Elliptical Nanoparticles Research Articles

Development of elliptic core-shell nanoparticles with fluorinated surfactants for 19F MRI.

Perfluorocarbon-encapsulated silica nanoparticles possess attractive features such as biological inertness and favorable colloidal properties for bioimaging with fluorine magnetic resonance imaging (19F MRI). Herein, a series of elliptic shaped silica nanoparticles with perfluorocarbon liquid perfluoro-15-crown-5 ether as core (PFCE@SiO2) were synthesized using fluorinated surfactants N-(perfluorononylmethyl)-N,N,N-trimethylammonium chloride (C10-TAC) and N-(perfluoroheptylmethyl)-N,N,N-trimethylammonium chloride (C8-TAC). The nanoparticles are characterized to obtain elliptic core-shell structures. PFCE@SiO2 showed strong 19F NMR signals of the encapsulated PFCE, indicating the potential as a highly sensitive 19F MRI probe. These elliptic PFCE@SiO2 nanoparticles provide a new option of 19F MRI probe with a morphology different from conventional nanospheres.

In silico and in vitro investigation of the role of Asparagus racemosus lead compound Shatavarin IV and associated silver nanoparticles

Antibiotic-resistant microbes are a global threat, necessitating the need for new antibacterials. Bioactive compounds obtained from Asparagus racemosus and silver nanoparticles synthesized from it were tested for antibacterial activity. The nanoparticles exhibited a UV absorbance peak at 415nm. SEM image revealed elliptical nanoparticles from 32.6 nm to 78.6 nm while the FTIR study of aromatic amine N-H and C-O stretching indicates the stability of the silver nanoparticle. Zeta potential and XRD tests confirmed the presence of silver nanoparticles in the root extract under stable conditions. Methanolic root extract and silver nanoparticles were found to be very effective against Bacillus subtilis (20mm), Salmonella typhimurium (20mm), Escherichia coli (20mm), Klebsiella pneumoniae (18mm), Staphylococcus aureus (17mm) and Pseudomonas aeruginosa (15mm) in comparison to ampicillin. AutoDock Tools 1.5.7 was used to perform molecular docking of Shatavarin IV against target proteins involved in breast cancer (PDB ID: 3O96), bacterial infections (PDB ID: 2ZCO), viral infections angiotensin (PDB ID: 4APH) and inflammation (PDB ID: 7PHS). The respective best docking scores are -18.66, -18.07 -14.57 and -15.84 Kcal/Mol respectively. Sarsasapogenin and Kaempferol also showed favorable docking scores with specific target proteins. Shatavarin IV is found to target amino acid(s) and the standard drugs of each category such as Remdesivir for viral, Diclofenac for inflammation, Tamoxifen for cancer and Plazomicin for bacterial infections. This study reveals that Asparagus racemosus bioactive compound Shatavarin IV is a suitable lead compound for the treatment of cancer, viral, bacterial infections and inflammatory conditions.

Enhancement of second-harmonic field and nonlinear dispersion via a composite of elliptical cylinder nanoparticles

This work is a numerical description of the interaction between optical pulses and plasmonic oscillations in nanoparticle composites. We present a numerical demonstration of enhanced second-harmonic generation (SHG) in plasmonic nanoparticles caused by collective resonances. The SHG and dispersion associated with core–shell nanoparticles are studied based on the Drude model. The shape of nanoparticles and the SHG enhancement factor are closely intertwined. It is shown that shape effects can be applied to enhance the SHG from plasmonic nanoshells and also the absorption and dispersion of a nonlinear dielectric function of the recommended structure are evaluated. At metal–dielectric interfaces, it has been demonstrated that the association of plasmonic nanostructures with nonlinear dielectric systems provides useful platforms for boosting frequency conversion processes. In addition, examining the effect of various geometrical parameters on the slow-light factor reveals a reduction in the slow-light spectrum, laying the groundwork for optical pulse storage and retrieval in optical communication applications in the future. This core–shell nanoparticle structure is attractive for a wide range of applications, including optical communication devices, due to the mentioned unique optical properties.

Morphology, structural properties, impedance spectroscopy, AC conductivity, and dielectric relaxation properties of boron subphthalocyanine chloride amorphous films

Through the use of thermal evaporation, boron subphthalocyanine chloride (B-subPcCl) films were created. X-ray diffraction pattern reveals that the B-subPcCl is characterized by amorphous nature, while atomic force microscopy images show that the surface topography of B-subPcCl is composed of homogeneous elliptical nanoparticles with grain size and roughness of 90 and 70 nm, respectively. The impedance measurements of B-subPcCl film at the temperature ranges of 298–398 K were studied and were fitted to the analog of a Rp//CPE equivalent electrical circuit model. The relationship between AC conductivity and frequency at different temperatures demonstrated that the correlated barrier hopping (CBH) model dominates the transport charge mechanism between the closest sites. The DC conductivity parameters were calculated, and they were compared with the relative organic compounds. The dependence of the dielectric constant (ε 1) and the dielectric loss (ε 1) on frequency showed a significant decrease of ε 1 and ε 2 values as the frequency increased. At different temperatures, the variation of the imaginary modulus (M 2) of B-subPcCl with frequency showed a relaxation process with an activation energy of 0.066 eV.

Fe(III)-coordination-driven fabrication of self-supplying oxygen and charge-convertible nanoplatform for enhanced photodynamic therapy of tumor

The hypoxic microenvironment of tumors severely limits the effect of oxygen-dependent photodynamic therapy. Coordination-induced self-assemblies fabricate from metal ions and polymer ligands present potential advantages in catalytic reaction-mediated O2 production, high drug loading efficiency and system stability, as well as enhanced tumor targeting. In this work, self-supplying O2 and pH-induced charge-convertible nanoplatforms (termed as Sp-NPs) were fabricated through coordination-induced self-assembly of meso-tetrakis(4-carboxyphenyl)porphyrin (TCPP) modified and carboxylated pH sensitive polymeric ligand, poly (isobutylene-alt-maleic anhydride-conjugated-methoxy-poly(ethyleneglycol)-conjugated-imidazole-conjugated-ethylenediamine-grafted-TCPP) [PIMA-mPEG-API-EDA-TCPP], and ferric ions (Fe3+) for enhanced photodynamic therapy of cancer. The Sp-NPs displays uniform elliptic nanoparticles with size of around 90 nm and excellent stability in a variety of biomimetic biological media. Moreover, Sp-NPs bearing charge-convertible feature can flip the surface charge from negative to positive in the weakly acidic tumor extracellular condition, resulting in enhanced the cellular internalization. After entering more acidity tumor cells by endocytosis, Sp-NPs can be detonated to activate photosensitizers and release Fe3+ that can catalyze endogenous hydrogen peroxide (H2O2) to produce O2, leading to a prominent enhancement of fluorescence imaging and reactive oxygen species (ROS) generation in the tumor. Importantly, this nanoplatform exhibits a more potent cancer cell killing efficiency with good biosafety compared to that were treated with free TCPP. Therefore, incorporation self-oxygenation-boosted ROS strategy and pH-induced charge-convertible mechanism into this platform offered a great promise for cancer therapy.

Core-Coordinated Elliptic Polymer Nanoparticles Loading Copper(II) and Chlorambucil for Cooperative Chemodynamic/Chemotherapy.

Chemodynamic therapy (CDT) reflects an innovative cancer treatment modality; however, to enhance its relatively low therapeutic efficiency, rational combination with extra therapeutic modes is highly appreciated. Here, core-coordinated amphiphilic, elliptic polymer nanoparticles (Cu/CBL-POEGEA NPs) are constructed via the self-assembly of a glutathione (GSH)-responsive polymer-drug conjugate, bearing side-chain acylthiourea (ATU) motifs which behave as ligands capable of coordinating Cu(II), such a design is featured by combined chemo (CT)/CDT with dual GSH depletion collectively triggered by the Cu(II) reduction reaction and disulfide bond breakage. To do so, an amphiphilic random copolymer poly[oligo(ethylene glycol)ethyl acrylate-co-thiourea] [P(OEGEA-co-ATU)] is synthesized, followed by conjugation of chlorambucil (CBL) to ATU motifs linked via a disulfide bond, thus yielding the targeted P[OEGEA-co-(ATU-g-CBL)]. In such a system, hydrophilic POEGEA serves as the biocompatible section and ATU motifs coordinate Cu(II), resulting in core-coordinated elliptic Cu/CBL-POEGEA NPs. Benefitting from the GSH-induced reduction reaction, Cu(II) is converted into Cu(I) and subsequently react with endogenous H2O2 to create •OH, realizing GSH-depletion-promoted CDT. Additionally, the disulfide bond endows GSH-responsive CBL release and provokes further GSH decline, finally realizing combined CDT/CT toward enhancing antitumor outcomes, and in vitro as well as in vivo studies indeed reveal remarkable efficacy. Such a system can provide valuable advantages to create novel nanomedicines toward cascade antitumor therapy.

Adaptive Pattern and Motion Control of Magnetic Microrobotic Swarms

Reconfigurable microrobotic swarms and controllable active matter systems have drawn extensive attention recently. Developing effective actuation strategies and control schemes that enable embodied intelligence of microscopic swarms are both major challenges. In this work, we realize the generation of an elliptical paramagnetic nanoparticle swarm (EPNS) with enhanced dexterity for adaptive locomotion, and subsequently a fuzzy control strategy is developed for automatically tuning pattern deformation, orientation, and position of the swarm. By adjusting the input field, the aspect ratio of the EPNS will change accordingly, and we demonstrate its adaptive navigation through curved and narrowed channel by performing pattern reconfigurations. Moreover, using the proposed control strategy, precise matches can be reached between the controlled swarms and the desired patterns. Finally, to show the high compatibility of the control strategy, we employ ribbon-like colloidal swarms driven by oscillating magnetic field, and the results also validate the effectiveness of the strategy.

Absorption of light by ultra-thin silicon films covered with a monolayer of elliptical metal nanoparticles

The absorption of Si films covered with an array of elliptical metal nanoparticles (NPs) of identical orientation and shape is investigated theoretically. We consider silicon films with thickness in the range of 80–200 nm. The symmetry axis of the NPs is taken perpendicular to the surface of silicon surface and their short axis has a radius of 10 nm in the plane of the Si film. A 10-nm-thick SiO2 layer separates the submonolayer NP coverage from the silicon film. The spectral properties of the considered hybrid system are studied in terms of its effective susceptibility. Specifically, the dependence of light absorption by the NPs covering the ultrathin Si film on their morphology and material composition is established. For chromium and silver NPs, the appearance of collective absorption modes in the hybrid structures is predicted.

Effects of nanoparticle size and shape in clathrin-mediated endocytosis

Nanoparticles have been extensively adopted to deliver therapeutic drug molecules to cells through clathrin-mediated endocytosis (CME). The size and shape of nanoparticles are important factors in the design of a drug delivery system. Both the clathrin coat and actin force induce the bending of the membrane during CME. However, due to the complex coupled effects of size, shape, and surface properties, nanoparticle shape effects are difficult to elucidate through experiments. Herein, we establish a comprehensive framework considering both the actin force and the dynamic assembly of the clathrin coat. To explore the effect of the nanoparticle size and shape on CME, we construct a clathrin coat growth model with actin force feedback. The clathrin coat growth model, nanoparticle internalization efficiency, and transportation efficiency are discussed through numerical analysis. The transportation efficiency is defined by the energy cost of the cell absorbing unit dose target drug. Numerical results illustrate that the proposed clathrin coat growth model is consistent with the actual physiological process, especially for CME considering receptor-mediated effects. The elliptical nanoparticle exhibits higher internalization and transportation efficiencies. A larger nanoparticle has lower internalization efficiency but higher transportation efficiency. Our results demonstrate that the internalization and transportation efficiencies of nanoparticles with an intermediate aspect ratio are higher than those with low or high aspect ratios. Our model provides insight into the intrinsic mechanism of CME and useful guidance for the practical design of the size and shape of nanoparticles for biopharmaceutical research.

Metamaterial perfect absorber using elliptical nanoparticles in a multilayer metasurface structure with polarization independence.

A metamaterial perfect absorber (MPA) using elliptical silver nanoparticles is proposed and investigated to provide 100% absorption for both transverse electric and transverse magnetic polarizations with a wide range of incident angles and polarization independence. Metamaterial absorbers with narrow absorption performance over a wide frequency range are significantly desired in sensing applications. Incident angle insensitivity and polarization angle independence are key features of MPAs. The output characteristics are examined using the three-dimensional finite difference time domain method. The effective medium theory and transmission line theory are applied to investigate the simulation results. Here, the 100% absorption occurs at resonance wavelength of λres = 2290 nm, and maximum sensitivity and figure of merit become 200 nm/RIU and 720 RIU-1, respectively. The results show that an absorption spectrum is insensitive to the incident angle of 0°-60°. The proposed device can be used as a high-performance biosensor and photodetector.

Optical pulling force upon elliptical cylinder nanoparticles in the infrared range

In order to investigate optical pulling forces exerted by an electromagnetic field, we develop a theoretical framework based on electrostatic theory and Maxwell stress tensor. We apply this framework to calculate the optical pulling force on elliptical cylinder nanoparticles with gain medium, which we put forward as an alternative material platform to optimize and tailor tractor beams. Moreover, the optical force can be further enhanced and flexibly tuned by controlling the physical and geometrical parameters of the proposed structure. The pulling and pushing force could be switched by changing the location of the hemisphere witch has complex susceptibility in the structure. Altogether, our theoretical findings can pave the way to increase the use of this structure for further applications based on active nanoparticles

Resonant dynamics of the magnetization of uniaxial nanoparticle

Analysis of equilibrium conditions was carried out and resonant precessional dynamics of magnetization of a single-domain magnetically uniaxial ellipsoidal particle. Considered the case when magnetic field is along the easy magnetization axis. the easy magnetization axis is directed parallel to the axis of symmetry of the ellipsoid and transverse to pumping by a weak high-frequency field. Features of the behavior of the magnetization were discovered. It has been revealed that the magnetization has features of resonant behavior: large resonant precession angles with amplitude 0.5M0, elliptical deviations of the precession trajectory from circular at a negative value of the effective anisotropy field, and the presence of a frequency region with nonlinear precession for an oblate nanoparticle. Keywords: ferromagnetic resonance, elliptical nanoparticles, transverse bias field, effective anisotropy, bistability, easy magnetization axis, nonlinear effects.

Studying the surface morphology, linear and nonlinear optical properties of manganese (III) phthalocyanine chloride/FTO films

Scientific review of laser protective materials is currently primarily focused on improving linear transmittance and developing the optical limiting ability. Due to its unique large π electronic conjugated structure, phthalocyanine has become a successful optical limiting material. Thin films of manganese (III) phthalocyanine chloride (MnPcCl) were formed on FTO substrates using traditional thermal deposition techniques. The X-ray diffraction demonstrated that there is an amorphous structure for MnPcCl films. AFM's surface morphology shows that the MnPcCl film is homogeneous and formed by spherical and elliptical nanoparticles. The thickness dependences of both linear and nonlinear optical properties of MnPcCl films were also investigated via UV–Vis-IR measurements. The absorption coefficient examination indicated that the films were distinguished by an indirect transition with two energy gaps. The power of the He–Ne (633 nm) and green (533 nm) lasers were used to estimate optical limiting behavior. The MnPcCl film deposited on the FTO revealed a high optical laser limitation that could be acceptable for different nonlinear optical devices, like laser filters.

Dispersion and light loss reduction in photonic crystal fibers using nanoparticles optimization

The dispersion of optical fiber can damage optical information, thus limiting data transfer speed and transmission distances. In this paper, a new structure is presented by applying metal nanoparticles for photonic crystal fibers (PCF) so that minimizes dispersion and optical loss. The proposed PCF uses circular and elliptical shape nanoparticles, then their number and location is optimized by PSO algorithm. Applying metal nanoparticles in PCF substrate causes increases the conductivity and increases light excitation, which increases light absorption and decreasing dispersion. By changing the shape, location, and type of nanoparticles, a structure with minimal dispersion and light loss is provided. In this paper, we applied three elliptical and three circular nanoparticles using the PSO results. The hexagonal PCF is designed with air grids and radius of 5.8 µm, and then circular and elliptical gold particles are used instead of air holes. Simulation results show that the loss is 7e−4 dB/cm at wavelengths between 1.3 and 1.65 µm and the dispersion is obtained less than 0.3 ps/nm/km. The light loss and dispersion are reduced compared to other related studies.

Modeling and control of probe distance, substrate and probe of AFM using AFSMC in the presence of disturbances

Controlling the motion and its associated parameters is among the most important topics in the field of manipulation and displacement of nanoparticles. Accordingly, this article considers the control of nanomanipulation process in three general areas: 1) the distance between probe and surface, 2) the substrate, and 3) the probe of atomic force microscope (AFM). This study benefits from the adaptive fuzzy sliding-mode (AFSMC) control technique. Moreover, elliptical and cubic geometries are utilized. The results for the control of probe distance from substrate show that the system attains the acceptable value of 50 nm after 0.8 s. The desired output for the derivative of distance is fulfilled after 0.07 s. The results for the control of substrate in the horizontal direction show that for different values of λ, the desired value is obtained in different manners. The comparison between the results of this study and previous researches using the sliding mode control and proportional-integral-derivative method indicates the accuracy of the proposed method. The simulation results of the control of atomic force microscope probe for elliptical and cubic geometries demonstrate that the deviation of probe for these two geometries reaches its desired value in less than 0.04 s. However, the main difference is observed when investigating the position of atomic force microscope probe; the elliptical nanoparticle with an average radius of 75 nm has a delay of around 0.02 s for reaching the desired value compared with the cubic nanoparticle with a side length of 75 nm. In addition, the overshoot of elliptical geometry is more than that of cubic case. Finally, motion tracking along a specific path is simulated. In addition, trajectory assessment is realized on an actual experimental surface.

Optimum path planning of elliptic and cubic nanoparticles using one and dual probe atomic force microscopes

In this article, optimum path planning of elliptic and cubic nanoparticles by one and dual probe atomic force microscopes is investigated. Four different parameters are considered in the cost function, including area under critical time–force diagram, critical indentation depth, path smoothness and area under force–time diagram of primary impact of nanoparticles. Also three different obstacles are added to process to make it more real. The layout of obstacles are various in each geometry. Since surfaces are rough, the effects of roughness (surface and particle) are considered in process. Genetic algorithm method has been used for path planning.

Novel cobalt\u2013carbon@silica adsorbent

Recently, carbon nanostructures are of high importance due to their unique characteristics and interesting applications. Pyrolysis of anthracene with cobalt complex Co(2,2′-bipy)Cl2(1), where (2,2′-bipy) is 2,2′-bipyridine, in the absence and presence of silica gave in high yield cobalt-carbon nanocomposite CoCNC (2) and CoCNC@SiO2(3) at 600 °C and 850 °C, respectively. They were characterized using SEM, TEM, PXRD, Raman and XPS. (3) and (2) contain core–shell cobalt(0)/cobalt oxide-graphite with or without silica support. PXRD indicates that (2) contains crystalline hexagonal α-Co and cubic β-Co phases while (3) contains only cubic β-Co phase and silica. The structure of (2) is 3D hierarchical carbon architecture wrapping spherical and elliptical cobalt nanoparticles. (3) consists of graphitized structures around cobalt nanoparticles embedded in the silica matrix. XPS reveals that the nanocomposites contain oxygen functional groups that enhance uptake of cationic dyes. CoCNC@SiO2(3) has higher capacity and thus is better adsorbent of Basic Violet 3 than CoCNC (2). The Langmuir adsorption capacity of (3) is 19.4 mg g−1 while column capacity is 12.55 mg g−1 at 25 °C. Freundlich isotherm and pseudo-second-order kinetic models fit well the adsorption data. Thermodynamics indicate that adsorption(3) is exothermic. Column regeneration was tested for three cycles and Yan et al. was found the best kinetic model.

Nanomanipulation of elliptic and cubic nanoparticles with consideration of the impact theories

This article investigates the effect of impact on the dynamic modeling and simulation of cubic and elliptic nanoparticles in the manipulation process based on atomic force microscopy (AFM). First, the dynamic equations prior to the motion are presented. Then, according to these equations, two assumptions are considered for nanoparticles motion. Using the Hertz, JRK, and Jamari theories as well as the approximate impact relation of Hunter, the effects of impact in motion are also taken into consideration. The results indicated that after 3 s and under constant, linear, second-order and sinusoidal forces, the elliptic nanoparticle moves, respectively, less than 0.08 µm, 0.1143 µm, 0.36 µm and 25 nm. In addition, the results of cubic nanoparticles nanomanipulation show that the cubic nanoparticle moves less than 0.08 µm in 3 s under constant force scheme. This type of nanoparticle does not move when acted upon by a linear force along the Z-axis, while it shows a displacement of 0.0117 µm along the Y-axis. After the same 3 s, it moves about 0.37 µm and less than 25 nm under second-order and sinusoidal forces, respectively.

Modeling and simulation of the dynamics, contact mechanics and control of the nanomanipulation of elliptical porous alumina nanoparticles based on atomic force microscopy

Nowadays, AFM-based robots are widely utilized for transporting different nanoparticles. Using this devise as a tool for nanomanipulation, it is possible to specify the exact location of a nanoparticle in micro/nano-scale. In the fields of dynamics, contact mechanics and control of nanomanipulation for atomic force microscopy, accurate investigation and analysis of the motion of nanoparticles and the robustness of the control algorithm are among the most important goals that arise. In fact, one tries to achieve these two goals by applying the appropriate dynamics and control to the system. Moreover, the controlled displacement of nanoparticles and accurate and proper dynamic modeling can greatly help manipulation. Therefore, in the present study, static, dynamic, and contact mechanics models for the nanomanipulation of elliptical porous alumina nanoparticles were developed. Also, sliding and rolling modes were considered for this type of nanoparticles. The dynamic results showed that, for elliptical porous nanoparticles, increasing the porosity coefficient first leads to sliding and increases the difference between the forces required for sliding and rolling. However, for simple elliptical nanoparticles, the particle first rolls and then slides on the surface. In addition, by using contact mechanics equations, the penetration depth between the nanoparticle and the substrate and that between the nanoparticle and the tip were calculated to be approximately 6.2 nm and 1.4 nm, respectively. Subsequently, a sliding mode controller was modeled in order to control the deviation of the probe from the vertical and the displacement in the direction of motion. The results showed that convergence was achieved in less than 0.1s for all porosity coefficients considered.

Experimental study on thermo-hydraulic performance of nanofluids in diverse axial ratio elliptical tubes with a built-in turbulator

Due to the low heat transfer efficiency of common heat exchange systems, an improved heat exchange system was developed. Enhanced tubes (elliptical tubes with a built-in turbulator) instead of a smooth tube were used and TiO2-water nanofluids were substituted for water to intensify the heat transfer. The influences of turbulator (presence or absence), axial ratios of elliptical tubes (Z=1.235, 1.471, 1.706), nanoparticle concentration (ω=0.0 wt%, 0.1 wt%, 0.3 wt%, 0.5 wt%), and Reynolds number (Re=400–12,000) on the flow and heat transfer properties of TiO2-water nanofluids were studied. Thermal and exergy efficiency were used to research the comprehensive thermo-hydraulic characteristics of these heat transfer enhancement technologies. The thermo-hydraulic properties of nanofluids all showed an increasing trend with the growing axial ratio, nanoparticle concentration and Reynolds number. Nanofluids (ω=0.5 wt%) in an elliptical tube (Z=1.706) with a built-in turbulator showed the best thermal performance, which could be increased by 33.8% in comparison with water at best. The thermal efficiency index increased first and then decreased with the Re. Nanofluids in elliptical tubes with a built-in turbulator can clearly promote heat transfer under the identical condition.