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The study aimed to apply biosilica nanoparticles from renewable resources for improving soil quality as a type of fertilizer carier. The silica particles having a purity of about 98 % were extracted from rice husk at the calcination temperatures of 550 °C, 600 °C, 650 °C, and 700 °C. The required materials properties were investigated by advanced measurement techniques. All samples showed the amorphous structure with Si–O–Si bond and the particles' agglomeration with the average size of 10–50 nm and principle electronic structures with the typical spectra of Si and O 2. When the synthesized silica was used as the medium to release absorbed nutrients in a controlled manner, surface properties, including the Brunauer–Emmett–Teller area and the average pore diameter were evaluated between 179 m2/g to 570 m2/g, and 4 nm–40 nm, respectively. The measured electrokinetic potential of the synthesized particles was between −20 mV and −36 mV guaranteeing the stability when they are dispersed in the aqueous environment. The experimental results showed that the silica particles calcinated at 650 °C had the best properties. [ABSTRACT FROM AUTHOR]

Gelatin methacrylate (GM) and sodium alginate (SA) are two biomaterials that have been widely employed in tissue engineering, particularly in 3D bioprinting. However, they have some drawbacks including undesirable physico‐mechanical properties and printability, hindering their application. This work developed an interpenetrating polymeric network (IPN) of GM and SA reinforced with silica nanoparticles (SNPs) to deal with hydrogels’ drawbacks. Besides, for cross‐linking, visible light is used as an alternative to UV light to prevent disruptions in cellular metabolism and immune system reactions. Four GM/SA/SNP hydrogels different in SNPs concentration (0, 0.5, 1, and 2 w/w%) are studied. The performance of the hydrogels is evaluated in terms of physico‐mechanical properties (viscoelasticity, compressive modulus, degradation, and swelling), rheological properties, and biological properties (fibroblast cell growth and adhesion, and MTT assay). The results demonstrated that the GM/SA/SNP hydrogel with 1% SNPs provided desirable physical (645% swelling and 59.3% degradation), mechanical strength (270 kPa), rheological (tan δ of almost 0.14), and biological performances (≈98% viability after 3 days) while maintaining appropriate printability. The findings suggest that the GM/SA/SNP hydrogel holds great potential for applications in soft tissue regeneration. [ABSTRACT FROM AUTHOR]

By using piezoelectric materials, it is possible to convert clean and renewable energy sources into electrical energy. In this paper, the effect on the piezoelectro-elastic response of piezoelectric-fiber-reinforced nanocomposites by adding silica nanoparticles into the polyimide matrix is investigated by a micromechanical method. First, the Ji and Mori–Tanaka models are used to calculate the properties of the nanoscale silica-filled polymer. The nanoparticle agglomeration and silica–polymer interphase are considered in the micromechanical modeling. Then, considering the filled polymer as the matrix and the piezoelectric fiber as the reinforcement, the Mori–Tanaka model is used to estimate the elastic and piezoelectric constants of the piezoelectric fibrous nanocomposites. It was found that adding silica nanoparticles into the polymer improves the elastic and piezoelectric properties of the piezoelectric fibrous nanocomposites. When the fiber volume fraction is 60%, the nanocomposite with the 3% silica-filled polyimide exhibits 39%, 31.8%, and 37% improvements in the transverse Young's modulus E T , transverse shear modulus G T L , and piezoelectric coefficient e 31 in comparison with the composite without nanoparticles. Furthermore, the piezoelectro-elastic properties such as E T , G T L , and e 31 can be improved as the nanoparticle diameter decreases. However, the elastic and piezoelectric constants of the piezoelectric fibrous nanocomposites decrease once the nanoparticles are agglomerated in the polymer matrix. A thick interphase with a high stiffness enhances the nanocomposite's piezoelectro-elastic performance. Also, the influence of volume fractions of the silica nanoparticles and piezoelectric fibers on the nanocomposite properties is studied. [ABSTRACT FROM AUTHOR]

Given the inevitable human exposure owing to its increasing production and utilization, the comprehensive safety evaluation of silica nanoparticles (SiNPs) has sparked concerns. Substantial evidence indicated liver damage by inhaled SiNPs. Notwithstanding, few reports focused on the persistence or reversibility of hepatic injuries, and the intricate molecular mechanisms involved remain limited. Here, rats are intratracheally instilled with SiNPs in two regimens (a 3‐month exposure and a subsequent 6‐week recovery after terminating SiNPs administration) to assess the hepatic effects. Nontargeted lipidomics revealed alterations in lipid metabolites as a contributor to the hepatic response and recovery effects of SiNPs. In line with the functional analysis of differential lipid metabolites, SiNPs activated oxidative stress, and induced lipid peroxidation and lipid deposition in the liver, as evidenced by the elevated hepatic levels of ROS, MDA, TC, and TG. Of note, these indicators showed great improvements after a 6‐week recovery, even returning to the control levels. According to the correlation, ROC curve, and SEM analysis, 11 lipids identified as potential regulatory molecules for ameliorating liver injury by SiNPs. Collectively, the work first revealed the reversibility of SiNP‐elicited hepatotoxicity from the perspective of lipidomics and offered valuable laboratory evidence and therapeutic strategy to facilitate nanosafety. [ABSTRACT FROM AUTHOR]

Dodecenylsuccinic anhydride was used as a surface modifier to further modify amino-functionalized silica nanoparticles, and the modified nanoparticles (RNS-1A-DDSA) showed good dispersion stability in both nonpolar PAO6 and polar DIOS base oils. The tribological properties of RNS-1A-DDSA were evaluated using an oscillating reciprocal friction and wear tester (SRV-5), and it was found to exhibit excellent tribological properties in both base oils with different polarities. EDS and SEM were used to characterize the wear surfaces, and combined with the results of AFM and QCM adsorption experiments, the reason for the applicability of RNS-1A-DDSA in both polar and non-polar base oils was deduced. [ABSTRACT FROM AUTHOR]

The coconut (Cocosnucifera) is renowned for its endocarp, commonly referred to as the coconut shell, which is believed to harbor a high concentration of silicon, potentially serving as a source for the production of silicon nanoparticles (SiO2NPs). This study demonstrated the synthesis of SiO2NPs derived from coconut shells and their application in the removal of metal contaminants, notably copper. SiO2NPs were synthesized with a recovery rate of 25.6%, yielding a white powder through the sol–gel method. Analysis via ultraviolet–visible (UV–Vis) spectroscopy revealed an absorbance peak maximum at 345 nm, indicative of strong surface plasmon resonance, thus confirming SiO2NPs formation. Morphological characterization conducted through field-emission scanning electron microscopy (FE-SEM) and field-emission transmission electron microscopy (FE-TEM) confirmed the smooth-faced nature of the SiO2NPs, presenting finely clumped particles with an average size of 62 nm. Furthermore, X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDX) analyses exhibited distinct peaks corresponding to oxygen (O) and silicon (Si), confirming SiO2NPs formation. X-ray diffraction (XRD) analysis confirmed the amorphous nature of the particles, with a 25% weight loss observed at 500 °C according to thermogravimetric analysis (TGA). Assessment of the adsorption capacity for heavy metals from water solutions by spiking various copper (II) sulfate concentrations indicated the highest adsorption rate at 0.05 M copper, diminishing with increased copper ion concentrations. Evaluations utilizing different SiO2NPs concentrations demonstrated optimal copper (Cu) removal efficiency at 0.2 g/mL SiO2NPs. [ABSTRACT FROM AUTHOR]

A concept to prepare a highly hydrophobic composite with self-healing properties has been designed and verified. The new material is based on a composite of a crystalline hydrophobic fluoro wax, synthesized from montan waxes and perfluoroethylene alcohols, combined with spherical silica nanoparticles equipped with a hydrophobic shell. Highly repellent layers were prepared using this combination of a hydrophobic crystalline wax and silica nanoparticles. The novel aspect of our concept was to prepare a ladder-like structure of the hydrophobic shell allowing the inclusion of a certain share of wax molecules. Wax molecules trapped in the hydrophobic structure during mixing are hindered from crystallizing; therefore, these molecules maintain a higher mobility compared to crystallized molecules. When a thin layer of the composite material is mechanically damaged, the mobile wax molecules can migrate and heal the defects to a certain extent. The general preparation of the composite is described and XRD analysis demonstrated that a certain share of wax molecules in the composite are hindered to crystallize. Furthermore, we show that the resulting material can recovery its repellent properties after surface damage. [ABSTRACT FROM AUTHOR]

Hollow silica nanoparticles (HSNPs) have hygroscopic properties because of their high specific surface area and surface hydroxyl groups. However, compared with other hygroscopic materials, their hygroscopic properties are relatively weak, which limits the further application of HSNPs. One feasible method to enhance their hygroscopic properties is by combining highly hygroscopic materials with hollow silica nanoparticles. To take advantage of the high hygroscopicity of polyacrylic acid (PAA) when combined with the high specific surface area of the hollow particles, PAA was coated on the inner and outer surfaces of the silica shell of the nanoparticles in this study to prepare hollow nanoparticles with a PAA/silica/PAA multilayer structure. The size of the PAA/silica/PAA multi-layer nanoparticles is about 85 nm, and the shell thickness is 25 nm. The specific surface area of the multi-layer nanoparticles is 58 m2/g. The water vapor adsorption capacity of multi-layer structure hollow nanoparticles was increased by 160% compared with the HSNPs (increased from 45.9 cm3/m2 to 109.1 cm3/m2). Meanwhile, at the same content of PAA, the PAA/silica/PAA-structured particles will adsorb 9% more water vapor than the PAA/silica-structured particles. This indicates that the high specific surface area structure of the hollow particles will enhance the adsorption ability of PAA toward water vapor. This novel structure of PAA-HSNPs is expected to be used as a humidity-regulating material for filler in environmental and architectural applications. [ABSTRACT FROM AUTHOR]

In this study, Taylor-vortex reactor was adopted to synthesize silica nanoparticles from sodium silicate solution and carbon dioxide. The outstanding advantages of the reactor have been demonstrated by comparing the synthesis results of silica nanoparticles by Erlenmeyer reactor. The results showed that silica particles synthesized from Taylor-vortex reactor are smaller in size than silica particles synthesized from the Erlenmeyer reactor. SEM images and histogram of particle size distribution obtained from experiments clearly exhibited that the concentration of SiO2 in the solution, reaction temperature, and rotation speed of the cylinder significantly affected morphology as well as size of the silica particles.

Abstract Background Silica nanoparticles (SNPs) have immense potential in biomedical research, particularly in drug delivery and imaging applications, owing to their stability and minimal interactions with biological entities such as tissues or cells. Results With synthesized and characterized cyanine-dye-doped fluorescent SNPs (CSNPs) using cyanine 3.5, 5.5, and 7 (Cy3.5, Cy5.5, and Cy7). Through systematic analysis, we discerned variations in the surface charge and fluorescence properties of the nanoparticles contingent on the encapsulated dye-(3-aminopropyl)triethoxysilane conjugate, while their size and shape remained constant. The fluorescence emission spectra exhibited a redshift correlated with increasing dye concentration, which was attributed to cascade energy transfer and self-quenching effects. Additionally, the fluorescence signal intensity showed a linear relationship with the particle concentration, particularly at lower dye equivalents, indicating a robust performance suitable for imaging applications. In vitro assessments revealed negligible cytotoxicity and efficient cellular uptake of the nanoparticles, enabling long-term tracking and imaging. Validation through in vivo imaging in mice underscored the versatility and efficacy of CSNPs, showing single-switching imaging capabilities and linear signal enhancement within subcutaneous tissue environment. Conclusions This study provides valuable insights for designing fluorescence imaging and optimizing nanoparticle-based applications in biomedical research, with potential implications for targeted drug delivery and in vivo imaging of tissue structures and organs. Graphical Abstract

Abstract Background Powder-based fingermark ridge visibility enhancement is a common technique employed in crime scenes due to ease of application and robustness of the application method. Pigmented powders created a contrast between the surfaces and developed ridgelines and are generally metals or metal oxides based. Previous research showed the successful development of fresh latent fingermarks using rice husk-derived silica nanoparticles on various surfaces. Nevertheless, there has been less previous evidence for the efficiency of the silica nanoparticle powder on aged fingermark development. Therefore, the aim here is to investigate the efficacy of the powder on aged fingermarks relative to commercial formulation to gauge the feasibility of having naturally derived powder as a possible alternative for field application and commercialisation. Results Rigorous testing over a range of non- and semi-porous surfaces at varied ageing conditions revealed a minimal disparity in the performance of both powders on most surfaces. Still, silica nanoparticles exhibited superiority in terms of selectivity on silica-based surfaces. Close up analysis of developed fingermarks using electron microscope exposed clear demarcation between fingermark ridges and valleys using silica nanoparticles. Conclusions Findings revealed that the interaction chemistry between powder particles and surface material either enhances or lowers the fingermark development capacity depending on the type of surface tested.

Background: Silica nanoparticles (SNPs) have immense potential in biomedical research, particularly in drug delivery and imaging applications, owing to their stability and minimal interactions with biological entities such as tissues or cells. Results: With synthesized and characterized cyanine-dye-doped fluorescent SNPs (CSNPs) using cyanine 3.5, 5.5, and 7 (Cy3.5, Cy5.5, and Cy7). Through systematic analysis, we discerned variations in the surface charge and fluorescence properties of the nanoparticles contingent on the encapsulated dye-(3-aminopropyl)triethoxysilane conjugate, while their size and shape remained constant. The fluorescence emission spectra exhibited a redshift correlated with increasing dye concentration, which was attributed to cascade energy transfer and self-quenching effects. Additionally, the fluorescence signal intensity showed a linear relationship with the particle concentration, particularly at lower dye equivalents, indicating a robust performance suitable for imaging applications. In vitro assessments revealed negligible cytotoxicity and efficient cellular uptake of the nanoparticles, enabling long-term tracking and imaging. Validation through in vivo imaging in mice underscored the versatility and efficacy of CSNPs, showing single-switching imaging capabilities and linear signal enhancement within subcutaneous tissue environment. Conclusions: This study provides valuable insights for designing fluorescence imaging and optimizing nanoparticle-based applications in biomedical research, with potential implications for targeted drug delivery and in vivo imaging of tissue structures and organs. [ABSTRACT FROM AUTHOR]

Silica nanoparticles (SiNPs) and graphene oxide (GO) are two promising nanomaterial that have attracted considerable attention for their unique properties and applications. However, the conventional synthesis methods of SiNPs and GO often involve hazardous chemicals and high energy consumption, which pose environmental and economic challenges. Therefore, green and sustainable synthesis methods of SiNPs and GO are highly desirable. In this review, we summarize the recent advances in the green synthesis of SiNPs and GO using various natural sources, such as plants, fungi, bacteria, algae, clay, etc. We also discuss the functionalization of SiNPs and GO with acrylic resin to form hybrid nanocomposites for anti-corrosion applications. The advantages and challenges of these green methods are highlighted, and the future prospects are outlined. This review aims to provide a comprehensive overview of the current state-of-the-art in the green synthesis of SiNPs and GO-based nanocomposites for anti-corrosion applications, and to inspire further research in this emerging field. [ABSTRACT FROM AUTHOR]

Background: Powder-based fingermark ridge visibility enhancement is a common technique employed in crime scenes due to ease of application and robustness of the application method. Pigmented powders created a contrast between the surfaces and developed ridgelines and are generally metals or metal oxides based. Previous research showed the successful development of fresh latent fingermarks using rice husk-derived silica nanoparticles on various surfaces. Nevertheless, there has been less previous evidence for the efficiency of the silica nanoparticle powder on aged fingermark development. Therefore, the aim here is to investigate the efficacy of the powder on aged fingermarks relative to commercial formulation to gauge the feasibility of having naturally derived powder as a possible alternative for field application and commercialisation. Results: Rigorous testing over a range of non- and semi-porous surfaces at varied ageing conditions revealed a minimal disparity in the performance of both powders on most surfaces. Still, silica nanoparticles exhibited superiority in terms of selectivity on silica-based surfaces. Close up analysis of developed fingermarks using electron microscope exposed clear demarcation between fingermark ridges and valleys using silica nanoparticles. Conclusions: Findings revealed that the interaction chemistry between powder particles and surface material either enhances or lowers the fingermark development capacity depending on the type of surface tested. [ABSTRACT FROM AUTHOR]

A new strategy for a catalytic C−C bond forming cascade reaction comprising acetal hydrolysis and Knoevenagel condensation is presented here. The heterogeneous nanocatalyst is prepared by immobilizing an ionic liquid on the surface of highly monodisperse silica nanoparticles. This work is the first example of showing that there is no need to use bifunctional acid‐base catalysts for a cascade reaction including the hydrolysis of benzaldehyde dimethyl acetal to benzaldehyde and the subsequent Knoevenagel condensation of the resulting benzaldehyde with malononitrile. It is shown here that these reactions can proceed smoothly with a mono‐functional heterogeneous catalyst that contains a neutral ionic liquid. It has been proposed that such a neutral ionic liquid can "switch on" to an acidic catalyst in conjunction with water. The selected ionic liquid has potentially biodegradability characteristics, which is an important issue to achieve a sustainable catalyst. The simple procedure for preparing both the ionic liquid and the monodisperse silica nanoparticles provides opportunities for a large‐scale synthesis of the catalyst. This work introduces a breakthrough in the design and synthesis of heterogeneous catalysts for acid/base catalyzed cascade organic reactions. [ABSTRACT FROM AUTHOR]

Germination, development, and production of directly seeded agricultural products may be impacted by a variety of abiotic stresses. Silica nanoparticle seed priming has the ability to reduce the impact of external stressors. Stress brought on by salt has now become a barrier to wheat (Triticum turgidum) farming success. The goal of the current research was to clarify the effectiveness of seed priming with silica nanoparticles in reducing salt-induced stress in wheat plants. In this research, silica nanoparticle at three distinct concentrations—300, 600 and 900 ppm—was used for seed priming either alone or in combination with sodium chloride (2.3 and 4.6 ds/m). The application of silica nanoparticles considerably improved seedling development while salinity stress greatly decreased germination percent and seedling growth. Seed priming significantly increased shoot length (11.53%), root length (22.76%), seedling length (17.57%), shoot weight (35.56%), root weight (19.14%), germination stress tolerance index (91.55%), shoot length stress tolerance index (11.58%), root length stress tolerance index (22.6%), shoot weight stress tolerance index (35.54%) and root weight stress tolerance index (18.12%) under high saline treatment (4.6 ds/m). The significance of nano-silica in reducing the detrimental effects of salt stress on wheat seed growth is highlighted by the current investigation. The results showed that silica nanoparticle seed priming could enhance seedling early development under salt stress. [ABSTRACT FROM AUTHOR]

This work reports the fabrication of a large‐sized hydrogel sheet with enhanced mechanical and adhesive properties. The fabrication involves the introduction of carboxymethyl‐modified cellulose nanofibers (m‐CNFs) and solid silica nanoparticles (SSNs) as physical cross‐linkers into acrylic acid monomer (AA), followed by bar coating and photopolymerization. The addition of the nanomaterials to the monomer solution renders it viscous, enabling the fabrication of A4‐sized hydrogel sheets with uniform thickness and enhanced mechanical and adhesive properties. Interestingly, the combined incorporation of both the nanomaterials generates a synergistic effect to improve the properties much more, which results from the hierarchical rupture of the multiple hydrogen‐bonded interactions among the poly(acrylic acid) (PAA) matrix, m‐CNFs, and SSNs. Under optimal conditions, the hydrogel sheet incorporated with the dual crosslinkers exhibits a sevenfold higher toughness and a sixfold increased peel strength than plain PAA, together with good biocompatibility. Furthermore, when mesoporous silica nanoparticles (MSNs) with active agent loading into their pores are incorporated instead of SSNs, the active agent can be released from the hydrogel sheet in a sustained or temperature‐sensitive manner, indicating that the system is potentially applicable to transdermal drug delivery system with no additional adhesive. [ABSTRACT FROM AUTHOR]

Foam stability tests were performed using sodium dodecyl sulfate (SDS) surfactant and SiO2 nanoparticles as foaming system at different asphaltene concentrations, and the half-life of CO2 foam was measured. The mechanism of foam stability reduction in the presence of asphaltene was analyzed by scanning electron microscope (SEM), UV adsorption spectrophotometric concentration measurement and Zeta potential measurement. When the mass ratio of synthetic oil to foam-formation suspension was 1:9 and the asphaltene mass fraction increased from 0 to 15%, the half-life of SDS-stabilized foams decreased from 751 s to 239 s, and the half-life of SDS/silica-stabilized foams decreased from 912 s to 298 s. When the mass ratio of synthetic oil to foam-formation suspension was 2:8 and the asphaltene mass fraction increased from 0 to 15%, the half-life of SDS-stabilized foams decreased from 526 s to 171 s, and the half-life of SDS/silica-stabilized foams decreased from 660 s to 205 s. In addition, due to asphaltene-SDS/silica interaction in the aqueous phase, the absolute value of Zeta potential decreases, and the surface charges of particles reduce, leading to the reduction of repulsive forces between two interfaces of thin liquid film, which in turn, damages the foam stability.

[Display omitted] We have learned from the recent COVID-19 pandemic that the emergence of a new virus can quickly become a global health burden and kill millions of lives. Antiviral drugs are essential in our fight against viral diseases, but most of them are virus-specific and are prone to viral mutations. We have developed broad-spectrum antivirals based on multivalent nanoparticles grafted with ligands that mimic the target of viral attachment ligands (VALs). We have shown that when the ligand has a sufficiently long hydrophobic tail, the inhibition mechanism switches from reversible (virustatic) to irreversible (virucidal). Here, we investigate further how ligand density and particle size affect antiviral efficacy, both in terms of half-inhibitory concentration (IC 50) and of reversible vs irreversible mechanism. We designed antiviral silica nanoparticles modified with 11-mercaptoundecane-1-sulfonic acid (MUS), a ligand that mimics heparan sulfate proteoglycans (HSPG) and we showed that these nanoparticles can be synthesized with different sizes (4–200 nm) and ligand grafting densities (0.59–10.70 /nm2). By testing these particles against herpes simplex virus type 2 (HSV-2), we show that within the size and density ranges studied, the antiviral IC 50 is determined solely by equivalent ligand concentration. The nanoparticles are found to be virucidal at all sizes and densities studied. [ABSTRACT FROM AUTHOR]

Efforts to improve the properties of composites have involved extensive studies regarding the effective incorporation of a polymer matrix and inorganic fillers. In this work, we generated a stable organosilica sol with high concentration and high purity by surface modification with silane coupling agents, then integrated it with an epoxy matrix. The silica nanoparticle/epoxy composite exhibited improved tensile strength because of the uniform distribution of silica in the matrix, as well as the interfacial chemical bonding between polymer and silica nanoparticles; these factors resulted in effective load transfer from matrix to fillers. Additionally, the application of copper-clad laminates (CCLs) with prepreg-containing silica nanoparticles led to substantial improvements in mechanical properties, including peel strength (0.46 kgf/cm) and storage modulus (30.0 GPa), compared with conventional CCLs lacking silica nanoparticles. These results suggest that prepregs containing surface-modified silica nanoparticles have great potential for use as printed circuit board substrate materials in high-performance electronics. [ABSTRACT FROM AUTHOR]

[Display omitted] The adsorption of proteins on nanoparticles (NPs) largely decides the fate and bioeffects of NPs in vivo. However, bio-fluids are too complicated to directly study in them to reveal related mechanisms, and current studies on model systems often ignore some important biological factors, such as metal ions. Herein, we evaluate the effect of Ca2+ at physiological concentrations on the protein adsorption on negatively-charged silica NP (SNP50). It is found that Ca2+, as well as Mg2+ and several transition metal ions, significantly enhances the adsorption of negatively-charged proteins on SNP50. Moreover, the Ca2+-induced enhancement of protein adsorption leads to the reduced uptake of SNP50 by HeLa cells. A double-chelating mechanism is proposed for the enhanced adsorption of negatively-charged proteins by multivalent metal ions that can form 6 (or more) coordinate bonds, where the metal ions are chelated by both the surface groups of NPs and the surface residues of the adsorbed proteins. This mechanism is consistent with all experimental evidences from metal ions-induced changes of physicochemical properties of NPs to protein adsorption isotherms, and is validated with several model proteins as well as complicated serum. The findings highlight the importance of investigating the influences of physiological factors on the interaction between proteins and NPs. [ABSTRACT FROM AUTHOR]

Recently, silica nanoparticles (NPs) have attracted considerable attention as biocompatible and stable templates for embedding noble metals. Noble-metal-embedded silica NPs utilize the exceptional optical properties of novel metals while overcoming the limitations of individual novel metal NPs. In addition, the structure of metal-embedded silica NPs decorated with small metal NPs around the silica core results in strong signal enhancement in localized surface plasmon resonance and surface-enhanced Raman scattering. This review summarizes recent studies on metal-embedded silica NPs, focusing on their unique designs and applications. The characteristics of the metal-embedded silica NPs depend on the type and structure of the embedded metals. Based on this progress, metal-embedded silica NPs are currently utilized in various spectroscopic applications, serving as nanozymes, detection and imaging probes, drug carriers, photothermal inducers, and bioactivation molecule screening identifiers. Owing to their versatile roles, metal-embedded silica NPs are expected to be applied in various fields, such as biology and medicine, in the future. [ABSTRACT FROM AUTHOR]

Foam stability tests were performed using sodium dodecyl sulfate (SDS) surfactant and SiO2 nanoparticles as foaming system at different asphaltene concentrations, and the half-life of CO2 foam was measured. The mechanism of foam stability reduction in the presence of asphaltene was analyzed by scanning electron microscope (SEM), UV adsorption spectrophotometric concentration measurement and Zeta potential measurement. When the mass ratio of synthetic oil to foam-formation suspension was 1:9 and the asphaltene mass fraction increased from 0 to 15%, the half-life of SDS-stabilized foams decreased from 751 s to 239 s, and the half-life of SDS/silica-stabilized foams decreased from 912 s to 298 s. When the mass ratio of synthetic oil to foam-formation suspension was 2:8 and the asphaltene mass fraction increased from 0 to 15%, the half-life of SDS-stabilized foams decreased from 526 s to 171 s, and the half-life of SDS/silica-stabilized foams decreased from 660 s to 205 s. In addition, due to asphaltene-SDS/silica interaction in the aqueous phase, the absolute value of Zeta potential decreases, and the surface charges of particles reduce, leading to the reduction of repulsive forces between two interfaces of thin liquid film, which in turn, damages the foam stability. [ABSTRACT FROM AUTHOR]

The preparation of bulk-fused silica glass using stimuli-responsive silica nanoparticle (SiNP) aggregation methods is a promising research topic. For instance, the use of a SiNP/polyethylene glycol (PEG)/polyvinyl butyral (PVB) system for thermoplastic nanocomposite preparation, followed by heat-treatment sintering, has emerged as a highly precise and scalable method for obtaining fused silica glass with a short processing time. In this study, transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS), and rheological analysis were used to investigate the dispersion of SiNPs in water, ethanol, water/ethanol, and water/ethanol/PEG mixtures. Furthermore, we investigated the effect of the different solvents on regulating external stimuli in the preparation of a SiNP slurry. Our results indicate that water/ethanol mixtures have a greater ability to obtain dispersed and thin slurries than water or ethanol alone, while the inclusion of PEG can further enhance this effect.The feedstocks obtained by this method is favorable for obtaining defect-free fused silica glass. In addition, agglomerates formed by SiNPs in a liquid environment can be rearranged and partially disassembled under the action of mechanical (shear) forces. Finally, optical profilometry tests showed that the sintered fused silica glass exhibited good surface quality replication, with a roughness Sa of only 148 nm. The finding in this study provides an idea for the preparation of commercial slurry for sintering fused silica glass. [ABSTRACT FROM AUTHOR]

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Diabetes has affected nearly half a billion people worldwide. According to current guidelines, glycemic control is essential to mitigate diabetic complications. The antihyperglycemic effects of various chemically synthesized nanoparticles have been reported in animal models. However, their impact on humans has not been previously reported. This study was conducted to biosynthesize and assess the antihyperglycemic property of silica nanoparticles (SiO2-NPs) since they are non-toxic and biocompatible. SiO2-NPs biosynthesized using the endophytic fungus Fusarium oxysporum. In this collaborative study, 26 people, either hyperglycemic or euglycemic, diagnosed at the Endocrinology Outpatients, according to the American Diabetes Association, USA, were recruited. Silica nanoparticles were characterized and assessed for in vitro antihyperglycemic property using blood samples. Particle size distribution based on TEM images confirms that the average size of silica nanoparticle is 25 nm and is monodispersed in nature. The XRD pattern shows that only one broad peak at 2θ = 220 corresponds to the plane (101) of silica nanoparticles. UV Visible spectra show the λmax at 270 nm, peaks in FTIR at 1536 cm−1, 1640 cm−1, and 3420 cm−1 for the protein cap. The mean blood glucose was 120.2 mg/dL in the 'SiO2-NP untreated' group and decreased to 97.24 mg/dL in the 'SiO2-NP treated' group. A paired t-test (P-value < 0.0001) indicates a strong relationship between antihyperglycemia and silica NP. In our study, it has been observed that the biosynthesized silica nanoparticles using the endophytic fungus Fusarium oxysporum show antihyperglycemic property in vitro. [ABSTRACT FROM AUTHOR]

Abstract This work reports the fabrication of a large‐sized hydrogel sheet with enhanced mechanical and adhesive properties. The fabrication involves the introduction of carboxymethyl‐modified cellulose nanofibers (m‐CNFs) and solid silica nanoparticles (SSNs) as physical cross‐linkers into acrylic acid monomer (AA), followed by bar coating and photopolymerization. The addition of the nanomaterials to the monomer solution renders it viscous, enabling the fabrication of A4‐sized hydrogel sheets with uniform thickness and enhanced mechanical and adhesive properties. Interestingly, the combined incorporation of both the nanomaterials generates a synergistic effect to improve the properties much more, which results from the hierarchical rupture of the multiple hydrogen‐bonded interactions among the poly(acrylic acid) (PAA) matrix, m‐CNFs, and SSNs. Under optimal conditions, the hydrogel sheet incorporated with the dual crosslinkers exhibits a sevenfold higher toughness and a sixfold increased peel strength than plain PAA, together with good biocompatibility. Furthermore, when mesoporous silica nanoparticles (MSNs) with active agent loading into their pores are incorporated instead of SSNs, the active agent can be released from the hydrogel sheet in a sustained or temperature‐sensitive manner, indicating that the system is potentially applicable to transdermal drug delivery system with no additional adhesive.

A concept to prepare a highly hydrophobic composite with self-healing properties has been designed and verified. The new material is based on a composite of a crystalline hydrophobic fluoro wax, synthesized from montan waxes and perfluoroethylene alcohols, combined with spherical silica nanoparticles equipped with a hydrophobic shell. Highly repellent layers were prepared using this combination of a hydrophobic crystalline wax and silica nanoparticles. The novel aspect of our concept was to prepare a ladder-like structure of the hydrophobic shell allowing the inclusion of a certain share of wax molecules. Wax molecules trapped in the hydrophobic structure during mixing are hindered from crystallizing; therefore, these molecules maintain a higher mobility compared to crystallized molecules. When a thin layer of the composite material is mechanically damaged, the mobile wax molecules can migrate and heal the defects to a certain extent. The general preparation of the composite is described and XRD analysis demonstrated that a certain share of wax molecules in the composite are hindered to crystallize. Furthermore, we show that the resulting material can recovery its repellent properties after surface damage.

BackgroundSilica nanoparticles (SiNPs) enter the human body through respiratory tract, digestive tract, and skin, causing body damage. Lung is one of the main damaged organs. ObjectiveTo observe the expressions of complement activated fragment C3a and its receptor C3aR in the lungs of mice exposed to SiNPs through respiratory tract, and to explore the involvement of C3a/C3aR in lung injury induced by SiNPs exposure. MethodsThe ultrastructure of SiNPs (particle size 5-20 nm) was determined under a transmission electron microscope, and the hydrodynamic diameter and surface Zeta potential of SiNPs were determined using a nanoparticle size analyzer. A total of 88 SPF C57BL/6J mice were randomly divided into five groups: a blank control group without any treatment (14 mice), a vehicle control group treated with 50 μL stroke-physiological saline solution by intratracheal instillation (14 mice), and three SiNPs exposure groups (low-dose group, medium-dose group, and high-dose group with 20 mice in each group, who were given 50 μL SiNPs suspension of 7, 21, and 35 mg·kg−1 respectively and exposed once every 3 days for 5 times). The mice were anesthetized on day 1 (1-day model group) and day 15 (15-day model group) after exposure, then sacrificed after extraction of bronchoalveolar lavage fluid (BALF), and lung tissues were retained. The morphological changes of lung tissues were observed by HE staining, the expression level of C3a in BALF was detected by enzyme-linked immunosorbent assay, the deposition of C3a and C3aR in lung tissues were observed by immunohistochemistry, the protein expression level of C3aR was determined by Western blotting, and the localization and semi-quantitative detection of C3a and C3aR in lung tissues was observed by immunofluorescence. ResultsSiNPs agglomerated in stroke-physiological saline solution. The average hydrodynamic diameter was (185.60±7.39) nm and the absolute value of Zeta potential was (43.33±0.76) mV. The condition of mice in the 1-day model group and the 15-day model group was good, while 2 mice died in the medium-dose group of the 1-day model group due to misoperation. The autopsy results of the two mice showed congestion of the lung tissue, emphysema, and no imperfection of trachea integrity. No death was observed in other dose groups. The HE staining results showed pathological damage to the mouse lung, including alveolar wall thickening and inflammatory cell infiltration after SiNPs exposure. The pathological damage became more serious with the increase of dose. Regarding pathological changes, the 15-day model group was slightly relieved compared with the 1-day model group, but there were still pathological changes. The enzyme-linked immunosorbent assay results showed that there was no difference in the expression level of C3a between the blank control group and the vehicle control group (P＞0.05), the expression levels of C3a in the medium-dose group and the high-dose group were significantly higher than that in the vehicle control group (P

Silica nanoparticle (SiNP) exposure induces severe pulmonary inflammation and fibrosis, but the pathogenesis remains unclear, and effective therapies are currently lacking. To explore the mechanism underlying SiNPs-induced pulmonary fibrosis, we constructed in vivo silica exposure animal models and in vitro models of silica-induced macrophage pyroptosis and fibroblast transdifferentiation. We found that SiNP exposure elicits upregulation of pulmonary proteins associated with pyroptosis, including NLRP3, ASC, IL-1β, and GSDMD, while the immunofluorescence staining co-localized NLRP3 and GSDMD with macrophage-specific biomarker F4/80 in silica-exposed lung tissues. However, the NLRP3 inhibitor MCC950 and classical anti-fibrosis drug pirfenidone (PFD) were found to be able to alleviate silica-induced collagen deposition in the lungs. In in vitro studies, we exposed the fibroblast to a conditioned medium from silica-induced pyroptotic macrophages and found enhanced expression of α-SMA, suggesting increased transdifferentiation of fibroblast to myofibroblast. In line with in vivo studies, the combined treatment of MCC950 and PFD was demonstrated to inhibit the expression of α-SMA and attenuate fibroblast transdifferentiation. Mechanistically, we adopted high throughput RNA sequencing on fibroblast with different treatments and found activated signaling of relaxin and osteoclast differentiation pathways, where the expression of the dysregulated genes in these two pathways was examined and found to be consistently altered both in vitro and in vivo. Collectively, our study demonstrates that SiNP exposure induces macrophage pyroptosis, which subsequently causes fibroblast transdifferentiation to myofibroblasts, in which the relaxin and osteoclast differentiation signaling pathways play crucial roles. These findings may provide valuable references for developing new therapies for pulmonary fibrosis.

The utilization of nanoparticles in agricultural land is widely increasing worldwide. The present study takes the advent from converting the rice husk waste to silica nanoparticles (SiNPs) to be used in two years of field experiments, as fertigation treatment, against reducing irrigation by drip system. In this respect, the experiments comprised of three drip irrigation regimes (i.e., 60, 80, and 100 % of crop evapotranspiration, ETc) and four levels of SiNPs (0, 100, 200, and 300 mg L−1). The results indicated that limited irrigation reduced the plant fresh weight, plant height, and yield of eggplants by 15, 25, and 30 %, an average of two years, at the level of 60 % ETc compared to 100 % ETc. However, these negative impacts were alleviated by SiNPs via improving the photosynthetic pigments and relative water content where the plants supplemented with 300 mg L−1 SiNPs had the highest improving effects to be 3.8 mg g−1 FW and 76 % compared to 2.2 mg g−1 FW and 63 % (average of two years), respectively at the drought level of 60 % ETc. Furthermore, SiNPs ameliorated the oxidative damage induced by different water regimes by lessening lipid peroxidation and hydrogen peroxide (10.9 and 85.4 µM g−1 FW) compared to their drought level 60 % ETc (14 and 113 µM g−1 FW). This was associated with stimulating the antioxidant enzyme system by promoting the activities of peroxidases (ascorbate- and guaiacol-dependent types), catalase, and superoxide dismutase as the concentration of silica NPs increased to be (173.84, 12.2, 49.5, and 41 unit/mg/min, respectively) at 60 % ETc and 300 mg L−1 SiNPs compared to only 60 % ETc (100.5, 7.9, 32, and 30.5 unit/mg/min, respectively). Also, efficiently increasing SiNPs levels highly significantly restrained the ionic homeostasis in the leaves of eggplant via retaining the reduction of silicon, potassium, calcium, and magnesium contents at 300 mg L−1 silica NPs especially at 60 % ETc (33, 19, 4.5, and 6 mg g−1 DW, respectively) compared to the corresponding drought level (17.33, 7, 2.1, and 3.7 mg g−1 DW, respectively) which reflected on the up-regulation of water status. Such amelioration effects of SiNPs were recommended during the two studied seasons. Altogether, the synthesized SiNPs efficiently mitigated the negative impacts of limited drip irrigation levels on ionic homeostasis, pigments, oxidative stress, and antioxidant system especially at the level of 300 mg L−1.

[Display omitted] Pharmaceutical formulation of oral dosage forms is continuously challenged by the low solubility of new drug candidates. Pickering emulsions, emulsions stabilized with solid particles, are a promising alternative to surfactants for developing long-term stable emulsions that can be tailored for controlled release of lipophilic drugs. In this work, a non-emulsifying lipid-based formulation (LBF) loaded with fenofibrate was formulated into an oil-in-water (O/W) emulsion synergistically stabilized by stearic acid and silica (SiO 2) nanoparticles. The emulsion had a droplet size of 341 nm with SiO 2 particles partially covering the oil–water interface. In vitro lipid digestion was faster for the emulsion compared to the corresponding LBF due to the larger total surface area available for digestion. Cellulose biopolymers were added to the emulsion to produce a gel for semi-solid extrusion (SSE) 3D printing into tablets. The emulsion gel showed suitable rheological attributes for SSE, with a trend of higher viscosity, yield stress, and storage modulus (G′), compared to a conventional self-emulsifying lipid-based emulsion gel. The developed emulsion gel allows for a non-emulsifying LBF to be transformed into solid dosage forms for rapid lipid digestion and drug release of a poorly water-soluble drug in the small intestine. [ABSTRACT FROM AUTHOR]

In recent years, the use of nanotechnology-based methods has become widespread in the treatment of ocular diseases. Silica nanoparticles (SiO 2 NPs) are most common used NPs in medical field due to their physicochemical properties. SiO 2 NPs can easily cross biological membranes and interact with basic biological structures, causing structural and functional changes in cells. In this study, it was aimed to investigate the dose dependent effect of SiO 2 NPs on retinal pigment epithelium (RPE) in vitro using electrobiophysical, biochemical and histological methods. A commercially purchased human RPE (hARPE-19) cell line was used in this study. Cells were divided into four groups as control, 50 μg/mL SiO 2 , 100 μg/mL SiO 2 and 150 μg/mL SiO 2 groups. Cell index, apoptotic activity, cell cycle and oxidative stress markers were measured in all groups. Findings in the present study showed that SiO 2 nanoparticles reduced cell proliferation, increased oxidative stress, apoptosis and arrest in the G 0 /G 1 phase of the cell cycle as dose dependent manner in ARPE-19 cells. In conclusion, SiO 2 exposure can induce cytotoxic effects in RPE cell line. The results of this study provide clues that exposure to SiO 2 nanoparticles may impair visual function and reduce quality of life. However, further studies are needed in this regard. • SiO 2 nanoparticles are used as drug carriers in the treatment of many eye diseases. • SiO 2 nanoparticles have toxic effects that should not be ignored. • SiO 2 nanoparticles reduce cell proliferation in hARPE19 cells. • SiO 2 nanoparticles induce apoptosis and Go/G1 arrest in hARPE19 cells. • SiO 2 nanoparticles cause induce oxidative stress leading to cell death in hARPE19 cells. [ABSTRACT FROM AUTHOR]

Fumed silica (SiO2) is often applied in the modification of thin‐film composite (TFC) forward osmosis (FO) membranes due to its hydrophilicity. However, a key challenge to be solved is to improve its compatibility with organic matrices and dispersion in the material. In this study, we synthesized well‐designed nanoparticles of (3‐aminopropyl)trimethoxysilane‐modified SiO2 (APTMS‐SiO2) and applied them for the first time in the preparation of FO membranes. Furthermore, we systematically investigated the effects of different pretreated SiO2, SiO2 dosages, draw solution types, and concentrations on FO membranes. The results showed that APTMS‐SiO2 thin‐film nanocomposite with a silica dosage of 0.1 wt.% has the highest water permeate flux (Jw) (26.25 LMH, 370.43 % higher than the control TFC of 5.58 LMH) and the minimum specific reverse solute flux (SRSF) of 0.17 g/L with 1 M NaCl as the draw. The incorporation of APTMS effectively prevented mutual agglomeration of SiO2 and improved its dispersion. The Jw of 13.36 LMH after seven cycles and the rejection of above 96.6 % for Congo Red and 95.8 % for Rhodamine B indicated potential reusability and dye rejection. This work presents an alternative approach to prepare FO membranes with enhanced water flux and increased selectivity, and it also offers insights for the treatment of printing and dyeing wastewater using FO. [ABSTRACT FROM AUTHOR]

Surface-enhanced Raman scattering technology plays a prominent role in spectroscopy. By introducing plasmonic metals and photonic crystals as a substrate, SERS signals can achieve further enhancement. However, the conventional doping preparation methods of these SERS substrates are insufficient in terms of metal-loading capacity and the coupling strength between plasmonic metals and photonic crystals, both of which reduce the SERS activity and reproducibility of SERS substrates. In this work, we report an approach combining spin-coating, surface modification, and in situ reduction methods. Using this approach, a photonic crystal array of SiO2@Au core–shell structure nanoparticles was prepared as a SERS substrate (SiO2@Au NP array). To study the SERS properties of these substrates, Rhodamine 6G was employed as the probe molecule. Compared with a Au-SiO2 NP array prepared using doping methods, the SiO2@Au NP array presented better SERS properties, and it reproduced the SERS spectra after one month. The detection limit of the Rhodamine 6G on SiO2@Au NP array reached 1 × 10−8 mol/L; furthermore, the relative standard deviation (9.82%) of reproducibility and the enhancement factor (1.51 × 106) were evaluated. Our approach provides a new potential option for the preparation of SERS substrates and offers a potential advantage in trace contaminant detection, and nondestructive testing. [ABSTRACT FROM AUTHOR]

Oil-based drilling fluids for deep well drilling should have stability and high temperature resistance, and water-in-oil inverse emulsions are a good choice as oil-based drilling fluids. In deep well drilling, high temperature will cause polymer surfactants to degrade and phase separation occurs. The octadecyltrimethoxysilane modified silica nanoparticles are used to form a stable water-in-oil inverse emulsion in a drilling fluid model, so that the emulsion fluid forms 60 µm water droplets. In addition, rheology shows that the use of hydrophobic silica nanoparticles can obtain stable water-in-oil inverse emulsions, the properties of which can be modified by adjusting the properties and content of the nanoparticles. The aging test at 120 °C shows that it has good stability at high temperatures and is suitable for deep well drilling operations. [ABSTRACT FROM AUTHOR]

In this study, we were able to create highly dispersed silica nanoparticles with diameters of less than one nm by changing the sol-gel technique. During the poly-condensation process, a strong magnetic field was applied to the silica sol to control particle size. The size of silica nanoparticles has a substantial impact on preparation elements such pH, magnetic field intensity, and exposure time. These parameters can be changed in a systematic manner to reduce or increase particle size. A dynamic light scattering test was also used to investigate the effect of a magnetic field on the particle size and dispersion of silica dust. Despite the fact that silica is naturally diamagnetic, the magnetic field has a considerable impact on their size growth. Magnetic fields altered the typical influence on silicon structure, resulting in crystal formation in the silicon sample under consideration. Many applications require small particle sizes and/or a narrow particle size dispersion. The building blocks of nanotechnology are usually made of low-dimension particles. The experts concluded that additional research into such strange phenomena will be required in the future. [ABSTRACT FROM AUTHOR]

Bleeding complications are associated with substantial tissue morbidities and mortalities. Biomimetic composite materials that possess the ability to sufficiently stimulate and augment different physiological mechanisms of hemostasis are highly desirable to reduce bleeding-related casualties, which, however, are still largely under-explored. This study aims to develop a composite hemostatic system by combining collagen hydrogel with tissue factor (TF)-integrated liposome and silica nanoparticle, which could integrate the platelet plug-promoting capacity of collagen with the abilities of the latter two components to activate the extrinsic and intrinsic pathways of coagulation respectively. Several hydrogel compositions were synthesized and characterized. We show that lipidated TF and silica were evenly distributed in the collagen-based hydrogels, while exhibiting tunable release kinetics in simulated body fluid. Time-to-coagulation test revealed that each component in the TF-liposome/silica/collagen ternary hydrogels was hemostasis-active, and their combination showed enhanced and potent procoagulant performance, without detectable cytotoxicity against NIH/3T3 model cells. These results suggest that collagen hydrogels with embedded TF-liposome and silica nanoparticle may serve as a platform for an effective hemostatic composite that incorporates all the basic known pathways of coagulation. [ABSTRACT FROM AUTHOR]

In this study, we have prepared silica nanoparticles (SiNPs) from biomass (rice husk) and organic precursor (TEOS) by sol‐gel precipitation method and compared their efficacy for theranostics applications. In the preparation of SiNPs, we have studied the effects of different parameters such as solvent, catalyst, temperature, water and precursor on the shape and size of SiNPs. It shows that the size of SiNPs was increased with an increase in the concentration of ethanol and acid catalyst; the particle size was decreased with an increase in reaction temperature and precursor. To develop the drug for photodynamic therapy against the target tumor cells, protoporphyrin (PpIX), an efficient photosensitizer is functionalized on the surface of SiNPs. The drug loading potential was studied by the conjugation of 5‐Fluorouracil on the surface of functionalized SiNPs. From the results, we suggest that the functionalized SiNPs will be used for combined therapeutic and diagnostic in biomedical applications. [ABSTRACT FROM AUTHOR]

Recently, silica nanoparticles (NPs) have attracted considerable attention as biocompatible and stable templates for embedding noble metals. Noble-metal-embedded silica NPs utilize the exceptional optical properties of novel metals while overcoming the limitations of individual novel metal NPs. In addition, the structure of metal-embedded silica NPs decorated with small metal NPs around the silica core results in strong signal enhancement in localized surface plasmon resonance and surface-enhanced Raman scattering. This review summarizes recent studies on metal-embedded silica NPs, focusing on their unique designs and applications. The characteristics of the metal-embedded silica NPs depend on the type and structure of the embedded metals. Based on this progress, metal-embedded silica NPs are currently utilized in various spectroscopic applications, serving as nanozymes, detection and imaging probes, drug carriers, photothermal inducers, and bioactivation molecule screening identifiers. Owing to their versatile roles, metal-embedded silica NPs are expected to be applied in various fields, such as biology and medicine, in the future.

Purpose – The purpose of this study was to develop an accurate, selective, low-cost and user-friendly colorimetric pad to detect formaldehyde at low concentration. Design/methodology/approach – 1-phenyl-1,3-butanedione, a reactive chemical, was selected to develop the colorimetric pad for indoor air formaldehyde measurement. Silica nanoparticle impregnated with the reactive chemical was coated on the cellulose filter surface to increase the reactive site. A certified formaldehyde permeation tube was used to generate six varied concentrations between 0.01 and 0.10 ppm in a test chamber. The color intensity on the pads was measured using an image processing program to produce a formaldehyde concentration reading chart. The colorimetric pad was tested for optimum reaction time, accuracy, precision, stability, selectivity and shelf life. Findings – The color of the pads changed from white to yellow and the color intensity varied with the concentrations and appeared to be stable after exposure to formaldehyde for 8 hours. At room temperature, the stability of the pad was 7 days, and shelf life was 120 days. The accuracy, precision and bias of the pad were 12.38%, 0.032 and 6.0%, respectively. Carbonyl compounds, benzene and toluene did not interfere with the reading of this developed colorimetric pad. Originality/value – The developed colorimetric pad meets NIOSH's criteria for an overall accuracy of ±25%, bias = 10%. They were accurate at low concentrations, user-friendly and had low cost compared to an electronic direct reading instrument (cost of chemicals and materials was 21.50 Bath or 0.69 USD per piece) so that favorable for the use of general people for health protection.

The effect of brine salinity, cation type, pH, and produced sand on zeta potential (ZP) measurements with and without the presence of silica nanoparticles is investigated through pH measurement, static tests for sand and ZP measurements as well as Field Emission Scanning Electron Microscope (FESEM) analyses. Three important factors were investigated: composition of the injected brine, surface charge and pH. Their influence on stability of nanoparticles in the injected brine and amount of sand segregation was determined and the analysis of the new outcomes based on rock/brine ZP measurements was reported. The results show that the use of silica nanoparticles with high pH helps in preventing sand production and that pH has a main effect on the surface charge of the sand particle released, affecting the ZP of the solution. Nanoparticles can be active as a coating on sand grains and prevent sand segregation during water flooding. Divalent cations have been found to acquire a more substantial impact on neutralizing the negative charge of the sand particles than monovalent cations at the same concentration and pH conditions at 25 ℃. The value of ZP becomes of higher negative value with the decrease of brine salinity. The effectiveness of SiO2 nanoparticles is quite different for soft water and smart water. For soft water, the nanoparticles work more effective at pH higher than 8; and for smart water, the nanoparticles perform better at pH lower than 8. To reduce sand production with the use of silica nanoparticles, it is highly suggested to increase pH, as pH and sand production mechanisms were observed to be inversely related.

Agro-waste can provide a non-metallic, environmentally friendly bio-precursor for the production of green silica nanoparticles. To manufacture silica nanoparticles from rice husk, biogenic silica nanoparticles were generated using an alkaline precipitation approach. Rice husk as a source of silica nanoparticles is environmentally and economically valuable because it is a plentiful lower price agricultural derivative that can be used to help with waste management. During the synthesis process, the dose of rice husk ash was used at 5 g at pH 7, alkali dose concentration of 0.5 M, reaction period of 3.5 h, and temperature of 90°C that produced maximum silica nanoparticles with a yield of 88.5%. To optimize the silica nanoparticle production from rice husk ash Box Behnken Design (BBD) a subcategory of the response surface methodology (RSM) was accomplished. BBD model was successfully matched, as evidenced by the high correlation values of adjusted R2 0.9989 and predicted R² 0.9977. Silica nanoparticles' amorphous form generated from rice husk ash is indicated by XRD analysis 2θ peak at 22.12° and UV-Vis Spectroscopy absorbance peak at 312 nm. The amorphous shape of silica is amorphous and crystalline defined through XRD. nanoparticles generated from rice husk ash is indicated by FESEM analysis and EDX analysis, confirming that the SiO2 elemental configuration comprises the highest concentration of Si and O. The existence of a siloxane group in the produced compound was revealed by FTIR spectra stretching vibrations at 803.69 and 1089.05 cm-1. [ABSTRACT FROM AUTHOR]

Elastin-like polypeptides (ELPs) are attractive materials for the green preparation of silica nanoparticles via biomimetic silicification. However, the critical factors affecting the ELP-mediated silicification remain unclear. Herein, the role of tunable amino acid residues of ELPs in silicification was studied using three ELPs (ELPs[V9F-40], ELPs[KV8F-40], and ELPs[K5V4F-40]) and their fusion proteins (ELPs[V9F-40]-SpyCatcher, ELPs[KV8F-40]-SpyCatcher, and ELPs[K5V4F-40]-SpyCatcher) with different contents of lysine residues. Bioinformatics methods were employed for the first time to reveal the key physicochemical parameters correlated with silicification. The specific activity of ELPs was increased with the promotion of lysine content with a high correlation coefficient (R = 0.899). Furthermore, exogenous acidic protein SpyCatcher would hinder the interactions between the silica precursors and ELPs, leading to the significantly decrease in specific activity. The isoelectric point (p I) of ELPs presented the highest correlation to silicification with a coefficient of 0.963. The charges of the ELPs [K5V4F-40] at different pH were calculated based on the sequence or structure. Interestingly, the excellent correlation between charges based on structure and specific activity was obtained. Collectively, the novel methods developed here may pave a new way for rational design of ELPs or other peptides for efficient and green preparation of silica nanomaterials for biomedicine, biocatalysis, and biosensor. [ABSTRACT FROM AUTHOR]