Silica Nanoparticles In Water Research Articles

High-Throughput Silica Nanoparticle Detection for Quality Control of Complex Early Life Nutrition Food Matrices.

The addition of nanomaterials to improve product properties has become a matter of course for many commodities: e.g., detergents, cosmetics, and food products. While this practice improves product characteristics, the increasing exposure and potential impact of nanomaterials (<100 nm) raise concerns regarding both the human body and the environment. Special attention should be taken for vulnerable individuals such as those who are ill, elder, or newborns. But detecting and quantifying nanoparticles in complex food matrices like early life nutrition (ELN) poses a significant challenge due to the presence of additional particles, emulsion-droplets, or micelles. There is a pressing demand for standardized protocols for nanoparticle quantification and the specification of "nanoparticle-free" formulations. To address this, silica nanoparticles (SiNPs), commonly used as anticaking agents (AA) in processed food, were employed as a model system to establish characterization methods with different levels of accuracy and sensitivity versus speed, sample handling, and automatization. Different acid treatments were applied for sample digestion, followed by size exclusion chromatography. Morphology, size, and number of NPs were measured by transmission electron microscopy, and the amount of Si was determined by microwave plasma atomic emission spectrometry. This successfully enabled distinguishing SiNP content in ELN food formulations with 2-4% AA from AA-free formulations and sorting SiNPs with diameters of 20, 50, and 80 nm. Moreover, the study revealed the significant influence of the ELN matrix on sample preparation, separation, and characterization steps, necessitating method adaptations compared to the reference (SiNP in water). In the future, we expect these methods to be implemented in standard quality control of formulation processes, which demand high-throughput analysis and automated evaluation.

Efficient end-to-end simulation of time-dependent coherent X-ray scattering experiments.

Physical optics simulations for beamlines and experiments allow users to test experiment feasibility and optimize beamline settings ahead of beam time in order to optimize valuable beam time at synchrotron light sources like NSLS-II. Further, such simulations also help to develop and test experimental data processing methods and software in advance. The Synchrotron Radiation Workshop (SRW) software package supports such complex simulations. We demonstrate how recent developments in SRW significantly improve the efficiency of physical optics simulations, such as end-to-end simulations of time-dependent X-ray photon correlation spectroscopy experiments with partially coherent undulator radiation (UR). The molecular dynamics simulation code LAMMPS was chosen to model the sample: a solution of silica nanoparticles in water at room temperature. Real-space distributions of nanoparticles produced by LAMMPS were imported into SRW and used to simulate scattering patterns of partially coherent hard X-ray UR from such a sample at the detector. The partially coherent UR illuminating the sample can be represented by a set of orthogonal coherent modes obtained by simulation of emission and propagation of this radiation through the coherent hard X-ray (CHX) scattering beamline followed by a coherent-mode decomposition. GPU acceleration is added for several key functions of SRW used in propagation from sample to detector, further improving the speed of the calculations. The accuracy of this simulation is benchmarked by comparison with experimental data.

Computational investigation of the effects of polymer grafting on the effective interaction between silica nanoparticles in water.

Understanding and control of the effective interaction between nanoscale building blocks (colloids or nanoparticles) dispersed in a solvent is an important prerequisite for the development of bottom-up design strategies for soft functional materials. Here, we have employed all-atom molecular dynamics simulations to investigate the impact of polymer grafting on the solvent-mediated effective interaction between the silica nanoparticles (Si-NPs) in water, and in turn, on its bulk structural and thermodynamic properties. We found that the nature of the short grafting polymers [characterized by their interaction with water (hydrophobicity or hydrophilicity) and molecular weight] has a profound effect on the range and strength of the effective interaction between the Si-NPs. The hydrophobic polymer [such as polyethylene (PE)]-grafting of Si-NP gives rise to a more attractive interaction between the Si-NPs compared to the hydrophilic polymer [such as polyethylene glycol (PEG)] and non-grafted cases. This study further provides fundamental insights into the molecular origin of the observed behavior of the effective pair interactions between the grafted Si-NPs. For PE-grafted Si-NPs, the confined water (water inside the cavity formed by a pair of Si-NPs) undergoes a partial dewetting transition on approaching below a critical inter-particle separation leading to a stronger attractive interaction. Furthermore, we report that the effective attraction between the PE-grafted Si-NPs can be reliably controlled by changing the grafting PE density. We have also investigated the bulk structural and thermodynamic behavior of the coarse-grained Si-NP system where the particles interact via effective interaction in the absence of water. We believe that the insights gained from this work are important prerequisites for formulating rational bottom-up design strategies for functional materials where nano- (or, colloidal) particles are the building blocks.

Hematological, immuno-antioxidant disruptions, and genes down-regulation induced by Aeromonas veronii challenge in Clarias gariepinus: The ameliorative role of silica nanoparticles.

Aeromonas veronii is a pathogenic bacterium associated with various diseases in aquaculture. However, few studies address the antibacterial activity using nanoparticles (NPs). Hence, the current study is innovative to evaluate the antibacterial efficacy of silica nanoparticles (SiNPs) against A. veronii infection in-vitro with a trial for treatment in-vivo. Primarily, we assessed the in-vitro antibacterial activity against A. veronii. Further, we investigated the hematological profile, immune-antioxidant response, and gene expression of African catfish (Clarias gariepinus) in response to SiNPs exposure and the A. veronii challenge. Fish (N = 120; weight: 90 ± 6.19 g) were distributed into four groups (30 fish/group) for a ten-days-treatment trial. The first (control) and second (SiNPs) groups were treated with 0 mg/L and 20 mg/L SiNPs in water, respectively. The third (A. veronii) and fourth (SiNPs+A. veronii) groups were treated with 0 mg/L and 20 mg/L SiNPs in water, respectively, and infected with A. veronii (1.5×107 CFU/mL). Results demonstrated that SiNPs displayed an in-vitro antibacterial activity against A. veronii with a 21 mm inhibitory zone. A. veronii infection caused a high mortality rate (56.67%) and substantial reductions in hematological indices and immune indicators [nitric oxide (NO) and immunoglobulin M (IgM)]. Additionally, marked decline in the level of antioxidants [superoxide dismutase (SOD), catalase (CAT), and reduced glutathione content (GSH)] as well as down-regulation in the immune-related genes [interleukins (IL-1β and IL-8) and tumor necrosis factor-alpha (TNF-α)] and antioxidant-related genes [SOD1, glutathione peroxidase (GPx), and glutathione-S-transferase (GST)] were the consequences of A. veronii infection. Surprisingly, treatment of A. veronii-infected fish with SiNPs lessened the mortality rate, enhanced the blood picture, modulated the immune-antioxidant parameters, and resulted in gene up-regulation. Overall, this study encompasses the significant role of SiNPs, a new versatile tool for combating hematological, immuno-antioxidant alterations, and gene down-regulation induced by A. veronii infection and sustainable aquaculture production.

Single and multi-pulse based X-ray photon correlation spectroscopy.

The ability of pulsed nature of synchrotron radiation opens up the possibility of studying microsecond dynamics in complex materials via speckle-based techniques. Here, we present the study of measuring the dynamics of a colloidal system by combining single and multiple X-ray pulses of a storage ring. In addition, we apply speckle correlation techniques at various pulse patterns to collect correlation functions from nanoseconds to milliseconds. The obtained sample dynamics from all correlation techniques at different pulse patterns are in very good agreement with the expected dynamics of Brownian motions of silica nanoparticles in water. Our study will pave the way for future pulsed X-ray investigations at various synchrotron X-ray sources using individual X-ray pulse patterns.

Ratiometric hypoxia detection by bright organic room temperature phosphorescence of uniformed silica nanoparticles in water

AbstractOrganic room temperature phosphorescence (RTP) in water has attracted much attention recently for its potential biological applications. However, it remains a formidable challenge to achieve efficient RTP from pure organic compounds in aqueous phase due to the dramatic deactivation of triplet excited states in water and the poor water dispersibility of large organic particles/crystals. Represented herein is covalent incorporation of a pure organic monochromophore in silica nanoparticles (SiNPs) featuring fluorescence and bright phosphorescence in aqueous solution. The covalent bonding of organic phosphors in polysiloxane framework was found to show excellent water dispersibility, at the same time suppress the non‐radiative deactivation of triplet excited states especially from water, thus leading to high phosphorescence quantum yields (up to 22%) and long lifetimes (up to 3.5 ms) in aqueous phase. More strikingly, oxygen‐insensitive fluorescence as internal reference and oxygen‐dependent phosphorescence as oxygen indicator from the organic chromophore in the porous SiNPs realized ratiometric hypoxia detection with ultrasensitivity (KSV = 449.3 bar−1).

Influence of Surface Charge on the Functional Properties of Silica Nanoparticles and Cellular Toxicity

The effect of silica nanoparticles with a different surface charge on the cell viability of Caco-2 and RAW 264.7 cell lines was studied. Silica nanoparticles with narrow size distribution were prepared by Stobers method. These silica nanoparticles surface charge was varied from highly positive to highly negative, were single functionalized by APTES and multi functionalized by cysteine for amine and carboxyl groups. All other properties of the nanoparticles were kept constant. The unfunctionalized nanoparticles were used as control. Fourier Transform Infrared spectroscopy (FTIR) confirmed the presence of amine and carboxyl groups present on the surface of silica nanoparticles. The zeta potential measurements confirmed the successful modification of surface charge of silica nanoparticles in water. SEM images showed that the negatively charged, positively charged, and unfunctionalized nanoparticles with similar size and shape. MTT assay results indicated that the toxicity of SiO2 was cell type-dependent. CaCo-2 cells were highly resistant to nanoparticle treatment whereas RAW 264.7 (macrophages) predominantly charge dependent. The difference in toxicity could be attributed to the difference in the physiological function of each cell line. Among the three kinds of nanoparticles (negative, positive, and untreated), positively charged nanoparticles showed higher toxicity, which might be due to the attractive interaction between the negatively charged cell membrane and positively charged SiO2 nanoparticles.

Mechanistic study on silica nanoparticles-assisted guar gum polymer flooding for enhanced oil recovery in sandstone reservoirs

Nanoparticles-assisted polymer flooding has attracted the attention of researchers for its enhanced rheological properties and stability of the chemical slugs. The present work deals with the rheological properties of guar gum with and without silica nanoparticles in the temperature range from 25 °C to 75 °C. It is found that the viscosity of guar gum solution increases significantly with increasing concentration of silica nanoparticles. Imbibition experiments were performed with waxy crude oil-saturated sandstone cores using 2000 ppm brine, 4000 ppm guar gum solution, 0.2 wt% silica nanoparticles in distilled water, and 4000 ppm guar gum containing 0.2 wt% silica nanoparticles as test fluids for understanding the mechanism of wettability alteration in the presence of silica nanoparticles and guar gum. Mixture of 0.2 wt% silica nanoparticles and 4000 ppm guar gum shows higher oil recovery (∼36 % original oil-in-place) compared to other test solutions in imbibition experiments. Contact angles between crude oil and sandstone rock were measured in presence of 2000 ppm brine, 0.025 wt% silica nanoparticles in water, and guar gum (2000 ppm)-silica nanoparticles (0.025 wt%) mixture. Guar gum containing silica nanoparticles are effective in changing the contact angle towards water-wet state (Contact angle ∼115°) from oil-wet state (contact angle ∼72°). No significant phase change is observed during the phase behavior experiment except for light emulsion formation. Finally, core flooding experiments were conducted with guar gum, silica nanoparticles solution, and mixture of silica nanoparticles and guar gum for additional oil recovery to verify the effectiveness of the chemical slugs. Results showed that the addition of silica nanoparticles to guar gum solution improves the effectiveness of guar gum polymer by recovering 44.3 % of original oil-in-place. A comparative study was also conducted to show the performance of silica nanoparticles-assisted guar gum solution for additional oil recovery. Most of the research works have focused on the application of silica nanoparticles-induced polyacrylamide and xanthan gum chemical slugs in enhanced oil recovery. However, laboratory study based on the application of silica nanoparticles-induced guar gum solution in additional oil recovery adds some interesting findings to the literature compared to the existing information.

Scattering of GHz coherent acoustic phonons by silica nanoparticles in water probed with the time-domain Brillouin spectroscopy

Coherent acoustic phonons detected by time-domain Brillouin spectroscopy (TDBS) in a liquid medium are strongly attenuated when silica nanoparticles sediment in the liquid. The decrease in the optical signal is due to the strong acoustic scattering by silica nanoparticles whose size matches the wavelength of phonons at the frequency of the Brillouin shift. The control of the acoustic wave-front with nanoparticles thus strongly reduces the undesired Brillouin response of the liquid medium. This is demonstrated with a thin transparent film in water, mimicking a biological sample in a nutritive serum. While strong Brillouin scattering in the particle-free liquid hampers the measurement in the film, we show that TDBS can however be performed in a film of a thickness less than the optical wavelength when scatterers sediment in the liquid.

Oxidation/reduction control of the VO2 nanoparticle in the nano-confined space of the hollow silica nanoparticle

Vanadium dioxide (VO2) exhibits a good thermochromic property which can be used in a smart window. To improve its poor visible transparency, immobilization of the VO2 nanoparticles on the silica shell of hollow nanoparticles was proposed. In addition to improving the particle dispersibility of the VO2 and to reducing stress from repeated phase transitions of the VO2 between monoclinic and tetragonal, the hollow interior can reduce any undesirable oxidation of the VO2 to V3O7, V2O5, etc., along with the thermal decomposition behavior of organic compounds around the vanadium atom. The hollow silica nanoparticles with micropores (less than 2 nm) were prepared by a previously-reported template method. Through the pores, the vanadium precursor with a chelate ligand solution penetrates into the hollow interior. The vanadium intermediate formed by adding water was then captured by the silica shell. During the crystallization process under a nitrogen atmosphere, 10–30 nm of VO2 particles were immobilized on the silica shell with a high dispersibility by optimization of the vanadium precursor concentration, and ratios of vanadium/water and vanadium/hollow silica nanoparticles. The VO2/hollow silica nanoparticles in water exhibited a higher visible transparency than that of the commercial VO2. In addition, their thermochromic property in the infrared region was close to that of the commercial one.

Experimental and theoretical investigation of CO2 mass transfer enhancement of silica nanoparticles in water

Nanofluids have novel characteristics that make them potentially useful for different applications. Realizing modest mass transfer enhancement in conventional nanofluids, in this study, mass-transfer of carbon dioxide in pure water and water-based nanofluids dispersed with silica nanoparticles at different initial pressures up to 15 MPa and at temperatures of 35 °C and 45 °C was investigated. Deionized water and two nanofluids at different concentrations with volume of 150 cm3 were used for this purpose. CO2 was brought in contact with each solution in a pressure-volume-temperature (PVT) cell with no mixer. Additionally, carbon dioxide diffusion coefficients at different pressures were estimated based on Fick's law. The obtained results demonstrated that water/silica nanofluid with 0.5 wt% and 0.1 wt% increased the carbon dioxide diffusion coefficient up to 39.2% and 11.9% compared to that in pure distilled water, respectively. Moreover, it was observed that the measured diffusion coefficient of carbon dioxide in water increased with temperature rise from 35 °C to 45 °C at constant pressure. However, it could be seen that, the diffusion coefficient decreased with pressure at constant temperature. It was concluded that among the enhancement mechanisms of nanoparticles, (i.e. grazing effect and Brownian motion), Brownian motion would play the main role in mass transfer enhancement.

Adsorption of benzyldimethyldodecylammonium bromide on silica nanoparticles in water

Adsorption of the cationic surfactant benzyldimethyldodecylammonium bromide (BDDABr) on silica nanoparticles with ~ 12 and 31 nm in size (denoted as S-SiO2 and L-SiO2, respectively) is investigated at various solid dosages (Cs, 10–40 g/L), pH (3–10), and temperature (T, 298–308 K). No Cs-effect is observed in the adsorption. However, it is interestingly found that, besides pH and T, the size of the silica particles has an obvious influence on the adsorption. The adsorption may show the Langmuir type (L-type), S-type, and “double plateau” type (LS-type) isotherms, depending on silica particle sizes and pH. Increasing pH may lead to a change in the isotherm types from S-type through LS-type to L-type. The S-type and LS-type isotherms can be adequately described using the one-step and two-step surface micellization models, respectively. The affinity of the S-SiO2 toward BDDABr is lower than that of the L-SiO2, consistent with the dissociation tendency of their surface hydroxyl groups.

Investigation of Spontaneous Imbibition by Using a Surfactant-Free Active Silica Water-Based Nanofluid for Enhanced Oil Recovery

Interests in using nanofluids for enhanced oil recovery (EOR) applications has been increasing. Herein, a novel surfactant-free water-based nanofluid for EOR was constructed using active silica nanoparticles. Active silica nanoparticles were synthesized via condensation of hexanedioic acid with the −OH group of silica. Water-based nanofluid was obtained by transforming carboxyl into carboxylate on the surface of active silica nanoparticles in water. The particle size of the active silica nanoparticles in water ranged from 10 to 20 nm. The interfacial activity of the nanoparticles was endowed through the shape change of the active silica nanoparticle surface groups to minimize their interface energy. The morphology and surface components of the active silica nanoparticles were characterized by transmission electron microscopy and Fourier transform infrared spectroscopy. The interfacial activity of the active silica nanoparticles was proved through interfacial tension and interfacial dilational modulus meas...

Synthesis of 4,4′-(arylmethylene)bis(3-carboxymethyl-1-phenyl-1H-pyrazol-5-ol)s using ionic liquid attached to colloidal silica nanoparticles in water

An efficient synthesis of 10 4,4′-(arylmethylene)bis(3-carboxymethyl-1-phenyl-1 H-pyrazol-5-ol)s, eight of which are novel, was achieved by a one-pot three-component reaction of phenylhydrazine, dimethyl acetylenedicarboxylate and an arylaldehyde using bis(1(3-methoxysilylpropyl)-3-methyl-imidazolium) copper tetrachloride tethered to colloidal silica nanoparticles as catalyst under microwave irradiation in water. The advantages of the present process are atom economy, high catalytic activity, excellent yields, short reaction times and utilisation of microwave heating as a clean procedure. The catalyst was recyclable.

Hydrophobization of Silica Nanoparticles in Water: Nanostructure and Response to Drying Stress.

We report on the impact of surface hydrophobization on the structure of aqueous silica dispersions and how this structure resists drying stress. Hydrophilic silica particles were hydrophobized directly in water using a range of organosilane precursors, with a precise control of the grafting density. The resulting nanostructure was precisely analyzed by a combination of small-angle X-ray scattering (SAXS) and cryo-microscopy (cryo-TEM). Then, the dispersion was progressively concentrated by drying, and the evolution of the nanostructures as a function of the grafting density was followed by SAXS. At the fundamental level, because the hydrophobic character of the silica surfaces could be varied continuously through a precise control of the grafting density, we were able to observe how the hydrophobic interactions change particles interactions and aggregates structures. Practically, this opened a new route to tailor the final structure, the residual porosity, and the damp-proof properties of the fully dried silica. For example, regardless of the nature of the hydrophobic precursor, a grafting density of 1 grafter per nm2 optimized the interparticle interactions in solution in view to maximize the residual porosity in the dried material (0.9 cm3/g) and reduced the water uptake to less than 4% in weight compared to the typical value of 13% for hydrophilic particles (at T = 25 °C and relative humidity = 80%).

Molecular Dynamics Simulation for Surface and Transport Properties of Fluorinated Silica Nanoparticles in Water or Decane: Application to Gas Recovery Enhancement

Determination of surface and transport properties of nanoparticles (NPs) is essential for a variety of applications in enhanced oil and gas recoveries. In this paper, the impact of the surface chemistry of silica NPs on their hydro- and oleo-phobic properties as well as their transport properties are investigated in water or decane using molecular dynamics simulation. Trifluoromethyl or pentafluoroethyl groups as water and oil repellents are placed on the NPs. It is found that the density and residence time of liquid molecules around the NPs are modulated considerably with the existence of the functional groups on the NPs’ surfaces. Also, much larger density fluctuations for liquids close to the surface of the NPs are observed when the number of the groups on the NPs increases, indicating increased hydrophobicity. In addition, the diffusion coefficient of the NPs in either water or decane increases with increasing the number or length of the fluorocarbon chains, demonstrating non-Brownian behavior for the NPs. The surface chemistry imparts a considerable contribution on the diffusion coefficient of the NPs. Finally, potential of mean force calculations are undertaken. It is observed that the free energy of adsorption of the NPs on a mineral surface is more favorable than that of the aggregation of the NPs, which suggests the NPs adsorb preferably on the mineral surface.

Synthesis of 4,4´-(arylmethylene)bis(3-carboxymethyl-1-phenyl-1H-pyrazol-5-ol)s using an ionic liquid attached to colloidal silica nanoparticles in water_esi

Synthesis of 4,4´-(arylmethylene)bis(3-carboxymethyl-1-phenyl-1H-pyrazol-5-ol)s using an ionic liquid attached to colloidal silica nanoparticles in water_esi

Rice Husk Ash-Derived Silica Nanofluids: Synthesis and Stability Study.

Nanofluids, colloidal suspensions consisting of base fluids and nanoparticles, are a new generation of engineering working fluids. Nanofluids have shown great potential in heat/mass transfer applications. However, their practical applications are limited by the high production cost and low stability. In this study, a low-cost agricultural waste, rice husk ash (RHA), was used as a silicon source to the synthesis of silica nanofluids. First, silica nanoparticles with an average size of 47 nm were synthesized. Next, by dispersing the silica nanoparticles in water with ultrasonic vibration, silica nanofluids were formed. The results indicated that the dispersibility and stability of nanofluids were highly dependent on sonication time and power, dispersant types and concentrations, as well as pH; an optimal experiment condition could result in the highest stability of silica nanofluid. After 7 days storage, the nanofluid showed no sedimentation, unchanged particle size, and zeta potential. The results of this study demonstrated that there is a great potential for the use of RHA as a low-cost renewable resource for the production of stable silica nanofluids. Graphical Rice husk ash was used as a low-cost renewable resource for production of silica nanofluids with high stability.

Anisotropic Shape Changes of Silica Nanoparticles Induced in Liquid with Scanning Transmission Electron Microscopy.

Liquid-phase transmission electron microscopy (TEM) is used for in-situ imaging of nanoscale processes taking place in liquid, such as the evolution of nanoparticles during synthesis or structural changes of nanomaterials in liquid environment. Here, it is shown that the focused electron beam of scanning TEM (STEM) brings about the dissolution of silica nanoparticles in water by a gradual reduction of their sizes, and that silica redeposites at the sides of the nanoparticles in the scanning direction of the electron beam, such that elongated nanoparticles are formed. Nanoparticles with an elongation in a different direction are obtained simply by changing the scan direction. Material is expelled from the center of the nanoparticles at higher electron dose, leading to the formation of doughnut-shaped objects. Nanoparticles assembled in an aggregate gradually fuse, and the electron beam exposed section of the aggregate reduces in size and is elongated. Under TEM conditions with a stationary electron beam, the nanoparticles dissolve but do not elongate. The observed phenomena are important to consider when conducting liquid-phase STEM experiments on silica-based materials and may find future application for controlled anisotropic manipulation of the size and the shape of nanoparticles in liquid.

Ambient-curable superhydrophobic fabric coating prepared by water-based non-fluorinated formulation

Superhydrophobic coatings can be applied to fabrics to provide water repellent and easy clean properties. Hence, there is an intensive commercial demand for environmentally friendly, cost effective, and scalable technologies of superhydrophobic fabric coatings. Herein, we report a water-based and non-fluorinated sol–gel formulation for ambient curable superhydrophobic fabric coatings. The coating material was prepared by surface modification of silica nanoparticles with (3-aminopropyl) triethoxysilane (APTES) and hexadecyltrimethoxysilane (HDTMS). In this formulation, APTES stabilizes the dispersion of silica nanoparticles in water, and also enhances the adhesion of modified nanoparticles on fabric surfaces. The silica nanoparticles and HDTMS respectively contribute to the superhydrophobic performance by enhancing the surface roughness and reducing the surface free energy. The aqueous coating solution can be applied to fabric surfaces by one-step spraying process, and the coating is ambient curable at room temperature. This facilitates scale-up applications with simplified treatment processes. Coatings have been applied on various fabrics including polyester, cotton and mixed cotton/polyester. Superhydrophobic properties have been verified for coated cotton and cotton/polyester. Static water contact angles above 150° with hysteresis around 10° for 2μL water droplets have been achieved. The durability of the coating was tested by washing/drying cycles and abrasion cycles.