Beilstein Journal of Nanotechnology最新文献

In this study, we employ the non-equilibrium Green's function (NEGF) method combined with density functional theory (DFT) to compare electron transport through several layers of nanoscale graphene and hexagonal boron nitride (h-BN). Calculations were performed for one to six layers, corresponding to thicknesses of 0.5-3.0 nm, respectively. Electron transport was computed perpendicular to the layers in the stacking direction. We compared the decay of the current with the number of layers and evaluated the ability of h-BN to filter currents as a material coating. To investigate the effect of disorder, we included two major defects in the graphene lattice, namely, nitrogen doping and Stone-Wales defects. Nitrogen doping transforms graphene from a zero-bandgap semiconductor to a metal, while Stone-Wales defects open the bandgap. For h-BN, we considered Stone-Wales defects. A detailed comparison of electron transport through five materials, that is, multilayer nanoscale graphene, N-doped multilayer nanoscale graphene, Stone-Wales-defective multilayer nanoscale graphene, h-BN, and Stone-Wales-defective h-BN allowed us to understand the currents at the nanoscale and the chemical and structural control over the electron transport. The slopes of the current decay with thickness enabled us to extrapolate trends for electron transport in thicker multilayer carbon and h-BN materials.

Passiflora setacea seed oil is a natural source of bioactive unsaturated fatty acids, notably linoleic acid (ω-6) and oleic acid (ω-9), with promising antioxidant and anti-inflammatory potential for dermatological applications. However, its direct use is limited by poor physicochemical and organoleptic properties. This study aimed to develop and optimize a topical microemulsion (ME) system incorporating P. setacea seed oil using quality by design principles to address formulation challenges. The oil was extracted via Soxhlet and characterized by gas chromatography-mass spectrometry and thermal analysis. A full factorial design, followed by a Box-Behnken design, was employed to optimize the formulation based on critical quality attributes and the defined quality target product profile. The optimized ME presented a hydrodynamic diameter of approximately 22 nm and polydispersity index below 0.2 and remained stable for 60 days. The ME was gelled with sodium carboxymethyl cellulose, while vitamin E and Liquid Germall^® Plus were incorporated as antioxidant and preservative agents, respectively, yielding the final topical gel formulation. Cytocompatibility assays demonstrated high cell viability for ME at concentrations below 2 mg/mL in RAW 264.7 macrophages and 0.5 mg/mL in human umbilical vein endothelial cells. Overall, this work presents a promising nanotechnology-based topical delivery platform for P. setacea seed oil, employing quality by design principles to ensure formulation performance, stability, and skin cell compatibility.

Nanocrystals (NCs) of silver antimony sulfide (AgSbS₂) in the cubic phase were successfully synthesized using the hot-injection method. This study is the first to investigate the cytotoxic effects of these NCs on human breast adenocarcinoma (MCF-7), colon cancer cell lines (HT-29), and fibroblast cell lines (L929). Additionally, the antibacterial properties of the NCs against gram-positive (Staphylococcus aureus and Bacillus subtilis) and gram-negative (Escherichia coli) pathogenic bacteria were evaluated, along with their DPPH scavenging activities. The crystal structure of the synthesized NCs was elucidated through XRD analysis, revealing characteristic diffraction peaks corresponding to the (111), (200), (220), (311), and (222) planes of the AgSbS₂ phase. TEM and SEM techniques were used to comprehensively characterize the NCs. The results showed that spherical NCs were predominantly formed, with an average diameter of approximately 32 ± 10 nm. Cytotoxicity studies demonstrated a significant inhibitory effect of the NCs, particularly on cancer cell lines (MCF-7 and HT-29), in a dose-dependent manner over a 24 h period. These findings highlight the potential of the NCs as anticancer agents. Furthermore, the synthesized NCs demonstrated potent antibacterial properties against the tested microorganisms and notable antioxidant effects by efficiently eliminating DPPH activity. This research highlights the potential of AgSbS₂ NCs as versatile agents with applications in biomedical and environmental domains, including cancer therapy, antimicrobial strategies, and free radical neutralization.

Carbon nanomaterials (CNMs), including graphene, carbon nanotubes, and carbon dots, have attracted considerable interest as nanocarriers for drug delivery due to their unique physicochemical properties. Their high surface area, biocompatibility, and modifiable surface chemistry make them highly attractive for a range of biomedical applications. However, concerns regarding toxicity and regulatory hurdles remain major barriers to clinical translation. Current research is therefore focused on standardizing CNM synthesis and characterisation methods, minimizing toxicity, and facilitating regulatory approval. Despite these challenges, CNMs hold substantial promise for enhancing therapeutic delivery, particularly in areas such as cancer treatment. This perspective highlights critical considerations in the development of CNM-based nanocarriers, spanning from initial design to clinical implementation.

To achieve precise measurements of small displacements in non-contact atomic force microscopy, it is crucial to control the position of moving parts with high accuracy. This is commonly accomplished by piezo actuators, for instance, in the form of tube piezos for positioning the tip or optics. For their calibration, we propose an approach based on the dynamic response signal from a fiber interferometer used for cantilever displacement detection. The fine-positioning z-piezo of the fiber is calibrated by the analysis of measurements of the dynamic interferometer response signal recorded for various cantilever oscillation amplitudes and varied distances between the cantilever and the fiber end. Furthermore, we demonstrate the cantilever oscillation amplitude calibration under conditions of various amounts of tube piezo contraction and extension. The merits and limits of accuracy for such type of calibration are discussed.

This study introduces a multifrequency atomic force microscopy (AFM) technique that synergistically integrates PeakForce tapping mode with higher eigenmode vibrations to achieve simultaneous high-resolution topographical imaging and to access additional contrast channels for distinguishing material regions or compositions. Unlike conventional multimodal AFM, our method employs non-resonant and higher eigenmode frequencies to achieve robust topographical and compositional mapping. Our experimental results indicate that the superposition of high-eigenmode vibrations, when applied at low amplitudes, does not significantly interfere with the topographical and nanomechanical mappings obtained via the PeakForce tapping method. Furthermore, the technique's dual capability, that is, quantitative mechanics via quasi-static force curves and qualitative material-sensitive information via eigenmode vibration signals, facilitates effective compositional differentiation in heterogeneous nanomaterials while significantly simplifying the requirements for probe selection, which are typically necessary for material differentiation via the standard PeakForce tapping method. This innovation enhances the technique's practicality and extends compatibility to a wider array of probe types.

Gecko adhesion, enabled by micro- and nanoscale structures known as setae and spatulae, has prompted extensive research. We present a concurrent multiscale computational model of a seta that integrates molecular dynamics to capture molecular interactions at the spatula-substrate interface and finite element method to simulate the mechanical behavior of the larger setal shaft. This hybrid approach enables synchronized simulations that resolve both fine-scale interfacial dynamics and overall structural deformation. The model reproduces key aspects of spatula behavior during adhesion and detachment, showing that spatula-substrate contact evolves through a combination of bending, sliding, and peeling, depending on the spatula's initial orientation. Our results further demonstrate that lateral sliding can delay detachment, thereby enhancing adhesion strength. The computed pull-off forces and observed mechanisms are consistent with atomic force microscopy measurements and previous simulations. These results align with existing experimental and computational studies. They also overcome scale and resolution limitations inherent in single-scale models.

Macroporous materials containing surfaces with chiral groups are highly relevant for applications in the chromatographic separation of enantiomers. Despite these materials being highly engineered and commercially available, optimization was often done empirically. A rational design of future and improved solid phases for chiral chromatography requires that one understands how the chemical structure of a surface influences the stereoselectivity of the enantiomers at the surface. Despite the difference in the interaction enthalpies being only in the 1-2 kJ·mol^-1 range, an ideal surface would exclusively interact with one enantiomer. However, the question of which selectivity is sufficient or necessary to reach separation is an important point. We have employed the two enantiomers of a chiral, nitroxide-based spin probe as guests in organo-modified macroporous host materials and applied ESR spectroscopy as a tool to investigate their rotational mobility. Using a well-established and commercially available material confirmed the method's reliability. The data underline how crucial the choice of the right solvent is if one wants to reach sufficient selectivity. Together with a series of custom-made organosilica aerogels, it is shown that adjusting solvent and surface properties so that the two enantiomers (+) and (-) experience a different chemical environment is key. Otherwise, there might be a dynamic equilibrium between surface-adsorbed and mobile spin probes without stereodifferentiation. With this knowledge, it was possible to reach higher selectivity values than for the commercial material. A particularly interesting result was that better performance could be achieved if one attaches bulky, hydrophobic groups directly to the stereocenter. The effect of such neighboring groups on the enantioselectivity highly depends on the distance they have to the stereocenter.

Hyaluronic acid (HA) and β-caryophyllene (βCp) are two promising agents in biomedical research, each offering unique therapeutic benefits. The successful integration of these compounds into a single, functional nanofiber system presents a significant technical challenge, demanding innovative strategies to ensure their compatibility and sustained activity. This study addresses this critical challenge through the rational design and fabrication of hybrid core-shell nanofibers manufactured via coaxial electrospinning. Poly(lactic acid) (PLA) was used as an outer shell providing structural integrity and effectively encapsulating a core comprising a nanoemulsion containing β-caryophyllene (NE-βCp) alongside HA. A rigorous optimization of the electrospinning process was critical, involving the systematic evaluation of key parameters. This optimization successfully identified the optimal core formulation (1% w/w HA, 2% w/w NE) and process parameters (17 kV applied voltage, 6.25 flow rate ratio (0.04 mL/h inner; 0.25 mL/h outer), 12 cm needle-to-collector distance). These conditions provided highly uniform fibers with an average diameter of 439 ± 100 nm, notably 37% larger than fibers without the lipid core. Furthermore, maintaining ambient relative humidity below 45% proved essential for processing stability. Comprehensive morphological characterization via scanning electron microscopy confirmed the uniformity of the fibers. At the same time, confocal microscopy, cross-sectional imaging, and attenuated total reflectance with Fourier transform infrared (ATR-FTIR) spectroscopy provided compelling evidence for the successful formation of the intended core-shell structure. The resulting nanofibers exhibited surface hydrophobicity, suggesting potential for anti-adhesive membrane applications. Thermal and crystalline analyses demonstrated improved thermal stability upon NE-βCp incorporation. Collectively, these results provide robust evidence for the feasibility of producing multifunctional nanofiber membranes that successfully integrate a polymer-lipid hybrid core encapsulated within a PLA shell, highlighting substantial potential for biomedical applications by overcoming key material integration hurdles.

Adhesives produced by marine organisms offer remarkable performance and serve as a major source of inspiration for developing biomimetic adhesives. However, a thorough understanding of their composition and operating mechanism is essential for advancing such applications. Sabellariid tubeworms are model organisms in bioadhesion research, and their adhesive system has been characterized in several studies. However, some aspects of cement formation are still poorly understood and several differences have been pointed out between the two main model species. This study aims to investigate the adhesive system of Sabellaria alveolata by identifying new potential adhesive proteins, as well as describing the ultrastructure and elemental composition of the cement cells and their secretion. Different adhesive proteins are packaged in one or the other of two types of cement cells, namely, those containing homogeneous granules and those containing heterogeneous granules with lamellar inclusions. Phosphoserine has been identified as one of the main modified amino acids in tubeworm cement and, using in situ hybridization, we propose that FAM20C kinases would be the enzymes responsible for the phosphorylation of serine residues in adhesive proteins. Comparison between the ultrastructure of the granules and that of the cement suggests that the inclusions of the heterogeneous granules would inflate through a still unexplained process to form hollow spheroids dispersed in the cement matrix, leading to the formation of a complex composite material.