Nanoparticle Radius Research Articles

Computational Modeling of Light Scattering in Polymer Nanoparticles for Optical Characterization

The scattering of light by polymeric nanoparticles is a crucial phenomenon in various applications, ranging from nanomedicine to nanophononics. This study introduces a theoretical framework for differentiating between absorption and scattering spectra in light interactions with these nanoparticles. Characteristic spectral data of nanoparticles synthesized via the reprecipitationmethod and suspended in an aqueous medium analyzed under electromagnetic radiation. These nanoparticles exhibit two primary optical phenomena: absorption and scattering. To fully understand their optical response, it is essential to separate these phenomena. This study established a relationship between wavelength variation, nanoparticle size, and radiation loss due to scatteringin an aqueous medium. Additionally, we calculated extinction efficiency and extinction factors as functions of wavelength, taking into account variations in nanoparticle radii and refractive indices.

Selenium nanoparticles stabilized with chitosan for fortifying dairy products

Relevance. One solution to the problem of selenium deficiency is the enrichment of socially important food products, in particular dairy products, with bioavailable forms of selenium. Such forms include selenium nanoparticles. The aim of the work is to develop a dairy product enriched with selenium nanoparticles stabilized with chitosan.Methods. According to dynamic light scattering spectroscopy, a sample of selenium nanoparticles stabilized with chitosan has a monomodal size distribution with an average hydrodynamic particle radius of 25 nm.Results. Quantum chemical modeling of selenium nanoparticles stabilized by chitosan has revealed that the most energetically favorable interaction is the interaction of the surface of selenium nanoparticles with the hydroxo group attached to the C3 glucosamine residue of chitosan. A study was conducted of the influence of technological parameters on the stability of selenium nanoparticles stabilized with chitosan. It was found that increasing the exposure time leads to an increase in the average hydrodynamic radius of selenium nanoparticles stabilized by chitosan. In the case of pH, an inverse relationship is observed: particles with the largest average hydrodynamic radius are found in samples with an acidic environment (pH ˂ 5). As part of a study of the influence of technological parameters on the stability of selenium nanoparticles stabilized by chitosan, it was found that selenium nanoparticles stabilized by chitosan can be used as a source of selenium for food products that have a neutral pH, but can be subjected to heat treatment at temperatures above 70 °C in for 5–15 minutes, in particular pasteurized milk. A study of pasteurized milk fortified with selenium nanoparticles stabilized by chitosan showed that there were no significant changes in titratable acidity, surface tension and pH of milk, as well as the average hydrodynamic radius of casein micelles after milk fortification. The value of antioxidant activity increases by 0.88% — from 6.50 to 7.38%.

Dynamics of nanoparticle radius and inter-particle spacing on the nanofluid flow over an extending sheet with Cattaneo–Christov heat flux and inclined magnetic field impacts

Dynamics of nanoparticle radius and inter-particle spacing on the nanofluid flow over an extending sheet with Cattaneo–Christov heat flux and inclined magnetic field impacts

Neutron and X-ray Scattering Characterization of Silica Nanoparticle-Stabilized Polymer Hybrid Latex Particles.

A robust route to produce poly(methyl methacrylate) (pMMA) hybrid latex particles (radius ∼250 nm) that are selectively "armored" with silica nanoparticles (radius 12.5 nm) through addition of vinyltriethoxysilane was previously shown ( J. Colloid Interface Sci. 2018, 528, 289-300).Depending on synthesis conditions, the extent of nanoparticle attachment could be varied; however, the mechanism behind this attachment during latex growth remained unclear. The dual population of particles present (silica + polymer) means that particle sizing by dynamic light scattering is ambiguous. Furthermore, the low glass transition temperature (Tg) of polymers such as poly(butyl acrylate) (pBA) typically used in film-forming applications for decorative coatings (i.e., paints) means that the hybrid latex particles are too "soft" for robust analysis through atomic force microscopy (AFM) and scanning electron microscopy (SEM). Here, we show that small- and ultrasmall-angle neutron scattering (SANS and USANS), along with complementary data from small-angle X-ray scattering (SAXS), reveals that these armored hybrid latex particles adopt a raspberry-type configuration, supporting their core-shell structure. The number of nanoparticles present on the surface of the hybrid latex can be adjusted by addition of one of a diverse range of alkyl- or perfluoroalkyl-silanes to alter silica nanoparticle hydrophobicity, and quantified through analysis of scattering data. The approach therefore provides a novel, nonperturbative, and in situ method of quantifying nanoparticle attachment to polymer latex particles.

The mechanism of the influence of ultrasound on the nucleation and growth of A2B6 nanoparticles in a colloidal solution

The mechanism of the influence of ultrasound on the nucleation and growth of A2B6 nanoparticles in a colloidal solution was investigated. The proposed theory is based on an increase in the temperature of the colloidal solution and the diffusion coefficient of the monomer under the influence of ultrasonic cavitation. It was established that ultrasound leads to a decrease in the critical radius of colloidal nanoparticles. And when the radius of nanoparticles exceeds this critical value, their growth is observed. The dependence of the growth rate of CdSe nanoparticles on their radius at different temperatures and intensities of ultrasound was researched. It is shown that at the beginning of nanocrystal growth, an increase in intensity of ultrasound leads to an increase in the growth rate, followed by a sharp decrease. This makes it possible to synthesize colloidal quantum dots that are more uniform in size with the help of ultrasonic treatment.

Size-dependent melting and freezing and thermal expansion of Pb nanoparticles in lead-borate glass

We investigated the thermal behavior of Pb nanocrystals and Pb nanodroplets embedded in lead-borate glass by small-angle X-ray scattering (SAXS). Analyzing the SAXS intensities recorded in situ during the heating and cooling processes we determined the dependence on the radius of the melting and freezing temperatures of Pb nanoparticles embedded in the glass. Modeled SAXS intensity functions yielded several parameters associated with the theoretical functions characterizing the relationships between nanoparticle radius and melting and freezing temperatures. The temperature-dependent SAXS intensity profiles were further employed to determine the thermal expansion coefficients of Pb nanocrystals and nanodroplets within the glass matrix. Our findings reveal that the coefficient of thermal expansion for solid Pb nanocrystals exceeds that of bulk Pb crystals, underscoring distinctive thermal behavior at the nanoscale. Conversely, the coefficient of thermal expansion for liquid Pb nanodroplets is notably lower than that observed for bulk liquid Pb.

Dynamics of non-Newtonian methanol conveying aluminium alloy over a rotating disc: consideration of variable nanoparticle radius and inter-particle spacing

The advancement of non-Newtonian nanofluid innovation is a crucial area of research for physicists, mathematicians, manufacturers, and materials scientists. In engineering and industries, the fluid velocity caused by rotating device and nanofluid has a lot of applications such as refrigerators, chips, heat ex-changers, hybrid mechanical motors, food development, and so on. Due to the tremendous usage of the non-Newtonian nanofluid, the originality of the current study is to explore the influence of nanoparticle radii and inter-particle spacing effects on the flow characteristics of Casson methanol-based aluminium alloy (AA7072) nanofluid through a rotating disc with Joule heating and magnetic dipole. The present problem is modeled in the form of partial differential equations (PDEs), and these PDEs are converted into ordinary differential equations with the help of suitable similarity transformations. The analytical solution to the current modeled problem has been obtained by using the homotopy analysis method (HAM) and numerical solutions are obtained by employing Runge–Kutta–Fehlberg method along with shooting technique. The main purpose of the present research work is to analyze the behavior of the velocity and temperature of the nanofluid for small and large radius of the aluminium alloy (AA7072) nanoparticles and inter-particle spacing. The radial and tangential velocities are enhanced due to rising ferro-hydrodynamic interaction parameter and the skin friction force for radial and tangential directions are enhanced 10.51% and 2.16% when h = 0.5. Also, the heat transfer rate is reduced 18.71% and 16.70% when h = 0.5% and R p = 1.5. In fact, the present results are compared with the published results and they met good agreement.

A PCF Sensor Design Using Biocompatible PDMS for Biosensing.

A novel photonic crystal fiber (PCF) sensor for refractive index detection based on polydimethylsiloxane (PDMS) is presented in this research, as well as designs for single-channel and dual-channel structures for this PDMS-PCF sensor. The proposed structures can be used to develop sensors with biocompatible polymers. The performance of the single-channel PDMS-PCF sensor was studied, and it was found that adjusting parameters such as pore diameter, lattice constant, distance between the D-shaped structure and the fiber core, and the radius of gold nanoparticles can optimize the sensor's performance. The findings indicate that the detection range of the single-channel photonic crystal is 1.21-1.27. The maximum wavelength sensitivity is 10,000 nm/RIU with a resolution of 1×10-5 RIU, which is gained when the refractive index is set to 1.27. Based on the results of the single-channel PCF, a dual-channel PDMS-PCF sensor is designed. The refractive index detection range of the proposed sensor is 1.2-1.28. The proposed sensor has a maximum wavelength sensitivity of 13,000 nm/RIU and a maximum resolution of 7.69×10-6 RIU at a refractive index of 1.28. The designed PDMS-PCF holds tremendous potential for applications in the analysis and detection of substances in the human body in the future.

Ferromagnetic and ohmic effects on nanofluid flow via permeability rotative disk: significant interparticle radial and nanoparticle radius

The significance of interparticle spacing and nanoparticle radius for the case of single-phase nanofluid flow has often been neglected. Tremendous applications of this phenomenon can be witnessed in different fields, especially in electron microscopes, heat exchange processes, and many others. This research highlights this vital aspect of Ohmic heating in nanofluid flow over a spinning disk. To ensure the novelty, a ferromagnetic nanoparticle (Manganese ferrite) has been incorporated to examine interparticle spacing and particle radius to explore the features of heat transfer. The ferromagnetic nanofluids are vital in carriers for drug delivery systems, in cancer treatment, design of systems for hyperthermia therapy, in microfluidic devices used for chemical synthesis, etc. The quantiles of dimensional equations are converted into dimensionless ones by adopting similarity transformations and to solve highly coupled nonlinear equations numerically, built-in bvp5c MATLAB tool is utilized. The effect of a few revealed factors, the velocity and temperature distributions, are examined via visualization. Furthermore, streamlined plots are also visualized. The outcomes produced showed excellent agreement with those made in the literature in the same direction by assuming some exceptional cases on different gradients. Further, the outstanding results are reported as; the permeability of the surface produces the suction velocity, and the enhanced suction velocity attenuates the fluid velocity in either of the case of pure and nanofluid. The increase in thermal radiation boosts up the heat transfer rate whereas the augmentation in the Eckert number retards it significantly.

General model of nonradiative excitation energy migration on a spherical nanoparticle with attached chromophores

Theory of multistep excitation energy migration within the set of chemically identical chromophores distributed on the surface of a spherical nanoparticle is presented. The Green function solution to the master equation is expanded as a diagrammatic series. Topological reduction of the series leads to the expression for emission anisotropy decay. The solution obtained behaves very well over the whole time range and it remains accurate even for a high number of the attached chromophores. Emission anisotropy decay depends strongly not only on the number of fluorophores linked to the spherical nanoparticle but also on the ratio of critical radius to spherical nanoparticle radius, which may be crucial for optimal design of antenna-like fluorescent nanostructures. The results for mean squared excitation displacement are provided as well. Excellent quantitative agreement between the theoretical model and Monte–Carlo simulation results was found. The current model shows clear advantage over previously elaborated approach based on the Padé approximant.

Practical method for studying the dispersion behavior of TiC nanoparticles in molten Mg

The dispersion behavior of TiC nanoparticles in molten Mg was investigated by using molecular dynamics simulations based on Li's theoretical model of nanoparticle capture. First, the contact angles between molten Mg and the TiC substrate were calculated over a temperature range of 973–1173 K, and the error was within 10% of the experimental values. The calculated contact angles and Li's theory, confirmed that the dispersion behavior of TiC nanoparticles in molten Mg can be of three types. Subsequently, the effects of the nanoparticle radius and temperature on the dispersion behavior of TiC nanoparticles in molten Mg were studied. The results showed that TiC nanoparticles having a radius of less than 55.8 nm can be uniformly dispersed in molten Mg at 973 K. For TiC nanoparticles having a mean particle radius of 60 nm, the temperature must exceed 1045 K to achieve self-dispersion of the nanoparticles in the Mg melt. This study presents a practical computational technique for the preparation of Mg matrix nanocomposites.

Force analysis and distribution evolution of Fe3O4 nanoparticles in magnetic fluids

The effective utilization of magnetic nanoparticles in ferromagnetic fluids relies on their distribution and properties, which can be influenced by their arrangement at both micro and macro scales. In this paper, we present a dynamic model to analyze the motion and forces of nanoparticles in magnetic fluids, aiming to describe their distribution evolution under magnetic and flow fields. Finite element simulations using COMSOL software are employed, and a dimensionless ordering coefficient is proposed to quantitatively evaluate the status of nanoparticle distribution. The results indicate that reducing fluid viscosity, increasing magnetic field strength, and increasing magnetic particle radius can facilitate the attainment of an optimal ordered state for nanoparticles in magnetic fluids. However, prolonged exposure to a magnetic field can lead to particle agglomeration, hindering the effective manipulation of nanoparticles. To mitigate rapid agglomeration, we employ an intermittent magnetic field exposure strategy during the curing process of a magnetic slurry consisting of PVDF, DMF, and Fe3O4 nanoparticles. The tests reveal that with increasing magnetic field exposure time, the increase rate of the ordering coefficient initially progresses slowly, then gradually accelerates, and eventually reaches equilibrium. This approach successfully addresses the rapid agglomeration of magnetic particles observed in the simulation results. Consequently, precise control over the nanoparticle radius, magnetic field strength, and carrier fluid viscosity allows for meticulous regulation of the ordered distribution state of magnetic particles. This breakthrough has significant potential in expanding the application and research opportunities of magnetic materials.

Silicon nanoparticles stuck graphene from graphite: Simulations of formation, deformation and lubrication

The study first simulates formation of the graphene-stuck silicon nanoparticles from the silicon nanoparticle embedded into the annealed graphite. Covering graphene on nanoparticle can be more conveniently by using graphite instead of graphene. Graphene and silicon of the obtained nanoparticles show the tightly bonding situation to each other. In the annealing cases of 500, 1000 and 1500 K, the annealing at the higher temperature provides the stronger bond. The study then investigates their deformation and lubrication. The nanoparticles show the high stability under experiencing the pressure up to 3 GPa. As used as solid lubricants in contact with the diamond slab at 0.5–3 GPa, they provide the friction coefficients of 0.00022–0.00649, which strongly depend on the nanoparticle size. The nanoparticles provide the better mechanical and lubrication properties than the corresponding bare silicon nanoparticles. Thus, the study provides the method to cover graphene on nanoparticle from graphite and the obtained nanoparticles well experience the pressure and have the high lubricity. In order to avoid the damage to the silicon nanoparticle and graphite and increase the bond between them, the hole on graphite should have its radius larger than (or close to) the silicon nanoparticle radius plus the stable adsorption distance. The stability and lubricity are more advanced with increasing the nanoparticle size; therefore, experimental methods may be used to design such particles of large sizes for these behaviors. Friction dependent on the roughness is also investigated.

A comparative analysis of spherically and cylindrically shaped nanoparticles containing nanofluid flows over a permeable rotating disk affected by nanoparticles radius and nanolayer

The aim of this paper is to present a comparative analysis of spherically and cylindrically shaped nanoparticles immersed separately in a graphene oxide/water nanofluid mixture over a rotating disk influenced by Hall current. The disk’s surface is permeable with suction/injection impact. In order to reveal the thermal integrity of the flow, the effect of nanoparticle diameter and the liquid–solid interfacial layer at the molecular level is also introduced. Estimates of thermal conductivity, interfacial layer thickness and the radius of both spherical and cylindrical particles are taken from experimental studies and utilized to investigate the thermal behavior of the flows. The Tiwari–Das model for nanofluid flow is considered that incorporates the thermal radiative impact in the energy equation. The equations obeying boundary layer theory are resolved to ordinary differential equations using a transformation, and further numerically computed with the bvp4c scheme. The velocities and the temperature profiles are graphically demonstrated versus the dimensionless parameters. Quantities of physical interest such as surface heat flux and surface drag coefficient are tabulated numerically. The results show that the surface drag is larger for nanofluids having cylindrical particles than for nanofluids containing spherical particles. Is also found that the heat transfer rate is greater for nanofluids containing cylindrical particles than spherical particles at higher interfacial layer thicknesses.

SYNTHESIS AND CHARACTERIZATION OF SELENIUM NANOPARTICLES STABILIZED WITH DIDECYLDIMETHYLAMMONIUM CHLORIDE

As part of this work, a synthesis procedure was developed and the characteristic of selenium nanoparticles stabilized with didecyldimethylammonium chloride (DDAC) was carried out. Nanoparticles were obtained by chemical reduction in an aqueous medium. Selenous acid was used as a selenium-containing precursor, ascorbic acid was used as a reducing agent, and didecyldimethylammonium chloride was used as a stabilizer. To determine the optimal parameters for the synthesis of selenium nanoparticles stabilized with didecyldimethylammonium chloride, a multifactorial experiment was carried out. The input parameters were the concentration of selenous acid, the concentration of didecyldimethylammonium chloride (DDAC) and the concentration of ascorbic acid. The average hydrodynamic radius of selenium particles, which was determined by the method of dynamic light scattering, was considered as an output parameter. The optimal parameters for the synthesis of selenium nanoparticles (R from 15 to 25 nm) have been established: reducing agent concentration – from 1.076 mol/l to 2.118 mol/l, stabilizer concentration – from 0.006 mol/l to 0.085 mol/l, precursor concentration – from 0.004 mol /l to 0.236 mol/l. At the next stage of research, the effect of solution pH on the average hydrodynamic radius of selenium nanoparticles was determined. It was shown that in the pH range from 1.81 to 2.21, the average hydrodynamic radius of selenium nanoparticles does not change significantly, which indicates the aggregative stability of selenium nanoparticles in this range. In the pH range from 2.21 to 4.56, there is a sharp increase in the average hydrodynamic radius from 21 to 497 nm. At pH ˃ 7.96, coagulation of selenium particles is observed.

Detection of Envelope Glycoprotein Domain III (ED III) Based on Surface-Enhanced Raman Scattering for Dengue Diagnosis

Surface-enhanced Raman Scattering (SERS) based ED III protein detection has been conducted as a dengue virus diagnosis. ED III is one of the ectodomains of the envelope located along the surface of the dengue virus and acts as a receptor for the virus with its host cells. The SERS substrate used in this study is On-Spec-lite SERS by NECTEC and fabricated as a grating surface coated with gold. The imaging results from SEM show that the average radius of gold nanoparticles on OnSpec-lite SERS is 60 nm. On the grating-Au surface, the grating period is 588 nm with 50 nm thickness of gold thin film. OnSpec-lite SERS has a more significant increase in Raman intensity than the grating-Au surface when detecting ED III using Raman spectroscopy. The amino acids in the ED III Raman bands are Glycine, Alanine, Histidine, and Proline. The highest intensity Raman band that appears is 850 cm-1. Based on the research done in dengue virus detection, ED III has a typical Raman peak of 850 cm-1 which is the Raman band of Glycine and Alanine with CCN symmetry stretching vibration mode (𝑣(CCN)). This distinctive characteristic of ED III can be used as a diagnostic to detect dengue virus.

Endocytosis efficiency and targeting ability by the cooperation of nanoparticles.

Cooperative wrapping of nanoparticles (NPs) with small sizes is an important pathway for the uptake of NPs by cell membranes. However, the cooperative wrapping efficiency and the effects of NPs' rigidity remain ambiguous. With the aid of computer simulations, we show that the complete wrapping mechanism of cooperative endocytosis is that the aggregation of NPs leads to greater wrapping forces than the single NP case, which triggers the increase of the wrapping degree and in turn further increases the wrapping forces until they are finally fully taken up. The effects of the NP size, initial distance, interaction strength, arrangement and stiffness on cooperative endocytosis were systematically studied. The cooperative wrapping efficiency increases as the NP radius increases. Hexagonal close packed NPs have the highest internalization efficiency. When the interactions are strong, softer NPs exhibit higher endocytosis efficiency. We further propose two strategies by combining NPs with different wrapping properties for targeting applications. By combining two NPs decorated with different types of ligands, the combination NPs can only be fully endocytosed by the cell membrane with two cognate types of receptors and adhere to the normal cell membrane with only one type of receptor. We also design composite NPs using a large NP non-covalently decorated with several small NPs. By harnessing the competition between the ligand-receptor interactions and the excluded volume interactions between the small NPs and the lipid membrane, the composite NPs have targeting ability towards the cancer cell membrane. The design concept of combining NPs with different wrapping properties for drug targeting applications may be very promising in biomedicine.

Approaches through effects of Hall current, nanoparticle radius, inter-particle spacing and multiple slips on the suspension of copper-water nanofluid with gyrotactic microorganisms

In this comprehensive study, the dynamic behavior of a copper-water nanofluid infused with gyrotactic microorganisms, focusing on the effects of Hall current, nanoparticle radius, inter-particle spacing, and multiple slip mechanisms is investigated. Through advanced numerical simulations and rigorous analysis, intricate relationships between the parameters and the suspension’s characteristics are uncovered. Comparison of the present results show a good agreement with the published results. The research findings unveil the potential for fine-tuning transport processes, manipulating thermal properties, and controlling dispersion and aggregation in nanofluids. These insights hold promise for a wide array of applications, from enhancing heat exchangers and cooling systems to pioneering biomedical devices utilizing gyrotactic microorganisms for targeted drug delivery and sensing. This study not only advances the fundamental understanding of nanofluid dynamics but also paves the way for innovative developments across various scientific and engineering domains.

Detection of DNA using gold nanoparticle-coated silica nanoparticles

We report a sensitive lateral flow assay (LFA) in which the assay colour change originated from reporter labels constructed from silica spheres (radius = 450 nm) coated with approximately 3.9 × 103 gold nanoparticles (radius = 8.5 nm). These reporter labels were modified with DNA and deposited in the conjugation area of an LFA device assembled on wax-patterned Fusion 5 paper. Test and control zones of the device were pre-loaded with capture probe formed by avidin-coated mesoporous silica nanoparticles attached with biotin-tagged DNA sequences. Proof-of-concept was demonstrated by the detection of a partial sequence of the actin gene of Colletotrichum truncatum. The DNA target could be detected with an LOD of 46 pM, which was 5 times lower than a comparative assay using gold nanoparticles alone. The assay showed good selectivity against the Colletotrichum species C. scovillei and C. gloeosporioides, as well as against DNA from the fungal genera Aspergillus niger and Alternaria alternata. There was negligible change in sensor response over storage for one month at room temperature. The LFA was used to detect PCR products following extraction from mycelium.

Strong Coupling Dynamics of a Quantum Emitter near a Topological Insulator Nanoparticle.

We study the spontaneous emission dynamics of a quantum emitter near a topological insulator Bi2Se3 spherical nanoparticle. Using the electromagnetic Green's tensor method, we find exceptional Purcell factors of the quantum emitter up to 1010 at distances between the emitter and the nanoparticle as large as half the nanoparticle's radius in the terahertz regime. We study the spontaneous emission evolution of a quantum emitter for various transition frequencies in the terahertz and various vacuum decay rates. For short vacuum decay times, we observe non-Markovian spontaneous emission dynamics, which correspond perfectly to values of well-established measures of non-Markovianity and possibly indicate considerable dynamical quantum speedup. The dynamics turn progressively Markovian as the vacuum decay times increase, while in this regime, the non-Markovianity measures are nullified, and the quantum speedup vanishes. For the shortest vacuum decay times, we find that the population remains trapped in the emitter, which indicates that a hybrid bound state between the quantum emitter and the continuum of electromagnetic modes as affected by the nanoparticle has been formed. This work demonstrates that a Bi2Se3 spherical nanoparticle can be a nanoscale platform for strong light-matter coupling.