Beilstein Journal of Nanotechnology最新文献

Drug delivery systems (DDSs) are an important tool for obtaining medicines with improved physicochemical properties, especially for drugs with stability, absorption, and biodistribution impairments. Among the DDSs, we can highlight hydrogels and nanogels, which are easy to obtain, show good biocompatibility, and have several applications in the design of drug carriers for dermal and ocular administration. In this review, we introduce a brief concept on hydrogels, underlining compounds such as chitosan and alginate, and methods used for their preparation. Nanogels, with their attractive features, such as high drug encapsulation and penetration enhancer embedding, are also addressed. Finally, the application of these systems in dermal pathophysiological processes through the incorporation of drugs for enhancing skin permeation brings out promising prospects for innovation which may arise in the drug delivery field.

Photodynamic therapy (PDT) is a non-invasive treatment involving a photosensitizer (PS), light source, and tissue oxygen. Protoporphyrin IX (PpIX) is commonly used as a PS due to its tumor-targeting properties and phototoxicity. However, the physicochemical properties of PpIX foster self-aggregation, which is a challenge for its incorporation into pharmaceutical formulations. This study aimed to evaluate the solubility of PpIX in distinct solvent systems to support the development of novel pharmaceutical formulations. The shake-flask method was employed, using purified water, 50% ethanol (EtOH50), 77% ethanol (EtOH77), absolute ethanol (EtOHabs), and polymeric systems containing 10% (w/w) poloxamer 407 (P407) in water, in EtOH50 or in EtOH77. Approximately 10 to 25 mg of PpIX was added to 25 mL of the solvent, and the solutions were stirred at 100 rpm, at 37 °C, for up to 96 h. The PpIX concentration was measured by using a validated method (R = 0.9973), with equilibrium reached within 30 min. The dissolution profiles of the micellar systems were also evaluated using the Korsmeyer-Peppas model with lag time (t _lag), which indicated a Fickian diffusion mechanism, preceded by a thermodynamically driven accommodation stage of PpIX into the micelles. The solubility of PpIX ranged from 0.138 mg/mL in water to 0.593 mg/mL in water containing 10% (w/w) P407. The solubility of PpIX in EtOH50 and EtOH77 with 10% (w/w) P407 was 0.503 and 0.507 mg/mL, respectively, while EtOHabs yielded the lowest solubility among ethanolic solvents (0.179 mg/mL). These results indicate that water and EtOHabs are unsuitable solvents for PpIX, whereas the nanostructured systems containing P407 showed the greatest potential for future pharmaceutical applications, mainly the aqueous one because of its low toxicity considering topical preparations.

Climate change has intensified the proliferation of disease vectors, such as Aedes aegypti, the primary transmitter of dengue, chikungunya, and zika viruses. Although the two recently licensed dengue vaccines represent a significant advancement, vector management remains the primary strategy for preventing these urban arboviruses. In this context, the development of pesticides that offer safer alternatives for the environment and human health has become urgent. In this study, a chitosan-based nanocomposite was developed as a delivery system for rotenoids isolated from Clitoria fairchildiana seeds, leveraging their larvicidal activity against third-instar larvae of Ae. aegypti. The nanocomposite was synthesized using a controlled ionic gelation method incorporating the TPP-β-CD inclusion complex, which resulted in nanoparticles with smaller size, improved polydispersity index, and enhanced stability, evidenced by a higher zeta potential. FTIR analysis confirmed rotenoid incorporation into the nanocomposite and suggested hydrogen bonding or potential covalent interaction with chitosan functional groups. Bioassays demonstrated that the nanocomposite achieved an LC₅₀ of 91.7 ppm, representing a 23.6% increase in larvicidal efficacy compared to the rotenoids in their natural form. The nanocomposite also induced dose-dependent morphological and physiological alterations in the larvae, including damage to the peritrophic matrix, evidenced by abnormal anal excretion, and tissue melanization and formation of melanotic pseudotumors. These responses may be associated with increased production of reactive oxygen species in the larval midgut, consistent with previous findings for the nonencapsulated rotenoids. Importantly, empty nanoparticles exhibited no adverse effects on larval survival, which is attributed to the biocompatibility and nontoxic nature of chitosan, a biodegradable polysaccharide structurally related to the insect exoskeleton and widely recognized for its environmental safety. Additionally, neither rotenoids nor the CS/TPP-β-CD-rot nanocomposite exerted cytotoxic effects, confirming their favorable safety profile. These findings highlight the potential of nanotechnology to enhance the efficacy of bioactive compounds while minimizing environmental and human health risks, offering a sustainable and innovative strategy for vector control.

Zinc sulfide nanotubes have garnered significant attention as potential candidates for chemical sensing applications owing to their exceptional structural, electronic, and optical properties. In this study, we employed density functional theory (DFT) to explore the sensing capabilities of a ZnS (3,3) nanotube (ZnS NT) for detecting chloropicrin (CP, CCl₃NO₂), a highly toxic gas. To elucidate the sensing mechanism, we systematically analyze the adsorption configurations, Mulliken charge transfer, band structure, density of states, optical absorption, and optical conductivity of the ZnS NT-CP system. Our findings reveal that the interaction between CP and ZnS NT induces notable changes in the electronic and optical properties of the nanotube, including a substantial bandgap reduction of up to ≈40% for the specific orientation A. The adsorption energy ranges from -0.389 to -0.657 eV, indicating weak physisorption. The Mulliken charge transfer varies between 0.06e and 0.109e, confirming effective but nondestructive interaction. A favorable recovery time of ≈3.533 μs at room temperature, along with a significant red shift in the absorption spectra and optical conductivity peaks, highlight the potential of ZnS NT for designing sensitive and reusable CP gas sensors.

Nanomechanical maps to test the mechanical response of the outer envelope of Pseudomonas aeruginosa were obtained utilizing atomic force microscopy in force-volume mode in the low range of loading forces when exposed to hypotonic (Milli-Q water), isotonic (PBS), and hypertonic (0.5 M NaCl) solutions. Imaging and mechanical testing showed that bacteria are highly resilient to deformation and can withstand repetitive indentations in the range of 500 pN. Analysis of force spectra revealed that although there are differences in the mechanical response within the first stages of nanoindentation, similar values in the slopes of the curves reflected a stable stiffness of about k _B = 20 mN/m and turgor pressures of P _t = 12.1 kPa. Interestingly, a change in the nonlinear regime of the force curves and a gradual increase in maximal deformation by the AFM tip from hypotonic to hypertonic solutions suggest a softening of the outer envelope, which we associate with intense dehydration and membrane separation between inner and outer envelopes. Application of a contact mechanics model to account for the minute differences in mechanical behavior upon deformation provided Young's moduli in the range of 0.7-1.1 kPa. Implications of the presented results with previously reported data in the literature are discussed.

The Gauss neuron is a nonlinear signal converter, whose transfer function (TF) is described by the derivative of some sigmoidal dependence. A superconducting Gauss neuron can be implemented as a two-junction interferometer shunted symmetrically by an additional inductance. This work analyzes three cases of asymmetry that can occur in the experimental samples of Gauss neurons, that is, unequal critical currents of the interferometer's Josephson junctions, asymmetric inductive shunting, and asymmetry of the input signal supply. We illustrate the modifications in equations and the shape of the TF compared to the symmetric case. The analysis performed provides an explanation for the key features observed in a previously conducted experiment.

High-entropy alloy nanoparticles (HEA NPs) represent a promising material class with significant potential in various applications, such as heterogeneous catalysis or magnetic devices. This is due to their exceptional compositional tunability arising from the synergistic interplay of multiple elements within a single particle. While laser-synthesized, surfactant-free colloidal HEA NPs have already been reported, the underlying formation mechanism remains unknown, particularly the underexplored preference of amorphous over crystalline structures warrants further investigation. Herein, we present a systematic study of laser-generated equimolar CrMnFeCoNi nanoparticles, focusing on structural differences, arising from varying pulse durations during synthesis in organic solvents (acetone, ethanol, acetonitrile). In a systematic experimental series using high-resolution transmission electron microscopy, scanning transmission electron microscopy with energy-dispersive X-ray spectroscopy, selected-area electron diffraction, X-ray diffraction, electron energy loss spectroscopy, in situ heating, post-irradiation experiments, and differential scanning calorimetry we demonstrate that a pulse-duration-driven structural difference occurs during laser ablation in liquid is observable to the three utilized solvents. While picosecond-pulsed laser ablation in liquid produces polycrystalline HEA NPs, nanosecond-pulsed laser ablation favors a metastable amorphous structure. Particle cores in all cases exhibit a homogeneous distribution of the metals Cr, Mn, Fe, Co, and Ni, while particle shells were found to vary between manganese-enriched oxide layers and thin graphitic carbon coatings. The discovery of the structure-directing mechanism allows one to select between crystalline or amorphous HEA NP products, simply by choice of the laser pulse duration in the same, well-scalable setup, giving access to colloidal particles that can be further downstream processed to heterogeneous catalysts or magnets. In that context, the outstanding temperature stability up to 375 °C (differential scanning calorimetry) or 500 °C (transmission electron microscopy) may motivate future application-relevant work.

In this study, we employed traditional methods and deep learning models to improve resolution and quality of low-resolution AFM images made under standard ambient scanning. Both traditional methods and deep learning models were benchmarked and quantified regarding fidelity, quality, and a survey taken by AFM experts. The deep learning models outperform the traditional methods and yield better results. Additionally, some common AFM artifacts, such as streaking, are present in the ground truth high-resolution images. These artifacts are partially attenuated by the traditional methods but are completely eliminated by the deep learning models. This work shows deep learning models to be superior for super-resolution tasks and enables significant reduction in AFM measurement time, whereby low-pixel-resolution AFM images are enhanced in both resolution and fidelity through deep learning.

Transmission X-ray microscopes (TXMs) are now increasingly used for quantitative analysis of samples, most notably in the spectral analysis of materials. Validating such measurements requires quantitatively accurate models for these microscopes, but current TXM models have only been tested qualitatively. Here we develop an experimental and theoretical framework for evaluation of TXMs that uses Mie theory to compute the electric field emerging from a nanosphere. We approximate the microscope's condenser illumination by plane waves at the mean illumination angle and the zone plate by a thin lens. We find that this model produces good qualitative agreement with our 3D measurements of 60 nm gold nanospheres, but only if both β and δ for the complex refractive index n = 1 - δ + iβ of gold are included in the model. This shows that both absorption and phase properties of the specimen influence the acquired TXM image. The qualitative agreement improves if we incorporate a small tilt into the condenser illumination relative to the optical axis, implying a small misalignment in the microscope. Finally, in quantitative comparisons, we show that the model predicts the nanosphere's expected absorption as determined by Beer's law, whereas the microscope underestimates this absorption by 10-20%. This surprising observation highlights the need for future work to identify the microscope feature(s) that lead to this quantitative discrepancy.

In this paper, comparative studies of selected properties of titanium dioxide (TiO₂) coatings deposited using electron beam evaporation (EBE) and ion beam-assisted deposition (IBAD) are presented. Post-process annealing at 800 °C was also conducted to examine its impact on the properties of the prepared coatings. After annealing at 800 °C, a transition from amorphous to the anatase phase occurred for all coatings. In particular, an increase in ion beam current led to a reduction in crystallite size by approximately 30% compared to coatings prepared by conventional EBE process. The average anatase crystallite size for annealed films was in the range of 30.8 to 43.5 nm. A detailed SEM analysis of surface morphology and cross sections revealed that the TiO₂ films prepared by IBAD had smaller, rounded grains and were denser compared to those deposited by EBE. Optical properties showed high transparency of 77-83% in the visible wavelength range for all as-prepared thin films. However, annealing caused a decrease of the transparency level by 32% for films deposited by EBE, while for films from the IBAD process the decrease was less than 10%. The use of an ion gun increased the hardness of the TiO₂ films from 2.4 to 3.5 GPa (I _ibg = 4 A). Although a similar relationship was observed for coatings after annealing, hardness values were lower than for as-deposited coatings. The most notable differences were observed in the abrasion tests, where the IBAD process significantly enhanced the abrasion resistance of the coatings. This research highlights the potential of IBAD to prepare dense, adhesive, and durable TiO₂ coatings with improved optical and mechanical properties, suitable for applications requiring enhanced wear resistance.