ACS Applied Nano Materials最新文献

Single-walled carbon nanotubes (SWNTs) hold great promise as conductive agents in high-performance lithium-ion batteries owing to their exceptional electrical and mechanical properties. However, their synthesis is highly sensitive to temperature, which often leads to structural defects and poor dispersion. These issues considerably impede the formation of conductive networks and compromise the stability of battery performance. Therefore, precise temperature control is critical for improving the quality of SWNTs and facilitating their practical application. In this study, a mixed catalyst of ferrocene and sublimed sulfur was employed to systematically investigate the effect of reaction temperature on SWNTs synthesis. A uniform SWNTs slurry with low iron content was prepared, and the electrochemical performance of the as-synthesized SWNTs was evaluated using LiFePO₄ as the cathode material. Raman spectroscopy and BET measurements revealed an exceptionally narrow optimal temperature window for high-quality SWNT growth. At 1000 °C, highly graphitized SWNTs with low defect density and high specific surface area were obtained. In contrast, lower temperatures resulted solely in multiwalled carbon nanotubes (MWNTs), while excessively high temperatures led to progressive degradation in SWNT properties. The SWNTs synthesized at 1000 °C significantly reduced the charge transfer resistance of LiFePO₄ electrodes even at an ultralow loading of 0.2 wt %, endowing the electrodes with superior performance. This efficient and controllable synthesis strategy provides a robust foundation for the stable and large-scale production of SWNTs.

This work presents an efficient and sustainable heterogeneous manganese nanocatalyst (Mn₃O₄-N@Al₂O₃) for the selective hydrogenation of various nitroarenes to aryl amines using molecular hydrogen. The performance of the Mn₃O₄-N@Al₂O₃ catalyst is evaluated through a series of reactions demonstrating excellent selectivity in hydrogenating the nitro group while preserving functional groups such as aldehyde, ketone, amides, carboxylic acid, nitrile, and olefins. The high selectivity and conversion were maintained even in a gram-scale reaction (∼1 g), performed for the synthesis of active pharmaceutical intermediates, including 2,6-dichloroaniline, 2,2′-(ethane-1,2-diyl)aniline, 2-aminobenzenethiol, and 3-chloro-4-fluoroaniline. Additionally, naphthalene-1,5-diamine and 4-amino-2,6-dichlorophenol were synthesized on a ∼1 g scale, which are key intermediates for producing naphthalene-1,5-diisocyanate and hexaflumuron, respectively. The analytical characterization data reveal that the catalysts consist of Mn₃O₄ nanoparticles dispersed on the surface of Al₂O₃ with an average size of 4.04 nm. The reaction mechanism was elucidated by tracking intermediates at different stages of the reactions, indicating a direct route without the formation of any condensation products.

To elucidate the luminescence mechanism of gold nanoclusters (Au NCs) with a controllable dual band, which is suitable for applications to bioimaging and chemical sensing, photoluminescence (PL) and electrochemiluminescence (ECL) of Au NCs are investigated with varying ligand densities. Despite the similar sizes of Au NCs, the dual band of orange-red and near-infrared in PL and ECL depends on the ligand density on the surface of the NCs. Besides, the intensities of the two bands in PL change with excitation energy, while those in ECL change with electric potential, suggesting that the two bands are attributable to two chromophoric motifs with distinct characters of Au–S bonds. Au(I)–S motifs with charge transfer characteristics exhibit noticeable pH-dependence, while Au(0)–S motifs are mainly correlated to Au cores bound to ligands. The time profiles of the two bands are independent of relative intensities, indicating that energy transfer is not primarily responsible for the relative intensities despite the coexistence of the two motifs. Accordingly, unique features of luminescence are ascribed to the excitation of the two motifs, as well as the density of the two motifs, influenced by ligand density, suggesting molecule-like electronic transitions in Au NCs. We propose a mechanism to improve the controllability of Au NCs, which includes the ligand density and excitation energy, to tune the color and efficiency of luminescence for a wide range of applications.

Oncolytic viruses (OVs) represent a promising approach for cancer therapy, but their clinical efficacy is often hindered by pre-existing antiviral immunity and tumor drug resistance. To overcome these obstacles, we developed an iron-based metal–organic framework (MOF_Fe) nanoplatform for OV delivery, which not only protects the virus from neutralizing antibodies in circulation but also enhances intratumoral virus spread through radiation therapy (RT)-induced ferroptosis. The MOF_Fe-OV complex (MOF_Fe@OV) demonstrated prolonged circulation, enabling it to infect cancer cells without being cleared systemically. Notably, RT in combination with MOF_Fe@OV induces iron-dependent ferroptosis, which not only directly kills tumor cells but also increases tumor cell susceptibility to the OVs. In xenograft models of esophageal cancer, MOF_Fe@OV + RT achieved significant tumor regression (70.2% volume reduction compared to the control group). Mechanistically, the combined therapy triggered strong ferroptosis in tumor cells via the reduction expression of GPX4 by 65.7%. This study established MOF_Fe@OV + RT as a multifunctional platform that integrates viral therapy, ferroptosis induction, and radiosensitization to overcome biological barriers in OV delivery, thereby offering a clinically translatable strategy for enhanced tumor lysis.

Cancer treatment remains a significant challenge due to the complex tumor microenvironment (TME) and hypoxic conditions, which significantly contribute to drug resistance. In this study, we report the development of a new multifunctional nanoparticle system exhibiting dual functionality for effective cancer therapy. The nanoplatform integrates a near-infrared aggregation-induced emission (AIE) luminogen 3T with oxygen-generating MnO₂ nanoparticles to achieve simultaneous hypoxia relief and effective antiproliferative activity. An in vitro study demonstrated its excellent antiproliferative activity and the ability to generate oxygen in both monolayer cultures and tumor spheroids. The synthesized PEG-3T-MnO₂ nanoparticles were able to generate 3.4-fold reactive oxygen species (ROS) and induced changes in the mitochondrial membrane potential, leading to induction of apoptosis. An increase in 40.4% apoptotic population was observed in the highly aggressive metastatic MDA-MB-231 cells after treatment. Further, Western blot analysis revealed a decrease in the expression of hypoxia-inducible factor-1α (HIF-1α). Overall, the PEG-3T-MnO₂ nanoparticles represent an innovative approach to modulate the TME, a promising strategy by alleviating hypoxia and potentially improving overall treatment efficacy.

Three-dimensional (3D) plasmonic Ag/Au alloy aerogels with hierarchical porosity and interconnected networks were fabricated via a facile one-pot reduction–gelation strategy. This approach enables simultaneous reduction, alloying, and self-assembly of Ag and Au, producing aerogels with tunable composition, uniform mesoporosity, and abundant plasmonic hotspots. Structural and optical characterizations confirm homogeneous alloying within a robust 3D framework, broadband plasmonic resonance, enhanced electromagnetic field localization, and minimal charge transfer resistance, collectively enabling ultrasensitive and reproducible surface-enhanced Raman spectroscopy (SERS) detection. Systematic tuning of Au content identifies Ag-1Au as optimal, balancing plasmonic enhancement, chemical stability, and long-term durability. The aerogels allow qualitative and quantitative detection of illicit drugs, including amphetamine, ketamine, morphine, tetrahydrocannabinol (THC), and synthetic cannabinoids, with detection limits down to 10^–9 to 10^–11 M and excellent reproducibility. Moreover, the platform effectively detects cannabinoids in complex matrices, such as electronic cigarette liquids, demonstrating practical applicability. This work establishes a facile, scalable, and highly controllable strategy to construct high-performance Ag/Au aerogels for ultrasensitive chemical sensing and forensic applications.

This work proposes a selective fluorescence sensing platform that uses carbon dots (CDs) embedded in molecularly imprinted polymers (MIPs) to detect physiologically relevant biomarkers, such as glucose and sialic acid. Pristine CDs were synthesized via pyrolysis using galactose as the carbon source. To improve fluorescence stability and prevent leaching in aqueous environments, CDs were encased in a silica shell with APTES using the Stöber method. CDs@MIP were then synthesized by integrating silica-coated CDs into the MIP matrix. Based on the template molecule employed during the synthesis, two types of CDs@MIP, namely, G-MIP (glucose-MIP) and SA-MIP (sialic acid-MIP), were produced. The resultant polymers, G-MIP and SA-MIP, displayed a fluorescence turn-on mechanism with enhanced selectivity and sensitivity for glucose and sialic acid, respectively. Detection limits of 0.0657 ppm (0.365 μM) for glucose and 0.0962 ppm (0.311 μM) for SA were obtained. This enabled the detection of analytes in the micromolar range required for most physiological applications. The mechanism of fluorescence enhancement during the analyte interaction was attributed to hydrogen bonding with CDs, which was verified using FTIR spectroscopy, fluorescence lifetime measurements, and computational studies. In the current study, the turn-on fluorescence of CDs, together with the specialized identification capability of MIPs, provided a powerful platform for selective biosensing that has been incorporated into portable smartphone-based detection systems.

Graphene-based electrochromic devices have garnered significant attention owing to their rapid response and broad band tunability. The performance of such devices is highly dependent on the thickness of the graphene film. However, the fabrication of uniform multilayer graphene films with desired thicknesses in the tens of nanometers via chemical vapor deposition remains challenging to date. In this study, reduced graphene oxide (rGO) membranes with tailored thicknesses were prepared using a vacuum filtration method, and the performance of electrochromic devices based on ionic liquid intercalation into these as-prepared rGO membranes was systematically investigated. It was found that the transmittance modulation depth (%) is dependent on the thickness of the rGO membranes, with the maximum value reaching 34.72% in a wavelength range of 0.45–1.10 μm, which corresponds to a membrane thickness of 32 nm. Through careful optimization of the preparation process, the devices exhibited enhanced switching speeds (typically, a charging time of 0.7 s and a discharging time of 0.2 s), which are faster than those reported for devices using graphitic films, and the underlying mechanism is proposed. Besides, the reflectance modulation depth reached 52.83% in a wavelength range of 2–16 μm. Our approach overcomes the existing limitations associated with the preparation of uniform multilayer graphene films with desired thicknesses for electrochromic applications using the chemical vapor deposition method. This work also holds great promise for the development of high-speed switching and flexible smart windows as well as for applications in dynamic optical camouflage.

Highly sensitive and fast detection of trimethylamine (TMA) is essential for applications, such as food freshness evaluation and environmental monitoring. In this work, W-doped Fe₂O₃/NiO nanomaterials with a flower-like architecture were synthesized and systematically investigated for TMA sensing. Structural and surface analyses confirmed that W doping effectively reduced the crystalline size, increased the specific surface area, and introduced abundant oxygen vacancies, while maintaining a porous nanosheet morphology. The sensor exhibited outstanding performance toward TMA at 237.5 °C, with a high response of 62.7 (100 ppm), ultrafast response/recovery times (3/17 s), a low detection limit of 30 ppb, excellent selectivity against common interfering gases, strong repeatability, and stability over 30 days. Density functional theory calculations further revealed that W doping lowers the oxygen vacancy formation energy (from 5.36 to 4.74 eV) and enhances the adsorption energy for TMA (−4.11 eV), supporting the experimentally observed high selectivity.