Beilstein Journal of Nanotechnology最新文献

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.

Shape-and size-controlled synthesis of nanomaterials has been a long-term aim and challenge of modern nanotechnology. Despite many synthesis methods are still mainly focused on the production of near-spherical NPs, a number of emerging applications require nanomaterials of nonspherical shape and developed surface, which determine the functional performance of nanostructured devices. Laser ablation in liquids has been demonstrated as a clean, simple, and versatile NP synthesis method. However, the conditions of NP formation and growth are favouring the production of spherical NPs. There are fewer studies of shape control during laser ablation. With that in mind, this perspective article represents a view on the current stage of the development of laser ablation in liquids from the perspective of shape control of the forming nanomaterials. The key parameters influencing the NP shape are highlighted, including the composition of a liquid, laser focusing conditions and introduction of external fields, and the mechanism of their impact on the conditions for anisotropic NP formation and growth. The description of the methods developed for the control over nanomaterial morphology is summarized by the vision of the current challenges and development routes of laser ablation in liquids.

Contact resonance atomic force microscopy (CR-AFM) has been used in many studies to characterize variations in the elastic and viscoelastic constants of materials along a heterogeneous surface. In almost all experimental work, the quantitative modulus of the surface is calculated in reference to a known reference material, rather than calculated directly from the dynamics models of the cantilever. We measured the cantilever displacement with very high sampling frequencies over the course of the experiment and captured its oscillations that result from thermal energy. Using short-term Fourier transformations, it was possible to fit the thermal resonance peak of the normal displacement to track the frequency and Q-factor of the cantilever during an experiment, using a similar process to that used to calibrate the normal bending stiffness of cantilevers. With this quantitative data, we have used the dynamic mechanics models relating the contact stiffness of the tip/cantilever pressing into a surface with the oscillation frequency of the cantilever and show that they did not accurately model the experiment. Several material combinations of tip and sample were examined; tip size and cantilever stiffness demonstrate that existing models cannot capture the physics of this problem. While concrete solutions to use analytical models to interpret CR-AFM data have not been found, a possible solution may include revisiting the analytical model to capture a potentially more complex system than the current model, improved matching the cantilever/sample stiffness to obtain a larger variation in contact stiffness with frequency, or investigating the use of higher-order modes that may achieve this improved match.

The development of modern metal deposition techniques like focused ion/electron beam-induced deposition (FIBID/FEBID) relies heavily on the availability of metal-organic precursors of particular properties. To create a new precursor, extensive testing using specialized gas injection systems is required along with time-consuming and costly chemical analysis typically conducted using scanning electron microscopy (SEM). This process can be quite challenging due to its complexity and expense. Here, the response of new metal-organic precursors, in the form of supported thick layers, to the ion beam irradiation is studied through analysis of the chemical composition and morphology of the resulting structures. This is done using SEM backscattered electron/energy-dispersive X-ray spectroscopy along with machine learning data processing techniques. This approach enables a comprehensive fast examination of precursor decomposition processes during FIB irradiation and provides valuable insights into how the precursor's composition influences the final properties of the metal-rich deposits. Although solid-layer irradiation differs from gas-phase deposition, we think that our method can be employed to optimize pre-screen and score new potential precursors for FIB applications by significantly reducing the time required and conserving valuable resources.