Search Results (2,911)

Mesoporous silica nanoparticles have been synthesized through sol–gel synthesis in basic conditions. Gemini surfactants having urea in the headgroups were used as pore-forming agents. The effect of the spacer length of the surfactant on the particle morphology was studied on the sub-micrometer and nanometer scales using nitrogen porosimetry, small-angle X-ray scattering (SAXS), ultra-small-angle neutron scattering, and scanning and transmission electron microscopy (SEM, TEM). Depending on the spacer, spherical and/or cylindrical nanoparticles formed in different proportions, as revealed by statistical analysis of SEM micrographs. All prepared materials showed the hexagonal pore structure characteristic of the MCM-41 molecular sieves, with the exception of the sample prepared using the gemini surfactant with the shortest spacer length. The influence of the spacer length on the lattice parameter of the pore network, as well as the average size of the ordered domains, has been assessed by SAXS and TEM. Detailed analysis of the TEM images revealed a spread of the lattice parameter in a range of 10–20%. The broadening of the diffraction peaks was shown to be due to the combination of the effects of the finite domain size and the variance of the lattice parameter across the crystalline domains. The structural differences between the silica gels synthesized with the different surfactants were related to the variation of the micelle morphologies, reported in previous light scattering and small-angle scattering experiments. No connection could be revealed between the micelle shape and size and the pore sizes, showing that surfactants with a broad range of spacer lengths can equally well be used for the preparation of MCM-41 materials. Full article

Background: Silver fluoride medicaments effectively arrest caries progression but cause permanent staining. Nanoparticles are increasingly utilised in paediatric dentistry due to their antimicrobial properties. Aim: This study reports the synthesis and characterisation of silver and selenium nanoparticles stabilised with natural agents. Methods: Six silver and selenium nanoparticles were chemically synthesised and stabilised using biocompatible eco-friendly capping agents, including casein, bovine serum albumin, chitosan, citrate, and tannic acid. Characterisation was performed using Tyndall scattering, UV-Vis spectroscopy, transmission electron microscopy, and ICP-OES. Results: The synthesised particles were spherical in shape, ranging in size from 2.5 to 24 nm for silver and 35 to 43 nm for selenium. Elemental analysis confirmed the absence of heavy metals. Conclusions: These findings highlight the successful synthesis of capped silver and selenium nanoparticles. The observed characteristics suggest potential relevance for future antimicrobial applications in paediatric dentistry. Full article

Iron oxide nanoparticles (IONPs) have emerged as key materials in magnetic hyperthermia (MH), a minimally invasive cancer therapy capable of selectively inducing apoptosis, ferroptosis, and other cell death pathways while sparing surrounding healthy tissue. This review synthesizes advances in the design, functionalization, and biomedical application of magnetic nanoparticles (MNPs) for MH, highlighting strategies to optimize heating efficiency, biocompatibility, and tumor targeting. Key developments include tailoring particle size, shape, and composition; doping with metallic ions; engineering multicore nanostructures; and employing diverse surface coatings to improve colloidal stability, immune evasion, and multifunctionality. We discuss preclinical and clinical evidence for MH, its integration with chemotherapy, radiotherapy, and immunotherapy, and emerging theranostic applications enabling simultaneous imaging and therapy. Special attention is given to the role of MNPs in immunogenic cell death induction and metastasis prevention, as well as novel concepts for circulating tumor cell capture. Despite promising results in vitro and in vivo, clinical translation remains limited by insufficient tumor accumulation after systemic delivery, safety concerns, and a lack of standardized treatment protocols. Future progress will require interdisciplinary innovations in nanomaterial engineering, active targeting technologies, and real-time treatment monitoring to fully integrate MH into multimodal cancer therapy and improve patient outcomes. Full article

The main aim of this work is to define the limits of detection (LOD) and quantification (LOQ) for polyethylene (PE) particles using a pyrolysis and oxidation-based method, the thermal Rock-Eval^® device, combined with a mathematical extrapolation procedure. The influences of particle size and shape on the thermal degradation of PE polymers are also investigated in this study. Thermal Total HC and Tpeak parameters, recently used to characterize polymer samples, are evaluated as a function of both polymer grain size and shape. Results indicate a LOD for the investigated PE polymers of around 1.7–2 μg in 60 mg of composite sediment (28–33 ppm). A conservative LOQ for the PE samples ranges between 5 and 6 μg (83–100 ppm). The LOQ is on the same order of magnitude for any size or shape of the studied PE polymers. By contrast, the LOD for the PE samples is slightly affected by both the polymer grain size and shape. Results also demonstrate that it is possible to detect PE nanoparticles of 79 nm in size. Finally, this study provides specific Rock-Eval^® parameters, linear regressions, and a mathematical extrapolation procedure that can be used to better quantify very small PE mass contents, including nanoplastics in environmental samples. Full article

The exceptional surface (ES) in non-Hermitian physics has attracted much attention due to its strong robustness and enhanced frequency splitting in the sensing field. However, the detection limit of the ES-based sensing structure is still limited by the mode linewidth in the optical microcavity. In this paper, we demonstrate that Sagnac–Fizeau shift in a microcavity based on an ES separates the dark mode from the bright mode, further enhancing the frequency splitting in the transmission spectrum. Moreover, a strategy for manipulating spectral line shape is realized by the phase in the reflection loop. Compared with the traditional ES-based sensing structure, the proposed nanoparticle sensing mechanism significantly reduces the detection limit for weak perturbations. This work will contribute to the development of high-precision nanoparticle sensors. Full article

Poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) is a conductive water-processable polymer with many important applications in organic electronics. The electrical conductivity of PEDOT:PSS layers is very diverse and can be changed by changing the processing and post-deposition conditions, e.g., by using different solvent additives, doping or modifying the physical conditions of the layer deposition. Despite many years of intensive research on the relationship between the microstructure and properties of these layers, there are still gaps in our knowledge, especially with respect to the detailed understanding of the charge carrier transport mechanism in organic semiconductor thin films. In this work, we investigate the effect of acid doping of PEDOT:PSS thin films on the intra-chain and inter-chain conductivity by developing a model that treats PEDOT:PSS as a nanocomposite material. This model is based on the effective medium theory and uses the percolation theory equation for the electrical conductivity of a mixture of two materials. Here its implementation assumes that the role of the highly conductive material is attributed to the intra-chain conductivity of PEDOT and its quantitative contribution is determined based on the optical Drude–Lorentz model. While the weaker inter-chain conductivity is assumed to originate from the weakly conductive material and is determined based on electrical measurements using the van der Pauw method and coherent nanostructure-dependent analysis. Our studies show that doping with methanesulfonic acid significantly affects both types of conductivity. The intra-chain conductivity of PEDOT increases from 260 to almost 400 Scm⁻¹. Meanwhile, the inter-chain conductivity increases by almost three orders of magnitude, reaching a critical state, i.e., exceeding the percolation threshold. The observed changes in electrical conductivity due to acid doping are attributed to the flattening of the PEDOT/PSS gel nanoparticles. In the model developed here, this flattening is accounted for by the inclusion shape factor. Full article

Magnetic iron oxide nanoparticles (MIONPs) represent a versatile magnetic nanoparticle (NP) system with considerable, yet underexplored, potential in diverse applications, particularly in emerging biomedical fields such as magnetic resonance imaging, magnetic hyperthermia, targeted drug delivery, and biosensing. The successful translation of MIONPs into these applications requires reproducible synthesis methods and precise control over particle uniformity in terms of size, shape, and composition. However, reproducibility in nanoparticle synthesis remains a persistent challenge, limiting the ability of researchers to replicate results and integrate MIONPs into application-oriented studies. In recent years, substantial efforts have been directed toward elucidating synthesis mechanisms and improving both reproducibility and particle uniformity, enabling notable advances in the biomedical deployment of MIONPs. This review summarizes progress in the synthesis of MIONPs, with emphasis on three widely employed precursors: iron oleate, iron acetylacetonate, and iron pentacarbonyl. The discussion focuses on key findings in NP synthesis, relevant chemical aspects, and the magnetic properties of MIONPs, which are critical for optimizing their functional performance. By consolidating recent advances, this review aims to provide a reliable framework for the preparation of high-quality MIONPs and to support their effective use in specific biomedical applications. Full article

The growing ineffectiveness of common antibiotics against multidrug-resistant pathogens has made antimicrobial resistance (AMR) a serious global health concern. This review emphasizes that natural antibiotics from animals, bacteria, fungi, and plants are worthy alternatives for combating this crisis. Evolutionary pressure has shaped these molecules, leading to antibiotic-resistant bacteria that can withstand single-target synthetic drugs but are vulnerable to multiple attack pathways (e.g., cell wall disruption, protein synthesis inhibition, biofilm interference) from natural compounds. Natural antibiotics are frequently incorporated into treatment strategies or drug-delivery systems for minimizing side effects, reducing doses, and improving their effectiveness. The review discusses recent progress in this field, describing the mechanisms of action of natural antibiotics, their incorporation into several drug-delivery systems, and their ‘omics’-driven discovery to improve production, while expressing the challenges that remain. Extracellular application of these compounds, however, is compromised by their low stability in the extracellular environment; furthermore, formulation advancements, such as nanoparticle encapsulation, have been shown to enhance the bioavailability and activity of these substances. Combining indigenous knowledge and modern scientific advances, natural antibiotics may be developed to fight AMR both as monotherapy and adjuvants in a sustainable way. Leveraging these synergies, alongside the latest advances in research, is key to bridging the antibiotic discovery–resistance gap and may provide a route to clinical translation and global AMR control. The promise of natural antibiotics is clear, but their path to mainstream medicine is fraught with obstacles like reproducibility, standardization, and scalability. It is more realistic to see these substances as powerful complements to existing therapies, not outright replacements. Their true strength is in their ability to interfere with resistance mechanisms and create new possibilities for drug development, positioning them as a vital, though complicated, part of the global effort to combat AMR. Full article

The viscous rheological behavior of suspensions of mixtures of fumed silica nanoparticles (N20) and rod-shaped cellulose nanocrystals (NCC) were studied experimentally. The fumed silica concentration varied from 2 to 11.3 wt% and the NCC concentration varied from 0.99 to 6.73 wt%. The suspensions of pure fumed silica, pure NCC, and mixtures of N20 and NCC were non-Newtonian shear-thinning in nature. The viscosity versus shear rate data of all suspensions of pure and mixed additives could be described satisfactorily by a power-law model. The consistency and flow behavior indices of the suspensions were strongly dependent on the concentrations of both N20 and NCC. While the consistency index increased sharply with the increases in additive (N20 and NCC) concentrations, the flow behavior index generally decreased with the increases in N20 and NCC concentrations. Thus, the suspensions became more shear-thinning with the increases in N20 and NCC concentrations. The shear-thinning of suspensions was due to two different mechanisms: the orientation of rod-shaped cellulose nanocrystals in the flow direction with the increase in shear rate and the break-up of large agglomerates of fumed silica aggregates with the increase in shear rate. Full article

The present study aimed to evaluate the impact of varying dietary concentrations of calcium oxide nanoparticles (CaO-NPs) on important health regulators in Zebra fish (Danio rerio) using integrative physiological, histopathological, and computational approaches. The co-precipitation method was used to synthesize NPs and characterization was performed through DLS, XRD, FESEM, EDX, and FTIR depicting spherical-shaped CaO-NPs with a hydrodynamic diameter of 91.2 nm. Adult Danio rerio were administered with three different feed regimes enriched with 2.4 (T1), 1.6 (T2), and 0.8 (T3) mg CaO-NPs/kg for 30 days. Growth, survival, NP accumulation, and histological assessments, and bioinformatic studies, were performed to understand interactions of NPs with fish metabolic proteins. The T3 group demonstrated the highest survival (75%) and weight gain (+39.31%), and exhibited the lowest accumulation of CaO-NPs in the brain (0.133 mg/L), liver (0.642 mg/L), and intestine (0.773 mg/L) with no evident histological alterations, whereas T1 group exhibited major liver and intestinal damage. Molecular docking targeting the NRF-2 oxidative stress pathway revealed strong binding affinities of NPs with catalase (−3.7), keap1a (−3.5), keap1b (−3.3), and mafk (−2.4), highlighting potential modulation of redox homeostasis. Hence, a 0.8mg CaO-NPs/kg feed dose is recommended to promote potential health benefits in Danio rerio, which can be further applicable to commercial aquaculture for enhanced fish health while minimizing toxicity. Full article

Background/Objectives: Curcumin (Cur) has various biological properties, including anti-microbial, antioxidant, anticancer, anti-diabetic, anticarcinogenic, antitumor, and anti-inflammatory activities. However, using Cur in functional food products is challenging because of its low solubility in an aqueous environment, rapid degradation, and low bioavailability. Nanostructure delivery systems provide a high surface area to volume ratio and sustainable release properties. Methods: Coconut protein nanoparticles (CPNPs) have been fabricated through heat treatment at 85 °C and pH 2 for 5 h. The formation of CPNP-Cur was used to improve Cur solubility, followed by antioxidant activity at neutral pH in an aqueous solution. Results: The maximum efficiency and loading capacity of Cur in CPNP were 96.6% and 19.32 µg/mg protein, respectively. Scanning electron microscopy indicated the spherical and organized shape of CPNP with a small size of 80 nm. The fluorescence quenching of CPNP-Cur confirmed the potential of Cur to bind to the tryptophane and tyrosine residues in CPNP. The structural properties of CPNP and CPNP-Cur were investigated using FTIR and X-ray diffraction. The antioxidant activity of samples, measured with the ABTS radical scavenging method, demonstrated that the antioxidant capacity of the aqueous solution of Cur was significantly enhanced through the encapsulation into CPNP. The steady release of Cur was observed in the simulated gastrointestinal tract, and the percentage of the cumulative release increased up to 29.2% after 4 h. Conclusions: Our findings suggest that CPNP was a suitable nanocarrier for Cur due to improved antioxidant activity and controlled release behavior. These results are valuable for the development of coconut protein nanoparticles to use as a novel nano-delivery system of bioactive components. Full article

This work presents the design and fabrication of microstructured hydrophobic surfaces via fused filament fabrication (FFF) 3D printing with polylactic acid (PLA). Three geometric patterns—triangular-based prisms (TG), truncated pyramids (TP), and truncated ellipsoidal cones (CET)—were developed to modify the surface wettability. Morphological analysis revealed that the printer resolution limits the accurate reproduction of sharp CAD-defined features. Despite this, TG structures exhibited superhydrophobic behavior evaluated through static water contact angles (WCAs), reaching up to 164° along the structured direction and so representing a 100% increase relative to flat PLA surfaces (WCA = 82°). To improve print fidelity, TP and CET geometries with enlarged features were introduced, resulting in contact angles up to 128°, corresponding to a 56% increase in hydrophobicity. The truncated shapes enable the fabrication of the smallest features achievable via the FFF technique, while maintaining good resolution and obtaining higher contact angles. In addition, surface functionalization with fluoropolymer-coated SiO₂ nanoparticles, confirmed by SEM and Raman spectroscopy, led to a further slight enhancement in wettability up to 18% on the structured surfaces. These findings highlight the potential of FFF-based microstructuring, combined with surface treatments, for tailoring the wetting properties of 3D-printed polymeric parts with promising applications in self-cleaning, de-icing, and anti-wetting surfaces. Full article

Low-dimensional carbon nanostructures such as nanotubes, nanocones, and nanofibers can be grown in chemical vapor deposition (CVD) synthesis using catalyst nanoparticles. It is commonly observed that the morphology of solid catalyst nanoparticles continuously fluctuates during multi-walled carbon nanotube (MWCNT) growth. Interestingly, when the diameter of the inner tube of the growing MWCNT reduces below a threshold value, the catalyst nanoparticle snaps out of the MWCNT and recovers its spherical shape. If the MWCNT is tapered, the catalyst nanoparticle may also break. In this study, large-scale molecular dynamics simulations and nanomechanical modeling are employed to elucidate the complete process of MWCNT growth coupled with morphological change in the catalytic nanoparticles. It is shown that the tendency to decrease the surface energy of the catalyst nanoparticle is the major underlying driving force for the variation in morphology under the mechanical constraint of the growing MWCNT. Importantly, the predicted critical inner CNT radius at the onset of the shape recovery is in excellent agreement with experimental observations. The combination of molecular dynamics simulations and theoretical modeling offer an alternative perspective on co-evolution of catalyst nanoparticles and the growth of low-dimensional carbon nanostructures. Full article

This study investigates the morphological evolution of epitaxial indium antimonide (InSb) nanowires (NWs) grown via chemical vapor deposition (CVD). We systematically explored the influence of key growth parameters—temperature (300 °C to 480 °C), source material composition, gold (Au) nanoparticle catalyst size, and growth duration—on the resulting NW morphology, specifically focusing on NW length and tapering. Our findings reveal that the competition between axial and radial growth modes, which are governed by different growth mechanisms, dictates the final nanowire shape. An optimal growth condition was identified that yields straight and minimally tapered InSb NWs. High-resolution transmission electron microscopy (TEM) confirmed that these nanowires grow preferentially along the <110> direction, and electrical characterization via field-effect transistor (NW-FET) measurements showed that they are n-type semiconductors. Full article

Although laser cavitation was discovered half a century ago, novel geometries and regimes to excite this effect have been vigorously explored during the past few decades. This research is driven by a variety of applications of laser cavitation in demanding branches of science and technology, such as microfabrication, synthesis of nanoparticles, manipulation of cells, surgery, and lithotripsy. In this work, we combine experimental studies using high-repetition-rate imaging and numerical simulations to uncover a novel regime of the laser cavitation observed upon excitation of a liquid by a train of laser pulses with the pulse energy of 140 mJ and duration of 1.2 μs delivered through a quartz optical fiber. Once the lifetime of the initial cavitation bubble (excited by the first laser pulse) is larger than the period between pulses, which is 34.3 μs, the secondary pulses in the train pass the gas in a bubble and evaporate additional liquid. This results in the formation of a cascaded cavitation bubble of larger volume and elongated shape of $4.6$ mm length compared to $3.8$ mm in case of excitation by a single laser pulse. In addition, the results of acoustic measurements confirm the presence of shock waves in the applied liquid. Finally, potential applications of the uncovered laser cavitation regime are discussed. Full article