Synthesis Of Silica Nanoparticles Research Articles

Recent Trends in Morphology-Controlled Synthesis and Application of Mesoporous Silica Nanoparticles.

The outstanding journey towards the investigation of mesoporous materials commences with the discovery of high surface area porous silica materials, named MCM-41 (Mobil Composition of Matter-41) according to the inventors’ name Mobile scientists in the United States. Based on a self-assembled supramolecular templating mechanism, the synthesis of mesoporous silica has extended to wide varieties of silica categories along with versatile applications of all these types in many fields. These silica families have some extraordinary structural features, like highly tunable nanoscale sized pore diameter, good Brunauer–Emmett–Teller (BET) surface areas, good flexibility to accommodate different organic and inorganic functional groups, metals etc., onto their surface. As a consequence, thousands of scientists and researchers throughout the world have reported numerous silica materials in the form of published articles, communication, reviews, etc. Beside this, attention is also given to the morphology-oriented synthesis of silica nanoparticles and their significant effects on the emerging fields of study like catalysis, energy applications, sensing, environmental, and biomedical research. This review highlights a consolidated overview of those morphology-based mesoporous silica particles, emphasizing their syntheses and potential role in many promising fields of research.

Controlled synthesis of mesoporous silica nanoparticles with tunable architectures via oil-water microemulsion assembly process

Mesoporous silica nanoparticles (MSNs) have received extensive attention owing to their fascinating properties in recent years. However, the controllable synthesis of MSNs with different morphologies and the transformation of various structures by using simple oil-water microemulsion assembly methods remains a challenge. Herein, a facile microemulsion assembly approach has been developed to fabricate MSNs with various morphologies, tunable particle diameter (135–280 nm), and pore size (2.8–32.8 nm). In the same reaction system, the evolution of walnut-like MSNs to mulberry-like MSNs has been easily achieved. The amount of pentanol not only plays an important role in the evolution of pore sizes but also significantly affects the interfacial interaction between soft templates and silica precursors, which is critical to the morphology of the resulting particles. As a result, wrinkle-like, dendritic-like, walnut-like, and mulberry-like mesoporous nanospheres can be synthesized. More importantly, MSNs with visible voids in the center can be successfully obtained during the synthesis process when the appropriate pentanol is employed. Other experimental parameters, such as the amount of isopropanol, the concentration of surfactant, and the concentration of alkali, were also investigated. A possible mechanism is proposed to account for the formation and growth of MSNs. The Au@NH2-MSNs composite nanostructures can be used as a catalyst for the reduction of 4-nitrophenol by NaBH4 into 4-aminophenol and exhibit superior catalytic performance.

Robust synthesis of mono-dispersed spherical silica nanoparticle from rice husk for high definition latent fingermark development

Silica is one of the most functional metalloid oxides with a widespread application as semiconductor, fillers, silicone and ceramic primarily due to its structural versatility. In this work, a robust step-wise thermochemical treatment was successfully formulated for the controlled fabrication of high-purity mono-dispersed spherical silica nanoparticle from rice husk. The silica nanoparticle with the desired morphology was formed in two stages; thermal-assisted seed particle formation followed by particle growth through acidification of the solvent modified sodium silicate solution. The obtained powder was characterised, and the effectiveness of the powder for latent fingermark development across varied donors and surfaces was tested at the introductory level. The formed spherical particles were in the range of 200 to 400 nm, as confirmed by FESEM and HRTEM analysis. Minimising the degree of silica nanoparticle agglomeration notably affected their selectivity to fingermark residue. There was a striking improvement in the selectivity of the silica nanoparticle to fingermark residue. The improvement was attributed to the strong interaction between the silica nanoparticle and the lipid components in the fingermark residue, as compared to the commercial white powder that works solely based on mechanical adherence. Additionally, the size and morphology of the fabricated silica nanoparticle were optimised to enhance the clarity of the developed fingermark. Findings of this study could improve quality of fingermarks obtained in a crime scene due to considerably lower background interference without compromising the effectiveness of fingermark development.

Facile approach for the synthesis of spherical mesoporous silica nanoparticles from sodium silicate

We developed a facile synthetic method for the preparation of spherical mesoporous silica nanoparticles from a sodium silicate solution. Spherical mesoporous silica with an overall size of several hundreds of nanometers was obtained through a simple sol–gel process using acetic acid and polyethylene glycol (PEG) as a pH adjuster and morphology directing agent, respectively. In this method, PEG is an essential component that affects the shape of silica particles and that leads to the formation of mesopores on silica. Additionally, the size of the mesopores could be easily controlled by changing the reaction temperature. Thus, we successfully synthesized spherical silica nanoparticles with tunable mesopores ranging from 3 to 40 nm. This synthetic method can be valuable in developing customized porous silica nanoparticles using an inexpensive silica resource.

Droplet-based Microfluidic Device for the Synthesis of Silica Nanoparticles

Microfluidic reactors are advantageous for nanomaterial synthesis due to their capability to provide controlled reaction environment. In this work, a droplet based microfluidic reactor is designed for the synthesis of silica nanoparticles. The synthesis is carried out in a very controlled environment and a uniform size and shape distribution is achieved. The classical synthesis protocol for silica nanoparticles is modified to use nonpolar solvents in the reaction so that this platform can later be used for coating hydrophobic nanomaterials. Therefore, this study not only presents a new device but also a new synthesis method. The results are compared with conventional batch wise synthesis methods and the obtained nanoparticles showed better size distribution.

Synthesis and application of rice husk silica nanoparticles for chemical enhanced oil recovery

Silica (SiO2) nanoparticles were synthesized from rice husk (RH) via wet milling method and evaluated for enhanced oil recovery (EOR) applications. Physical properties of RH-SiO2 nanoparticles (RH-SNP) with its size distribution were explored through field emission scanning electron microscopy (FESEM) and dynamic light scattering (DLS). Stability, functional groups and purity of RH-SNP were determined by zeta potential, Fourier-transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD), respectively. Effect of RH-SNP on the precipitation and thermal degradation of oilfield polyacrylamide (HPAM) was studied using Brookfield RST rheometer. Interfacial tension (IFT) properties of RH-SiO2 polymeric nanofluid (RH-SPNF) at interface of oil and water (O/W) were investigated using Easy-Dyne KRUSS tensiometer. Subsequently, oil displacement efficiency of RH-SPNF was determined and compared with oilfield HPAM at reservoir conditions using Fars EOR high-pressure high-temperature (HPHT) core flooding equipment. The wet milling method was effective in producing RH-SNP of size ranges 43.9–59.5 nm with a purity of 98% through the mechanism of nucleation, Brownian motion and coalescence. Rheological results show that RH-SNP inhibited the precipitation and thermal degradation of oilfield HPAM. IFT of RH-SPNF showed a monotonic tendency as temperature increased. HPAM and RH-SPNF flooding showed an incremental oil recovery of approximately 10% and 24%, respectively. Emulsion generated using RH-SPNF shows higher stability and resistance to coalescence. Finally, mobility ratio of water flooding approaches unity faster, compared to HPAM and RH-SPNF. Overall, the low energy utilization, use of low-cost and benign raw material make RH-SNP and the extraction method an appropriate substitute to commercially available SiO2 nanoparticles.

Advances in Methods for Recovery of Ferrous, Alumina, and Silica Nanoparticles from Fly Ash Waste

Fly ash or coal fly ash causes major global pollution in the form of solid waste and is classified as a “hazardous waste”, which is a by-product of thermal power plants produced during electricity production. Si, Al, Fe Ca, and Mg alone form more than 85% of the chemical compounds and glasses of most fly ashes. Fly ash has a chemical composition of 70–90%, as well as glasses of ferrous, alumina, silica, and CaO. Therefore, fly ash could act as a reliable and alternative source for ferrous, alumina, and silica. The ferrous fractions can be recovered by a simple magnetic separation method, while alumina and silica can be extracted by chemical or biological approaches. Alumina extraction is possible using both alkali- and acid-based methods, while silica is extracted by strong alkali, such as NaOH. Chemical extraction has a higher yield than the biological approaches, but the bio-based approaches are more environmentally friendly. Fly ash can also be used for the synthesis of zeolites by NaOH treatment of variable types, as fly ash is rich in alumino-silicates. The present review work deals with the recent advances in the field of the recovery and synthesis of ferrous, alumina, and silica micro and nanoparticles from fly ash.

A facile and controllable one-pot synthesis approach to amino-functionalized hollow silica nanoparticles with accessible ordered mesoporous shells

The development of a practical synthetic method to functionalize hollow mesoporous silica with organic groups is of current interest for selective adsorption and energy storage applications. Herein, a facile and controllable one-pot approach for the synthesis of monodisperse amino-functionalized hollow mesoporous silica nanoparticles is presented. A novel solid-to-hollow structural transformation procedure of the silica nanoparticles is presented. The structural transformation is easily designed, as observed through transmission electron microscopy, by tailoring the HCl and N-lauroylsarcosine sodium molar ratio and the water content in the sol-gel. Ordered and radially oriented in situ amino-functionalized mesochannels were successfully introduced into the shells of the hollow silica nanoparticles. A formation mechanism for the hollow mesoporous silica materials is discussed.

Synthesis and characteristics of silica nano-particles using modified sol–gel method in microreactor

Abstract Sol-gel is one of the known and widely applied techniques in nano-particles synthesis. However, the conventional batch sol–gel method produces silica nano-particles with uneven shapes and wide size distribution. In the present work, silica nano-particles will be synthesized using a traditional sol–gel method and a modified sol–gel technique by creating a microfluidic reactor. A polydimethylsiloxane microreactor was first designed and fabricated using the direct writing method. The microfluidic reactor was designed with a micro-droplets generation junction where the reactants are mixed to generate droplets where each droplet as an independent reactor. The synthesis process involved tetraethyl orthosilicate as a precursor, acetic acid as a catalyst and water as a hydrolysing agent. Transmission electron microscopy (TEM) was used to measure and evaluate the nano-particles size and distribution of the two sol–gel methods implemented. The silica nano-particles synthesized from conventional bench-scale sol–gel method showed poor monodispersity and not in a perfect spherical configuration that has an average size of 95 ± 4 nm. In contrast, highly monodispersed silica nano-particles were produced using a microreactor with an average size of 6 ± 1.3 nm, and the particles were in a perfect spherical configuration. The nano-particles produced from microflow system showed a reduction of 93.68% in size. The results indicated clearly that the micro-mixing associated with the micro-droplets generation is dynamically controlling the shape and size of the formulated nano-particles by controlling the droplet's internal mixing mechanism.

Environmentally Friendly Method of Silicon Recycling: Synthesis of Silica Nanoparticles in an Aqueous Solution

Future decades will experience tons of silicon waste from various sources, with no reliable recycling route. The transformation of bulk silicon into SiO2 nanoparticles is environmentally significant because it provides a way to recycle residual silicon waste. To address the needs of silicon recycling, we develop a top-down approach that achieves 100% conversion of bulk silicon to silica nanoparticles with outcome sizes of 8-50 nm. In addition to upcycling the potential of silica, our method also possesses several advantages, such as simplicity, scalability and controllable particle size distribution. Many fields of science and manufacturing, such as optics, photonics, medical, and mechanical applications, require size-controllable fabrication of silica nanoparticles. We demonstrate that control over temperature and hydrolysis time has a significant impact on the average particle size and distribution shape. Additionally, we unravel the process of nanoparticle formation using a theoretical nucleation model and quantum density functional theory calculations. Our results provide a theoretical and experimental basis for silica nanoparticle fabrication and pave the way for further silicon conservation research.

Antibacterial Activity of Mouthwash Incorporated with Silica Nanoparticles against S. aureus, S. mutans, E. faecalis: An in-vitro Study

Silica based nanoparticles are used in various fields of medical sciences to diagnose, control disease, for genetic disorders, owing to their size, surface area, biocompatibility and low toxicity. In dentistry, silica nanoparticles have been used as dental filler, teeth whitening agent but limited evidence is there regarding antimicrobial activity against oral pathogens. Therefore, the current study was conducted to assess the anti-bacterial activity of mouthwash incorporated with silica nanoparticles against oral pathogens. Tetraethoxysilane, ammonium hydroxide, absolute ethanol were used and centrifuged to obtain the silica nanoparticle pellet. XRD analysis was done to confirm the characterization of the thus obtained silica nanoparticle. The mouthwash was prepared with the synthesized silica nanoparticle as the main constituent. Agar well diffusion method was used to assess the antimicrobial activity against S. mutans, S. aureus and E. faecalis. The XRD analysis confirmed the amorphous nature of the synthesized silica nanoparticles. The zone of inhibition was found to increase as the concentrations increased mainly for S. aureus and E. faecalis. The synthesized nanoparticles incorporated mouthwash showed good potential as antimicrobial agents against strains of gram positive bacteria. Further animal studies/in vivo research should be conducted to validate the above findings.

DDAO Controlled Synthesis of Organo-Modified Silica Nanoparticles with Encapsulated Fluorescent Boron Dipyrrins and Study of Their Uptake by Cancerous Cells.

The design of cargo carriers with high biocompatibility, unique morphological characteristics, and capability of strong bonding of fluorescent dye is highly important for the development of a platform for smart imaging and diagnostics. In this paper, BODIPY-doped silica nanoparticles were prepared through a “one-pot” soft-template method using a sol-gel process. Several sol-gel precursors have been used in sol-gel synthesis in the presence of soft-template to obtain the silica-based materials with the most appropriate morphological features for the immobilization of BODIPY molecules. Obtained silica particles have been shown to be non-cytotoxic and can be effectively internalized into the cervical cancer cell line (HeLa). The described method of synthesis allows us to obtain silica-based carriers with an immobilized fluorescent dye that provide the possibility for real-time imaging and detection of these carriers.

Sacrificial sulphonated polystyrene template-assisted synthesis of mesoporous hollow core-shell silica nanoparticles for drug-delivery application

Spherical mesoporous hollow core-shell silica nanoparticles (HCSNs) of size 200 ± 50 nm with tunable thickness from 20 to 60 nm are synthesized using a sacrificial sulphonated polystyrene (PS, particle size 160 nm) template. A facile method is adopted for the sulphonation of PS using sulphuric acid, which enhanced the negative charge on the surface of PS as confirmed by zeta potential analysis and Fourier transform infrared radiation analysis. The thickness of the silica shell is tuned by altering the concentration of the silica precursor and is found to increase due to the use of the sulphonated PS template. N2 adsorption/desorption studies reported the variation of specific surface area of HCSNs from 644.1 to 197.8 m2 g−1 and average pore size from 1.55 to 3.4 nm. The drug release behaviour of HCSNs with different shell thicknesses is investigated using doxorubicin as the model drug. A delay in the drug release for ~300 min is successfully achieved by employing HCSNs with enhanced thickness of 60 nm. Application of HCSNs in targeted drug delivery was further supported by the in-vitro cytotoxicity studies carried out on lung adenocarcinoma cells.

Dusty-Plasma-Assisted Synthesis of Silica Nanoparticles for in Situ Surface Modification of 3D-Printed Polymer Scaffolds

We report a rapid and easy method for the synthesis of silica nanoparticles (SiNps) from a liquid precursor. Specifically, plasma-enhanced chemical vapor deposition of a very small amount of a liquid precursor, tetraethoxysilane (300 μL), for a very short exposure time (5 min) resulted in the generation of dusty plasma of SiNps with a narrow size distribution. The prepared SiNps were systematically characterized with various analytical techniques. Furthermore, this method was found to modify the surface of the 3D-printed polyester scaffold with SiNps in a very quick and efficient manner.

Synthesis and Testing of Functional Mesoporous Silica Nanoparticles for Removal of Cr(VI) Ions From Water

This work reports a reliable and reproducible synthesis and in situ functionalization protocol for the synthesis of amino-functionalized mesoporous silica nanoparticles (MSNs). The porous amino-functional (pSiO2-NH2) nanoparticles were fully characterized by high-resolution transmission electron microscopy (TEM), X-ray diffraction (XRD), Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and nitrogen adsorption-desorption (BET) analyses. The size of the particles was in the range of 80-200 nm with a specific surface area (SSA) of 721 m2 g-1, and the pore diameter was 31Å. The pSiO2-NH2 nanoparticles were tested for their efficiency in removing Cr(VI) ions from water. Almost quantitative removal of the ions was achieved by using the particles just within two hours. The adsorption efficiency of the particles was about 50 mg g-1. The synthesized porous silica particles can be repeatedly used as nano adsorbent for the adsorption removal of Cr(VI) ions from water. The nanoparticles can be potentially used for the selective capture, removal, and recovery of various other metal ions that can be complexed by amino groups.

Facile synthesis of cetyltrimethylammonium bromide-loaded mesoporous silica nanoparticles for efficient inhibition of hepatocellular carcinoma cell proliferation

We report the synthesis of cetyltrimethylammonium bromide (CTAB)-loaded mesoporous silica nanoparticles (MSNs) as efficient anticancer agents. The chemical composition and structure, drug loading capacity, and in vitro cytotoxicity of CTAB-MSNs were analyzed. Our results reveal that CTAB-MSNs display a uniform pore structure, extensive surface area, and high drug-loading capacity, of approximately 37.2% by weight. The viability assessments showed that CTAB-MSNs exhibited superior human hepatoma (HepG2) cell killing compared to free CTAB. Therefore, CTAB-MSNs may have advantages over conventional cancer therapies.

Preparation of silica nanoparticles facilitated by Saccharum munja plant

The sol–gel method is used for the synthesis of silica nano particles from Saccharum munja plant. Dried Saccharum munja plant was heated at 600 °C for 4 h to convert into Saccharum munja ash (SMA). By solution of sodium hydroxide, silica was extracted from the ash of Saccharum munja along with the sodium silicate. Silica was precipitated by H2SO4 at pH 4, sodium dodecyl sulfate and cetyl-tri-methyl-ammonium bromide were used as a surfactants and water/butanol were taken in same ratio. Different parameters like aging temperature, time, surface coverage and the effect of surfactant are tested to identify the favorable conditions for producing the homogeneous mixture of silica nanoparticles. X-ray diffraction and scanning electron microscopy data reveal that silica nanoparticles are amorphous and have size in the range of 30–50 nm. The results obtained by this method show the economic importance of the Saccharum munja.

Production and characterization of silica nanoparticles from fly ash: conversion of agro-waste into resource

A chemical method to synthesize amorphous silica nanoparticles from the incinerated paddy straw has been introduced. The synthesis was conducted through the hydrolysis by alkaline-acidic treatments. As a result, silica particles produced with the sizes were ranging at 60–90 nm, determined by high-resolution microscopy. The crystallinity was confirmed by surface area electron diffraction. Apart from that, chemical and diffraction analyses for both rice straw ash and synthesized silica nanoparticles were conducted by X-ray diffraction and Fourier-transform infrared spectroscopy. The percentage of silica from the incinerated straw was calculated to be 28.3. The prominent surface chemical bonding on the generated silica nanoparticles was with Si–O–Si, stretch of Si–O and symmetric Si–O bonds at peaks of 1090, 471, and 780 cm−1, respectively. To confirm the impurities of the elements in the produced silica, were analyzed using X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy. The stability of silica nanoparticles was investigated using thermogravimetric analysis and zeta potential. The measured size from zeta potential analysis was 411.3–493 nm and the stability of mass reduction was located at 200 °C with final amount of mass reduced ∼88% and an average polydispersity Index was 0.195–0.224.

Thermal and Mechanical Characterization of an Aeronautical Graded Epoxy Resin Loaded with Hybrid Nanoparticles.

Synthesized silica nanoparticles (SiO2) were coated with a thin polydopamine (PDA) shell by a modified one-step procedure leading to PDA coated silica nanoparticles (SiO2@PDA). Core-shell (CSNPs) characterization revealed 15 nm thickness of PDA shell surrounding the SiO2 core (~270 nm in diameter). Different weight percentages of CSNPs were employed as filler to enhance the final properties of an aeronautical epoxy resin (RTM6) commonly used as matrix to manufacture structural composites. RTM6/SiO2@PDA nanocomposites were experimentally characterized in terms of thermal stability and mechanical performances to assess the induced effects by the synthesized CSNPs on pristine matrix. Thermal stability was investigated by thermogravimetry and data were modelled by the Doyle model and Kissinger methods. An overall enhancement in thermal stability was achieved and clearly highlighted by modelling results. Dynamic Mechanical Analysis has revealed an improvement in the nanocomposite performances compared to the neat matrix, with an increase in the glassy (+9.5%) and rubbery moduli (+32%) as well as glass transition temperature (+10 °C). Fracture Toughness tests confirmed the positive effect in damage resistance compared to unloaded resin with an impressive variation in critical stress intensity factor (KIC) and critical strain energy (GIC) of about 60% and 138%, respectively, with the highest SiO2@PDA content.

Synthesis and application of mesoporous silica nanoparticles as gas migration control additive in oil and gas cement

Cement failure has been widely reported to be one of the major causes of many catastrophic accidents in the oil and gas industry. Lack of cement integrity and strength has been associated with the potentially harmful gas migration from the reservoir into the wellbore. In this study, the potential application mesoporous silica nanoparticles as gas migration control additive for oil and gas cement was evaluated. Here, mesoporous silica nanoparticles were prepared using micelle templating sol-gel method and its performance as the additive was assessed against the commercial micro- and nano-sized silica particles. Based on the result, it is revealed that all of the cement samples prepared with or without additives exhibited sufficient rheological properties for field application. Nonetheless, results showed that silica nanoparticles addition would result in a slight increase in viscosity and yield point reduction of the cement slurry. Further investigations suggested that silica nanoparticles could also accelerate the hydration process due to their ability to provide a large surface area for nucleation reaction and the formation of C–S–H seeds. As a result, this would lead to the creation of a denser and stronger cement structure, which exhibits low porosity and permeability features. According to the result, the most optimum formulation was achieved when the cement was mixed with 0.0132 wt% of a mesoporous silica nanoparticle, with the compressive strength value of 6.67 MPa and the values of porosity and permeability of 8.94% and 2.47 × 10−17 m2 (0.025 mD), respectively.