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In this study, the polyethylene oxide (PEO)/SiO2 nanoparticles (NPs) nanocomposite films with various SiO2 NPs concentrations were prepared using an in situ formation of NPs in the polymer matrix for self‐cleaning antireflected surface applications. The effect of SiO2 NPs in PEO/SiO2 NPs nanocomposite films on the structural, morphological, chemical, thermal, optical, and electrical properties of PEO/SiO2 NPs nanocomposite films was performed. According to the x‐ray diffraction and the differential scanning calorimetry analysis, the crystallinity degree of the nanocomposite films decreases by increasing the SiO2 NPs concentrations. The bandgap energy of PEO/SiO2 NPs nanocomposite films decreases from 3.95 to 3.55 eV as the SiO2 NPs concentration increases up to 10 wt.%. The average electrical conductivity of the PEO/SiO2 NPs nanocomposite films increases from 5.1 × 10−7 to 2.0 × 10−6 S/cm as the SiO2 NPs concentration increases up to 10 wt.%. The refractive index decreases to 1.64 at 550 nm for the PEO/SiO2 NPs nanocomposite films with 10 wt.% of SiO2 NPs, and the water contact angle decreases to around 0° after thermal treatment, which confirms that the PEO/SiO2 NPs nanocomposite films can be used as self‐cleaning antireflected surfaces. [ABSTRACT FROM AUTHOR]

Abstract Background By 2050, the world population will increase to 10 billion which urged global demand for food production to double. Plant disease and land drought will make the situation more dire, and safer and environment-friendly materials are thus considered as a new countermeasure. The rice blast fungus, Magnaporthe oryzae, causes one of the most destructive diseases of cultivated rice worldwide that seriously threatens rice production. Unfortunately, traditional breeding nor chemical approaches along control it well. Nowadays, nanotechnology stands as a new weapon against these mounting challenges and silica nanoparticles (SiO2 NPs) have been considered as potential new safer agrochemicals recently but the systematically studies remain limited, especially in rice. Results Salicylic acid (SA) is a key plant hormone essential for establishing plant resistance to several pathogens and its further affected a special form of induced resistance, the systemic acquired resistance (SAR), which considered as an important aspect of plant innate immunity from the locally induced disease resistance to the whole plant. Here we showed that SiO2 NPs could stimulate plant immunity to protect rice against M. oryzae through foliar treatment that significantly decreased disease severity by nearly 70% within an appropriate concentration range. Excessive concentration of foliar treatment led to disordered intake and abnormal SA responsive genes expressions which weaken the plant resistance and even aggravated the disease. Importantly, this SA-dependent fungal resistance could achieve better results with root treatment through a SAR manner with no phytotoxicity since the orderly and moderate absorption. What’s more, root treatment with SiO2 NPs could also promote root development which was better to deal with drought. Conclusions Taken together, our findings not only revealed SiO2 NPs as a potential effective and safe strategy to protect rice against biotic and abiotic stresses, but also identify root treatment for the appropriate application method since it seems not causing negative effects and even have promotion on root development. Graphical Abstract

Background: By 2050, the world population will increase to 10 billion which urged global demand for food production to double. Plant disease and land drought will make the situation more dire, and safer and environment-friendly materials are thus considered as a new countermeasure. The rice blast fungus, Magnaporthe oryzae, causes one of the most destructive diseases of cultivated rice worldwide that seriously threatens rice production. Unfortunately, traditional breeding nor chemical approaches along control it well. Nowadays, nanotechnology stands as a new weapon against these mounting challenges and silica nanoparticles (SiO2 NPs) have been considered as potential new safer agrochemicals recently but the systematically studies remain limited, especially in rice. Results: Salicylic acid (SA) is a key plant hormone essential for establishing plant resistance to several pathogens and its further affected a special form of induced resistance, the systemic acquired resistance (SAR), which considered as an important aspect of plant innate immunity from the locally induced disease resistance to the whole plant. Here we showed that SiO2 NPs could stimulate plant immunity to protect rice against M. oryzae through foliar treatment that significantly decreased disease severity by nearly 70% within an appropriate concentration range. Excessive concentration of foliar treatment led to disordered intake and abnormal SA responsive genes expressions which weaken the plant resistance and even aggravated the disease. Importantly, this SA-dependent fungal resistance could achieve better results with root treatment through a SAR manner with no phytotoxicity since the orderly and moderate absorption. What's more, root treatment with SiO2 NPs could also promote root development which was better to deal with drought. Conclusions: Taken together, our findings not only revealed SiO2 NPs as a potential effective and safe strategy to protect rice against biotic and abiotic stresses, but also identify root treatment for the appropriate application method since it seems not causing negative effects and even have promotion on root development. [ABSTRACT FROM AUTHOR]

Mixtures of silica nanoparticles (SiO2 NPs) and natural organic matter (NOM) are ubiquitous in natural aquatic environments and pose risks to organisms. Ultrafiltration (UF) membranes can effectively remove SiO2 NP–NOM mixtures. However, the corresponding membrane fouling mechanisms, particularly under different solution conditions, have not yet been studied. In this work, the effect of solution chemistry on polyethersulfone (PES) UF membrane fouling caused by a SiO2 NP–NOM mixture was investigated at different pH levels, ionic strengths, and calcium concentrations. The corresponding membrane fouling mechanisms, i.e., Lifshitz–van der Waals (LW), electrostatic (EL), and acid–base (AB) interactions, were quantitatively evaluated using the extended Derjaguin–Landau–Verwey–Overbeek (xDLVO) theory. It was found that the extent of membrane fouling increased with decreasing pH, increasing ionic strength, and increasing calcium concentration. The attractive AB interaction between the clean/fouled membrane and foulant was the major fouling mechanism in both the initial adhesion and later cohesion stages, while the attractive LW and repulsive EL interactions were less important. The change of fouling potential with solution chemistry was negatively correlated with the calculated interaction energy, indicating that the UF membrane fouling behavior under different solution conditions can be effectively explained and predicted using the xDLVO theory.

In the last years, mixtures of silica nanoparticles and surfactants have been widely and successfully used to stabilize a multiplicity of aqueous foams and emulsions with current and potential applications in the engineering processes. The physicochemical properties and large-scale industrial production of silica nanoparticles, as well as the practical and cheap methods offered by surfactants to modify the nanoparticles' wettability, are the main reasons for the silica nanoparticle-surfactant pair to be an effective combination on the stabilization of both aqueous foams and emulsions. This state-of-the-art review aims to offer a well-defined picture of the contemporary research on foams and emulsions (oil-in-water, water-in-oil, and the particular case of the bicontinuous ones) stabilized by mixtures of silica nanoparticles and surfactants (cationic, anionic, nonionic, and zwitterionic) featuring the top results and outlining future research in the area. Attention is paid to the processes and materials where the foams and emulsions discussed are present. The function of silica nanoparticles-surfactants synergy on stabilizing foams and emulsions is also discussed.

Doped polymeric hybrid thin films based on Poly-Methyl-Meth-Acrylate (PMMA) and Poly-vinyl-alcohol (PVA) doped with silica nanoparticles (SiO2 NPs) are synthesized using the dip-coating technique. The as-prepared (PMMA-PVA)/SiO2 nanocomposite (wt% of SiO2 NPs = 2%, 4%, 8%, and 16%) are deposited on glass substrates. Transmittance (T%) and reflectance (R%) are measured using a UV–Vis spectrometer. Furthermore, other related optical parameters such as absorption coefficient (α), optical constants (n and k), and optical dielectric functions (ε1 and ε2) are calculated using experimental transmittance, reflectance spectra and well-established classical models such as Tauc, Urbach and Spitzer-Fan and Drude models. The Tauc model is used to estimate the optical bandgap energy. Incorporation of specific concentrations of SiO2 NPs into PMMA-PVA polymeric matrix leads to a noticeable decrease of the optical bandgap. The optical bandgap of un-doped PMMA-PVA thin-film is estimated to be 4.069 eV. Consequently, bandgap engineering and manipulation of optical properties are possible. Additionally, refractive indices (n) of undoped PMMA-PVA polymeric thin films are calculated to be in the range (1.48–1.72). To elucidate and identify vibrational modes of thin films, Fourier-transform infrared spectroscopy (FTIR) is employed in the spectral range (500 cm−1–4000 cm−1). The results obtained are useful for a better understanding of the lattice dynamics. Moreover, thermal stability of thin films is investigated using thermogravimetric (TGA) technique. Remarkably, TGA thermograms reveal that doped thin films are thermally stable below 110C. Consequently, investigated thin films may have the potential to be key candidates for real-time optical and optoelectronic devices.

Silicon dioxide (SiO2) has been used as a food additive (E551) for decades. However, some safety concerns have been raised recently due to the detection of silica nanoparticles (SiO2 NPs) in a variety of foodstuffs and their unknown long-term health risk to humans. In order for risk assessment to be conducted, it is essential to establish a reliable, valid, and pragmatic method for analysis of SiO2 NPs in foods for estimation of exposure. This paper presents an effective approach for both size characterization and mass quantification of SiO2 NPs in commercial high-fat coffee creamer using asymmetric flow field-flow fractionation (AF4) coupled to inductively coupled plasma mass spectrometry (ICP-MS). SiO2 NPs from coffee creamer were well extracted after cleanup with hexane in a two-phase (hexane vs. water) aqueous environment. Size determination of SiO2 NPs was performed by on-line AF4-ICP-MS based on calibration with monodispersed standards. The dominant primary size of SiO2 NPs in the studied sample was 36.5 nm. The mass percentages of SiO2 NPs (vs. total SiO2) were 18.6% for the dominant primary nano-silica particles by prechannel calibration and 35.7% for total SiO2 NPs (≤ 100 nm) by postchannel calibration, with recoveries of 89–96% for the former and 75% for the latter. The established approach was demonstrated to be efficient and practical for routine analysis of polydispersed SiO2 NPs with wide nano-size distribution in coffee creamer. This method may be extended to monitor the presence of SiO2 NPs in other similar complex food matrices. [ABSTRACT FROM AUTHOR]

Silica nanoparticles (SiO2 NPs) synthesized by the Stober method were used as drug delivery vehicles. Doxorubicin hydrochloride (DOX·HCl) is a chemo-drug absorbed onto the SiO2 NPs surfaces. The DOX·HCl loading onto and release from the SiO2 NPs was monitored via UV-VIS and fluorescence spectra. Alternatively, the zeta potential was also used to monitor and evaluate the DOX·HCl loading process. The results showed that nearly 98% of DOX·HCl was effectively loaded onto the SiO2 NPs’ surfaces by electrostatic interaction. The pH-dependence of the process wherein DOX·HCl release out of DOX·HCl-SiO2 NPs was investigated as well. For comparison, both the free DOX·HCl molecules and DOX·HCl-SiO2 NPs were used as the labels for cultured cancer cells. Confocal laser scanning microscopy images showed that the DOX·HCl-SiO2 NPs were better delivered to cancer cells which are more acidic than healthy cells. We propose that engineered DOX·HCl-SiO2 systems are good candidates for drug delivery and clinical applications.

Silica nanoparticles (SiO2 NPs) synthesized by the Stober method were used as drug delivery vehicles. Doxorubicin hydrochloride (DOX·HCl) is a chemo-drug absorbed onto the SiO2 NPs surfaces. The DOX·HCl loading onto and release from the SiO2 NPs was monitored via UV-VIS and fluorescence spectra. Alternatively, the zeta potential was also used to monitor and evaluate the DOX·HCl loading process. The results showed that nearly 98% of DOX·HCl was effectively loaded onto the SiO2 NPs' surfaces by electrostatic interaction. The pH-dependence of the process wherein DOX·HCl release out of DOX·HCl-SiO2 NPs was investigated as well. For comparison, both the free DOX·HCl molecules and DOX·HCl-SiO2 NPs were used as the labels for cultured cancer cells. Confocal laser scanning microscopy images showed that the DOX·HCl-SiO2 NPs were better delivered to cancer cells which are more acidic than healthy cells. We propose that engineered DOX·HCl-SiO2 systems are good candidates for drug delivery and clinical applications. [ABSTRACT FROM AUTHOR]

• Doped hybrid (PMMA-PVA)/SiO 2 NPs polymeric thin films are prepared using dip coating technique. • The transmittance, reflectance, refractive index, extinction coefficient, absorption coefficient and the optical bandgap energy are measured and characterized. • Transmittance of (PMMA-PVA)/SiO 2 NPs nanocomposite thin films decreases as incorporating SiO 2 NPs in the polymeric matrix is increased. • FTIR absorbance spectra of (PMMA-PVA)/SiO 2 NPs are measured in the spectral range of 500 cm−1 up to 4000 cm−1 to elucidate vibrational modes. • Synthesized nanocomposite thin films are found to be thermally stable at temperatures below 110 °C. Doped polymeric hybrid thin films based on Poly-Methyl-Meth-Acrylate (PMMA) and Poly-vinyl-alcohol (PVA) doped with silica nanoparticles (SiO 2 NPs) are synthesized using the dip-coating technique. The as-prepared (PMMA-PVA)/SiO 2 nanocomposite (wt% of SiO 2 NPs = 2%, 4%, 8%, and 16%) are deposited on glass substrates. Transmittance (T%) and reflectance (R%) are measured using a UV–Vis spectrometer. Furthermore, other related optical parameters such as absorption coefficient (α), optical constants (n and k), and optical dielectric functions (ε 1 and ε 2) are calculated using experimental transmittance, reflectance spectra and well-established classical models such as Tauc, Urbach and Spitzer-Fan and Drude models. The Tauc model is used to estimate the optical bandgap energy. Incorporation of specific concentrations of SiO 2 NPs into PMMA-PVA polymeric matrix leads to a noticeable decrease of the optical bandgap. The optical bandgap of un-doped PMMA-PVA thin-film is estimated to be 4.069 eV. Consequently, bandgap engineering and manipulation of optical properties are possible. Additionally, refractive indices (n) of undoped PMMA-PVA polymeric thin films are calculated to be in the range (1.48–1.72). To elucidate and identify vibrational modes of thin films, Fourier-transform infrared spectroscopy (FTIR) is employed in the spectral range (500 cm−1–4000 cm−1). The results obtained are useful for a better understanding of the lattice dynamics. Moreover, thermal stability of thin films is investigated using thermogravimetric (TGA) technique. Remarkably, TGA thermograms reveal that doped thin films are thermally stable below 110C. Consequently, investigated thin films may have the potential to be key candidates for real-time optical and optoelectronic devices. [ABSTRACT FROM AUTHOR]

We propose a novel derived optical model fitted to the experimental transmittance of PVC-PS hybrid thin films doped with Silica nanoparticles. The films are synthesized using a simple dip-coating method. The model has successfully interpreted the experimental spectral behaviour of transmittance of amorphous semiconductors and dielectric thin films. Interestingly, our model reproduces the optical parameters of the investigated thin films in good agreement with those predicted by Tauc plot. The great advantage of the proposed model over other models lies in its ability to explain the correlations between the film thickness and the optical bandgap. Furthermore, we investigate the structural, physical, and optical properties of PVC-PS- SiO 2 thin films, in relevance to the silica percentage content. XRD measurements show that the as-prepared polymeric thin films are amorphous. In addition, SEM micrographs indicate that silica nanoparticles are well dispersed on the surface of the PVC-PS thin films with an average diameter of 100-400 nm. The effect of annealing parameters is also investigated to optimize the projected water contact angle of PVC-PS- SiO 2 thin films. At annealing temperature of 2000° C , films become hydrophobic. The transmittance T% of the PVC-PS thin films is found to be about 83% in the visible region. The T% enhances to 90% upon adding silica NPs into PVC-PS polymeric thin films. Obtaining coatings with high transmittance is of crucial importance for several optoelectronic and photonic applications., (© 2020 The Author(s).)