ACS Nanoscience Au最新文献

This work experimentally investigates a mechanism of rectification in molecular junctions proposed by van Dyck and Ratner, supported by theoretical modeling. The defining feature of the mechanism is the spatial separation of frontier molecular orbitals such that each tracks the two leads independently. We achieve this orbital separation in oligophenyleneethylene molecular wires with electron-rich thiols and electron-poor pyridines at their termini. Density functional theory (DFT) calculations show localization of the frontier molecular orbitals at these termini that increases with the molecular length. Measurements of rectification ratios in molecular ensemble junctions using eutectic Ga-In (EGaIn) top-contacts and Au bottom-contacts reveal a length dependence that is almost completely insensitive to the insertion of a nonconjugated methylene spacer between the thiol anchor and conjugated backbone. Simulations using nonequilibrium Green's function + DFT methods show that transport is dominated by the lowest unoccupied molecular orbitals, which track the EGaIn electrode, leading to rectification. These results validate the approach of creating molecular rectifiers by spatially separating the frontier molecular orbitals and show an approach to modeling their behavior under bias in ensemble junctions.

Dendritic cells (DCs) represent pivotal targets in immunotherapy, gene therapy, and vaccine delivery for major diseases including cancer, autoimmune diseases, and transplant rejection. Overcoming the challenge of efficient gene delivery via conventional nonviral molecules into primary DCs has been a persistent obstacle. Within this research, we introduce an innovative gene delivery system utilizing magnetic iron oxide nanocubes (MCs) encapsulated with a biocompatible polymer, poly-(lactic-co-glycolic acid) (PL), and a cationic polymer, poly-(2-(dimethylamino)-ethyl methacrylate) (PD), facilitated by a magnetic field. Positively charged MC-PL-PD and MC-PL-PD/PD (double coating of PD) composites were synthesized, and plasmid DNA (pMAX-GFP) attachment ensued. The nanocomposite with double layers coated with PD displayed increased positive charge despite the incorporation of plasmid DNA. In addition, these nanocomposites exhibited superparamagnetic properties with a saturation magnetization of 4.5 emu/g. At concentrations ranging from 25 to 100 μg/mL, the nanocomposites demonstrated minimal toxicity on bone marrow-derived dendritic cells (BMDCs) and exhibited efficient cellular uptake under the influence of a magnetic field. Composites with higher positive charges and increased amounts demonstrated enhanced plasmid transfection efficiency without activating BMDCs. These findings suggest that using MC-PL-PD and MC-PL-PD/PD nanocomposites as carriers holds promise as a viable and effective gene delivery platform to primary DCs, revealing their potential in advancing gene-based therapeutic approaches.

Near-infrared (NIR) fluorescence imaging is a powerful, noninvasive tool for cancer diagnosis, enabling real-time, high-resolution visualization of biological systems. While most probes target the first NIR window (NIR-I, 700-900 nm), recent advances focus on the second window (NIR-II, 1000-1700 nm), which offers deeper tissue penetration and reduced interference from scattering and autofluorescence. However, many current NIR-II nanoprobes show suboptimal brightness and limited validation in more human-centric models. Here, we present an orthogonal strategy combining molecular engineering, by modulating the amount and position of thiophene moieties in semiconducting polymers (SPs), with protein nanoengineering to develop ultrabright NIR-II imaging probes optimized for ex vivo bioimaging in large animal models. The molecular tuning amplifies the NIR-II fluorescence brightness while screening endogenous proteins as encapsulating matrices to improve colloidal stability and enable active targeting. Molecular docking identified bovine serum albumin as the effective candidate, and the resulting protein-complexed nanoprobes were characterized for size, colloidal stability under physiological conditions, and optical performance. Imaging performance was evaluated using tumor-mimicking phantoms in porcine lungs, simulating cancer surgery, and injected at clinically relevant concentrations into ovine brains and porcine ovaries for microvascular visualization and tissue discrimination, respectively. In all scenarios, our protein-complexed nanoprobes outperformed the FDA-approved clinical dye indocyanine green in signal-to-background ratios. Initial in vitro assays confirmed their hemocompatibility, biocompatibility, and cellular uptake in ovarian adenocarcinoma cells. This integrated approach offers a promising platform for developing next-generation ultrabright NIR-II nanoprobes with improved brightness and stability, advancing the potential for image-guided surgery and future clinical translation.

An ordered multispectral array of Au coated ellipse nanopillars was successfully fabricated via laser interference and nanoimprint lithography. The fabricated plasmonic substrate features a gradient plasmonic response in both translational and rotational directions across the chip, relative to a polarized UV-vis light source. Structural characterization of the substrate suggests that the gradient response is induced by the anisotropic valleys connecting the ellipse nanopillars in a hexagonal arrangement, resulting in varying nanopillar relative heights in various cross sections of the array. These gradual geometrical changes in the nanostructure allow control of the plasmonic response through two degrees of freedom (e.g., spatial translation or source polarization) on a single nanoimprinted chip. We also show that the fabricated substrate is viable for biosensing applications.

The industrial-scale production of solid lipid nanoparticles (SLNs) faces significant challenges, such as degradation during freezing and the reliance on toxic solvents for cryoprotection and active ingredient solubility, hindering their effective storage and commercialization. This study presents an innovative and sustainable approach to SLNs formulation by incorporating a natural deep eutectic solvent-based system (NaDES) as an integral part of the system. The research evaluated the cryoprotective potential of NaDES at different concentrations and freezing methods, demonstrating their ability to stabilize aluminum chloride phthalocyanine (AlClPc)-loaded SLNs during freezing and enable drying protocols to enhance particle concentration. SLNs formulations with high colloidal stability were obtained, containing 12.5% NaDES, based on low-energy methodologies and high added value. Additionally, the use of NaDES enabled a 12.5% reduction in the water content in the formulation and acted as an efficient cryoprotectant, allowing for the freezing of SLNs without compromising particle integrity. These advancements suggest a greener and potentially scalable methodology for SLNs production, positioning NaDESs as promising cryoprotectants that may enhance formulation stability, improve commercial viability, and reduce production and storage costs. This innovation may represent an initial step toward improving nanoparticle preservation and facilitating future industrial translation, with the potential to broaden nanoparticle application in nanotechnology.

The transfer of inorganic nanoparticles (NPs) into water is usually considered a challenge, as NPs are preferably synthesized in organic solvents and commonly bear hydrophobic ligands. Consequently, various methods have been reported to achieve their transfer to aqueous media. Among these, a polymer coating using amphiphilic polymers represents a particularly useful approach. These polymers can interact with the NP surface via their hydrophobic moieties, while their hydrophilic side remains exposed to the aqueous media, thus enabling dispersion in water. In this paper, we present the facile synthesis of several fluorinated, hydrosoluble amphiphilic polymers, and we study the coating of different types of metallic NPs, such as gold nanoparticles and quantum dots (QDs). Gold NPs were transferred via a phase transfer protocol, but for more sensitive QDs, we used the film hydration method. For QDs, the high hydrophobicity of fluorinated moieties on the polymer was particularly advantageous in repelling water and preserving the optical properties of QDs. Fractal arrangements in aqueous solution for polymer-coated QDs were analyzed by small-angle X-ray scattering (SAXS) but also observed by TEM. Additionally, we employed these fluorinated polymers to transfer two highly hydrophobic and fluorinated molecules (PERFECTA and PFCE), commonly used as contrast agents in ¹⁹F magnetic resonance imaging (¹⁹F MRI), into aqueous media. We evaluated their transverse and longitudinal relaxation times to assess their suitability for use as contrast agents for ¹⁹F MRI.

Spherical and hollow molecular cages based on planar triazine (C₃N₃) hubs and aromatic phenylene connectors have been developed. The cages exhibit topologies akin to C₂₀, C₆₀, and C₇₀ fullerenes with diameters that range from 2.3 to 4.9 nm. Apertures into the cage interiors are tuned by varying the aromatic connectors situated between the C₃N₃-units. The stabilities of the C₃N₃ cages increase with size owing to reduced bending strain of planar nodes and connectors that make up the spherical aromatic networks. Doping of the cages with Li⁺ reveals the capacity of the cages for significant adsorption of gaseous H₂ and CO₂. The design of graphene-like spherical cages is also discussed.

We uncover the mechanism behind the enhancement of photoluminescence yield in monolayer WS₂ through oleic acid treatment, a promising scalable strategy for defect healing. By inducing sulfur vacancies through thermal treatment and monitoring the changes in photoluminescence yield and emission spectra, we demonstrate that in contrast to super acids, oleic acid heals the sulfur vacancy by providing substitutional oxygen, instead of hydrogen. Using density functional theory calculations, we provide insight into the underlying mechanism governing the oleic acid-mediated sulfur vacancy healing process. Our findings suggest that effective defect passivation by oxygen doping can be achieved through chemical treatment, opening a pathway for oxygen doping in transition metal dichalcogenides. However, we also highlight the limitations of chemical treatment, which may only lead to small increases in photoluminescence yield beyond a certain point.

Crystalline molecular machines provide a promising platform for integrating dynamic molecular motion into nanoscale solid-state materials, where motion can be programmed, triggered, and harnessed for functional output. This perspective highlights recent advances in the design of crystalline molecular materials that support controlled molecular motion with a focus on three key types: rotors, gears, and motors. We discuss strategies to enable internal rotational freedom, realize mechanically correlated motion, and achieve molecular motion driven by external stimuli. By bridging molecular-level design with long-range crystalline order, these systems open new avenues for the development of molecular-based dynamic crystalline materials with engineered mechanical responses.

Silver-coated gold nanostars (AuNSt@Ag) offer a powerful platform for plasmon-enhanced sensing, yet their fabrication often compromises structural sharpness and spectral tunability. Here, we report a robust and flexible method for synthesizing AuNSt@Ag with precisely controlled localized surface plasmon resonance (LSPR) across a broad spectral range, achieved by systematically optimizing multiple synthetic parameters. Strikingly, surface-enhanced Raman scattering (SERS) performance reached a maximum for bimetallic nanostars with LSPR maxima near 605-615 nm, regardless of excitation wavelength (633 or 785 nm). This reveals that local near-field enhancement at Ag-coated tips, rather than spectral overlap, governs SERS efficiency in these AuNSt@Ag systems. The optimized AuNSt@Ag structures outperform previously reported analogues, exhibiting significantly enhanced SERS capabilities, including an 80-fold increase in signal compared to optimized monometallic AuNSt resonant with the 785 nm laser line. These findings establish a new design paradigm for highly tunable and high-performance plasmonic substrates for analytical sensing applications.