Effect Of Silica Nanoparticles Research Articles

Combating Spodoptera frugiperda (Lepidoptera: Noctuidae) with Moringa-Synthesized Silica Nanoparticles and Its Combination with Some Insecticides.

The fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith), is a major agricultural pest known for developing resistance to insecticides. This study investigated a novel approach to manage FAW by silica nanoparticles (SiNPs) synthesized from eco-friendly leaf extract of Moringa oleifera Lam. (Moringaceae). This green synthesis method offers a sustainable and potentially safer alternative to traditional chemical processes. SiNP formation was confirmed by various techniques: UV-visible spectrophotometer, X-ray spectroscopy with energy-dispersive (EDX), scanning electron microscopy (SEM), and dynamic light scattering (DLS). The effectiveness of SiNPs alone and their combination with three common insecticides (emamectin benzoate, indoxacarb, and chlorpyrifos) were evaluated against third instar larvae of fall armyworm. While SiNPs after 24h by leaf dipping method recorded limited insecticidal activity (LC50 = 9947.59mg/L), it significantly enhanced the potency of all three insecticides. Combining SiNPs with emamectin benzoate resulted in the most dramatic increase in effectiveness compared to the insecticide alone with LC50 = 0.295mg/L and 0.42mg/L, respectively. This research suggests that moringa extract can be a valuable resource for the green synthesis of nanoparticles potentially useful in pest control. This approach could potentially reduce the amount of insecticide needed for effective pest control, leading to a more sustainable and environmentally friendly agricultural practice.

Effect of SiC nanoparticles on mechanical and damping properties of epoxy/polysulfide rubber blend composite

Blend polymer matrix composite material are becoming more and more popular due to their promising mechanical properties. In this research, blend polymer mixture was make from epoxy resin (EP) blended with different weight percentages of polysulfide rubber (PSR) (0, 3, 6, 10, 15, and 20%). Then tensile, impact, bending strength and damping ratio were evaluated to get the high quality of mechanical properties for the blend matrix. Due to the requirements to enhance the mechanical properties of this blend; a various weight fraction of carbide silica (SiC) nanoparticle was used as a reinforcement in the ratios of (0, 1, 3, and 5%) by weight to the best ratio of the blended matrix. Tensile, impact, bending and damping ratio tests were also conducted to get the best mechanical properties for the blend materials. Experimental results for the blend matrix showed that adding polysulfide rubber to epoxy resin resulted in a decrease in Young’s modulus, tensile strength, and bending strength; however damping ratio and the impact strength increased. It is found that the weight fraction of 6% of PSR is the Better case, which gave the better mechanical characteristics properties for mixture. Utility of this mixture; it has intermediates between flexible properties of a mixture at the highest rate of PSR and brittle mechanical properties for EP resin. Mechanical and damping properties showed an increasing when the carbide silica (SiC) with a weight fraction of 3% added, then it decreased slightly.

Silica nanoparticles induce pulmonary damage in rats via VEGFC/D–VEGFR3 signaling-mediated lymphangiogenesis and remodeling

Silica nanoparticles (SiNPs) are widely used as drug carriers for improving drug delivery and retention. The lungs are highly sensitive to the toxicity of SiNPs entering the respiratory tract. Furthermore, pulmonary lymphangiogenesis, which is the growth of lymphatic vessels observed during multiple pulmonary diseases, plays a vital role in promoting the lymphatic transport of silica in the lungs. However, more research is required on the effects of SiNPs on pulmonary lymphangiogenesis. We investigated the effect of SiNP-induced pulmonary toxicity on lymphatic vessel formation in rats and evaluated the toxicity and possible molecular mechanisms of 20-nm SiNPs. Saline containing 3.0, 6.0, and 12.0 mg/kg of SiNPs was instilled intrathecally into female Wistar rats once a day for five days, then sacrificed on day seven. Lung histopathology, pulmonary permeability, pulmonary lymphatic vessel density changes, and the ultrastructure of the lymph trunk were investigated using light microscopy, spectrophotometry, immunofluorescence, and transmission electron microscopy. CD45 expression in lung tissues was determined using immunohistochemical staining, and protein expression in the lung and lymph trunk was quantified using western blotting. We observed increased pulmonary inflammation and permeability, lymphatic endothelial cell damage, pulmonary lymphangiogenesis, and remodeling with increasing SiNP concentration. Moreover, SiNPs activated the VEGFC/D–VEGFR3 signaling pathway in the lung and lymphatic vessel tissues. SiNPs caused pulmonary damage, increased permeability and resulted in inflammation-associated lymphangiogenesis and remodeling by activating VEGFC/D–VEGFR3 signaling. Our findings provide evidence for SiNP-induced pulmonary damage and a new perspective for the prevention and treatment of occupational exposure to SiNPs.

Preparation of Silica Composite Vitrimers via One‐Shot Transformation from Simple Polyesters

AbstractTo solve the conventional problems of chemically cross‐linked polymers, the vitrimer concept has attracted great attention because the associative bond‐exchange nature in vitrimers provides sustainable functions. So far, various vitrimer designs have been reported using different polymer species with compatible bond exchange mechanisms. However, the biggest barrier for the practical application may be the elaborated functional group modification of the starting components and the limited availability of suitable monomers. As a much simpler preparation, recently, a one‐shot preparation of vitrimers from commodity polyesters with no special reactive functional groups by blending and heating with tetra‐functional epoxy molecules and base catalysts has been proposed. In this study, further one‐shot preparation of composite vitrimers with silica nanoparticles (SNPs) is developed. The effects of SNPs on the cross‐linking process and thermo/mechanical properties are first assessed, which reveals the formation of a bound rubber phase on the surfaces of the SNPs. The bound rubber phase also affects the bond exchange features of vitrimers, especially the distribution of relaxation time. Overall, the present facile preparation of composite vitrimers with enhanced mechanical properties could be a hint for practical application, whereas the knowledge on the unique relaxation behaviors of composite vitrimers should be beneficial in the fundamental sense.

Silica Nanoparticles Promote Apoptosis in Ovarian Granulosa Cells via Autophagy Dysfunction.

Although silica nanoparticles (SNPs) are generally thought to be biocompatible and safe, the adverse effects of SNPs were also reported in previous studies. SNPs cause follicular atresia via the induction of ovarian granulosa cell apoptosis. However, the mechanisms for this phenomenon are not well understood. This study focuses on exploring the relationship between autophagy and apoptosis induced by SNPs in ovarian granulosa cells. Our results showed that 25.0 mg/kg body weight (b.w.)/intratracheal instillation of 110 nm in diameter spherical Stöber SNPs caused ovarian granulosa cell apoptosis in follicles in vivo. We also found that SNPs mainly internalized into the lumens of the lysosomes in primary cultured ovarian granulosa cells in vitro. SNPs induced cytotoxicity via a decrease in viability and an increase in apoptosis in a dose-dependent manner. SNPs increased BECLIN-1 and LC3-II levels, leading to the activation of autophagy and increased P62 level, resulting in the blockage of autophagic flux. SNPs increased the BAX/BCL-2 ratio and cleaved the caspase-3 level, resulting in the activation of the mitochondrial-mediated caspase-dependent apoptotic signaling pathway. SNPs enlarged the LysoTracker Red-positive compartments, decreased the CTSD level, and increased the acidity of lysosomes, leading to lysosomal impairment. Our results reveal that SNPs cause autophagy dysfunction via lysosomal impairment, resulting in follicular atresia via the enhancement of apoptosis in ovarian granulosa cells.

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.

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.

Role of Silica Nanoparticles in Abiotic and Biotic Stress Tolerance in Plants: A Review.

The demand for agricultural crops continues to escalate with the rapid growth of the population. However, extreme climates, pests and diseases, and environmental pollution pose a huge threat to agricultural food production. Silica nanoparticles (SNPs) are beneficial for plant growth and production and can be used as nanopesticides, nanoherbicides, and nanofertilizers in agriculture. This article provides a review of the absorption and transportation of SNPs in plants, as well as their role and mechanisms in promoting plant growth and enhancing plant resistance against biotic and abiotic stresses. In general, SNPs induce plant resistance against stress factors by strengthening the physical barrier, improving plant photosynthesis, activating defensive enzyme activity, increasing anti-stress compounds, and activating the expression of defense-related genes. The effect of SNPs on plants stress is related to the physical and chemical properties (e.g., particle size and surface charge) of SNPs, soil, and stress type. Future research needs to focus on the “SNPs–plant–soil–microorganism” system by using omics and the in-depth study of the molecular mechanisms of SNPs-mediated plant resistance.

Efficient Encapsulation and Controlled Release of N,N-Diethyl-3-methylbenzamide (DEET) from Oil-in-Water Emulsions Stabilized by Cationic Nanocellulose and Silica Nanoparticles

Oil-in-water emulsions containing N,N-diethyl-3-methylbenzamide (DEET) were developed aiming to extend the sustained release of the active compound, by using two oppositely charged nanomaterials, namely silica nanoparticles (SiNP) and cationic cellulose nanofibrils (CCNF), as stabilizers, and a mixture of food-grade nonionic surfactants to avoid precipitation by electrostatic aggregation. The formulations were stable for more than four months at room temperature, and strongly resistant to destabilization upon centrifugal and thermal stress. The results were correlated with the effect of SiNP on strengthening the network formation of CCNF in the aqueous phase by electrostatic interactions, which increased the viscosity of the external phase and, hence, emulsion stability. There was a significant size reduction of the internal oil phase containing DEET in the presence of CCNF, which was attributed to the increased viscosity in the external aqueous phase, as well as to interfacial stabilization. The combined action of CCNF and unmodified SiNP in the stabilization of the DEET-containing oil phase significantly decreased the release rate of the active compound, compared to non-emulsified DEET. Moreover, in the emulsions containing the CCNF/SiNP mixture there was a more sustained release for the period of 6 h, demonstrating the potential of these formulations for extended protection.

Investigation on strength enhancement of cement paste using biogenic nanoparticles

The present study attempts to understand the effect of hydrophobic water-dispersed biogenic silver nanoparticles (AgNPs) over commercial silica nanoparticles (SiNPs) on the fresh and hardened properties of cement paste. The average particle size of AgNPs is 10 nm, whereas that of reference SiNPs is 12 nm. The effect of AgNPs replacing 0.5 and 1% of binder material has been studied and compared with the effect of SiNPs. It is observed that the addition of AgNPs does not enhance water requirement for consistency; neither does it adversely impact the setting time. The results on compressive strength of cement paste show higher initial and long term strength for specimens blended with AgNPs with the percentage increment for 3–28 days strength ranging between 40 and 43%, whereas the same for SiNPs ranges from 26 to 29%. For optimized binary mixes with Alccofine, the strength increment from 3 to 28 days ranges from 8 to 30% for AgNPs, whereas for SiNPs it ranges from 10 to 43%. In case of binary mix with Fly Ash C, addition of AgNPs improves strength in the range from 31 to 40%, whereas SiNPs improves strength from 10 to 41%. The strength observed with AgNPs is comparable with those of commercial SiNPs with an additional advantage of reduced water demand for consistency, thus making it an attractive alternative for possible applications in mortar and concrete.

Retrofitting of Reinforced Concrete Beams using Lightweight RC Jacket Containing Silica Nano Particles and Glass Fiber

The concrete jacket method is a common method used in retrofitting buildings. Although this method has many advantages, engineers criticize it due to an increase in the structure's weight. In the present study, lightweight concretes containing silica nanoparticles (SNPs) and glass fibers (GF) have been used in concrete jackets to strengthen concrete beams. Several reinforced concrete (RC) beams were constructed and retrofitted using the proposed lightweight concrete jackets and their response to four-point loading was evaluated. The SNPs amount in the lightweight concrete jackets was 0, 2, 4, and 6% by weight of cement and the amount of GF was 1.5% by volume of concrete. Load-deflection curves were extracted and the response of the beams was examined by parameters such as crack load, yield load, maximum load, energy absorption capacity, and ductility. The proposed lightweight concrete jacket containing 1.5% of GFs in which 0, 2, 4, and 6% of SNPs were used, increased the energy absorption capacity by 33%, 54%, 61%, and 62%, respectively. The presence of SNPs in lightweight concrete reinforced by GFs leads to the filling of small cavities in the concrete. Also, the bearing capacity of the retrofitted RC beams increased with an increase in SNPs in the concrete jacket. A portion of this increase can be attributed to an increase in tensile and compressive strength of the proposed concrete, and the other part can be attributed to the effect of SNPs on the surrounding surfaces of the main beam and jacket.

Effects of Dietary Silica Nanoparticle on Growth Performance, Protein Digestibility, Hematology, Digestive Morphology, and Muscle Composition of Nile Tilapia, Oreochromis Niloticus

The use of nanotechnology in food production systems is being investigated globally, though there is limited research on its effect on fish nutrition. Therefore, this study aimed to identify the effects of silica nanoparticles (NPs) on the nutrition and physiology of tilapia, Oreochromis niloticus. Four isonitrogenous diets (300 g/kg crude protein) with NPs (0, 1, 2, and 3 mg/kg diet) were fed to fish (6.52 ± 0.20 g) in a recirculatory aquaculture system for 56 days. Throughout the study period, the effects of silica NP on survival rate, blood cell count, hemoglobin (Hb) level, condition factor (CF), and final product composition (except lipid content) were insignificant. However, growth performance and feed efficiency increased with an increasing level of silica NP, up to 2 mg/kg, and then decreased. This increase was due to the highest apparent protein digestibility and dry matter digestibility when fish were fed silica NP at 2 mg/kg. However, fish at the early stage showed better performance in all dietary groups than in later. Blood glucose (BG) content and histology of the kidney revealed that fish were stressed when a 3 mg/kg silica NP was used and they adapted through excessive excretion via expanded glomeruli. Though no significant effect on villi length was observed, silica NP increased the surface area widening the villi of the gut along with the number of goblet cells in the intestine significantly, when supplemented at a level of 2 mg/kg. The bioaccumulation of silica shows that incorporating silica NP in the fish feed will not compromise human health safety upon consumption. Although silica NP at 1 mg/kg and 3 mg/kg yielded some improvements to growth and final product quality, a 2 mg/kg silica NP generated the best results in all measured parameters.

Functionality of silica nanoparticles on hydration mechanism and microstructure of tricalcium aluminate

In this paper, a detailed reaction mechanism of tricalcium aluminate (C3A) in presence and absence of silica nanoparticles (SNPs) within 24 hr of hydration was studied. The effect of SNPs on an early stage of hydration was assessed through XRD (mineralogical analysis), TGA (quantification of hydrated products), FTIR (analysing chemical bonding) and FESEM (morphological study). The results indicate that SNPs promote C3A hydration at the very early stage of hydration (10 min of hydration), after that retardation in C3A hydration was observed and the pattern of reaction is consistent up to 24 hr of hydration. The retardation might be due to the surface coverage of C3A grain by calcium silicate hydrate (C-S-H) and calcium alumina silicate hydrate (C-A-S-H), thus, the reactivity of C3A decreases. This study presents a detailed inside reaction mechanism of C3A hydration with SNPs, which will help in understanding the influence of other admixtures (such as superplasticizers, accelerators and retarders) in SNPs modified cementitious system.

In vitro and in vivo uterine metabolic disorders induced by silica nanoparticle through the AMPK signaling pathway

Exposure to silica nanoparticles (SiNPs) has been suggested to cause physical disorders, yet the effects of SiNPs on female reproduction have not been illustrated. This study was implemented to explore the reproductive toxicity of SiNPs on female and reveal its underlying mechanisms. Methodologically, the fluorescein isothiocyanate (FITC)-SiNPs were synthesized by coupling with FITC and then used to track the biodistribution of SiNPs in vitro and in vivo. In total, 30 mice were intratracheally injected 0.25 g of FITC-SiNPs, and 6 mice injected with the same volume of saline were used as controls. The results showed that SiNPs penetrated the cellular membrane, triggering apoptosis and inhibiting proliferation, tube formation, and invasion of trophoblast. Mechanistically, SiNPs was demonstrated to dysregulate Fbp2, Cpt1a, Scd1, and Pfkl, and further induced accumulation of pyruvate and fatty acid in mitochondria through the AMPK signaling pathway, which finally activated the Caspase-3-dependent apoptosis. Consistently, the similar alterations of these genes were detected in vivo, and the uterine inflammatory infiltration aggravated with the extension of the observation duration. These results suggested that SiNPs induced trophoblast apoptosis and uterine inflammation, and ultimately caused acute reproductive toxicity on female. The underlying mechanism might be explained by the dysregulation of Fbp2/Cpt1a/Pfkl/Scd1 axis, which promoted the overload of glucose and lipid through the AMPK signaling pathway. These findings were of great significance to guide a comprehensive understanding of the reproductive toxicity of SiNPs as well as the development of environmental standards.

Evaluation of microstructure, thermal, and mechanical properties of the green lignin‐based polyurethane/hydrophobic silica nanocomposite foam

AbstractIn the present study, lignin‐based polyurethane foam (LPUF) and hydrophobic silica LPUF (SLPUF) were synthesized using different concentrations of silica nanoparticles (SNP). The effect of SNP on the structure and properties of SLPUF samples was investigated and compared with LPUF through the scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT‐IR), thermogravimetric analysis (TGA), dynamic mechanical thermal analysis (DMTA), and compressive tests. The FT‐IR results showed changes in the H bonding interactions between the structures of SLPUF samples. Moreover, the SEM results indicated a decrease in the cell size of SLPUF samples. Incorporation of SNP improved the thermal stability of SLPUF samples while the compressive strength of SLPUF samples decreased in comparison with LPUF. Furthermore, the DMTA results revealed a decrease in the glass transition temperature from 90°C (LPUF) to around 52°C (SLPUF samples). This means that applying the hydrophobic SNP changes the foam type from a rigid foam to soft one. Therefore, significant changes were observed in the physical–chemical properties of the SLPUF samples compared to the LPUF.

Understanding the mechanisms of silica nanoparticles for nanomedicine.

As a consequence of recent progression in biomedicine and nanotechnology, nanomedicine has emerged rapidly as a new discipline with extensive application of nanomaterials in biology, medicine, and pharmacology. Among the various nanomaterials, silica nanoparticles (SNPs) are particularly promising in nanomedicine applications due to their large specific surface area, adjustable pore size, facile surface modification, and excellent biocompatibility. This paper reviews the synthesis of SNPs and their recent usage in drug delivery, biomedical imaging, photodynamic and photothermal therapy, and other applications. In addition, the possible adverse effects of SNPs in nanomedicine applications are reviewed from reported in vitro and in vivo studies. Finally, the potential opportunities and challenges for the future use of SNPs are discussed.This article is categorized under:Nanotechnology Approaches to Biology > Nanoscale Systems in BiologyTherapeutic Approaches and Drug Discovery > Emerging Technologies

Photodynamic Therapy Activity of New Porphyrin-Xylan-Coated Silica Nanoparticles in Human Colorectal Cancer.

Photodynamic therapy (PDT) using porphyrins has been approved for treatment of several solid tumors due to the generation of cytotoxic reactive oxygen species (ROS). However, low physiological solubility and lack of selectivity towards tumor sites are the main limitations of their clinical use. Nanoparticles are able to spontaneously accumulate in solid tumors through an enhanced permeability and retention (EPR) effect due to leaky vasculature, poor lymphatic drainage, and increased vessel permeability. Herein, we proved the added value of nanoparticle vectorization on anticancer efficacy and tumor-targeting by 5-(4-hydroxyphenyl)-10,15,20-triphenylporphyrin (TPPOH). Using 80 nm silica nanoparticles (SNPs) coated with xylan-TPPOH conjugate (TPPOH-X), we first showed very significant phototoxic effects of TPPOH-X SNPs mediated by post-PDT ROS generation and stronger cell uptake in human colorectal cancer cell lines compared to free TPPOH. Additionally, we demonstrated apoptotic cell death induced by TPPOH-X SNPs-PDT and the interest of autophagy inhibition to increase anticancer efficacy. Finally, we highlighted in vivo, without toxicity, elevated anticancer efficacy of TPPOH-X SNPs through improvement of tumor-targeting compared to a free TPPOH protocol. Our work demonstrated for the first time the strong anticancer efficacy of TPPOH in vitro and in vivo and the merit of SNPs vectorization.

New approach for mapping and physiological test of silica nanoparticles accumulated in sweet basil (Ocimum basilicum) by LA-ICP-MS

Behavior of silica nanoparticles (SiNPs) in sweet basil was studied using laser ablation inductively coupled plasma mass spectroscopy (LA-ICP-MS) as an in situ monitoring tool. Although the use of SiNP for environmental applications is interesting, detailed studies in plants for distributional mapping and quantitative determination have been difficult because the detection of 28Si+ suffers from severe molecular interference and high background in ICP-MS. In this work, yttrium/fluorescein-isothiocyanate-doped silica nanoparticles (Y/FITC-doped SiNPs) synthesized in our lab were used to substitute for undoped SiNP, allowing the doped 89Y+ to be monitored instead of 28Si+, while retaining the same surface properties. Based on this model, the physiological influence was studied by nourishing them with a nutrient solution spiked with the synthesized SiNPs and a co-pollutant, Cs ion. Mapping images obtained by LA-ICP-MS showed distinct accumulation patterns associated with exposure. For example, Cs was distributed widely over the leaves, whereas SiNPs were concentrated in specific regions such as main veins, leaf margins, and tips. Furthermore, the possible effect of SiNP and Cs on the photochemical reaction was confirmed through monitoring the change of the concentration of chlorophyll and carotenoid and the superoxide dismutase (SOD) activity.

Surface functionalization of silica nanoparticles to enhance aging resistance of asphalt binder

Abstract Oxidation aging of asphalt pavement is among most prevalent factors causing pavement distresses. Introduction of silica nanoparticles (SNPs) has been found promising to reduce oxidation aging of asphalt binder. However, the effectiveness of SNPs is limited by their poor dispersion caused mainly by SNP agglomeration requiring significant mechanical energy in processing to ensure dispersion. This paper examined merits of surface functionalization of SNPs with (3-aminopropyl) triethoxysilane (APTES) to improve its dispersion in asphalt binder using conventional processing techniques at relatively high loading of SNPs with low mechanical energy input. The morphology, size, amount of amine functional groups of APTES surface-modified SNPs (APTES-SNPs) were characterized and optimized by scanning electron microscope (SEM), dynamic light scattering (DLS), Fourier-transform infrared spectroscopy (FTIR) and fluorescence measurement. The comparison between the surface-modified and pristine SNPs on the anti-aging and rheological properties of asphalt binder was conducted. The asphalt binders which contained APTES-SNPs demonstrated much better resistance to oxidative aging as evidenced by enhanced rheological properties compared to those containing pristine SNPs. The findings from this research provides insights as to the effect of APTES-SNPs on aging resistance of asphalt binder.

In-situ Synthesis of SiO2 Nanoparticles on Polyester Fabric as Benign Multi-purpose Catalysts

Here, silica nanoparticles (NPs) as safe multi-purpose catalysts were in situ synthesized on PET fabric to achieve a higher quality fabric. The PET fabric was treated in an aqueous solution of sodium silicate and ammonia at boil for 1 h to insitu synthesis silica NPs along with aminolysis of the fabric. Effect of silica NPs as the multi-purpose catalysts on the fabric were subjected to various analysis such as self-cleaning, hydrophilic, antibacterial and antifungal properties and also thermal resistance. The surface morphology, the crystalline structure and elemental analysis were studied by Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and map and energy dispersive X-ray (EDX) analysis. The optimized treated fabric indicated 4 s for the water to spread and 65° for contact angle provided higher hydrophilic properties. Silica NPs on the fabric showed thermo-catalytic behavior protecting against yellowing at high temperature (200 °C for 3 h) proved the higher thermal resistance of the treated fabric. Also, the fabric specified good self-cleaning properties through discoloration of methylene blue solution. Further, the treated fabric proposed 100 % anti-bacterial and anti-fungal activities against Staphylococcus aureus, Escherichia coli and Candida albican along with good cell viability. Overall, this research indicates silica NPs as multi-purpose catalysts including photo, bio and thermo-catalyst on the PET fabric using low price materials.