocoated polymer membranes were confirmed through X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). Electrical resistance trends were supported by XPS and Raman spectroscopy, indicating enhanced sp² carbon hybridization, an increased carbon–oxygen ratio and reduced structural disorder. This study highlights a scalable approach for integrating rGO into PCL, significantly enhancing the electrical properties of the composite and making it a promising candidate for applications in printed electronics and bioelectronics, including flexible biosensors and electroactive scaffolds for tissue engineering.

Solid-state transformers (SSTs) are critical components in modern power systems, requiring insulation materials with high thermal conductivity and low dielectric loss to withstand prolonged high-frequency electrical stress and elevated temperatures. Although polyimide (PI) is widely used in SSTs, its low thermal conductivity and high dielectric loss limit its long-term performance. To address these challenges, we developed polydopamine-modified boron nitride nanosheets (BNNS-PDA) as fillers for PI composites. The PDA modification significantly improves the compatibility between BNNS and the PI matrix, resulting in composites with enhanced thermal conductivity (0.679 W/(m·K) at 5 wt %, 2.2 times that of pure PI) and reduced dielectric loss (0.00617 at 20 kHz, 37% lower than pure PI). These improvements lead to a 65% increase in high-frequency aging lifetime under 3 and 20 kHz, as well as a 62.5% reduction in surface temperature rise under 2 and 20 kHz. Molecular dynamics (MD) simulations reveal that PDA modification increases the interfacial interaction energy and hydrogen bond density between the BNNS and PI, enhancing interfacial stability. Density functional theory (DFT) calculations further visualize and quantify intermolecular hydrogen bonding interactions. When integrated with phase-field modeling, these enhanced interactions are reflected by elevated energy barrier parameters (α), effectively delaying electrical breakdown, and mitigating Joule heating under high-frequency conditions. However, excessively high α values accelerate the breakdown, highlighting the need to optimize doping levels for balanced performance. This study provides a multiscale understanding of the relationship between interfacial modifications and macroscopic performance, offering a practical strategy for designing high-performance insulation materials for high-frequency applications.

Atomically thin transition metal dichalcogenides inherently exhibit native point defects due to the low formation energy of chalcogen vacancies limiting the performance of nano optoelectronic devices. We thoroughly explore the nature of native defects in metal–organic chemical vapor deposited pristine MoS₂ and Mo_1–xW_xS₂ monolayers utilizing high-resolution transmission electron microscopy. Our findings suggest that W alloying induces a tensile strain of 2.32%, which significantly reduces the sulfur vacancy defect density, thereby dramatically enhancing the photoluminescence yield by 32 times for x ≥ 0.5. This work provides insights into the relationship between native sulfur vacancy defects and strain in Mo_1–xW_xS₂ for improved device performance.

Carbon-based nanomaterials have garnered significant attention for their use in oxygen reduction reactions (ORRs) due to their distinctive electronic properties, adjustable structural features, and robust long-term operational stability. Recently, developing efficient electrochemical catalysts to produce hydrogen peroxide (H₂O₂) has become a crucial pursuit in the energy field. However, it is a challenge to precisely control the composition of the catalyst for H₂O₂ through a two-electron ORR. In this study, we demonstrated a strategy for fabricating highly selective two-electron ORR catalysts based on atomic-level cobalt (Co)-grafted porous carbon nanofibers. A series of Co-based catalysts with mesoporous structures were successfully fabricated by using cobalt nitrate and carbon quantum dots through electrostatic spinning, heat treatment processes under an ammonia atmosphere, and acid etching. With these processes, we are able to produce atomic-level Co coordinated with N₂–O₂ grown on mesoporous carbon nanofibers, as confirmed by synchrotron X-ray absorption spectroscopy and scanning transmission electron microscopy. Fine-tuning the surrounding atomic configuration of the Co atom enables a two-electron ORR for H₂O₂ production. For instance, at a potential of 0.65 V, the selectivity of the catalyst for H₂O₂ was as high as 96%, and the as-prepared catalyst exhibited a kinetic current density of 2.57 mA cm^–2 with a number of electron transfers of ∼2. This current investigation provides a simple and convenient method for preparing atomic-level Co grafted on a mesoporous nanofiber-based catalyst for efficient electrochemical H₂O₂ production.

Palladium–cobalt (PdCo) alloy nanofilms are expected to play important roles in future hydrogen (H) energy-based society and H-mediated spintronic devices due to their H absorption and large spin–orbit interaction (SOI). Large SOI causes magnetic anisotropy in PdCo films to be sensitive to film stress via the magnetoelastic coupling or inverse magnetostriction effect. Considering this situation, by employing several PdCo alloy nanofilms, we investigated the impact of initial magnetic anisotropy on H₂ sensitivity. Our systematic investigation revealed that instability in magnetic anisotropy is important, as it enables absorbed H atoms to induce a large change in magnetic properties, resulting in higher H₂ sensitivity. In addition to magnetic anisotropy, nanosized effects have also been revealed to be important for enhancing H₂ sensitivity. Based on the measured results and discussion, design guidelines for H₂ sensors and H-mediated devices are summarized. The results from this study facilitate the use of both present PdCo and other related alloy films and will help accelerate research and development on H₂ sensors and H-mediated devices.

This study evaluates the efficacy of an extracellular vesicles-liposome-darunavir (EV-Lip-DRV) formulation for the treatment of HIV neuropathogenesis, including neurocognitive disorders. The EV-Lip-DRV formulation was developed through a process involving thin-film hydration and extrusion, followed by ultrafiltration to remove unloaded DRV. The encapsulation efficiency was found to be 41.75 ± 2.19%, with a particle size of ∼189 nm and zeta potential of ∼−7.8 mV. The hemocompatibility test confirmed the safety of the formulation for red blood cells, while drug release profiles demonstrated a sustained release of DRV within 24 h. Our in vitro experiment showed that EV-Lip-DRV significantly reduces HIV replication in U1 macrophages and alters the pro-inflammatory cytokine and chemokine levels. Pharmacokinetic studies in C57BL/6 mice via intranasal administration revealed significantly enhanced drug delivery in the brain, relative to systemic circulation and other peripheral organs. Behavioral studies using EcoHIV-infected mice indicated significant improvements in HIV-associated impaired cognitive and motor functions when treated with the EV-Lip-DRV formulation compared to those with DRV alone. Furthermore, analysis of brain tissues from these mice showed significantly reduced HIV-associated inflammatory response, oxidative stress, DNA damage, and neuronal damage in EV-Lip-DRV as compared with DRV alone. Taken together, these findings suggest that EV-Lip is a promising vehicle for enhancing the delivery of antiretroviral drugs to the brain, potentially ameliorating symptoms associated with HIV neuropathogenesis and improving overall outcomes in HIV treatment.