ACS Nanoscience Au最新文献

Boron nitride nanotubes (BNNTs) are a promising nanomaterial due to their remarkable optical and mechanical properties, chemical robustness, and extended aspect ratios. Herein, we report the formation of strongly biaxially aligned thin films of BNNTs using automated slow vacuum filtration (SVF), as well as their cocomposites with single-wall carbon nanotubes (SWCNTs). Pure BNNT SVF-generated films are found to differ in optimization conditions from those identified previously for SWCNTs but display similar improvements in alignment and uniformity with advanced purification for nanotube length and homogeneity, with globally aligned films observed. Mixed, cocomposite, biaxially aligned films of BNNTs with SWCNTs are also described. Such films provide effective and efficient hosting capabilities for unique morphologies of distributed and individualized SWCNTs aligned by a wide-bandgap BNNT matrix. Concentrations upward of 25% SWCNT mass fraction were found to reside within majority-BNNT films without significantly disrupting the global composite structure; the SWCNT fraction, in turn, enabled probing of both local and global nematic alignment through their use as spectroscopic reporters. Leveraging the thickness and alignment control provided by our SVF implementation, both neat BNNT and composite films show great promise for advancing novel photonic and other thin-film nanocomposite applications requiring tailorable mechanical, thermal, optical, and electronic functionalities.

Lead halide perovskite (LHP) nanocrystals have demonstrated a significant electronic response to their local environment due to their ionic lattice nature. Here, we demonstrated their tunable dipole alignment via solution-processed methods. We synthesized LHP nanocubes and nanoplates in air and characterized them by UV–vis spectrophotometry and transmission electron microscopy. Using atomic force microscopy, UV–vis spectrophotometry, and back focal plane fluorescence microscopy, we characterized thin films of nanocubes on untreated glass, nanoroughened glass, and polymer film (poly(methyl methacrylate), PMMA), as well as a perovskite nanocubes-nanoplate binary film on etched glass. Most notably, the dipole orientation factor can be modulated from 0.47 to 0.59 (effective transition dipole moment angle from 47° to 40°) by using glass or PMMA, respectively. Understanding the tunable anisotropic transitions in these materials at the nanoscale is required to control light emission into specific modes, which will maximize efficiency in devices such as light-emitting diodes, photovoltaics, and quantum information technology.

This study investigates the photocatalytic performance of Cu₂O surfaces modified with halogen-substituted phenylacetylenes (4-XA), including 1-ethynyl-4-fluorobenzene (4-FA), 1-chloro-4-ethynylbenzene (4-CA), and 1-bromo-4-ethynylbenzene (4-BA), using an integrated theoretical and experimental approach. Through density functional theory (DFT) calculations and ultraviolet photoelectron spectroscopy (UPS) measurements, we analyze how these molecular decorators affect charge transfer dynamics and the electronic structure of the Cu₂O {100}, {110}, and {111} facets. Two distinct photocatalytic mechanisms are proposed: one where electrons reach the vacuum level through the molecular decorator and another where electrons escape directly through the Cu₂O surface via molecular-induced hybridized states. Our results show that 4-BA-modified {100} surfaces exhibit the strongest enhancement, which is attributed to the presence of in-gap molecular states, increased charge separation, and a significantly reduced work function. Experimental degradation of methyl orange validates the trend 4-BA > 4-CA > 4-FA, consistent with theoretical predictions. These findings highlight the crucial role of band structure engineering and provide guidelines for the rational design of high-performance molecularly decorated photocatalysts.

Template-stripped substrates provide on-demand access to clean, ultraflat gold surfaces, avoiding the need for laborious cleaning procedures or the use of expensive single-crystal electrodes. While these gold/adhesion layer/support sandwich structures are most conveniently prepared through the application of epoxy or optical adhesives, such composites exhibit instabilities in organic solvents that limit their wider application. Here we demonstrate that substrates with solvent-impermeable metal films can be used in previously problematic chemical environments after integration into a protective, custom-built (electrochemical) flow cell. We apply our methodology to probe different self-assembled monolayers, observing reproducible alkanethiol reductive desorption features, an exemplary redox response using 6-(ferrocenyl)hexanethiol, and corroborate findings that cobalt(II) bis(terpyridine) assemblies exhibit a low coverage. This work significantly extends the utility of these substrates, relative to mechanically polished or freshly deposited alternatives, particularly for studies of systems involving adsorbed molecules whose properties are strongly influenced by the nanoscopic features of the metal-solution interface.

Nanoscience is a relatively young research field that has been built on the shoulders of consolidated areas ranging from solid-state physics to biology. Its interdisciplinary nature imposes the flow of heterogeneous data from various domains of predefined conventions that ultimately prevents workflow standardization, raising the possibility of further fragmentation and compromising the reproducibility. This is the time to establish good practices for experimental nanoscientists. This work proposes a set of simple rules that can facilitate data management and improve their reusability. Implementing the proposed protocol can have high initial cognitive costs but can also save energy and time in the long term. By adopting these practices, researchers can ensure the reusability of their data early in a project and accelerate the writing process.

Ionic liquids have aroused great interest as solvents for the synthesis and stabilization of nanomaterials. The segregation between polar and apolar domains in ionic liquids with long alkyl groups provides kinetic stability for nanoparticle dispersions by rendering multiple free energy barriers for the aggregation. Similar effects also modulate the adsorption of nanoparticles over both liquid–vapor and liquid/solid interfaces. In this work, molecular dynamics simulations were performed to compute the potential of the mean force for the adsorption of spherical nanoparticles over solid substrates through films of imidazolium-based ionic liquids with different alkyl group lengths. While liquids with small alkyl groups produce simple profiles with barriers only close to the substrate, complex oscillatory forces arise between the nanoparticle and the substrate for ionic liquids with significant domain segregation. In addition, long-range solvent-mediated repulsive forces were also noted for liquids with an alkyl group long enough to display a smectic liquid crystal phase.

Plasmonic polarization conversion offers significant advantages over conventional methods, including a smaller device footprint and easier integration into photonic circuits. In this work, we numerically and experimentally investigate the polarization conversion properties of a plasmonic double-hole structure surrounded by circular nanograting, i.e., a bull’s eye antenna. Using a combination of polarimetric imaging via back focal plane (BFP) microscopy and Stokes parameter analysis, we demonstrate the functionality of our structure as a miniature on-chip polarization converter. Our results show that this nanostructure enables complex polarization transformations, including converting linear to circular polarization and vice versa. Polarization conversion efficiency is found to be dependent on the periodicity of the circular gratings and is particularly pronounced in the central region of Fourier space. Moreover, strong asymmetric scattering leads to distinctive patterns in the Stokes parameters across various incident polarization states. This work provides insights into the plasmonic manipulation of light polarization at the nanoscale with potential applications in miniature on-chip polarization convertors, polarization-controlled emitters, and advanced sensing technologies.

We demonstrate physically consistent and interpretable extended X-ray absorption fine structure (EXAFS) curve-fitting analyses for estimating element-selective local structures in multielement alloy nanoparticles (MEA NPs). The difficulty in analyzing multielement systems originates from the too large number of independent structural parameters to fit, far exceeding the information content of the typical experimental data. Herein, this challenge is overcome by simultaneously fitting multiple data at different absorption edges and temperatures while imposing constraints based on a physically reasonable model. Another advantage of our approach is interpretability; the individual contributions of the constituent elements to the static and dynamic structures are explicitly estimated as atomic radii and Einstein temperatures. This method is used to analyze MEA NPs composed of platinum-group metals and p-block metals, which have contrasting properties, including atomic radii, melting points, and electronegativities. The results indicate that the local structures reflect the intrinsic nature of the elements and are also influenced by the interactions among them. The local structures around the p-block metals in the MEA NPs are shown to be distinctively modulated compared with those in the corresponding monometals, which is attributed to the electronic interaction with the platinum-group metals based on ab initio calculations. Our method is expected to facilitate the experimental characterization of these structurally complicated nanomaterials, which have been analyzed relying on calculations, yielding more precise pictures of real systems for investigating structure-property relationships.

Pancreatic adenocarcinoma (PDAC) presents significant diagnostic challenges, necessitating improved imaging techniques. Here, we develop hybrid poly-(lactic-co-glycolic acid) (PLGA)-phospholipid nanoparticles (NPs) loaded with gadolinium (Gd) chelates and functionalized with albumin, adenosine, or glutamine to boost their internalization in PDAC cells and increase the detectability by magnetic resonance imaging (MRI). Gd-PLGA NPs were synthesized using an oil-in-water emulsion solvent extraction method and incorporating DSPE-PEG(2000)-methoxy and DPPE-PEG(2000) N-Hydroxysuccinimide (NHS) for surface functionalization with albumin, adenosine, or glutamine. NPs were characterized by dynamic light scattering for particle size and ζ potential measurements, in addition to ¹H NMR and proton nuclear magnetic relaxation dispersion to assess relaxivity and contrastographic properties, and stability studies were conducted in both HEPES-buffered saline and human serum. Reported studies demonstrated that all the preparations display a good stability, a hydrodynamic diameter lower than 200 nm, and a slight negative surface charge, with good potential for applications in cells and in vivo. In vitro studies on MiaPaca2 and Panc1 cell lines confirmed that functionalized NPs display higher cellular uptake and stronger MRI signal enhancement than unconjugated controls, with albumin-PLGA-lipid NPs leading to the greatest uptake. Our findings highlight a promising route toward a more sensitive, targeted MRI of PDAC, calling for in vivo studies to assess diagnostic potential and therapeutic applications.

This study examined the effects of berberine, a bioactive alkaloid, on the apoptosis, proliferation, migration, and oxidative stress of DBTRG brain cancer cells and evaluated its potential when incorporated into a nanoparticle-mediated drug delivery system. DBTRG cells treated with 0.5, 1, 5, or 10 μg/mL of berberine for 48 h showed increased apoptosis through both intrinsic and extrinsic pathways, as evidenced by elevated annexin V+/propidium iodide- cells relative to untreated controls. Berberine effectively reduced cell proliferation by inducing cell cycle arrest at G1 and G2/M phases. It also inhibited cell migration by downregulating matrix metalloproteinases and modifying the cytoskeletal structure, and alleviated oxidative stress by enhancing antioxidant enzyme activity and lowering reactive oxygen species production. To overcome the limitations of berberine's low bioavailability, a nanoparticle-based delivery system was developed. The gold-collagen-berberine (Au-Col-BB) nanocarrier was characterized using UV-vis spectrophotometry, Fourier-transform infrared spectroscopy, dynamic light scattering, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. Au-Col-BB nanoparticles were engineered to enhance berberine's loading capacity and therapeutic efficacy. These nanoparticles entered DBTRG cells via endocytosis and progressed through the endosome-lysosome pathway, which significantly increased cellular uptake and therapeutic effectiveness. Annexin V/propidium iodide staining and cell cycle analysis demonstrated that Au-Col-BB nanoparticles promoted DBTRG cell apoptosis. The sub-G1 phase cell population increased by 19.4% (p < 0.001) compared to controls, while the S phase population decreased by 5.6% (p < 0.001), indicating enhanced apoptotic activity and reduced proliferation. In vivo analysis via retroorbital sinus injection of Au-Col-BB into BALB/c mice (n = 5) confirmed the nanoparticles' structural integrity and safety, as well as efficient accumulation in brain tissue. These findings underscore berberine's potential as an anticancer agent, particularly when delivered through a nanoparticle-based system to address the challenges of limited bioavailability and achieve targeted delivery to cancer cells.