Search Results (155)

This study explores the critical role of airborne nanoparticle shape in air filtration performance, with direct relevance to the field of nanomaterials production. Aerosol particles ranging from 40 to 250 nm—including spherical Fe₂O₃, cubic MgO, straight rod-shaped ZnO, and curved or clustered COOH-functionalized nanotubes—were synthesized and tested to assess shape-dependent filtration behavior. The results indicate that the effect of particle morphology on filtration efficiency becomes markedly pronounced at larger particle sizes. For instance, at 250 nm, filtration efficiency differed by as much as 30% between spherical Fe₂O₃ and rod-shaped ZnO particles. These findings have substantial implications for industries engaged in large-scale nanomaterial synthesis, particularly where anisotropic or rod-like particles are prevalent. The potential for higher-than-anticipated atmospheric release of such particles underscores the need for refined environmental controls and monitoring. Furthermore, the current practice of using primarily spherical particles in air filter certification tests may require reconsideration to ensure accuracy and applicability to real-world scenarios involving non-spherical nanomaterials. Full article

The steady shear rheology of suspensions of mixtures of rod-shaped cellulose nanocrystals (NCC) and spherical starch nanoparticles (SNPs) was investigated experimentally over a broad range of NCC and SNP concentrations. The NCC concentration varied from about 1 to 6.7 wt% and the SNP concentration varied from 5 to 30 wt%. The suspensions of mixtures of NCC and SNPs were pseudoplastic (shear-thinning) in nature. The viscous behavior of suspensions of mixtures of NCC and SNPs could be described adequately using the power-law model. The power-law parameters, that is, consistency index and flow behavior index, were dependent on the concentrations of both NCC and SNPs. The consistency index increased substantially with increases in NCC and SNP concentrations. The flow behavior index generally decreased with an increase in NCC and SNP concentrations; that is, the suspension mixtures became more shear-thinning with increases in NCC and SNP concentrations. However, the dependence of the consistency index and flow behavior index on NCC concentration was much stronger as compared with the SNP concentration. Full article

Copper (II) oxide nanoparticles (CuO NPs) attract much attention as a promising antimicrobial agent. We studied the antibacterial properties of three types of CuO NPs against Escherichia coli bacteria: flake-shaped particles with a diameter of 50–200 nm and a thickness of 10–20 nm (CuO-CD synthesized by chemical deposition), spherical particles with a size of 20–90 nm (CuO-EE obtained by electrical explosion), and rod-shaped particles with a length of 100–200 nm and a diameter of 30 × 70 nm (CuO-CS commercial sample). We tested how the shape, size, and concentration of the NPs, and composition of the dispersion medium affected the properties of the CuO NPs. We prepared dispersions based on distilled water, a 0.9% NaCl solution, and the LB broth by Lennox and used Triton X-100 and sodium dodecyl sulfate (SDS) as stabilizers. The concentration of NPs was 1–100 mg L⁻¹. We showed that the dispersion medium composition and stabilizer type had the greatest influence on the antibacterial effects of CuO NPs. We observed the maximum antibacterial effect for all CuO NP types dispersed in water without a stabilizer, as well as in LB broth with the SDS stabilizer. The maximum inhibition of culture growth was observed under the influence of CuO-EE (by 30%) and in the LB broth with the SDS stabilizer (by 1.3–1.8 times depending on the type of particles). In the saline solution, the antibacterial effects were minimal; in some cases, the CuO NPs even promoted bacterial culture growth. SDS increased the antibacterial effects of NPs in broth and saline but decreased them in water. Finally, among the particle types, CuO-CS turned out to be the most bactericidal, which is probably due to their rod-shaped morphology and small diameter. At the same time, the concentration and aggregation effects of CuO NPs in the colloidal systems we studied did not have a linear action on their antibacterial properties. These results can be used in the development of antibacterial coatings and preparations based on CuO NPs to achieve their maximum efficiency, taking into account the expected conditions of their use. Full article

Titanium dioxide demonstrates promising potential in the energy storage field due to its high theoretical specific capacity and economic viability. However, its practical application is hindered by intrinsic limitations including low electronic conductivity and slow lithium-ion transport. In general, nature inspires the biotemplating synthesis of artificially functional materials with hierarchical structures. Learning from the bioinspired synthesis process, we adopt a facile biomimetic approach to synthesize graphene-based anatase TiO₂ nanoparticle/nanorod hierarchical structure. The rod-shaped anatase is assembled nanoparticles with a diameter of 20 to 50 nm, and the surface of graphene is deposited by nanoparticles of 5 to 10 nm. The composite also possesses a high surface area and a mesoporous structure. This unique structure not only reduces the transportation pathway of lithium ions and electrons but also enhances the electric conductivity and tolerates the volume change. As an anode electrode, the bioinspired hierarchical structure exhibits a high reversible capacity of 160 mA h g⁻¹ after 180 cycles at a current rate of 1C, highlighting the effectiveness of bioinspired design. Full article

Carbapenem-resistant Enterobacterales (CRE) is an emerging global concern. Specifically, carbapenemase-producing (CP) E. coli strains in CRE have recently been found in clinical, environmental, and food samples worldwide, causing many hospitalizations and deaths. Their rapid identification and characterization are paramount in control, management options, and treatment choices. Thus, this study aimed to characterize the cell surface properties of carbapenem-resistant (R) E. coli isolates and their interaction with glycan-coated magnetic nanoparticles (gMNPs) compared with carbapenem-susceptible (S) E coli. This study used two groups of bacteria: The first group included E. coli (R) isolates harboring carbapenemases and had no antibiotic exposure. Their initial gMNP–cell binding capacity, with cell surface characteristics, was assessed. In the second group, one of the E. coli (R) isolates and E. coli (S) had long-term serial antibiotic exposure, which we used to observe their cell surface characteristics and gMNP interactions. Initially, cell surface characteristics (cell morphology and cell surface charge) of the E. coli isolates were evaluated using confocal laser scanning microscope (LSCM) and a Zetasizer, respectively. The interaction of gMNPs with the E. coli isolates was assessed through LSCM and transmission electron microscope (TEM). Further, the gMNP–cell attachment was quantified as a concentration factor (CF) through the standard plating method. The results showed that the CF values of all E. coli (R) were significantly different from those of E. coli (S), which could be due to the differences in cell characteristics. The E. coli (R) isolates displayed heterogeneous cell shapes (rod and round cells) and lower negative zeta potential (cell surface charge) values compared to E. coli (S). Further, this research identified the differences in the cell surface characteristics of E. coli (S) under carbapenem exposure, compared to unexposed E. coli (S) that impact their attachment capacity. The gMNPs captured more E. coli (S) cells compared to carbapenem-exposed E. coli (S) and all E. coli (R) isolates. This study clearly found that differences in cell surface characteristics impact their interaction with magnetic nanoparticles. The gained insights aid in further understanding adhesion mechanisms to develop or improve bacterial isolation techniques and diagnostic and treatment methods for CRE. Full article

Hydrogel nanocomposites that respond to external stimuli and possess switchable electrical properties are considered as emerging materials with potential uses in electrical, electrochemical, and biological devices. This work reports the synthesis and characterization of thermo-responsive and electroconductive hydrogel nanocomposites based on poly(N-isopropylacrylamide) (PNiPAAm) and gold nanoparticles (nanospheres—AuNPs and nanorods—AuNRs) using two different synthetic techniques. Method I involved γ-irradiation-induced crosslinking of a polymer matrix (hydrogel), followed by radiolytic in situ formation of gold nanoparticles, while Method II included the chemical synthesis of nanoparticles, followed by radiolytic formation of a polymer matrix around the gold nanoparticles. UV–Vis spectral studies revealed the presence of local surface plasmon resonance (LSPR) bands characteristic of nanoparticles of different shapes, confirming their formation and stability inside the polymer matrix. Morphological, structural, and physicochemical analyses indicated the existence of a stable porous polymer matrix, the formation of nanoparticles with a face-centered cubic structure, increased swelling capacity, and a slightly higher volume phase transition temperature (VPTT) for the hydrogel nanocomposites. Comparative electrochemical impedance spectroscopy (EIS) showed an increase in conductivity for the nano Au-PNiPAAm hydrogel nanocomposites compared to the PNiPAAm hydrogel, with a considerable rise detected above the VPTT. By reverting to room temperature, the conductivity decreased, indicating that the investigated hydrogel nanocomposites exhibited a remarkable reversible “on–off” thermo-switchable mechanism. The highest conductivity was observed for the sample with rod-shaped gold nanoparticles. The research findings, which include optical, structural, morphological, and physicochemical characterization, evaluation of the efficiency of the chosen synthesis methods, and conductivity testing, provide a starting point for future research on the given nanocomposite materials with integrated multifunctionality. Full article

Conjugated polymers (CPs), in particular poly(p-phenylene vinylene)s (PPVs), are recognized as “smart” materials with potential applications ranging from optoelectronic devices to emergent technologies and to precision medicine. The present communication reports on the synthesis and structural characterization of new dibrominated macromonomers and their derived PPVs, of rod–graft–coil architecture, whose grafted, biocompatible and hydrophilic side chains are either PEG-2000 or poly(2-methyl-2-oxazoline) or poly(2-ethyl-2-oxazoline). The Suzuki–Heck cascade reaction was used for PPVs’ obtainment. After PPVs’ structural characterization using specific techniques (such as ¹H-NMR; GPC), the micellar, fluorescent nanoparticles formed by spontaneous self-assembling during simple direct dissolution in water were evaluated using dynamic light scattering for their size, complementarily combined with Atom Force Microscopy (AFM) for their shape assessing. The PPV micelles’ photophysical properties were revealed using UV-vis spectroscopy and fluorescence measurements. Full article

The emergence of antibiotic-resistant Streptococcus pneumoniae necessitates the discovery of novel therapeutic agents. This study investigated the antimicrobial potential of green-synthesized gold nanoparticles (AuNPs) fabricated using Arthrospira platensis extract. Characterization using Fourier transform infrared spectroscopy revealed the presence of functional groups such as ketones, aldehydes, and carboxylic acids in the capping agents, suggesting their role in AuNP stabilization. Transmission electron microscopy demonstrated the formation of rod-shaped AuNPs with a mean diameter of 134.8 nm, as determined by dynamic light scattering, and a zeta potential of −27.2 mV, indicating good colloidal stability. The synthesized AuNPs exhibited potent antibacterial activity against S. pneumoniae, with a minimum inhibitory concentration (MIC) of 12 μg/mL, surpassing the efficacy of the control antibiotic, tigecycline. To elucidate the underlying mechanisms of action, an untargeted metabolomic analysis of the A. platensis extract was performed, identifying 26 potential bioactive compounds belonging to diverse chemical classes. In silico studies focused on molecular docking simulations revealed that compound 22 exhibited a strong binding affinity to S. pneumoniae topoisomerase IV, a critical enzyme for bacterial DNA replication. Molecular dynamics simulations further validated the stability of this protein–ligand complex. These findings collectively highlight the promising antimicrobial potential of A. platensis-derived AuNPs and their constituent compounds, warranting further investigation for the development of novel anti-pneumococcal therapeutics. Full article

In recent years, significant advancements in nanotechnology have facilitated the synthesis of zinc oxide (ZnO) nanoparticles with tailored sizes and shapes, offering versatile applications across various fields, particularly in biomedicine. ZnO’s multifunctional properties, such as semiconductor behavior, luminescence, photocatalytic activity, and antibacterial efficacy, make it highly attractive for biomedical applications. This study focuses on synthesizing ZnO nanoparticles via the microwave-assisted hydrothermal method, varying the precursor concentrations (0.3488 mol/L, 0.1744 mol/L, 0.0872 mol/L, 0.0436 mol/L, and 0.0218 mol/L) and reaction times (15, 30, and 60 min). Characterization techniques, including X-ray diffraction, scanning electron microscopy, transmission electron microscopy, BET surface area analysis, and Fourier transform infrared spectroscopy were employed to assess the structural, morphological, and chemical properties. The predominant morphology is observed to be platelets, which exhibit a polygonal shape with beveled corners and occasionally include short rod-like inserts. The thickness of the platelets varies between 10 nm and 50 nm, increasing with the concentration of Zn²⁺ in the precursor solution. Preliminary antimicrobial studies indicated that all strains (S. aureus, E. coli, and C. albicans) were sensitive to interaction with ZnO, exhibiting inhibition zone diameters greater than 10 mm, particularly for samples with lower precursor concentrations. Cell viability studies on human osteoblast cells demonstrated good compatibility, affirming the potential biomedical applicability of synthesized ZnO nanoparticles. This research underscores the influence of synthesis parameters on the properties of ZnO nanoparticles, offering insights for optimizing their design for biomedical applications. Full article

Bioactive glass nanoparticles (BGNs) are applied widely in tissue regeneration. Varied micro/nanostructures and components of BGNs have been designed for different applications. In the present study, nanorod-shaped mesoporous zinc-containing bioactive glass nanoparticles (ZnRBGNs) were designed and developed to form the bioactive content of composite materials for hard/soft tissue repair and regeneration. The nanostructure and components of the ZnRBGNs were characterized, as were their cytocompatibility and radical-scavenging activity in the presence/absence of cells and their ability to modulate macrophage polarization. The ZnRBGNs possessed a uniform rod shape (length ≈ 500 nm; width ≈ 150 nm) with a mesoporous structure (diameter ≈ 2.4 nm). The leaching liquid of the nanorods at a concentration below 0.5 mg/mL resulted in no cytotoxicity. More significant improvements in the antioxidant and M1-polarization-inhibiting effects and the promotion of M2 polarization were found when culturing the cells with the ZnRBGNs compared to when culturing them with the RBGNs. The doping of the Zn element in RBGNs may lead to improved antioxidant and anti-inflammatory effects, which may be beneficial in tissue regeneration/repair. Full article

Biomaterials, like hydroxyapatite (HAp), are the subject of many scientific investigations. Their specific application, however, is determined by the form and some characteristic features of the resulting material. Synthesis methods and optimization procedures leading to a product of predetermined characteristics are therefore of great interest. To broaden the existing knowledge, sonoprecipitation was investigated as a potential method for the production of nanosized HAp particles. The research was carried out in a static mixer (STM) immersed in the ultrasonic bath. The influence of operating conditions, e.g., ultrasonic power P_US (ε_US), ultrasonic frequency (f_US), and unit mixing power (ε_mix), was investigated in terms of nucleation intensity, product quality, and characteristics (particle size distribution (PSD), mean size, shape, etc.). As a result, the optimal conditions for the HAp nanoparticles synthesis (mean size: d~150 nm; length: L₁~250 nm; width: L₂~80 nm) in the form of needles/whiskers/rods—similar to the shape of the HAp present in natural human bones, free from agglomerates, with negligible signs of particle destruction—were determined. The formation of HAp of smaller sizes (d ≤ 100 nm) and more compact shapes (L₁~155 nm, L₂~90 nm), useful in bone regeneration processes, was also discussed. Full article

In the present work, magnesium oxide (MgO) and lead oxide (PbO) nanoparticles were prepared by the co-precipitation method. Their structural parameters and morphology were investigated using XRD, HRTEM, and FTIR. The formation of the phases was seen to have small average crystallite sizes and an orthorhombic crystal structure for both MgO and PbO nanoparticles. The results of HR-TEM showed irregularly shaped nanoparticles: quasi-spherical or rod-like shapes and spherical-like shapes for MgO and PbO nanoparticles, respectively. The produced nanoparticles’ size using X-ray diffraction analysis was found to be 17 nm and 41 nm for MgO and PbO nanoparticles, respectively. On the other hand, it was observed from the calculations that the optical band gap obeys an indirect allowed transition. The calculated values of the band gap were 4.52 and 4.28 eV for MgO and PbO NPs, respectively. The MB was extracted from the wastewater using the prepared composites via absorption. Using a variety of kinetic models, the adsorptions were examined. Out of all the particles, it was discovered that the composites were best. Furthermore, of the models currently under consideration, the pseudo-second-order model best fit the degradation mechanism. The resultant composites could be beneficial for degrading specific organic dyes for water purification, as well as applications needing a wider optical band gap. Full article

Using biomass to develop and obtain environmentally friendly and industrially applicable biomaterials is increasingly attracting global interest. Herein, cellulose nanocrystals (CNCs) and lignin nanoparticles (LNPs) were extracted from Lemna minor L., a freshwater free-floating aquatic species commonly called duckweed. To obtain CNCs and LNPs, two different procedures and biomass treatment processes based on bleaching or on the use of an ionic liquid composed of triethylammonium and sulfuric acid ([TEA][HSO₄]), followed by acid hydrolysis, were carried out. Then, the effects of these treatments in terms of the thermal, morphological, and chemical properties of the CNCs and LNPs were assessed. The resulting nanostructured materials were characterized by using Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) spectroscopy, thermo-gravimetric analysis (TGA), and scanning electron microscopy (SEM). The results showed that the two methodologies applied resulted in both CNCs and LNPs. However, the bleaching-based treatment produced CNCs with a rod-like shape, length of 100–300 nm and width in the range of 10–30 nm, and higher purity than those obtained with ILs that were spherical in shape. In contrast, regarding lignin, IL made it possible to obtain spherical nanoparticles, as in the case of the other treatment, but they were characterized by higher purity and thermal stability. In conclusion, this research highlights the possibility of obtaining nanostructured biopolymers from an invasive aquatic species that is largely available in nature and how it is possible, by modifying experimental procedures, to obtain nanomaterials with different morphological, purity, and thermal resistance characteristics. Full article