Morphology Of Silica Nanoparticles Research Articles

Factors Affecting Silica/Cellulose Nanocomposite Prepared via the Sol-Gel Technique: A Review.

Cellulose/silica nanocomposites, synthesised through the sol-gel technique, have garnered significant attention for their unique properties and diverse applications. The distinctive characteristics of these nanocomposites are influenced by a range of factors, including the cellulose-to-silica ratio, precursor concentration, pH, catalysts, solvent selection, temperature, processing techniques, and agitation. These variables play a pivotal role in determining the nanocomposites' structure, morphology, and mechanical properties, facilitating tailoring for specific applications. Studies by Raabe et al. and Barud et al. demonstrated well-deposited silica nanoparticles within the interstitial spaces of cellulosic fibres, achieved through TEOS precursor hydrolysis and the subsequent condensation of hydroxyl groups on the cellulose fibre surface. The introduction of TEOS established a robust affinity between the inorganic filler and the polymer matrix, emphasising the substantial impact of TEOS concentration on the size and morphology of silica nanoparticles in the final composites. The successful functionalisation of cellulose fibres with the TEOS precursor via the sol-gel method was reported, resulting in reduced water uptake and enhanced mechanical strength due to the strong chemical interaction between silica and cellulose. In research conducted by Feng et al., the silica/cellulose composite exhibited reduced weight loss compared to the pristine cellulose matrix, with the integration of silica leading to an elevated temperature of composite degradation. Additionally, Ahmad et al. investigated the effects of silica addition to cellulose acetate (CA) and polyethylene glycol membranes, noting an increase in Young's modulus, tensile strength, and elongation at break with silica incorporation. However, concentrations exceeding 4% (w/v) resulted in significant phase separations, leading to a decline in mechanical properties.

Silica Nanoparticle Acute Toxicity on Male Rattus norvegicus Domestica: Ethological Behavior, Hematological Disorders, Biochemical Analyses, Hepato-Renal Function, and Antioxidant-Immune Response.

With extensive production and various applications of silica nanoparticles (SiNPs), there is a controversy regarding the ecotoxicological impacts of SiNPs. Therefore, the current study was aimed to assess the acute toxicity of silica nanoparticles in male Rattus norvegicus domestica after 24 and 96 h. Hematological, serum biochemical, stress biomarker, and immune-antioxidant parameters were addressed. Chemical composition, crystal structure, and the particle shape and morphology of SiNPs were investigated using XRD, FTIR, BET, UV-Vis, and SEM, while TEM was used to estimate the average size distribution of particles. For the exposure experiment, 48 male rats were divided into four groups (12 rat/group) and gavaged daily with different levels of zero (control), 5, 10, and 20 mg of SiNPs corresponding to zero, 31.25, 62.5, and 125 mg per kg of body weight. Sampling was carried out after 24 and 96 h. Relative to the control group, the exposure to SiNPs induced clear behavioral changes such as inactivity, lethargy, aggressiveness, and screaming. In a dose-dependent manner, the behavior scores recorded the highest values. Pairwise comparisons with the control demonstrated a significant (p < 0.05) decrease in hematological and immunological biomarkers [lysozymes and alternative complement activity (ACH50)] with a concomitant reduction in the antioxidant enzymes [catalase (CAT), glutathione peroxidase (GPx), and superoxide dismutase (SOD)] in all exposed groups to SiNPs. On the contrary, there was a noticeable increase in biochemical parameters (glucose, cortisol, creatinine, urea, low-density lipoproteins (LDL), high-density lipoproteins (HDL), total protein, and albumin) and hepato-renal indicators, including alkaline phosphatase (ALP), alanine aminotransferase (ALT), and aspartate aminotransferase (AST), of all SiNP-exposed groups. It was observed that SiNPs induced acute toxicity, either after 24 h or 96 h, post-exposure of rats to SiNPs evidenced by ethological changes, hepato-renal dysfunction, hyperlipemia, and severe suppression in hematological, protein, stress, and immune-antioxidant biomarkers reflecting an impaired physiological status. The obtained outcomes create a foundation for future research to consider the acute toxicity of nanoparticles to preserve human health and sustain the environment.

Preparation and application of highly efficient and reusable TBAPIL@Si(CH2)3@nano-silica-based nano-catalyst for preparation of benzoxanthene derivatives

Tetrabutylammonium prolinate ionic liquid (TBAPIL) was prepared, and mesoporous silica nanoparticles (NPs) were synthesized. Both of these were linked through propyltriethoxysilane to prepare a reusable catalyst TBAPIL@Si(CH2)3@silica NPs (TBAPILS). The formation of TBAPIL was checked through Fourier-transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (NMR) analysis. X-ray diffraction analysis confirmed the structure of silica NPs and linking of TBPAIL on it. Transmission electron microscopy proved the flourishing development of silica NPs. Scanning electron microscopy graphs exposed the altering in morphology of silica NPs and TBAPILS. FT-IR analysis also confirmed the formation of TBAPILS catalyst. Moreover, the effectiveness of the TBAPILS was also checked for the synthesis of various derivatives of tetrahydrobenzoxanthenes-11-ones. The formation and structure of obtained compounds were confirmed by FT-IR, elemental analysis, 1HNMR and 13C NMR spectral analysis. The catalyst TBAPILS was found to be used successfully up to five cycles without significant loss of activity.

Urea-silica nanohybrids with potential applications for slow and precise release of nitrogen

The adoption of nanoparticles as carrier matrices in the production of hybrid functional materials is futuristic in agriculture applications. In this study, a greener, modified in-situ sol-gel route was employed to synthesize urea-silica nanohybrids with a high urea loading of 36% (w/w) and a loading efficiency of ~83%. Characterization studies indicated the successful incorporation of urea into silica nanoparticles and the formation of strong bonds between the nanoparticles and urea molecules without any substantial modification to the structure and morphology of silica nanoparticles. Aforesaid observations were further corroborated by the slow and sustained release behavior exhibited by nanohybrids in water for more than ten days. The developed urea-silica nanohybrids could be utilized as a potential candidate for slow-release nitrogen fertilizers.

Controlling the size of silica nanoparticles in filler nanomatrix structure of natural rubber

In the present work, size of silica nanoparticles in filler nanomatrix structure was controlled by graft-copolymerization of vinyltriethoxysilane (VTES) onto deproteinized natural rubber (NR) after NR was grafted with styrene to prepare NR-g-Sty-g-VTES. The structure of NR-g-Sty-g-VTES was characterized by FT-IR and NMR spectroscopy. It was demonstrated that the silica nanoparticles and polystyrene (PS) were successfully formed in natural rubber. The morphology of silica nanoparticle in the samples were observed with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was observed that very small silica nanoparticles, about 60 nm, were generated in NR-g-Sty-g-VTES. The tensile strength of NR-g-Sty-g-VTES was found increasing 7 times, that is from 3 MPa for NR to 20 MPa for NR-g-Sty-VTES. Storage modulus and loss modulus for NR-g-Sty-g-VTES were found remarkably increasing 20 and 25 times as those for NR, respectively. The formation of well-controlled silica nanoparticle in the nanomatrix was proved to bring about the superior properties for NR material.

A biology research of collagen/silica composite nerve scaffolds in vitro

Objective To discuss the effect of collagen/silicon composite scaffolds in the peripheral nerve regeneration, and evaluate the adhesion and proliferation of Schwann cells within the scaffolds. Methods In this study, from March, 2013 to May, 2014, the collagen/silicon composite scaffolds with 5, 10, 25, 50 and 100 μg/ml were made by freeze-drying technology, and the single collagen scaffold without silica nanoparticles was made with the same method as a control group. The diameter and size of the silica nanoparticles were measured by light scattering, and the morphology of silica nanoparticles were scanned by electron microscope. The cellular compatibility of composite scaffolds was inspected by cultivating Schwann cells on the scaffolds in vitro. The morphology of the Schwann cells in different sample were observed under optical microscope. The adhesion and proliferation effect of the Schwann cells on the scaffolds were determined by MTT. The DNA content of the cells were measured by fluorescence spectrophotometer. Experimental data were expressed by mean ± standard deviation (SD) values. Data were analyzed using One-way ANOVA followed by Bonferroni’s post hoc comparison tests. Statistics with a value of P < 0.05 indicated statistical significance. Results The average diameter of the nanoparticles mainly distributed from 150 to 190 nm and showed a spheric morphology. Morphologically, all the cultured cells were observed to be in healthy state in most scaffolds except for the scaffolds with 100 μg/ml silica nanoparticles. Whereas all the cells on other samples displayed spindle shape with axons spreading, and there was no obvious morphology difference for the cells on these samples. The results of cytocompatibility of the collagen/silica composite scaffolds using MTT assay showed that both the viability and proliferation of Schwann cells increased firstly and then decreased with the increasing concentration of silica nanoparticles. And the cells showed much better viability and proliferation when the concentration of silica nonoparticles was 25 μg/ml compared with other samples. While the cell viability was significantly decreased when the concentration of silica nonoparticles was larger than 50 μg/ml, which was consistent with the morphology results. The DNA contents of Schwann cells in scaffolds also increased firstly and then decreased with the increment of silica nanoparticles concentratin, and the cells in the composite scaffolds with 25 μg/ml silica nanoparticles showed the largest DNA contents. Conclusion The collagen/silica composite scaffold with 25 μg/ml may contribute to the regeneration of peripheral nerve in the future. Key words: Silica nanoparticles; Collagen; Nerve scaffold; Schwann cell

A facile method for synthesis and dispersion of silica nanoparticles in water-based drilling fluid

Silica nanoparticles were synthesized using the sol-gel method in an acidic environment containing tetraethyl orthosilicate (TEOS) and hydrochloric acid (HCl), and the particle size distribution and morphology of silica nanoparticles were determined using dynamic light scattering (DLS) analysis and field emission scanning electron microscopy (FE-SEM). The results show that the product is highly monodisperse and composed of amorphous SiO2 nanoparticles. Afterwards, a facile route for dispersion of nanoparticles in bentonite suspensions, low-salinity and high-salinity muds, was explained and the stability of the dispersions at different experimental conditions was investigated. Finally, the effect of silica nanoparticles on rheological properties and fluid filtration behavior was investigated using the API filter press test. The presented dispersion method in this study showed superior performance to previous dispersion methods.

Microwave-assisted synthesis of SiO2 nanoparticles and its application on the flame retardancy of poly styrene and poly carbonate nanocomposites

Various morphologies of silica nanoparticles were synthesized by a microwave-assisted Pechini method. Silica nanostructures were synthesized via a fast reaction between tetra ethyl ortho silicate and ammonia at presence citric acid and other effective agents in Pechini procedure. Then for preparation of polymer-matrix nanocomposites, SiO2 nanoparticles were added to poly carbonate (PC) and poly styrene (PS) matrices. Nanostructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR). The influence of SiO2 nanostructures on the flame retardancy of the polymeric matrix was studied using UL- 94 analysis. Our results show that the SiO2 nanostructure can enhance the flame retardant property of the poly carbonate matrix. PC shows better flame retardancy compare to poly styrene.

The shape and size effects of polycation functionalized silica nanoparticles on gene transfection

Silica nanoparticles are attractive candidates for the development of safe and efficient non-viral gene carriers, owing to their controlled morphologies, potential of facile surface modification and excellent biocompatibility as well as in vivo biodegradability. Conversely, the size and shape of nanoparticles are considered to have an intense influence on their interaction with cells and biological systems, but the effects of particle size and shape on gene transfection are poorly understood. In this work, a series of novel gene carriers were designed employing polycation modified silica nanoparticles with five different morphologies, while keeping uniform zeta potential and surface functionality. Then the effects of particle size and shape of these five different carriers on gene transfection were investigated. The morphology of silica nanoparticles is demonstrated to play an important role in gene transfection, especially when the amount of polycation is low. Chiral nanorods with larger aspect ratio were found to fabricate the most efficient gene carriers with compromised cytotoxicity. It was also noted that hollow nanosphere-based carriers exhibited better gene transfection performance than did solid counterparts. These results may provide new strategies to develop promising gene carriers and useful information for the application of nanoparticles in biomedical areas.