Amorphous Silica Nanoparticles Research Articles

Renal Fibrosis and Oxidative Stress Induced by Silica Nanoparticles in Male Rats and Its Molecular Mechanisms.

The utilization of amorphous silica nanoparticles (SiNPs) is gaining popularity in various applications, but it poses a potential risk to human and environmental health. However, the underlying causes and mechanisms of SiNPs-induced kidney damage are still largely unknown. This study aimed to investigate the SiNPs-induced damage in the kidney and further explore the possible mechanisms of SiNPs-induced nephrotoxicity. Thirty adult male rats were divided into 3 different groups. Rats in groups 2 and 3 were administered SiNPs at 2 dosage levels (25 and 100 mg/kg of body weight), while the rats in the control group received no treatment for 28 days. Reactive oxygen species (ROS), antioxidant enzyme activities (glutathione peroxidase [GPx], superoxide dismutase [SOD], and catalase [CAT]), glutathione (GSH) levels, and oxidation markers (such as lipid peroxidation [malondialdehyde (MDA)] and protein oxidation [protein carbonyl (PCO)]) were analyzed in the kidney tissue. Additionally, renal fibrogenesis was studied through histopathological examination and the expression levels of fibrotic biomarkers. The findings revealed that in vivo treatment with SiNPs significantly triggered oxidative stress in kidney tissues in a dose-dependent manner. This was characterized by increased production of ROS, elevated levels of MDA, PCO, and nitric oxide (NO), along with a significant decline in the activities of SOD, CAT, GPx, and reduced GSH. These changes were consistent with the histopathological analysis, which indicated interstitial fibrosis with mononuclear inflammatory cell aggregation, tubular degeneration, glomerulonephritis, and glomerular atrophy. The fibrosis index was confirmed using Masson's trichrome staining. Additionally, there was a significant upregulation of fibrosis-related genes, including transforming growth factor-beta 1 (TGF-β1), matrix metalloproteinases 2 and 9 (MMP-2/9), whereas the expression of tissue inhibitor of metalloproteinase 2 (TIMP2) was downregulated. This study provided a new research clue for the role of ROS and deregulated TGF-β signaling pathway in SiNPs nephrotoxicity.

A Case for Amorphous Silica Nanoparticle Exposure in the Development of Chronic Kidney Disease of Unknown Etiology

A Case for Amorphous Silica Nanoparticle Exposure in the Development of Chronic Kidney Disease of Unknown Etiology

First-Principles Prediction of Amorphous Silica Nanoparticle Surface Charge: Effect of Size, pH, and Ionic Strength.

The quantification of surface charge properties of silica nanoparticles is essential for several applications. To determine these properties, many experimental and theoretical methods have been introduced, which are time-consuming and/or challenging to use. In this study, a first-principles approach is developed to determine the surface charge properties of amorphous silica nanoparticles against the nanoparticle size, pH, and ionic strength without relying on experimental data. An amorphous silica nanoparticle of 1.34 nm diameter is simulated by using integrated molecular dynamics and Monte Carlo methods. A detailed analysis of the nanoparticle structure is provided by analyzing the types of silanol groups on the surface. Moreover, a model is developed to estimate the probability distribution of the surface silanol groups based on the nearest neighbor distances and the diameter of the nanoparticle to determine the number of surface silanols on larger nanoparticles. Thereafter, a computational chemistry approach is used to calculate the acid dissociation constants of the corresponding deprotonation reactions. The calculated constants and the point of zero charge value are in excellent agreement with experiments. The surface charge properties of the nanoparticle with various diameters are then estimated by using a mean-field model at different pH and ionic strength values. The results of the developed model are compared to the Poisson-Boltzmann equation as a reference model. The developed model predictions agree well with the reference model for low and mid-electrolyte concentrations (1 and 10 mM) and small nanoparticles (smaller than 100 nm). However, the developed model seems to qualitatively predict the surface charge properties more accurately than the Poisson-Boltzmann model for high electrolyte concentrations.

Xylulose 5-phosphate production using enzymes immobilized on silica nanoparticles and its application for biohydrogen generation

Development of green hydrogen production is one of sustainable approaches to replace fossil fuels. An in vitro cell-free synthetic enzymatic pathway (SyPaB) for hydrogen production is an alternative to less effective microbial fermentation. To increase the production of xylulose 5-phosphate (Xu5-P); the rate-limiting step's product in the ATP-free SyPaB for biohydrogen production powered by xylooligomers, immobilization of cellodextrin phosphorylase, phosphopentomutase, and ribose-5-phosphate isomerase, on silica nano-particles (SiNPs) was evaluated. Immobilization of 1 Unit/mL of each enzyme on 15 to 20 mg of amorphous SiNPs for 120 min, at 4 °C gave the highest immobilization yield. Immobilized enzymes along with other 10 free enzymes gave maximum hydrogen generation rate of 3.618 mmole/L.hr after 0.8 h which 1.3 fold higher than using 13 free enzymes at the same conditions. The study reveals that immobilized enzymes efficiently produce Xylulose 5-phosphate, and its application in effective biohydrogen production, indicating potential for future enzyme immobilization.

Eco-friendly Synthesis and Characterization of Amorphous Nanosilica from Rice Husk

Background: A significant amount of rice production waste is rice husk. It is not humifiable and turns into a significant environmental pollutant if not properly utilized. Rice husk contains silica nanoparticles, which is a major inorganic component. High purity amorphous silica nanoparticles can thus be produced using simple thermo-chemical procedures without polluting the environment by cutting out the release of carbon dioxide during the process. Methods: A study was carried out to extract amorphous silica nanoparticles from rice husk ash using an environmentally benign chemical process. Utilising a variety of material characterization techniques viz., X-ray diffraction (XRD), fourier-transform infrared spectroscopy (FT-IR), field emission scanning electron microscope (FESEM), energy dispersive X-ray spectroscopy (EDS) and Particle size analyser (PSA), the extracted nanoparticles properties were confirmed. Result: The amorphous behaviour of the silica sample was confirmed using transmission electron microscopy-selected area electron diffraction patterns and X-ray diffraction analyses, whilst siloxane and silanol groups were primarily discovered using Fourier-transform infrared spectroscopy. Images obtained using scanning electron and transmission electron microscopy showed initial nanoparticles to be present along with secondary microparticles, possibly as a result of their agglomeration. The extracted amorphous silica has particles with an average diameter of 35 nm. This synthesized silica nanoparticles can be used in agriculture, nano-additives, microelectronics, sensors and in other fields.

The Apoptosis Inhibitor Protein Survivin Is a Critical Cytoprotective Resistor against Silica-Based Nanotoxicity.

Exposure to nanoparticles is inevitable as they become widely used in industry, cosmetics, and foods. However, knowledge of their (patho)physiological effects on biological entry routes of the human body and their underlying molecular mechanisms is still fragmented. Here, we examined the molecular effects of amorphous silica nanoparticles (aSiNPs) on cell lines mimicking the alveolar-capillary barrier of the lung. After state-of-the-art characterization of the used aSiNPs and the cell model, we performed cell viability-based assays and a protein analysis to determine the aSiNP-induced cell toxicity and underlying signaling mechanisms. We revealed that aSiNPs induce apoptosis in a dose-, time-, and size-dependent manner. aSiNP-induced toxicity involves the inhibition of pro-survival pathways, such as PI3K/AKT and ERK signaling, correlating with reduced expression of the anti-apoptotic protein Survivin on the protein and transcriptional levels. Furthermore, induced Survivin overexpression mediated resistance against aSiNP-toxicity. Thus, we present the first experimental evidence suggesting Survivin as a critical cytoprotective resistor against silica-based nanotoxicity, which may also play a role in responses to other NPs. Although Survivin's relevance as a biomarker for nanotoxicity needs to be demonstrated in vivo, our data give general impetus to investigate the pharmacological modulation of Survivin`s functions to attenuate the harmful effects of acute or chronic inhalative NP exposure.

P26-04: A Case for Amorphous Silica Nanoparticle Exposure in the Development of Chronic Kidney Disease of Unknown Etiology

P26-04: A Case for Amorphous Silica Nanoparticle Exposure in the Development of Chronic Kidney Disease of Unknown Etiology

Amorphous silica nanoparticles cause abnormal cytokinesis and multinucleation through dysfunction of the centralspindlin complex and microfilaments

BackgroundWith the large-scale production and application of amorphous silica nanoparticles (aSiNPs), its adverse health effects are more worthy of our attention. Our previous research has demonstrated for the first time that aSiNPs induced cytokinesis failure, which resulted in abnormally high incidences of multinucleation in vitro, but the underlying mechanisms remain unclear. Therefore, the purpose of this study was firstly to explore whether aSiNPs induced multinucleation in vivo, and secondly to investigate the underlying mechanism of how aSiNPs caused abnormal cytokinesis and multinucleation.MethodsMale ICR mice with intratracheal instillation of aSiNPs were used as an experimental model in vivo. Human hepatic cell line (L-02) was introduced for further mechanism study in vitro.ResultsIn vivo, histopathological results showed that the rate of multinucleation was significantly increased in the liver and lung tissue after aSiNPs treatment. In vitro, immunofluorescence results manifested that aSiNPs directly caused microfilaments aggregation. Following mechanism studies indicated that aSiNPs increased ROS levels. The accumulation of ROS further inhibited the PI3k 110β/Aurora B pathway, leading to a decrease in the expression of centralspindlin subunits MKLP1 and CYK4 as well as downstream cytokines regulation related proteins Ect2, Cep55, CHMP2A and RhoA. Meanwhile, the particles caused abnormal co-localization of the key mitotic regulatory kinase Aurora B and the centralspindlin complex by inhibiting the PI3k 110β/Aurora B pathway. PI3K activator IGF increased the phosphorylation level of Aurora B and improved the relative ratio of the centralspindlin cluster. And ROS inhibitors NAC reduced the ratio of multinucleation, alleviated the PI3k 110β/Aurora B pathway inhibition, and then increased the expression of MKLP1, CYK4 and cytokinesis-related proteins, whilst NAC restored the clustering of the centralspindlin.ConclusionThis study demonstrated that aSiNPs led to multinucleation formation both in vivo and in vitro. ASiNPs exposure caused microfilaments aggregation and inhibited the PI3k 110β/Aurora B pathway through excessive ROS, which then hindered the centralspindlin cluster as well as restrained the expression of centralspindlin subunits and cytokinesis-related proteins, which ultimately resulted in cytokinesis failure and the formation of multinucleation.

Synthesis and characterization of amorphous nano silica from South African coal fly ash

In this study, amorphous silica nanoparticle was extracted from South African coal fly ash (SACFA), using a facile sol–gel synthesis method. Prepared amorphous silica nanoparticles (ASNPs) were characterized employing X-ray fluorescence (XRF) spectroscopy, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), transition electron microscope (TEM), Brauer Emmett Teller (SBET) surface area analysis, and ultraviolet–visible diffuse reflection spectroscopy (UV–vis DRS). XRF analysis suggests SACFA as fly ash class F. the XRD pattern, reveals the structural compositing of SACFA and the amorphous nature of extracted SNP, while the FTIR assay shows the presence of silanol and siloxane groups. SEM and TEM analysis revealed primary silica nanoparticles were roughly spherical with sizes of about 98 nm. EDX spectral confirms the presence of SiO2. The findings of this study demonstrate a simple sol–gel method of synthesizing amorphous nano silica from SACFA, thus suggesting the utilization of SACFA in high-tech and complex material preparation and applications in a more inventive manner.

CO2‐Induced Modulation of Si–O Bonds for Low Temperature Plastic Deformation of Amorphous Silica Nanoparticles with Enhanced Photoluminescence

Modulation of Si–O bonds under mild conditions has been a challenging issue in the field of material science, which is critical to manufacture high‐performance silica‐based optical and photonic devices. Herein, we introduce a nondestructive technique to achieve Si–O bond rearrangement, leading to plastic deformation and photoluminescence enhancement of amorphous silica nanoparticles using supercritical carbon dioxides in EtOH/H2O solution under mild temperature. Specifically, plastic deformation is achieved by treating hollow mesoporous silica nanospheres using supercritical CO2 at 40 °C under 20 MPa. Experimental and theoretical studies revealed the critical role of supercritical CO2 in the plastic deformation process, which can be intercalated into the hollow mesoporous silica nanospheres with anisotropic stresses and induces the rearrangement of Si–O bonds and transformation of ring structures. This work suggests a novel approach to engineer high‐performance nano‐silica glass components for numerous optical and photonic devices under mild condition.

The Impact of Mesoporous Silica Nanoparticles on Electrochemical Performance

Mesoporous silica nanoparticles were synthesized via sol–gel method to produce uniform size nanoparticles using n-Octadecyl-trimethoxy silane which gives a good dispersion of silica nanoparticles in hydrophobic mediums. Scanning electron microscopy (SEM), infrared spectroscopy, X-ray diffraction (XRD), thermal gravimetric analysis, and nitrogen adsorption-desorption tests were used to thoroughly investigate the nanocomposites' morphology and structure. BET results show a high surface are of 760 m2/g and specific high pore size (30Ȧ) and pore volume (0.336 cm3/g). The SEM results present that the mesoporous silica nanoparticles possess a well dispersed and uniform particle morphology and FTIR interpenetrating the well-prepared silica nanoparticles which possess Si-O-Si and Si-O bond. The XRD analysis confirmed the amorphous nature silica nanoparticles. The electrochemical properties of silica nanoparticles were evaluated in a potassium chloride solution. With the advantages of a large specific surface area and a suitable pore size distribution, a pair of broad and symmetric redox peaks centred at -0.15 V and 0.6 V appears. Mesoporous silica with a large effective specific surface area demonstrated excellent electrochemical performance, making them excellent candidates for supercapacitors and fuel cells.

Evidence-Based Prediction of Cellular Toxicity for Amorphous Silica Nanoparticles.

Developing a generalized model for a robust prediction of nanotoxicity is critical for designing safe nanoparticles. However, complex toxicity mechanisms of nanoparticles in biological environments, such as biomolecular corona formation, prevent a reliable nanotoxicity prediction. This is exacerbated by the potential evaluation bias caused by internal validation, which is not fully appreciated. Herein, we propose an evidence-based prediction method for distinguishing between cytotoxic and noncytotoxic nanoparticles at a given condition by uniting literature data mining and machine learning. We illustrate the proposed method for amorphous silica nanoparticles (SiO2-NPs). SiO2-NPs are currently considered a safety concern; however, they are still widely produced and used in various consumer products. We generated the most diverse attributes of SiO2-NP cellular toxicity to date, using >100 publications, and built predictive models, with algorithms ranging from linear to nonlinear (deep neural network, kernel, and tree-based) classifiers. These models were validated using internal (4124-sample) and external (905-sample) data sets. The resultant categorical boosting (CatBoost) model outperformed other algorithms. We then identified 13 key attributes, including concentration, serum, cell, size, time, surface, and assay type, which can explain SiO2-NP toxicity, using the Shapley Additive exPlanation values in the CatBoost model. The serum attribute underscores the importance of nanoparticle-corona complexes for nanotoxicity prediction. We further show that internal validation does not guarantee generalizability. In general, safe SiO2-NPs can be obtained by modifying their surfaces and using low concentrations. Our work provides a strategy for predicting and explaining the toxicity of any type of engineered nanoparticles in real-world practice.

47 Safe-by-Design Advanced Materials: A case Study on Paint Formulation

Abstract Paint formulations are complex mixtures of both dissolved and particulate components, both organic and inorganic. Amorphous silica nanoparticles are included to make the paint layer dirt-repellent. Over entire life cycle of the paints containing such silica nanoparticles, however, their complex multicomponent composition may raise several concerns as to their hazard when exposed to humans and environment, notably due to the potential release of the incorporated nano-objects. To mitigate such concerns, several Safe-by-Design target specifications can be performed to provide revised/modified paint formulations with reduced potential risk. Within EU H2020 funded project, HARMLESS (grant agreement 953183), a specific industrial case study focuses on worker exposure measurement at the industrial production site of silane modified silica nanoparticles and consumer exposure measurement during sanding of the painted surfaces containing such silica nanoparticles. First results indicate that the tested paint samples (with and without silica nanoparticles) have strong tendencies to generate airborne nano-objects during their sanding. However, the fraction of silica in the overall chemical composition of the airborne nano-objects is currently being investigated. A fraction of the dust generated during the paint sanding is being analysed for its hazard via advanced in vitro approaches combined with a battery of toxicological endpoint analyses. Based on the results, if the exposure concentration of silica nanoparticles is found to be exceeding its nano reference value (i.e. 40,000 cm-3 TWA) and exhibits deleterious biological impact, the size and surface of silica nanoparticles will be modulated accordingly by keeping an optimum balance between their functionality and risk

63 A Case for Amorphous Silica Nanoparticle Exposure in the Development of Chronic Kidney Disease of Unknown Etiology

Abstract We have hypothesized that sugarcane burning in developing countries contributes to an endemic kidney pathology in agricultural workers called chronic kidney disease of an unknown etiology (CKDu). Elemental analysis shows that sugarcane stalks contain a high percentage of amorphous silica (SiO2). Therefore, we hypothesized that burning of sugarcane generates silica nanoparticles (SiNPs) that present an inhalation hazard to these agricultural workers. To determine if SiNPs are present in sugarcane ash and kidney biopsies from agricultural workers, we utilized single particle inductively coupled plasma mass spectrometry and found SiNPs, which ranged in size from 190-212 nm, in sugarcane ash. In a small cohort of CKDu patients from El Salvador and Mexico, we found a significant increase in the number of SiNPs in their kidney biopsies within a similar size range as observed in sugarcane ash. Additionally, Wistar rats exposed to sugarcane ash intranasally for 24 weeks developed focal injury in the tubulointerstitium and glomeruli with deposition of SiNPs in the kidney. To further determine the cellular effects of SiNPs, we exposed human proximal convoluted tubule (PCT) cells to sugarcane ash, de-silicated ash, or sugarcane ash derived SiNPs. Despite not being directly cytotoxic to PCT cells at 24 hrs, SiNPs were taken up and generated reactive oxygen species. Vimentin staining confirmed PCT cells underwent epithelial-mesenchymal transition (EMT) following treatment with ash or SiNPs but not with de-silicated ash. These findings suggest SiNPs present in sugarcane ash are capable of driving EMT in PCT cells potentially contributing to a CKDu phenotype.

Extraction and Physicochemical Characterization of Highly-pure Amorphous Silica Nanoparticles from Locally Available Dunes Sand

This study synthesized highly pure silica nanoparticles from the northeast Algerian Sahara dunes sand as a low-cost silica source using a simple and environmentally friendly method. The silica nanoparticles were extracted using a sodium silicate solution as a precursor without employing any additive agents. The extracted silica’s crystalline structure, chemical composition, chemical bonding, microstructure, elemental analysis, thermal analysis, and optical characteristics were investigated. The X-ray diffraction patterns demonstrate the amorphous nature of the extracted silica. Furthermore, the X-ray fluorescence spectroscopy (XRF) and energy dispersive X-ray (EDX) results prove the high purity of the extracted silica (99% SiO2). However, the Fourier-transform infrared spectroscopy (FTIR) results corroborate the presence of silanol and siloxane groups. According to the SEM image analysis, the produced silica has an average particle size in the range of nanometers. Thermal analysis (TGA/DTA) exhibited the high thermal stability of the silica, and the optical band gap energy for silica nanoparticles was determined to be 3.75 eV. Therefore, dunes sand is an alternative source for developing high-purity silica nanoparticles, which have great potential for advanced material applications.

Key Role of Choline Head Groups in Large Unilamellar Phospholipid Vesicles for the Interaction with and Rupture by Silica Nanoparticles.

For highly abundant silica nanomaterials, detrimental effects on proteins and phospholipids are postulated as critical molecular initiating events that involve hydrogen-bonding, hydrophobic, and/or hydrophilic interactions. Here, large unilamellar vesicles with various well-defined phospholipid compositions are used as biomimetic models to recapitulate membranolysis, a process known to be induced by silica nanoparticles in human cells. Differential analysis of the dominant phospholipids determined in membranes of alveolar lung epithelial cells demonstrates that the quaternary ammonium head groups of phosphatidylcholine and sphingomyelin play a critical and dose-dependent role in vesicle binding and rupture by amorphous colloidal silica nanoparticles. Surface modification by either protein adsorption or by covalent coupling of carboxyl groups suppresses the disintegration of these lipid vesicles, as well as membranolysis in human A549 lung epithelial cells by the silica nanoparticles. Furthermore, molecular modeling suggests a preferential affinity of silanol groups for choline head groups, which is also modulated by the pH value. Biomimetic lipid vesicles can thus be used to better understand specific phospholipid-nanoparticle interactions at the molecular level to support the rational design of safe advanced materials.

Human dendritic cell maturation induced by amorphous silica nanoparticles is Syk-dependent and triggered by lipid raft aggregation

BackgroundSynthetic amorphous silica nanoparticles (SAS-NPs) are widely employed in pharmaceutics, cosmetics, food and concretes. Workers and the general population are exposed daily via diverse routes of exposure. SAS-NPs are generally recognized as safe (GRAS) by the Food and Drug Administration, but because of their nanoscale size and extensive uses, a better assessment of their immunotoxicity is required. In the presence of immune “danger signals”, dendritic cells (DCs) undergo a maturation process resulting in their migration to regional lymph nodes where they activate naive T-cells. We have previously shown that fumed silica pyrogenic SAS-NPs promote the two first steps of the adaptative immune response by triggering DC maturation and T-lymphocyte response, suggesting that SAS-NPs could behave as immune “danger signals”. The present work aims to identify the mechanism and the signalling pathways involved in DC phenotype modifications provoked by pyrogenic SAS-NPs. As a pivotal intracellular signalling molecule whose phosphorylation is associated with DC maturation, we hypothesized that Spleen tyrosine kinase (Syk) may play a central role in SAS-NPs-induced DC response.ResultsIn human monocyte-derived dendritic cells (moDCs) exposed to SAS-NPs, Syk inhibition prevented the induction of CD83 and CD86 marker expression. A significant decrease in T-cell proliferation and IFN-γ, IL-17F and IL-9 production was found in an allogeneic moDC:T-cell co-culture model. These results suggested that the activation of Syk was necessary for optimal co-stimulation of T-cells. Moreover, Syk phosphorylation, observed 30 min after SAS-NP exposure, occurred upstream of the c-Jun N-terminal kinase (JNK) Mitogen-activated protein kinases (MAPK) and was elicited by the Src family of protein tyrosine kinases. Our results also showed for the first time that SAS-NPs provoked aggregation of lipid rafts in moDCs and that MβCD-mediated raft destabilisation altered Syk activation.ConclusionsWe showed that SAS-NPs could act as an immune danger signal in DCs through a Syk-dependent pathway. Our findings revealed an original mechanism whereby the interaction of SAS-NPs with DC membranes promoted aggregation of lipid rafts, leading to a Src kinase-initiated activation loop triggering Syk activation and functional DC maturation.

Microstructural engineering of zeolite membranes through composite seed layers

MFI membranes were synthesized using composite seeds consisting of zeolite nanocrystals and amorphous silica nanoparticles. The weight compositions of zeolite and silica particles were tuned to 100/0, 75/25, 50/50, and 25/75, respectively, which were then deposited as seed layers on porous alumina support through rubbing. At the seeded growth condition at 135 °C for 24 h, the film thickness of zeolite membranes grown from 4 different seed layers was similar to 3 μm, along with preferential crystal orientation to (h 0 h) direction. The upper parts of the zeolite membrane shared comparable film characteristics independent of seed composition, according to FCOM images of the MFI membranes. On the other hand, the zeolite membrane prepared from a seed layer of 75 wt% zeolite and 25 wt% silica particles had the greatest N2/SF6 gas selectivity of >175 and N2 gas permeance of >3300 GPU. Porosimetry also showed that there are fewer non-zeolite pathways in the zeolite membrane. Such results were attributed to differences in silica loading in the seed layer, where the silica species effectively altered the microstructure of zeolite membranes. The grain size of zeolite membranes increases as silica particle loading increases, reducing the chance of non-zeolitic defects occurring at grain boundaries. The composite seed with a silica loading of 25% was particularly successful because it did not inhibit the intergrowth of zeolite seed crystals while sacrificing slight N2 gas permanence. Thus, adding silica nanoparticles to the seed layer can help reduce non-zeolite defects in MFI membranes, according to this research. Further research is needed to prove that this method can be applied to zeolite membranes with other zeolite frameworks.

Rice husk-derived mesoporous biogenic silica nanoparticles for gravity chromatography

Biogenic silica nanoparticle is a superb alternative to synthetic silica because of their highly active, polar, and porous nanostructure with a large interior area. Among the available agricultural bioresources, biogenic silica extracted from rice husks could be a simple, easily available, and cost-effective resource to use as the stationary phase for the column chromatographic technique. In the present study, highly pure amorphous biogenic silica nanoparticles (bSNPs) were synthesized using rice husk by a controlled combustion route followed by the sol-gel method. The bSNPs show better performance for the separation and isolation of ortho- and para-nitrophenol and nitroaniline. The outstanding performance of the as-synthesized bSNPs is attributed to the high surface area, high porosity, and presence of Si–OH polar bonds. These preliminary findings imply that rice husk, an agricultural waste, could be an alternative source of silica and applicable as a stationary phase in column chromatography.

Silica nanoparticles and variety: their efficacy and interaction on the tomato fruit worm ( Helicoverpa armigera hubner) population infesting tomato (Solanum lycopersicum L.)

Field experiments were conducted at the Teaching and Research Farms of the University of Maiduguri and Mohamet Lawan College of Agriculture, Maiduguri, Nigeria to determine the effects of silica nanoparticles and tomato variety on the tomato fruit worm (Helicoverpa armigera Hübner) (Lepidoptera: Noctuidae). The treatments each replicated thrice were factorially combined and laid out in a split-plot design with four tomato varieties namely: UC-82, Dan Syria, Roma VF and Tima and three concentrations of amorphous silica nanoparticles (1000 ppm, 2000 ppm and 3000 ppm) and cypermethrin (as a check). Insecticides were applied during the fruiting stage at 7 days interval for 8 weeks. Larval holes and marketable fruit yield were recorded. Silica nanoparticles at 3000 ppm resulted in fewer larval population (39.25) at p < 0.05 with a resultant decrease in number of damaged fruits (36.58) as compared to lower doses of 1000 ppm and 2000 ppm. Cypermethrin also gave minimum population of larvae (39.12). In all tested varieties, Roma VF had the lowest larval population (28.79). Variety Roma VF in combination with both cypermethrin and silica nanoparticle at 3000 ppm resulted in lower larval population (19.67) and (28.67) respectively. These results show that silica nanoparticle at 3000 ppm acting together with Roma VF appreciably controls H. armigera in tomato, making both practices important components of IPM against this larval pest.