Non-spherical Nanoparticles Research Articles

Comparative analysis of theories accounting for quantum effects in plasmonic nanoparticles

Understanding and accounting for quantum effects in nanoplasmonics is essential for accurate modeling and design of nanophotonic devices. In this paper, we investigate the influence of such quantum effects as spatial nonlocality and splitting of the wave function of conduction electrons near the surface of plasmonic nanoparticles on the extinction cross-section and the field enhancement factor. We apply the theory of generalized nonlocal optical response (GNOR) to describe the spatial nonlocality of noble metal particles. To consider the behavior of electrons near the metal–dielectric interface, mesoscopic boundary conditions are used, including the surface response functions (SRF) - the Feibelman parameters. We use the discrete source method (DSM), allowing for numerical analysis of the scattering problems taking into account quantum effects in the frame of both theories. The application of both GNOR and SRF approaches leads to a decrease in the amplitude of the plasmon resonance compared to the classical Maxwell theory and its shift to the shorter wavelength region (blue shift). The simulation results demonstrate significant differences between the two theories explaining the quantum effects arising in non-spherical plasmonic nanoparticles located in a dense environment. Specifically, compared with GNOR theory, SRF predicts a larger field enhancement. We found that quantum nonlocal effects are more significant for the enhancement factor at the particle surface than for the extinction cross-section. In addition, it was discovered that a denser environment leads to a significant increase in the blue shift of the plasmonic peak.

Sprayable inflammasome-inhibiting lipid nanorods in a polymeric scaffold for psoriasis therapy.

Localized delivery of inflammasome inhibitors in phagocytic macrophages could be promising for psoriasis treatment. The present work demonstrates the development of non-spherical lipid nanoparticles, mimicking pathogen-like shapes, consisting of an anti-inflammatory inflammasome inhibiting lipid (pyridoxine dipalmitate) as a trojan horse. The nanorods inhibit inflammasome by 3.8- and 4.5-fold compared with nanoellipses and nanospheres, respectively. Nanorods reduce apoptosis-associated speck-like protein and lysosomal rupture, restrain calcium influx, and mitochondrial reactive oxygen species. Dual inflammasome inhibitor (NLRP3/AIM-2-IN-3) loaded nanorods cause synergistic inhibition by 21.5- and 59-folds compared with nanorods and free drug, respectively alongside caspase-1 inhibition. The NLRP3/AIM-2-IN-3 nanorod when transformed into a polymeric scaffold, simultaneously and effectively inhibits RNA levels of NLRP3, AIM2, caspase-1, chemokine ligand-2, gasdermin-D, interleukin-1β, toll-like receptor 7/ 8, and IL-17A by 6.4-, 1.6-, 2.0-, 13.0-, 4.2-, 24.4-, 4.3-, and 1.82-fold, respectively in psoriatic skin in comparison to Imiquimod positive control group in an in-vivo psoriasis-like mice model.

High-Order Harmonics Generation Using Spherical and Non-Spherical Nanoparticles.

The conversion efficiency of 800 nm, 65 fs radiation toward high-order harmonic generation (HHG) in laser-induced plasmas containing spherical and non-spherical nanoparticles (NPs) produced during the laser ablation of different metals in water using 1064 nm, 70 ps pulses was analyzed. Non-spherical NPs of different forms (triangle, cubic, bowtie, rod, rectangular, ellipsoid, etc.) were synthesized during the aging of some spherical NPs (In, Al, and Cu) in water. These NPs were then dried on the glass substrates and ablated to produce plasmas comprising nanostructured species of different morphologies. It was shown that harmonic generation in all synthesized non-spherical NPs was less efficient by a factor of at least five than in the initial spherical NP. Meanwhile, the spherical NPs that maintained the morphology state during aging (Ni, Ag, Mn, and Au) showed almost similar HHG conversion efficiency compared to the fresh spherical NPs. In all cases, the HHG conversion efficiency using spherical and non-spherical nanoparticles was notably larger compared to the atomic and ionic single-particle plasmas of the same elemental composition. NP plasmas demonstrated featureless harmonic distributions, contrary to the indium and manganese atomic/ionic plasmas, when the resonance enhancement of harmonics was observed.

Angular momentum transfer from swift electrons to non-spherical nanoparticles within the dipolar approximation

In this work, we study the angular momentum transfer from a single swift electron to non-spherical metallic nanoparticles, specifically investigating spheroidal and polyhedral (Platonic Solids) shapes. While previous research has predominantly focused on spherical nanoparticles, our work expands the knowledge by exploring various geometries. Employing classical electrodynamics and the small particle limit, we calculate the angular momentum transfer by integrating the spectral density, ensuring causality through Fourier-transform analysis. Our findings demonstrate that prolate spheroidal nanoparticles exhibit a single blueshifted plasmonic resonance, compared to spherical nanoparticles of equivalent volume, resulting in lower angular momentum transfer. Conversely, oblate nanoparticles display two resonances — one blueshifted and one redshifted — resulting in a higher angular momentum transfer than their spherical counterparts. Additionally, Platonic Solids with fewer faces exhibit significant redshifts in plasmonic resonances, leading to higher angular momentum transfer due to edge effects. We also observe resonances and angular momentum transfers with similar characteristics in specific pairs of Platonic Solids, known as duals. These results highlight promising applications, particularly in electron tweezers technology.

A non-spherical nanoparticles system for the delivery of peptides using polymer grafted nanocellulose

AbstractPeptide drugs are increasingly used to treat a variety of diseases ranging from cancer, and infections to cardiovascular diseases. However, peptides can suffer from low stability in the bloodstream. Entrapment of peptides into nano-sized carriers of various types has widely been explored, but all of them have spherical shapes. Nanocellulose can in contrast serve as a non-spherical nanoparticle with a high aspect ratio. After the isolation of nanocellulose by TEMPO-mediated oxidation, the material needs to be modified with polymers to generate nanoparticles with high water-solubility that can also favourably interact with peptide drugs. We have here chosen insulin as the model drug, which can strongly interact with cationic polymers. As it is known that cationic polymer may retain charged drugs too tightly, we have selected poly(2-(dimethylamino)ethyl acrylate) PDMAEA as a degradable polymer that undergoes self-hydrolysis to poly(acrylic acid) in water. This polymer was compared to poly(N-(3-(dimethylamino)propyl) acrylamide) PDMAPAA, which is a stable cationic polymer. The cationic polymer was co-grafted with poly(2-hydroxyethyl acrylate) PHEA as a water-soluble neutral polymer using the three-component Passerini reaction. A combination of fluorescence and UV-Vis techniques were used to quantify the amount of polymer that was conjugated to the surface. The polymer-coated nanocellulose was labelled with the fluorescent cyanine dye Cy5 while insulin was labelled with Cy3 creating a FRET system that allows monitoring of the interaction between insulin and polymer in cell growth media. We observed that despite the self-hydrolysis of PDMAEA into a negatively charged polymer, the negatively charged insulin was not released in buffer solution according to the FRET studies. Only the addition of serum-supplemented cell growth media led to insulin release. The limited release was explained with the fact that insulin, as well as other peptides, have a mixture of negative and positive charges, with the pH value and the isoelectric point determining the balance between both. Negative-charged polymers can therefore still interact favourably with negatively charged peptides by interacting with cationic amino acids. Graphical Abstract

Cellular uptake of active nonspherical nanoparticles

Due to the potential applications in biomedical engineering, it becomes more and more important to understand the process of engulfment and internalization of nanoparticles (NPs) by cell membranes. Despite the fact that the interaction between cell membranes and passive particles has been widely studied, the interaction between cell membranes and self-propelled nonspherical NPs remains to be elucidated. Here, we present a theoretical model to systematically investigate the influence of the active force, aspect ratio of NPs, particle size, and membrane properties (adhesion energy density and membrane tension) on the cellular uptake of a nonspherical nanoparticle. It is found that the active force generated by an NP can trigger a type of first-order wrapping transition from a small partial wrapping state to a large one. In addition, the phase diagram in the force-aspect ratio (particle size, adhesion energy density, and membrane tension) space displays more complex behaviors compared with that for the passive wrapping mediated merely by adhesion. These results may provide useful guidance to the study of activity-driven cellular entry of active particles into cells.

Rough Fe3O4/gold nanostructure enhanced fluorescence of quantum dots for Salmonella typhimurium detection in cabbage

Salmonella typhimurium (S. typhimurium) is a leading biological factor of foodborne diseases. A sensitive detection for S. typhimurium is crucial to controlling fresh vegetable-related outbreaks. Here, fluorescence-based S. typhimurium detection in fresh cabbage samples has been reported which capitalizes on the plasmon-exciton interaction between non-spherical gold nanoparticles-covered iron oxide nanoparticles (Fe3O4@Au NPs) and gold quantum dots (Au QDs). Firstly, new synthesis methods for non-spherical Fe3O4@Au NPs and Au QDs are reported. Then, a two-fold emission enhancement and shortening of the lifetime were achieved from urchin-like NPs compared with those of spherical NPs. This finding was utilized for the detection of S. typhimurium. Results revealed that the changes in fluorescence emission were linearly correlated with the concentration of S. typhimurium within the range of 100–1000 colony forming unit per milliliter (CFU mL−1) and the limit of detection was 32 CFU mL−1 in fresh cabbage.

Micropolar (copper–water) nanofluid flow past a stretching sheet with nanosized particles shape impact

Nanosized particles can be administered via distinct routes involving intraperitoneal and intravenous injection, pulmonary inhalation, and oral administration. Nanosized particles have been advanced as efficient target-specific strategies for the treatment of cancer, acting as agents and also acting as nanocarriers. Over the last few years, various kinds of nanosized particles have been developed based on several components involving silica oxides, nanocrystals, carbon, metal oxides, polymers, quantum dots, lipids, and dendrimers, together with enhancing a variety of newly developed materials. The focus of this study is to analyze the effect of dissimilar shapes of nano-sized particles on fluid flow past a stretching surface that is permeable. For this purpose, a micropolar nanofluid with a base fluid of water is considered. Both spherical (sphere) and nonspherical (lamina)-shaped nanoparticles of copper are used to study the enhancement of thermal conductivity. The highly complex governing partial differential equations of the problem are converted into ODEs via similarity transformations. The converted ODEs are tackled with the help of the homotopy analysis method. Our study shows that the performance of nonspherical(lamina) nanoparticles is better than spherical(sphere) nanoparticles in the disturbance of fluid motion, microrotation, and energy.

Elastic scattering of gold and silver colloids: Difference between spherical and nonspherical nanoparticles

Light scattering of noble metal nanoparticles was widely used in solar cells, sensing and spectroscopy, so the research on the light scattering itself will be beneficial for their increasing applications. In this paper, gold and silver nanoparticles with different sizes and shapes were synthesized and their elastic scattering was investigated. The results demonstrate that the elastic scattering of metal nanoparticles is influenced by their size and shape, and the scattering behavior has a specific correlation with the surface plasmon resonance. The elastic scattering spectra of gold and silver nanospheres basically cover the extinction spectra, indicating plasmon resonance enhanced scattering of spherical nanoparticles. The elastic scattering spectra of nonspherical gold nanorods and silver nanoprisms only overlap the extinction peaks at short wavelengths. The elastic scattering is considered to be enhanced by the transverse resonance bands at short wavelengths for nonspherical gold or silver nanoparticles, but it cannot be contributed by the longitudinal resonance bands at the corresponding long wavelengths. This result will be helpful in selecting size and shape in the scattering application of plasmonic metal nanoparticles.

Lipid bilayer membrane interactions with nonspherical nanoparticles

Lipid bilayer membrane interactions with nonspherical nanoparticles

Significant Progress of Initiated Chemical Vapor Deposition in Manufacturing Soft Non-spherical Nanoparticles: Upgrading to the Condensed Droplet Polymerization Approach and Key Technological Aspects

Initiated chemical vapor deposition is a unique solvent-free and completely dry vapor-phase deposition technique used to synthesize organic polymer films. In this process, an activated initiator, monomer, and carrier gas are introduced into the reaction chamber simultaneously. This technique has been widely adopted. However, if the monomer and initiator are introduced into the chamber in stages—allowing gas-phase monomer deposition and condensation first, followed by initiator introduction and controlling the monomer partial pressure to be higher than the saturated vapor pressure—non-spherical polymer nanoparticles with dome-like shapes can be obtained. This advanced iCVD technique is referred to as the “Condensed Droplet Polymerization Approach”. This high monomer partial pressure gas-phase deposition is not suitable for forming uniformly composed iCVD films; but interestingly, it can rapidly obtain polymer nanodomes (PNDs). Using CDP technology, Franklin polymerized multifunctional nanodomes in less than 45 s, demonstrating a wide range of continuous particle size variations, from sub-20 nanometers to over 1 micron. This rapid synthesis included a variety of functional polymer nanodomes in just a matter of seconds to minutes. This review discusses the crucial process conditions of the Condensed Droplet Polymerization (CDP) Approach for synthesizing PNDs. The main focus of the discussion was on the two-step method for synthesizing PNDs, where the nucleation mechanism of PNDs, factors influencing their size, and the effect of pressure on the distinct condensation of monomer vapor into polymer nanodomes and polymer films were extensively explored.

Large eddy simulation-bivariate sectional model for non-spherical TiO2 nanoparticle synthesis in flame

Numerical simulation of nanoparticle synthesis in flame necessitates a high level of fidelity for turbulent flame, as well as delivers more detail insight into the evolution of structure and size distribution of particles undergoing various dynamic events. In the present work, a new simulation approach coupling large-eddy simulation (LES) and bivariate sectional model is proposed to explore the synthesis of nanoparticles in turbulent flame. More specifically, the nonlinear LES-partially stirred reactor model (NLES-PaSR) is utilized to simulate the turbulent flame, wherein the gradient-type structural subgrid-scale (SGS) model for turbulent flow and partially stirred reactor (PaSR) model for turbulent combustion are considered. In addition, the volume-based bivariate sectional model is thoroughly coupled with the LES model for the first time to describe the spatiotemporally resolved formation and growth of nanoparticles using particle number concentration and surface area concentration as two sets of variables. Compared directly with the LES-monodisperse (LES-Mono) and LES-univariate sectional (LES-UniSe) models, the LES-bivariate sectional (LES-BiSe) model has significant advantages in its ability to analyze and predict the size, morphology, as well as polydispersed particle size distribution (PSD) evolution of nanoparticles at a moderate computational cost simultaneously. In the LES framework, the proposed model successfully simulates the spatiotemporally resolved formation and growth of non-spherical TiO2 nanoparticle in turbulent diffusion burner. The predicted results derived from the LES-BiSe model are in good agreement with the experimental measurements. Also, the aggregate and primary particle size distribution shows highly temporal fluctuation, which mainly results from the continuous variations of particle path induced by the unsteady turbulent combustion. Furthermore, the present work demonstrates the profound dependence of particle morphological on both spatiotemporal evolution and their intrinsic size distribution. In particular, the large aggregates in the higher sections are commonly found as irregular structure with fractal-like dimensions.

Impact of nanosized particles on hybrid nanofluid flow in porous medium with thermal slip condition

A primary goal of this dissertation is to examine the magnetohydrodynamics (Al2O3 and Cu)/H2O hybrid nanofluid flow a porous medium with the nano-particles shape effect. The significant impact of thermal conductivity variation, slip condition and heat generation are also deliberated. The Spherical (Sphere) and non-Spherical (Lamina) types of Aluminum oxide (Al2O3) and Copper (Cu) nanoparticles are suspended in pure water (H2O) to form (Al2O3 and Cu)/H2O hybrid nanofluid. The modeled partial differential equations are transmuted into ordinary differential equations by using the similarity transformation technique. The converted ordinary differential equations (ODEs) are tackled analytically with the employing of well-known Homotopy analysis method (HAM). Also, the impacts of involving parameters on (Al2O3 and Cu)/H2O hybrid nanofluid velocity, temperature and Nusselt number are also taken into justification. A remarkable enhancement is noted the in non-Spherical (Lamina) shapes nanoparticles (Al2O3 and Cu) performance on temperature disturbance and heat transfer.

Shape-Induced Variations in Aromatic Thiols Adsorption on Gold Nanoparticle: A Novel Method for Accurate Evaluation of Adsorbed Molecules.

Nonspherical gold nanoparticles (GNPs) are increasingly used to enhance sensitivity and selectivity in analytical methods such as surface-enhanced Raman spectroscopy (SERS) for detecting trace biomarkers. However, there is limited research on the adsorption properties of aromatic thiols onto gold nanoparticles of different morphologies, where surface curvature varies significantly at the molecular level. In this study, we investigated the adsorption kinetics of 4-mercaptobenzoic acid, an aromatic molecule, on GNPs with different shapes using SERS. Our findings revealed significant differences in the adsorption behavior and binding site preferences of aromatic thiols on GNPs with distinct morphologies. While thiol molecules consider any surface site on nanospheres equally appealing, nanostars exhibit variations in curvature and surface energy, leading to initial binding with further repositioning from the tips of the nanostar after plasmon activation. To address these differences, we proposed a universal method to evaluate the quantity of tightly bound adsorbed molecules on GNPs independently of the particle size, shape, or concentration.

The Effect of Nanoparticle Composition on the Surface-Enhanced Raman Scattering Performance of Plasmonic DNA Origami Nanoantennas.

A versatile generation of plasmonic nanoparticle dimers for surface-enhanced Raman scattering (SERS) is presented by combining a DNA origami nanofork and spherical and nonspherical Au or Ag nanoparticles. Combining different nanoparticle species with a DNA origami nanofork to form DNA origami nanoantennas (DONAs), the plasmonic nanoparticle dimers can be optimized for a specific excitation wavelength in SERS. The preparation of such nanoparticle dimers is robust enough to enable the characterization of SERS intensities and SERS enhancement factors of dye-modified DONAs on a single dimer level by measuring in total several thousands of dimers from five different dimer designs, each functionalized with three different Raman reporter molecules and measured at four different excitation wavelengths. Based on these data, SERS enhancement factor (EF) distributions have been determined for each dimer design and excitation wavelengths. The structures and measurement conditions with the highest EFs are suitable for single-molecule SERS (SM-SERS), which is realized by placing single dye molecules into hot spots. We demonstrate that the probability of placing single molecules in a strongly enhancing hot spot for SM-SERS can be increased by using anisotropic nanoparticles with several sharp edges, such as nanoflowers. Combining a Ag nanoparticle with a Au particle in one dimer structure allows for a broadband excitation covering almost the whole visible range. The most versatile plasmonic dimer structure for SERS combines a spherical Ag nanoparticle with a Au nanoflower. Employing the discontinuous Galerkin time domain method, we numerically investigate the bare, symmetric dimers with respect to spectral and near-field properties, showing that, indeed, the nanoflowers induce multiple hot spots located at the edges which surpass the intensity of the spherical dimers, indicating the possibility for SM-SERS. The presented DONA structures and SERS data provide a robust basis for applying such designs as versatile SERS tags and as substrates for SM-SERS measurements.

The flow of anisotropic nanoparticles in solution and in blood.

The alignment of anisotropic nanoparticles in flow has been used for a range of applications such as the preparation of strong fibres and the assembly of in-plane aligned 1D-nanoobjects that are used for electronic devices, sensors, energy and biological application. Important is also the flow behaviour of nanoparticles that were designed for nanomedical applications such as drug delivery. It is widely observed that non-spherical nanoparticles have longer circulation times and a more favourable biodistribution. To be able to understand this behaviour, researchers have turned to analyzing the flow of non-spherical nanoparticles in the blood stream. In this review, an overview of microfluidic techniques that are used to monitor the alignment of anisotropic nanoparticles in solution will be provided, which includes analysis by small angle X-ray scattering (SAXS) and polarized light microscopy. The flow of these nanoparticles in blood is then discussed as the presence of red blood cells causes margination of some nanoparticles. Using fluorescence microscopy, the extent of margination can be identified, which coincides with the ability of nanoparticles to adhere to the cells grown along the wall. While these studies are mainly carried out in vitro using blood, initial investigations in vivo were able to confirm the unusual flow of anisotropic nanoparticles.

Development of Non-Spherical Platinum Nanoparticles on Carbon Supports for Oxygen Reduction Reaction

Proton exchange membrane fuel cells are anticipated to play an important role in decarbonizing the global energy system, but the performance of platinum (Pt) catalysts must be improved to make this technology more economical. Studies have identified non-spherical Pt nanoparticles on carbon supports as promising approaches to address this challenge. However, to realize the full benefits of these strategies, the catalyst synthesis procedures must be successfully simplified and scaled up, and the catalyst must perform well in half and full-cell tests. In this study, a surfactant-free one-pot method is developed to synthesize non-spherical Pt nanoparticles on Ketjen Black carbon, which is either non-treated (Pt/KB), acid-treated (Pt/KB-O), or nitrogen-doped (Pt/KB-N). The catalysts are synthesized in both small and large batches to determine the effect of scaling up the synthesis procedure. The nitrogen-doped carbon support shows a nearly identical morphological structure with uniform distribution of non-spherical Pt nanoparticles for both small and large batches’ synthesis compared with non-treated and acid-treated carbon samples. The comparative oxygen reduction reaction (ORR) activity shows that the Pt/KB-N prepared in small and large batches has better ORR activity, which is likely caused by uniformly distributed non-spherical Pt nanoparticles on the nitrogen-doped carbon support. All three catalysts show similar ORR durability, testing from 0.5–1.0 V, while Pt/KB-O displays slightly better durability from 1.0–1.5 V for carbon corrosion. These results will help inform the implementation of shape-controlled Pt catalysts on modified carbon supports in large scale.

Nanocomposite colloids prepared by the Ouzo effect

HypothesisThe organization of nanoparticles within nanocomposite colloids can imbue added functionality to these suprastructures. We hypothesize that the arrangement of nanoparticles in nanocomposite colloids can be systematically controlled by inducing co-precipitation of oil and a hydrophilic polymer in the presence of nanoparticles with a range of wetting properties. This process will produce oil core/polymer shell nanocapsules with nanoparticles strategically positioned within the suprastructures. ExperimentsCoprecipitation of oil and polymer in the presence of nanoparticles is performed in glass capillary microfluidics. Silica nanoparticles of varying surface properties and morphology are used to investigate the relationship between nanoparticle wetting properties and nanocolloid morphology. The features of the nanocomposites formed are investigated using electron microscopy, sessile drop, and zeta potential measurements. FindingsWhen spherical nanoparticles with wetting properties ranging from hydrophilic to hydrophobic are used, the nanocomposite morphologies formed range from nanoparticles partially engulfed in the polymer shell to nanoparticles embedded in the oil core of the nanocapsule. The number of nanoparticles introduced in the nanocomposite is adjusted by changing their concentration in the precursor solution. The structure of nanocolloids formed with non-spherical or hollow silica nanoparticles depends on their wetting properties.

Analysis of spiral plate heat exchanger used to cool vegetable oil with nanofluid consisting of water and non-spherical boehmite alumina nanoparticles

The objective is to use dimensionless analysis through the thermal efficiency method to determine the thermohydraulic performance of a spiral plate heat exchanger (SPHE) used to cool sunflower oil. The coolant consists of water as a base fluid and non-spherical Boehmite Alumina nanoparticles with a defined volume fraction. The concept of thermal efficiency for heat exchangers is used to determine the main quantities used in the analysis. Graphical results are presented for the number of thermal units (NTU), thermal efficiency, thermal effectiveness, hot fluid outlet temperature, thermal and viscous irreversibilities, and Bejan number. The analyzed heat exchanger provides excellent thermal performance for refrigerants consisting of water and non-spherical nanoparticles in platelets or cylindrical, with a volume fraction equal to 12%. Viscous dissipation significantly increases concerning the dissipation associated with pure water, but the cost-benefit is within reason for the proposed objective, within the flow rate under analysis.

Theoretical analysis using thermal efficiency concept in straight micro channel printed circuit heat exchanger

The objective is to analyze the thermal and hydraulic performance in a Micro Channel Straight Printed Circuit Heat Exchanger. Counterflow and parallel flow configurations were analyzed for water cooling using ethylene glycol-based fluid and platelet-shaped non-spherical Boehmite alumina nanoparticles. The work presents results from applying a dimensionless theory that uses the concepts of thermal efficiency of heat exchangers and quantities associated with the second law of thermodynamics. Thermal efficiency, thermal effectiveness, thermal and viscous irreversibilities, thermodynamic Bejan number, and outlet water temperatures are presented in graph form. The data obtained allow us to conclude that the heat exchanger can work in a range of water and refrigerant flow rates below the design parameters. With the inclusion of nanoparticles with a volume fraction equal to 5.0%, the flow rates of the refrigerant fluid can be significantly reduced. The analysis performed shows that the use of nanoparticles improves the operational cost-benefit of the heat exchanger with a significant reduction in the hot water outlet temperature.