Concentration Of Silica Nanoparticles Research Articles

Hydrophilic Silica Nanoparticles in O/W Emulsion: Insights from Molecular Dynamics Simulation

Previous studies have been carried out on the effect of silica nanoparticles (SNPs) on the stability of oil-water emulsions. However, the combining configuration of SNPs and oil droplets at the molecular level and the effect of SNP content on the coalescence behavior of oil droplets cannot be obtained through experiments. In this paper, molecular dynamics (MD) simulation was performed to investigate the adsorption configuration of hydrophilic SNPs in an O/W emulsion system, and the effect of adsorption of SNPs on coalescence of oil droplets. The simulation results showed: (i) SNPs adsorbed on the surface of oil droplets, and excessive SNPs self-aggregated and connected by hydrogen bonds. (ii) Partially hydrophilic asphaltene and resin molecules formed adsorption configurations with SNPs, which changed the distribution of oil droplet components. Furthermore, compared with hydrophobic asphaltene, the hydrophilic asphaltene was easier to combine with SNPs. (iii) SNPs would extend the oil droplet coalescence time, and the π-π stacking structures were formed between asphaltene and asphaltene or resin molecules to enhance the connection between oil droplets during the oil droplet contact process. (iv) Enough SNPs tightly wrapped around the oil droplet, similar to the formation of a rigid film on the surface of an oil droplet, which hindered the contact and coalescence of components between oil droplets.

Fabrication of Porous Carbon-Composite Nanofibers Via Electrospinning and Their Application in Ion Storage System

Nanoporous materials have attracted considerable attention for various potential applications in sensors, optical, magnetic and electronic devices due to their high specific surface area and distinctive physicochemical properties. Particularly, porous carbon-composite materials can be used in the field of catalysis, separation, purification, capture and energy storage/conversion systems. In this work, we prepared highly porous carbon-composite nanofibers with hollow-structures by electrospinning combined with hundreds of nanometers sized silica nanoparticles and 2D MXene flakes and demonstrated the applications in ion storage systems. Firstly, nanoparticles and MXene flakes embedded-polyacrylonitrile(PAN) was electrospun with single and dual nozzles, respectively. In the case of electrospinning via dual nozzle , PAN/Mxene solution and polymethyl methacrylate (PMMA) solution were used as shell and core materials, respectively. After the electrospinning process, the nanofibers were stabilized at 280oC, followed by a carbonization at 800oC for 1h. Selective removal of silica nanoparticles by HF solution after the carbonization and the decomposition of PMMA at 400oC resulted in the well defined hollow-structured carbon-composite nanofibers. The morphologies of the nanofibers depends on the concentration and size of silica nanoparticles and Mxene flakes and the each specific surface area was higher about 6 and 7 times than those of normal carbon nanofibers. Particularly, the carbonization of MXene-embedded nanofibers successfully removed the functional groups on the MXene such as –F and –OH which are known to hinder Li-ion transport. The hollow structured carbon composite nanofibers with tailored surface terminations and the increased specific surface area were utilized as a electrode materials of ion storage systems and showed improved electrochemical performance compared to normal carbon nanofibers or carbon-MXene composite paste. Figure 1

Microfluidics-Assisted Fabrication of Dual Stopband Photonic Microcapsules and Their Applications for Anticounterfeiting.

The assembly of two different kinds of colloidal particle-based photonic structures into an individual micro-object can achieve multifunctionality. In this study, core–shell photonic microcapsules with dual structural colors and photonic stop bands were prepared through a standard microfluidic technique. Photocurable resin suspension of silica nanoparticles and an aqueous suspension of nanogels were used as shell and core parts of microcapsules, respectively. The structural colors of shells and cores can be tuned by adjusting the concentrations of silica nanoparticles and soft nanogels in their corresponding suspensions. The individual microcapsules possess two distinct stop bands when the two suspensions are combined appropriately. Remarkably, the color information of the core part cannot be directly viewed at a macroscopic level (such as visual inspection) but can be detected at a microscopic scale (such as optical microscopy observation). The color information hidden enables the capability for information encryption and has potentially critical applications in anti-counterfeiting, display, and other fields.

Tuning the thermodynamic, optical, and rheological properties of thermoresponsive polymer solutions via silica nanoparticle shape and concentration

HypothesisThe shape and quantity of hydrophilic silica nanoparticles (NPs) can be used to tune the microstructure, rheology, and stability of phase-separating polymer solutions. In thermoresponsive polymer systems, silica nanospheres are well-studied whereas anisotropic NPs have little literature precedent. Here, we hypothesize that NP shape and concentration lower the onset of rheological and turbidimetric transitions of aqueous poly(N-isopropyl acrylamide) (PNIPAM) solutions. ExperimentsDifferential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), turbidimetry, and oscillatory rheology are utilized to examine interactions between NPs, PNIPAM, and water and to track changes in phase separation and rheological properties due to NP concentration and shape. FindingsNP addition reduces phase separation enthalpy due to PNIPAM-NP hydrogen bonding interactions, the degree to which depends on polymer content. While NP addition minorly impacts thermodynamic and optical properties, rheological transitions and associated rheological properties are dramatically altered with increasing temperature, and depend on NP quantity, shape, and polymer molecular weight. Thus NP content and shape can be used to finely tune transition temperatures and mechanical properties for applications in stimuli-responsive materials.

Synthesis and characterization of silica nanoparticles from rice husk and their effects on physiology of rice under salt stress

Silicon (Si) is considered a beneficial element for rice (Oryza sativa L.) The objective of this work was to investigate the effects of Si in the form of nanoparticles on growth and physiology of rice under salt stress. Silica nanoparticles (SNPs) were synthesized from rice husk by sol-gel method. The prepared SNPs powders were agglomerated in semi-spherical nano- sized particles with diameters in the range of 60-135 nm. Three rice cultivars namely ‘Pokkali’, ‘KDML105’ and ‘IR29’ were grown for 30 d in plastic pots, and then divided into four groups i.e., control, SNPs, NaCl and NaCl + SNPs. Foliar spray of 120 mg L-1 SNPs was given to the SNPs and NaCl + SNPs groups for 4 d. After that the plants in NaCl and NaCl + SNPs groups were exposed to 150 mM NaCl for 17 d. The salt-stressed plants suffered significant reductions in biomass, net photosynthesis rate (PN), and maximal quantum efficiency of photosystem II (PSII) photochemistry (Fv/Fm) while three stress indicators (malondialdehyde, hydrogen peroxide [H2O2] and proline) considerably increased. The SNPs mitigated the adverse effects of salt stress by increasing PN (18% to 116% increase) and lowering H2O2 (8% to 31% reduction) in all cultivars, compared with the values under salt stress, while proline was reduced by 7% in ‘KDML105’ and 19% in ‘IR29’. The H2O2 content was regulated by the increased activities of antioxidant enzymes, notably catalase, peroxidase and ascorbate peroxidase. The application method and concentrations of SNPs used for rice plants under stress should be further optimized for the highest benefit of growth and yield in the field conditions.

Stiffness enhancement of magnetorheological foam by structural modification using silica nanoparticles additive

Magnetorheological (MR) foam is a newly developed porous smart material that is able to change its properties continuously, actively, and reversibly in response to controllable external magnetic stimuli. Unfortunately, the stiffness or also known as storage modulus of MR foam is still rather low and insufficient, in the range of below 100 kPa only, due to weak interparticle interaction between CIPs and the foam matrix, which consequently restricts the potential of MR foam to be used in future sensor applications or in other semi-active devices. Therefore, the aim of this research is to enhance the structural and storage modulus of MR foam by adding silica nanoparticles as an additive. Consequently, MR foam samples with different compositions of silica nanoparticles in the range of 0–5 wt% were prepared via an in situ method. The rheological properties were tested under an oscillatory shear mode with the absence and presence of magnetic fields using a rheometer, with the input parameters of strains between 0.001% and 10% and range of magnetic flux density between 0 and 0.73 T for a magnetic field sweep test. The rheological findings show that with the addition of silica nanoparticles, particularly at 4 wt%, have enhanced the storage modulus of MR foam by 260%, which attributed to the highest stiffness from 45 to 162 kPa. Meanwhile, the change of storage modulus under the influence of magnetic fields (0 T–0.73 T) somehow showed small increment, about ∆1 kPa for each concentration of silica nanoparticles in MR foams, due to non-magnetic behavior of silica. The morphological characteristics of MR foams were described by an elemental analysis carried out by a using variable pressure scanning electron microscope (VPSEM) equipped with energy dispersive x-ray spectroscopy (EDX). The micrographs demonstrated large open-cell pores for MR foam, while MR foam with silica nanoparticles exhibited more closed-cell pores, associated with the enhancement of its storage modulus. It indicates that the silica nanoparticles have encouraged well dispersion of the particles in the foam matrix, which improved and strengthened the microstructure of MR foams through formation of silane coupling bonds of silica in the filler-matrix structure. Overall, incorporation of silica nanoparticles as an additive in the MR foam could provide advantage in enhancing the structure and mechanical properties of MR foam, for various future smart devices.

Effects of Chitosan and Silica Nanoparticles Against the Development and Growth of Red Chilli Anthracnose Disease Colletotrichum sp.

<b>Background and Objective:</b> <i>Colletotrichum</i> sp., is a pathogen that causes anthracnose disease that can reduce chilli production. One environmentally for controlling plant disease can be done using chitosan and silica nanotechnology. This study aimed to test the ability of chitosan and silica nanoparticles to inhibit the growth of <i>Colletotrichum</i> sp. and suppress the development of the diseases on chilli seeds. <b>Materials and Methods:</b> This research consisted of the pathogenicity test of chitosan and silica nanoparticles and chilli seed germination inhibition test to control the development of <i>Colletotrichum</i> sp., using a completely randomized design within 10 treatments and 3 replications. <b>Results:</b> The results showed that 100 ppm chitosan nanoparticles inhibited the growth of <i>Colletotrichum</i> sp. and conidia germination with inhibition percentages of 92.20 and 99.4%, respectively. In addition, the development of anthracnose on chilli seed germination has been suppressed by 93% at a 100 ppm concentration of silica nanoparticles. <b>Conclusion:</b> In conclusion, both single or mixed formulations of chitosan and silica nanoparticles were able to inhibit the growth and development of <i>Colletotrichum </i>sp. and increase the chilli seed viability.

Classification of nanofluids solutions based on viscosity values: A comparative study of random forest, logistic model tree, Bayesian network, and support vector machine models

In this paper, we investigated predictive modelling algorithms namely Logistic Model Tree (LMT), Bayesian Network (BN), Random Forest (RF), and Support Vector Machine (SVM) for classification of nanofluid solutions based on viscosity values in the presence of different concentration of salinity, silica nanoparticles, and polyacrylamide solutions. The performance of these classification models was verified through validation and testing data sets. As an initial evaluation, these models were used to classify nanofluid solutions into four classes based on viscosity values. The results obtained in this study can also be useful in establishing comparative analysis with different types of preprocessing methods such as centering, normalization, standardized and firstorder. After comparing the results of the four models of classification with each of preprocessing methods, the result of the nanofluid classification was acceptable. According to the classification results, the firstorder-BN model provided better results than the normalized RF model, and the best result of classification was obtained by LMT for nanofluid solutions. Using LMT, the Mean Absolute Error (MAE) and Root Mean Square Error (RMSE) for all tests with different preprocessing methods were 0.0709 and 0.2594, respectively. The proposed method is rapid to measure the viscosity values of nanofluid solutions in oil industry for polymer flooding in chemical enhanced oil recovery (C-EOR).

Silica Nanoparticle–Induced Reproductive Toxicity in Male Albino Rats via Testicular Apoptosis and Oxidative Stress

Amorphous silica nanoparticles (SiNPs) are being utilized in different fields such as medicine, cosmetics, and foods. However, the causes and mechanisms underlying SiNP testicular damage remain largely unclear. In the present study, we aimed to investigate this issue. Thirty male rats were randomly divided into three groups: control group (n = 10), 500 ppm SiNP–treated group (n = 10), and 1000 ppm SiNP–treated group (n = 10). SiNPs were given orally in drinking water for 30 days. Micronucleus assay was performed on blood RBCs. The concentrations of testicular malondialdehyde (MDA) and glutathione (GSH) and catalase (CAT) activity were measured. Moreover, the histopathological alterations and the expression of apoptotic (caspase-3) and pro-inflammatory and oxidative stress markers (iNOS) in testes and epididymis were analyzed and compared between the three groups. The results showed an increased level of micronucleus frequencies in the 1000 ppm–treated group, as well as increased levels of MDA and decreased activity of CAT and GSH content in testicular tissues in the 1000 ppm–treated group, suggesting DNA damage and oxidative stress mechanisms. Also, there were significant testicular histopathological alterations in this group. Furthermore, 1000-ppm SiNPs could enhance testicular apoptosis, inflammation, and oxidative stress by increasing the expression of apoptotic, pro-inflammatory, and oxidative stress genes including caspase 3 and iNOS in the examined tissue. The lower concentration of SiNPs did not produce any significant biochemical, histopathological, or immunohistochemical alterations whereas 1000-ppm SiNPs resulted in significant testicular changes by exacerbating apoptotic, inflammatory, and oxidative stress–mediated testicular damage.

One-step fabrication of superhydrophobic nanocomposite with superior anticorrosion performance

Superhydrophobic coatings having a self-cleaning ability and anticorrosion performance are desired in many industrial contexts; however, high costs and complex fabrication methods limit their application. In this study, thin anticorrosive superhydrophobic coatings were prepared by a scalable, simple, and inexpensive spraying method to protect AA2024-T3 surfaces. The two-component coatings were designed using fluoropolyurethane and varying concentrations of surface modified silica nanoparticles. Surface characterization was performed using contact angle and contact angle hysteresis measurements, field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectrum (EDS), and atomic force microscopy (AFM) techniques. Corrosion protection, water uptake, and adhesion strength of the coatings were evaluated by electrochemical impedance spectroscopy (EIS) and cross-cut tests, respectively. Increased silica nanoparticle concentrations up to 10 wt% led to increased contact angles from 92° to 167°. The lowest contact angle hysteresis was obtained for the coating containing 4 wt% nanoparticles. FE-SEM images showed that high concentrations of nanoparticles (more than 4 wt%) led to cracks in the coating surface. The best performance of a coating was observed when the coating contained 4 wt% nanosilica particles, resulting in a 164° water contact angle, almost 60 days of surface protection, an impedance value of 2.2 × 109 Ω·cm2, 0.9% water uptake, and marked adhesion strength. The impedance value of the coating with 4 wt% nanosilica particles was about 25× that of the blank sample.

Kinetics of Methane Hydrate Formation in the Presence of Silica Nanoparticles and Cetyltrimethylammonium Bromide

AbstractHydrate technology promoted the development of natural gas industry. Nanoparticles showed a broad prospect for hydrate technology because of their excellent mass and heat transfer characteristics. At an experimental temperature of 275.15 K and pressure of 5 MPa, silica nanoparticles and cetyltrimethylammonium bromide (CTAB) were used to investigate the characteristics (pressure drop, gas storage capacity, and formation rate). The experimental results showed that the higher the concentration of silica nanofluid, the shorter the induction time. Among the four silica nanoparticles concentration (0.1, 0.2, 0.3, and 0.5 wt%) tested in this work, the concentration of 0.3 wt% was optimal for the enhancement of CH4 hydrate formation. In the complex system composed of silica nanoparticles and CTAB, the surface of silica nanoparticles was positively charged by hydrolysis. The cationic active groups ionized by surfactants were aggregated to the surface of the particles under the Coulomb force. Methane molecules were gathered to hydrophobic groups by non‐polar adsorption, which was more conducive to hydrate formation. Compared to silica nanofluid, the total time for hydrate formation decreased by 66.2 %.

Acoustofluidics for simultaneous nanoparticle-based drug loading and exosome encapsulation

Nanocarrier and exosome encapsulation has been found to significantly increase the efficacy of targeted drug delivery while also minimizing unwanted side effects. However, the development of exosome-encapsulated drug nanocarriers is limited by low drug loading efficiencies and/or complex, time-consuming drug loading processes. Herein, we have developed an acoustofluidic device that simultaneously performs both drug loading and exosome encapsulation. By synergistically leveraging the acoustic radiation force, acoustic microstreaming, and shear stresses in a rotating droplet, the concentration, and fusion of exosomes, drugs, and porous silica nanoparticles is achieved. The final product consists of drug-loaded silica nanocarriers that are encased within an exosomal membrane. The drug loading efficiency is significantly improved, with nearly 30% of the free drug (e.g., doxorubicin) molecules loaded into the nanocarriers. Furthermore, this acoustofluidic drug loading system circumvents the need for complex chemical modification, allowing drug loading and encapsulation to be completed within a matter of minutes. These exosome-encapsulated nanocarriers exhibit excellent efficiency in intracellular transport and are capable of significantly inhibiting tumor cell proliferation. By utilizing physical forces to rapidly generate hybrid nanocarriers, this acoustofluidic drug loading platform wields the potential to significantly impact innovation in both drug delivery research and applications.

Nanosilica:Polycaprolactone ratio and heat treatment modify the wettability of nanosilica/polycaprolactone coatings for application in aqueous systems

This work evaluated the simultaneous effect of the nanosilica-NPS:polycaprolactone-PCL ratio and the heat treatment on the wettability of the NPS/PCL coatings for application in aqueous systems. Silica nanoparticles were synthesized via the sol-gel route using silica precursors. The polycaprolactone (PCL) were coated by Silica nanoparticles in a solution using different concentrations of silica nanoparticles. The NPS/PCL coatings were characterized by field emission gun scanning electron microscopy (FEG/SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and water contact angle (WCA). The results showed that water contact angle (WCA) decreased with the increment of the nanosilica achieving the maximum value of 67.60° ± 0.82 for the coating with the highest nano-silica particles (NPS-300). In addition, WCA values increase significantly after the heat treatment for the samples submitted to the highest NPS:PCL ratios (NPS-150T and NPS-300T), achieving a maximum value of 101.70° ± 0.94. These results are associated with the microstructural, thermal, and functional groups modifications showed by characterizations techniques In summary, this work provides new insights on wettability of hydrophobic materials nanoparticles that can be dispersed in aqueous systems.

Insight into the enhancing mechanism of silica nanoparticles on denitrification: Effect on electron transfer and microbial metabolism

Although silica nanoparticles (SiNPs) are produced in large numbers for industrial manufacturing and engineering applications, the effect of SiNPs on biotransformation in the environment is still not clear. In the current study, the effect of SiNPs in enhancing denitrification was investigated, and its mechanism was explored from the perspectives of electron transfer, microbial metabolism and bacterial community structure for the first time. Batch experiments showed that a concentration of SiNPs ranging from 0.05 to 5 g/L enhanced the bioreduction of nitrate. The mechanism study showed that SiNPs accelerated the extracellular electron transfer in the denitrification process due to their electron donating capacity, bonding action, and the secretion of more electron shuttles. During the denitrification process, SiNPs promoted metabolic activity, which mainly consists of promoting enzyme activities and electron transport system activity; these metabolic activity assays were positively correlated with SiNPs according to the structural equation modeling analysis. Moreover, SiNPs affected the composition of the microbial community, including denitrifying functional bacteria, silicon-activating bacteria and electron transfer active bacteria exhibiting a synergistic symbiosis. In addition, it was shown, by investigating two functional group-modified SiNPs, that the carboxyl modified SiNPs had the potential to be applied in nitrogen removal due to their performance and non-toxicity. This study presented a better insight into the role of SiNPs in biological transformation.

Temperature Dependent on Mechanical and Rheological Properties of EPDM-Based Magnetorheological Elastomers Using Silica Nanoparticles.

Temperature is one of the most influential factors affecting the performance of elastomer matrix in magnetorheological elastomer (MRE). Previous studies have utilized silica as a reinforcing filler in polymer composite and as a coating material in MRE to improve the thermal stability of the base material. However, the usage of silica as an additive in the thermal stability of MRE has not been explored. Thus, in this study, the effect of silica as an additive on the temperature-dependent mechanical and rheological properties of ethylene propylene diene monomer (EPDM)-based MREs was investigated by using 30 wt.% carbonyl iron particles (CIPs) as the main filler, with different contents of silica nanoparticles (0 to 11 wt.%). The microstructure analysis was examined by using field-emission scanning electron microscopy (FESEM), while the thermal characterizations were studied by using a thermogravimetric analyzer and differential scanning calorimetry. The tensile properties were conducted by using Instron Universal Testing Machine in the absence of magnetic field at various temperatures. Meanwhile, the rheological properties were analyzed under oscillatory loadings in the influence of magnetic field, using a rotational rheometer at 25 to 65 °C. The results revealed that the temperature has diminished the interfacial interactions between filler and matrix, thus affecting the properties of MRE, where the tensile properties and MR effect decrease with increasing temperature. However, the presence of silica capable improved the thermal stability of EPDM-based MRE by enhancing the interactions between filler and matrix, thus reducing the interfacial defects when under the influence of temperature. Consequently, the incorporation of silica nanoparticles as an additive in EPDM-based MRE requires more exploration, since it has the potential to sustain the properties of MRE devices in a variety of temperature conditions. Thus, the study on the temperature-dependent mechanical and rheological properties of MRE is necessary, particularly regarding its practical applications.

DLVO Modeling to Predict Critical Salt Concentration to Initiate Fines Migration Pre- and Post-Nanofluid Treatment in Sandstones

Summary The critical salt concentration (CSC) of injected water used for various water-based oil recovery operations is the salt concentration below which fine particles are released and their migration starts within sandstone reservoirs containing clays. This phenomenon could be one of the potential causes of formation damage and associated injectivity and productivity declines. This paper proposes a novel method of quantifying surface forces between fines and sand grains and using DLVO (named after Derjaguin, Landau, Verwey, and Overbeek) modeling to predict a CSC pre- and post-nanofluid treatment. Furthermore, the effectiveness of varying concentrations of silica nanoparticles (SNPs) in controlling fines migration and reducing CSC was modeled by the DLVO approach and experimentally validated. The experimental CSC was determined by performing corefloods and analyzing effluent turbidity and absorbance under various salinities of the injected brine to validate the developed models. The zeta potentials of sand-fine-brine (SFB) systems were measured and ranged from −35.2 to 29.5 mV. The average size of fine particles was 800 to 900 nm based on scanning electron microscopy (SEM) results. Using DLVO modeling before the application of nanoparticles (NPs), the CSC was predicted to be 0.11 M (6,400 ppm) NaCl brine, at which the total DLVO interaction energy shifted from attraction to repulsion. Moreover, another DLVO model was developed considering the effect of SNPs. Models predicted 0.085 M (4,900 ppm) and 0.075 (4,400 ppm) NaCl CSC values after the application of 0.05 and 0.1 wt% SNPs, respectively. Afterward, corefloods were performed that showed that the experimental results of CSC with and without SNPs treatment were in close agreement with the DLVO models. Fines migration was observed at 0.08 M (4,700 ppm) and 0.07 M (4,100 ppm) salinity after nanofluid treatments. Many oil recovery processes, including but not limited to low-salinity waterflooding and alkaline flooding, require the estimation of the CSC to avoid formation damage. The proposed DLVO model is instrumental to predict the CSC for monovalent NaCl brine pre- and post-nanofluid application without requiring extensive experimental work. Moreover, the use of nanofluid showed promising results in terms of fines migration control and reduction in CSC.

A Single-Step Digestion for the Quantification and Characterization of Trace Particulate Silica Content in Biological Matrices Using Single Particle Inductively Coupled Plasma-Mass Spectrometry.

The increased use of amorphous silica nanoparticles (SiNPs) in food products, materials science, cosmetics, and pharmaceuticals has raised questions about potential hazards in the environment and in human health. Although SiNPs are generally thought to be benign, recent studies have demonstrated toxicity in different cell and animal models. Despite their ubiquitous use, SiNPs are rarely analyzed quantitatively. Often, the methods used to analyze silicon and SiNPs are difficult, costly, require the use of dangerous reagents, and are prone to interferences. Additionally, characterization of SiNPs in complex matrices requires extensive sample preparation. To address this, we propose a single-step digestion method for the determination of trace SiNP content in biological matrices. For conventional inductively coupled plasma-mass spectrometry (ICP-MS) analysis, biological samples are often digested with concentrated HNO3. We found that with conventional ICP-MS, lower limits of detection (LLOD) of silicon are too high for trace analysis. However, we found that SiNPs are stable at a strong acidic pH; thus, concentrated HNO3 could be used to digest biological samples leaving SiNPs intact. Then, by analysis with single particle ICP-MS, we found that the smallest SiNP that could be read was 185nm in size. The concentration for the LLOD was found to be 0.032ppb with interday variability in sizing and concentration at 2.5% and 6.8% respectively. Utilizing this method, SiNPs were accurately sized and counted in cell pellets and media. Our proposed method can be used to accurately quantify and characterize SiNPs (or agglomerated SiNPs) larger than the derived LLOD in a variety of biological matrices and will assist in determining relationships between exposures of SiNPs and toxicity in humans and the environment.

Silica nanoparticles acute toxicity alters ethology, neuro-stress indices, and physiological status of African catfish (Clarias gariepinus)

Silica nanoparticles (SiNPs) are a new class of nanomaterials with unique properties due to their nanoscale size. Currently, SiNPs constitute a potential value in aquaculture; nonetheless, misuse induces toxicity to fisheries and ecosystems. Hence, the present prospective is a pioneer study that illustrates the acute toxicity of SiNPs to African catfish, Clarias gariepinus (B.) and the behavioral response in a renewal static system. Moreover, the influence of SiNPs on neuro-related, stress, immune-related, and oxidative stress indices was investigated. Fish groups of average body weights (73.09 ± 2.20 g) were exposed to 96-h of various concentrations of SiNPs including 0, 50, 100, 150, 200, 250, and 300 mg L−1 without water exchange. The value of 96-h LC50 of SiNPs was computed using Finney's probit analysis. Here we show that the exposure of fish to SiNPs resulted in remarkable ethological alterations such as lethargic, surfacing, inactive, slow swimming manner, and nervousness. By increasing the SiNPs concentration, the behavior scores and mortalities reached the upper limit of top values. The comparison with the control revealed a significant dose-dependent effect by increasing in the activity of 8-hydroxy-2-deoxyguanosine (8-OHdG) and malondialdehyde (MDA) with a concomitant elevation in the stress-controlled parameters (cortisol and nor-epinephrin) of all the fish groups undergone the SiNPs exposure. In contrast, there was a clear reduction in the acetylcholine esterase (AChE) level, immunological biomarkers (lysozymes and nitric oxide), and antioxidant enzymes (glutathione peroxidase (GPX) and superoxide dismutase (SOD)) of the exposed groups and the reduction elevated by increasing the SiNPs exposure concentration in comparison to the control group. Based on the study outcomes, the 96-h LC50 of SiNPs recorded 144.54 mg L−1 in C. gariepinus. We anticipate our assay to be a starting point for further applying the one-tenth of 96-h LC50- as an alternative safe treatment in therapy after considering the acute toxicity to preserve the aquaculture production and sustain human health. Additionally, it was approved that, the toxicity by the exposure to SiNPs observed clear alterations in fish behavior, neurological activity, immune and oxidative responses reflecting physiological disturbance.

“Glycolipid biosurfactant-silica nanoparticles” based green application for enhancement of oil recovery

Crude oil is still a major energy source, and it will continue to play a major role for several years to come. However, the industry is facing the challenge to cope the ever increasing demand and complexities on the recovery front in sustainable manner. To fulfill the continuous increase in demand, several enhanced oil recovery (EOR) techniques are in place to recover additional oil from depleting reservoirs. Among those possible technologies, biosurfactants and nanoparticles could possibly perform in a better and environmentally friendly manner. Here we show the possible EOR applications of glycolipids biosurfactants, either alone or in combinations with different concentrations of silica nanoparticles. Biosurfactants and nanoparticles were compatible, and it reduced both surface tension and interfacial tension values in the range of 26–28 mN/m, and 2.56–3.67 mN/m, respectively. Silica nanoparticles and glycolipid biosurfactants showed ∼10–30% additional oil recovery (AOR) from Berea sandstone core plugs, when tested individually at reservoir conditions. We observed ∼20–25% AOR using silica nanoparticles in combination with sophorolipids or rhamnolipids, where “NP + rhamnolipids” (40 ppm + 500 ppm, respectively) outperformed other combinations. To the best of our knowledge it is the first report for such combination to be used for environmentally friendly EOR applications.

Silica nanofluid in low salinity seawater containing surfactant and polymer: Oil recovery efficiency, wettability alteration and adsorption studies

Production of crude oil from a matured oil reservoir is challenging due to the low recovery factor. Hybrid methods have demonstrated potential in oil recovery from the matured crude oil reservoir. In recent years, the low salinity water with chemicals (viz., surfactant, polymer) and nanoparticles have brought the attention of the researchers due to their ability in altering the interfacial properties of the rock-oil-water systems favorable for crude oil recovery. The current interest by industries in injection fluid (i.e., low salinity water injection) has prompted the invention of a hybrid oil recovery agent for matured crude oil reservoirs. In the current study, a novel silica-based hybrid nanofluids (NFs) of variable silica nanoparticles (NPs) concentration in low salinity seawater with anionic surfactant (AOT: dioctyl sodium sulfosuccinate) and polymer (PVP–K30: polyvinylpyrrolidone) (sometimes referred to as SMART LowSal) are used as an injection fluid in a sand-pack reactor. Oil recovery from oil saturated sand-pack reactor is observed to enhance due to NFs (hybrid) injection after secondary recovery. The characteristic study of relative permeability curves discloses that sand surface was initially water-wet and converted to strongly water-wet in the presence of NFs. A nuclear magnetic resonance (1H NMR) study reveals that adsorption of the chemical appeared on the sand surfaces, which could be the reason for wettability alteration, and thereby enhanced oil recovery. Similarly, the scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDXA) of the sand samples before and after injection disclosed desorption of hydrocarbon from the sand surfaces after NFs injection. An additional 5–10% oil recovery is achieved after chemical flooding due to the injection of NFs. Adsorption isotherm study well agreed with the monolayer adsorption of surfactant on the sand surface.