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A simultaneous steady-state and transient photothermal-lens modality was used for both the thermal and optical parameters of aqueous dispersed systems (carbon and silica nanoparticles, metal iodides, surfactants, heme proteins, albumin, and their complexes). Heat-transfer parameters (thermal diffusivity and thermal effusivity), the temperature gradient of the refractive index, light absorption, and concentration parameters were assessed. To simultaneously measure thermal and optical parameters, the time scale of thermal lensing (characteristic time, tc) should correspond to an excitation beam size of 60–300 µm, and the relative time intervals 0.5÷5tc and (5÷20)tc should be selected for transient and steady-state measurements, respectively. Dual-beam thermal-lens spectrometers in a mode-mismatched optical schematic at various excitation wavelengths were built. The spectrometers implement back-synchronized detection, providing different measurement conditions for the heating and cooling parts of the thermal-lens cycle. By varying the measurement parameters depending on the dispersed system, the conditions providing the suitable precision (replicability, repeatability, and reproducibility) of thermal-lens measurements were found; setups with a broad excitation beam (waist size, 150 and 300 μm) provide longer times to attain a thermal equilibrium and, thus, the better precision of measurements of thermal diffusivity.

Pyrogallol molecules were successfully immobilized onto aminopropyl molecule functionalized MCM41 nanoparticles to obtain a fast and high gold adsorption capacity. The Taguchi statistical method was used to determine the factors affecting the gold(iii) adsorption efficiency. The effect of six factors, pH, rate, adsorbent mass, temperature, initial Au(iii) concentration and time, each with 5 levels, on the adsorption capacity was investigated by forming an L25 orthogonal. The analysis of variance (ANOVA) of each factor showed that all factors had significant effects on adsorption. pH 5, 250 rpm stirring speed, 0.025 g adsorbent mass, 40 °C temperature, 600 mg L−1 Au(iii) concentration and 15 min time were determined to be the optimum adsorption conditions. The maximum Langmuir monolayer adsorption capacity of APMCM1-Py for Au(iii) was calculated to be 168.54 mg g−1 at 303 K. The adsorption mechanism fits the pseudo-second-order kinetic model assuming the formation of a single chemical adsorption layer on the adsorbent surface. The adsorption isotherms are best represented using the Langmuir isotherm model. It exhibits a spontaneous endothermic behavior. FTIR, SEM, EDX and XRD analyses showed that mostly phenolic -OH functional groups adsorb Au(iii) ions on the APMCMC41-Py surface with their reducing character. These results enable the rapid recovery of gold ions from weakly acidic aqueous solutions by reduction of APMCM41-Py NPs. © 2023 The Royal Society of Chemistry.

In the current years, silica nanoparticles have become more favorable in various disciplines like medicine, nano-biotechnology, the food industry, and drug delivery due to their tunable physicochemical characteristics. In this paper, the silica nanoparticles were synthesized by hydrolysis and condensation of tetra-ethyl-ortho-silicate (TEOS) in an ethanolic medium using ammonia as a stimulator in the reaction. The chemical bond structures of silica nanoparticles were analyzed by Fourier Transform Infrared Spectroscopy (FT-IR) which confirmed the existence of the Si-O bonds according to the different absorption peaks of the samples. The amorphous structure of these nanoparticles was certified by finding the board peaks in the X-Ray Diffraction (XRD) patterns. The elemental chemical composition of silica nanoparticles was investigated by Energy Dispersive X-Ray Spectroscopy (EDX) where 61.48wt % of silicon and 23.48wt% of oxygen were found. Almost round-shaped spherical and uniform silica nanoparticles with smooth surfaces were investigated by Scanning Electron Microscopy (SEM) measurement. The different particle sizes of silica nanoparticles within the range of 95±5.59 to 280±7.8 nm were found by controlling the concentration of TEOS. The optical absorption spectra and band gap calculations were also analyzed by Ultraviolet-Visible (UV-Vis) spectrophotometry for the different concentrations of TEOS. The results revealed that with increasing the concentration of TEOS, the absorption spectra of silica nanoparticles increased and their optical bandgap decreased from 3.92 eV to 3.79 eV.

To improve the powder properties of active pharmaceutical ingredients (APIs), we coated APIs with silica nanoparticles using a dry process that allowed for direct compression into tablets. The dry coating performed with different apparatuses (a batch-type high-speed shear mixer (Mechanomill) and a continuous conical screen mill (Comil)) and properties of the resulting dry-coated APIs were compared. Ethenzamide (ETZ), which has low powder flowability, was selected as the host particle to be improved and the colloidal silicas Aerosil 200 and R972 were used as the guest particles. Both coating processes and types of silica nanoparticles improved the powder flowability (angle of repose) of ETZ under unstressed conditions. Inverse gas chromatography demonstrated that dry coating with silica nanoparticles reduced the surface free energy and improved the homogeneity of the surface energy distribution of ETZ particles. Under the stress conditions of a shear cell test, the Mechnomill-based treatment improved the powder flowability of ETZ from that of untreated ETZ; however, the Comil-based treatment did not improve the flowability. The mechanical shear force exerted by Comil was apparently insufficient for interactions between host and guest particles. However, the properties of tableted ETZ were enhanced even when the silica nanoparticles were coated using Comil.

The granary weevil, Sitophilus granarius (L.), is one of the most important internal feeders of stored grain. Nanotechnology has become one of the most promising new approaches for pest control in recent years. In our screening program, laboratory trials were conducted to determine the effectiveness of silica nanoparticles (SNPs) and zinc nanoparticles (ZNPs) against the larval stage and adults of S. granarius on stored wheat. Nanoparticles of silica and zinc were synthesized through a solvothermal method. They were then used to prepare insecticidal solutions of different concentrations and tested on S. granarius. Silica nanoparticles (SNPs) were found to be highly effective against S. granarius causing 100% mortality after 2 weeks. ZNPs were moderately effective against this pest.

Over the past few decades, the study of superhydrophobic coatings (SHCs) gained the significant interest of worldwide researchers due to their tremendous applications in various sectors including, the metal industry, membrane industry, automation, structures, marine, defense, and medicines. The literature is full of review papers on the basics of SHCs, their synthesis methods, and their applications. But, minimal reviews are available on silica nanoparticles-based SHCs. However, silica nanoparticles are well-known material for SHCs due to their abundance, economical, transparency and ease of surface modification by various surface-functionalizing agents compared to other nanomaterials. Furthermore, silica nanoparticles are the most preferred material for the generation of nano-level roughness in the coatings to exhibit superhydrophobicity. Therefore, there is a great need to work in this direction. This work is dedicated to the challenges, recent progress and applications of silica nanoparticles-based superhydrophobic coatings.

The present study investigates the adsorption and decolourisation efficacy of silica nanoparticles in textile effluent treatment. Silica nanoparticles synthesis was mediated by the indigenous actinomycetes species isolated from the effluent contaminated site using magnesium trisilicate hydrate as a substrate of silica. The presence of functional groups and morphological features of silica nanoparticles were confirmed by characterization techniques. The synthesized nanoparticles were further evaluated by encapsulating methods to study their viability and stability for treating effluents. The solids and toxic compounds concentrations were decreased in the effluents due to the immobilized silica nanoparticles treatment. The studies revealed 80% decolourisation efficiency for encapsulated native silica nanoparticles. Thus the present study suggests the use of immobilized silica nanoparticles in the form of encapsulation as a suitable technique to decolourise textile effluent by its adsorbent and decolourisation properties.

Hypothesis We developed a geometrical model to determine the theoretical maximum number of proteins that can pack as a monolayer surrounding a spherical nanoparticle. We applied our new model to study the adsorption of receptor binding domain (RBD) of the SARS-CoV-2 spike protein to silica nanoparticles. Due to its abundance and extensive use in manufacturing, silica represents a reservoir where the virus can accumulate. It is therefore important to study the adsorption and the persistence of viral components on inanimate surfaces. Experiments We used previously published datasets of nanoparticle-adsorbed proteins to validate the new model. We then used integrated experimental methods and Molecular Dynamics (MD) simulations to characterise binding of the RBD to silica nanoparticles and the effect of such binding on RBD structure. Findings The new model showed excellent fit with existing datasets and, combined to new RBD-silica nanoparticles binding data, revealed a surface occupancy of 32% with respect to the maximum RBD packing theoretically achievable. Up to 25% of RBD’s secondary structures undergo conformational changes as a consequence of adsorption onto silica nanoparticles. Our findings will help developing a better understanding of the principles governing interaction of proteins with surfaces and can contribute to control the spread of SARS-CoV-2 through contaminated objects.

Waterborne polyurethane (WPU) is widely applied in many fields; however, it is limited by its drawback of low mechanical strength and short lifespan. Polymer nanocomposites have been developed for many years to enhance the mechanical behavior of materials. Nevertheless, obtaining nanofillers with even dispersion to obtain improved mechanical performance is difficult. To solve the above problems, silica nanoparticles modified by furfuryl (furan@SiO2) were synthesized according to the sol–gel process. By introducing furan@SiO2 into a maleimide-terminated waterborne polyurethane matrix, a self-healing system was constructed through a DA/retro-DA process among furan groups and maleimide-terminated waterborne polyurethane, and a series of WPU films with different furan@SiO2 (WMPUS-x) contents were prepared. The structure of furan@SiO2 was clearly corroborated by TEM, SEM, FTIR, etc. Moreover, confirmed by tensile tests, the mechanical properties of all WPU samples were significantly improved due to the addition of rigid furan@SiO2, and their first self-healing efficiencies were all higher than 88%. In this article, a series of thermo-driven self-healable organic/inorganic nanohybrid polyurethane (WMPUS-x) films were prepared with different addition amount of furfuryl modified silica nanoparticles (furan@SiO2). The self-healable system was constructed via a DA/retro-DA process among furan@SiO2 and maleimide-terminated waterborne polyurethane. The results exhibited the addition of furan@SiO2 enhanced the mechanical behavior of all WPU samples.

Protein fouling on critical biointerfaces causes significant public health and clinical ramifications. Multiple strategies, including superhydrophobic (SHP) surfaces and coatings, have been explored to mitigate protein adsorption on solid surfaces. SHP materials with underwater air plastron (AP) layers hold great promise by physically reducing the contact area between a substrate and protein molecules. However, sustaining AP stability or lifetime is crucial in determining the durability and long-term applications of SHP materials. This work investigated the effect of protein on the AP stability using model SHP substrates, which were prepared from a mixture of silica nanoparticles and epoxy. The AP stability was determined using a submersion test with real-time visualization. The results showed that AP stability was significantly weakened by protein solutions compared to water, which could be attributed to the surface tension of protein solutions and protein adsorption on SHP substrates. The results were further examined to reveal the correlation between protein fouling and accelerated AP dissipation on SHP materials by confocal fluorescent imaging, surface energy measurement, and surface robustness modeling of the Cassie-Baxter to Wenzel transition. The study reveals fundamental protein adsorption mechanisms on SHP materials, which could guide future SHP material design to better mitigate protein fouling on critical biointerfaces.

The dynamic development of nanotechnology research has contributed to the fact that various types of nanoparticles are increasingly used on a large scale both for medical and biological purposes, but above all in many industrial fields. Such a wide application of nanoparticles is often connected with the need to estimate their characteristic parameters, such as size, size distribution or concentration. Existing instruments are usually quite expensive and not always available. Therefore, other cheaper and simpler methods based on analytical techniques are sought. In this paper, we have proposed a method to estimate the concentration of nanoparticles in solutions based on destabilization analyses of Pickering emulsions produced with their use. The fact of mutual relationship between emulsion concentration, nanoparticle concentration and emulsion stability was used here. The study was carried out using silica nanoparticles. It was presented how to apply the method and what are its limitations. Moreover, an example of its application for the determination of nanoparticle concentration in an unknown sample, obtained after analysis of the permeability of membranes in diffusion chambers, has been presented. The method can become a useful alternative for the determination of nanoparticle concentration in solution in places where no specialized equipment is available.

We study the slowing down of polymer dynamics in canonical nanocomposites made of strongly interacting mixtures of poly-2-vinyl pyridine and silica nanoparticles (radius R = 7 ± 2 nm) by means of l...

The use of silica nanoparticles (SNPs) has shown promising results in providing higher foam stability in chemically enhanced oil recovery (cEOR). In this study, hydrophobic SNPs stabilized in a car...

Risk assessment of nanomaterials requires not only standardized toxicity studies but also validated methods for nanomaterial surface characterization with known uncertainties. In this context, a first bilateral interlaboratory comparison on surface group quantification of nanomaterials is presented that assesses different reporter-free and labeling methods for the quantification of the total and accessible number of amine functionalities on commercially available silica nanoparticles that are widely used in the life sciences. The overall goal of this comparison is the identification of optimum methods as well as achievable measurement uncertainties and the comparability of the results across laboratories. We also examined the robustness and ease of implementation of the applied analytical methods and discussed method-inherent limitations. In summary, this comparison presents a first step toward the eventually required standardization of methods for surface group quantification.

Successful protein-based enrichment of uranyl, the predominant form of uranium from seawater, relies not only on selective binding of uranyl with a high affinity but also on the reusability of protein binder and a supporting matrix that is abundantly available at low cost. In this work, we propose a silica-binding peptide-enabled approach that allows the non-covalent immobilization of super uranyl-binding protein (SUP) onto silica nanoparticles for their repeated use. We first thoroughly examined solution conditions that affect the stability of uranyl-binding proteins and identified suitable physical conditions that are beneficial for the non-covalent SUP immobilization and subsequent capture of uranyl. We found that the molecular linker between SUP and silica binding peptide plays an important role in improving interaction strength between the silica nanoparticles and the engineered proteins. Consequently, we have demonstrated repeatable recovery and enrichment of uranyl ions from synthetic seawater using the engineered protein on silica nanoparticles. Our approach does not require chemical modification of silica nanoparticles, yet offers strong attachment of SUP to the silica interface and thus attractive reusability of protein-silica nanomaterials.

Self‐assembly processes guide disordered molecules or particles into long‐range organized structures due to specific supramolecular interactions among the building entities. Herein, we report a unique evaporation‐induced self‐assembly (EISA) strategy for four different silica nanoparticle systems obtained through peptide functionalization of the particle surface. First, covalent peptide‐silica coupling was investigated in detail, starting with the grafting of a single amino acid (L‐serine) and expanded to specific small peptides (up to four amino acids) and transferred to different particle types (MCM‐48‐type MSNs, solid nanoparticles, and newly developed virus‐like nanoparticles). These materials were investigated regarding their ability to undergo EISA, which was shown to be independent of particle type and amount of peptide anchored to their surface. This EISA‐based approach provides new possibilities for the design of future advanced drug delivery systems, engineered hierarchical sorbents, and nanocatalyst assemblies., Evaporation‐induced self‐assembly of a bioconjugate is reported. The formation of ring‐like structures was independent of different silica particle types and the amount of peptide conjugated to the material. This novel approach paves the way for further production of functional materials for separation, catalysis, and medical applications.

Listeria monocytogenes (L. monocytogenes) is one of the top five dangerous foodborne pathogens which widely exists in most raw food and has approximately 30 % mortality rate in high-risk groups. Food safety caused by foodborne pathogens is still a major problem faced by humans in all world. The conventional analytical methods currently used involve complex bacteriological tests and usually take several days for incubation and analysis. Thus, in order to prevent the spread of disease, the development of a detection method with high speed, high accuracy and sensitivity is urgent and necessary. Herein, we developed an approach for the identification and magnetic capture of L. monocytogenes by using core@shell Fe3O4@silica nanoparticles terminated with hydroxyl or amine groups. Our results show that both amine- and hydroxyl-terminated Fe3O4@silica core@shell nanoparticles functionalized with specific antibodies, present 95.2 %±6.2 % and 98.6 %±0.3 % capture efficacies, respectively. However, without conjugating the specific antibodies, the hydroxyl-terminated Fe3O4@silica nanoparticles exhibit 17.6 %±1.6 % efficacy, while the amine-terminated one remains 93.2 %±9.2 % capture efficiency ascribed to the high affinity. This study quantitatively uncovers the specific and non-specific recognitions relevant to the molecular-scale physiochemical interactions between the microorganisms and the functionalized particles, and the results from this work can be generalized and extended to other bacterial species by changing antibodies, also have important implications in developing advanced analytic methods.

A green protocol has been developed for the preparation of 2,2′-(arylmethylene)bis(3-hydroxy-5,5-dimethylcyclohex-2-en-1-ones) following the multicomponent condensation reaction between aromatic alde­hydes and dimedone with excellent yields. The reaction was carried out in water under microwave irradiation in the presence of montmorillonite KSF as a catalyst. The synthesized compounds were used for the functionaliza­tion of MCM-41 silica nanoparticles prepared by the modified Stober method.

The analysis of the recent advances in the field of the development of photochromic silica nanoparticles is presented.

Previous studies have been carried out on the effect of silica nanoparticles (SNPs) on the stability of oil–water emulsions. However, the combining configuration of SNPs and oil droplets at the molecular level and the effect of SNP content on the coalescence behavior of oil droplets cannot be obtained through experiments. In this paper, molecular dynamics (MD) simulation was performed to investigate the adsorption configuration of hydrophilic SNPs in an O/W emulsion system, and the effect of adsorption of SNPs on coalescence of oil droplets. The simulation results showed: (i) SNPs adsorbed on the surface of oil droplets, and excessive SNPs self-aggregated and connected by hydrogen bonds. (ii) Partially hydrophilic asphaltene and resin molecules formed adsorption configurations with SNPs, which changed the distribution of oil droplet components. Furthermore, compared with hydrophobic asphaltene, the hydrophilic asphaltene was easier to combine with SNPs. (iii) SNPs would extend the oil droplet coalescence time, and the π–π stacking structures were formed between asphaltene and asphaltene or resin molecules to enhance the connection between oil droplets during the oil droplet contact process. (iv) Enough SNPs tightly wrapped around the oil droplet, similar to the formation of a rigid film on the surface of an oil droplet, which hindered the contact and coalescence of components between oil droplets.

Cell membrane (CM) coating technology is increasingly being applied in nanomedicine, but the entire coating procedure including adsorption, rupture, and fusion is not completely understood. Previously, we showed that the majority of biomimetic nanoparticles (NPs) were only partially coated, but the mechanism underlying this partial coating remains unclear, which hinders the further improvement of the coating technique. Here, we show that partial coating is an intermediate state due to the adsorption of CM fragments or CM vesicles, the latter of which could eventually be ruptured under external force. Such partial coating is difficult to self-repair to achieve full coating due to the limited membrane fluidity. Building on our understanding of the detailed coating process, we develop a general approach for fixing the partial CM coating: external phospholipid is introduced as a helper to increase CM fluidity, promoting the final fusion of lipid patches. The NPs coated with this approach have a high ratio of full coating (~23%) and exhibit enhanced tumor targeting ability in comparison to the NPs coated traditionally (full coating ratio of ~6%). Our results provide a mechanistic basis for fixing partial CM coating towards enhancing tumor accumulation.

Combined stressors (high soil salinity and saline water irrigation) severely reduce plant growth and sugar beet yield. Seed inoculation with plant growth-promoting rhizobacteria (PGPR) and/or foliar spraying with silica nanoparticles (Si-NP) is deemed one of the most promising new strategies that have the potential to inhibit abiotic stress. Herein, sugar beet (Beta vulgaris) plants were treated with two PGPR (Pseudomonas koreensis MG209738 and Bacillus coagulans NCAIM B.01123) and/or Si-NP, during two successive seasons 2019/2020 and 2020/2021 to examine the vital role of PGPR, Si-NP, and their combination in improving growth characteristics, and production in sugar beet plants exposed to two watering treatments (fresh water and saline water) in salt-affected soil. The results revealed that combined stressors (high soil salinity and saline water irrigation) increased ion imbalance (K+/Na+ ratio; from 1.54 ± 0.11 to 1.00 ± 0.15) and declined the relative water content (RWC; from 86.76 ± 4.70 to 74.30 ± 3.20%), relative membrane stability index (RMSI), stomatal conductance (gs), and chlorophyll content, which negatively affected on the crop productivity. Nevertheless, the application of combined PGPR and Si-NP decreased oxidative stress indicators (hydrogen peroxide and lipid peroxidation) and sodium ions while increasing activities of superoxide dismutase (SOD; up to 1.9-folds), catalase (CAT; up to 1.4-folds), and peroxidase (POX; up to 2.5-folds) enzymes, and potassium ions resulting in physiological processes, root yield, and sugar yield compared to non-treated controls under combined stressors (high soil salinity and saline water irrigation). It is worth mentioning that the singular application of PGPR improved root length, diameter, and yield greater than Si-NP alone and it was comparable to the combined treatment (PGPR+Si-NP). It was concluded that the combined application of PGPR and Si-NP has valuable impacts on the growth and yield of sugar beet growing under combined stressors of high soil salinity and saline water irrigation.

Objective: Multidrug-resistant and pan-drug-resistant pathogens pose major challenges in the management of infections. Nanotechnology-based combination therapy is becoming more common, as it produces a synergistic antimicrobial effect. Study Design: Cross Sectional Study. Setting: Institute of Biogenetic Engineering (IBGE) Islamabad. Period: September 2015 to October 2017. Material & Methods: Silica nanoparticles were prepared by three different modifications using general Stober Method and the synthesized silica nanoparticles SiNPs were named as S1, S2 and S3. The synergism of Ciprofloxacin and Piperacillin-Tazobactam with a combination of silica nanoparticles was evaluated in LB grown culture to determine the sensitivity of Escherichia coli and pseudomonas aeruginosa. Results: The combined application of Ciprofloxacin and S1, S2 and S3 respectively retarded the growth of P. aeruginosa almost completely whereas E. coli showed minimal growth inhibition. Collective therapy of Piperacillin-Tazobactam with S1, S2 and S3 inhibits the normal growth pattern of both E. coli, P. aeruginosa as compared to the control. Conclusion: Combined application of silica nanoparticles and antibiotics inhibited the growth of MDR gram-negative bacteria in vitro.

The present work reported the synthesis and characterisation of β-cyclodextrin (βCD) grafted into silica (SiO2@βCD) nanoparticles (NPs). Morphology analysis shows that the prepared NPs have a spher...

In the present study, several polypropylene/silica nanocomposites (PP/SiO2), containing 3 and 5 wt.% of untreated silica nanoparticles in presence of stearic acid (SA) as modifier agent, were prepa...

This paper demonstrates the feasibility of a long-range antenna sensor embedded underneath a liquid repellent fabric to be employed as a wearable sensor in personal protective fabrics. The sensor detects and monitors hazardous aqueous liquids on the outer layer of fabrics, to add an additional layer of safety for professionals working in hazardous environments. A modified patch antenna was designed to include a meandering-shaped resonant structure, which was embedded underneath the fabric. Superhydrophobic fabrics were prepared using silica nanoparticles and a low-surface-energy fluorosilane. 4 to 20 μL droplets representing hazardous aqueous solutions were drop-cast on the fabrics to investigate the performance of the embedded antenna sensor. Long-range (S21) measurements at a distance of 2-3 m were performed using the antenna sensor with treated and untreated fabrics. The antenna sensor successfully detected the liquid for both types of fabrics. The resonant frequency sensitivity of the antenna sensor underneath the treated fabric exhibiting superhydrophobicity was measured as 370 kHz/μL, and 1 MHz/μL for the untreated fabric. The results demonstrate that the antenna sensor is a good candidate for wearable hazardous aqueous droplet detection on fabrics.

The bacterial cell differs somewhat from the cells found in plants and animals. Bacterial cells do not have a nucleus, and organelles are bound together by the membrane except for ribosomes. Moreover, viruses are not completely alive because they require a host to reproduce. Viruses usually remain infectious for a longer time on hard surfaces, as opposed to soft surfaces. So, viruses on plastic, glass, and metal last longer than those on fabrics. Low sunlight, low humidity and low temperatures extend the viability of most viruses. While viruses survive on hard surfaces, bacteria are more likely to persist in porous materials. In general, bacteria remain contagious for a longer time than viruses. How long the bacteria stay outside the body depends on how different external conditions are from their preferred environment and whether the bacteria can produce spores. Unfortunately, spores in adverse conditions may persist for a long time. Therefore, the current research has developed a material made of Titanium Dioxide; Sodium Silicate and Silica Nanoparticles that has the ability to eliminate bacteria and most of viruses in a biophysical field with a radius of 80 cm in a safe and effective manner. The effectiveness of the material was tested within independent research laboratories (see Appendix A and B). The results indicated the effectiveness of the material in eliminating bacteria on surfaces and in the water.

A multifunctional hybrid curing component (GSD) for epichlorohydrin-modified novolac resin (ENR) was synthesized via grafting poly(amidoamine) (PAMAM)-modified silica nanoparticles (SD) on graphene...

This study was aimed to evaluate the toxicological and biological effects of three nanoparticles (silver, hydrophilic and hydrophobic silica) at four concentrations (100, 200, 400 and 800 ppm) against 1st instar larvae of Sesamia cretica Lederer, 1857 and its effects on some maize characters. Each concentration and control was repeated 4 times (10 larvae/replicate). Larvae were fed on treated stem maize and mortality rate was recorded. After treatment with LC50 values, the survival larvae were collected and the larval duration, pupal duration, pupal weight, pupation percentage and adult longevity were recorded. Seedling maize plants were sprayed with three concentrations (50, 100 and 200 ppm) at 4 categories (every 1, 3, 7 and 14 days) to detect the effect of nanoparticles on leaf area, extended height and leaf chlorophyll content. Results showed that hydrophilic silica nanoparticle was the most effective, followed by silver nanoparticle then hydrophobic silica nanoparticle with LC50 121.19, 405.71 and 416.82 ppm, respectively. All nanoparticles led to increase in larval durations, reduction of egg number per female and decrease of eggs hatchability rate. All nanoparticles caused positive effect on leaf area, extended height and chlorophyll content. These nanoparticles may be recommended to control S. cretica with positive effects on plant characters.

Silica nanoparticle-impregnated Kevlar (SNK) fabric has better specific ballistic performance in comparison to its neat counterparts. For multifunctional structural applications using lightweight composites, combining this improved ballistic functionality with an acoustic functionality is desirable. In this study, acoustic characterization of neat and SNK samples is conducted using the normal-incidence impedance tube method. Both the absorption coefficient and transmission loss (TL) are measured in the 60–6000 Hz frequency range. The influence of parameters such as number of layers of neat or treated fabric, percentage by weight of nanoparticle addition, spacing between fabric layers, and residual porosity is examined. It is found that while absorption decreases with an increase in nanoparticle addition for frequencies above about 2500 Hz, increasing the number of layers shifts peak absorption to lower frequencies. By introducing an air-gap behind the fabric layer, dominant low-frequency (1000–3000 Hz) absorption peaks are obtained that correlate well with natural modes of mass-equivalent thin plates. Examining the influence of residual porosity by laminating the SNK samples reveals that it contributes to about 30–50% of the total absorption. Above about 1500 Hz, 3–5 dB of TL increase is obtained for SNK samples vis-à-vis the neat samples. TL is found to increase beyond that of the neat sample above a threshold frequency when an air-gap is introduced between two SNK layers. With an increase in the weight of nanoparticle addition, measured TL tends to be closer to mass law predictions. This study demonstrates that SNK fabric could provide improved acoustic performance in addition to its ballistic capabilities, making it suitable for multifunctional applications and could form the basis for the development of simplified models to predict the structural acoustic response of such nanoparticle–fabric composites.

The insertion of nanoparticles into smart hydrogels can diversify their functionalities by a synergistic combination of the components properties within the hydrogels. While these hybrid systems are attractive to the biomaterials field, careful design and control of their properties are required since the new interactions between the polymer and the nanoparticles can result in changes or the loss of hydrogels stimuli response. In order to understand the physicochemical aspects of the thermoresponsive systems, nanocomposites of poly(N-vinylcaprolactam) (PNVCL) and silica nanoparticles with different sizes and concentrations were synthesized. The UV-vis and DLS techniques showed that the PNVCL has a sharp phase transition at 34 °C, while the nanocomposites have a diffuse transition. The nanocomposites showed an initial coil-globule transition before the phase transition takes place. This was identified by the evolution of the hydrodynamic diameter of the nanocomposite globules before the cloud point temperature (Tcp), which remained constant for PNVCL. This new transition profile can be described by two stages in which microscopic volume transitions occur first, followed by the macroscopic transition that forms the hydrogel. These results show that the proposed nanocomposites can be designed to have tunable stimuli response to smaller temperature variations with the formation of intermediate globule states.

It is a fact that the use of antibiotics is inducing a growing resistance on bacteria. This situation is not only the consequence of a drugs’ misuse, but a direct consequence of a widespread and continuous use. Current studies suggest that this effect could be reversed by using abandoned antibiotics to which bacteria have lost their resistance, but this is only a temporary solution that in near future would lead to new resistance problems. Fortunately, current nanotechnology offers a new life for old and new antibiotics, which could have significantly different pharmacokinetics when properly delivered; enabling new routes able to bypass acquired resistances. In this contribution, we will focus on the use of porous silica nanoparticles as functional carriers for the delivery of antibiotics and biocides in combination with additional features like membrane sensitizing and heavy metal-driven metabolic-disrupting therapies as two of the most interesting combination therapies.

Numerous nanocarriers have been currently developed for intracellular delivery. The potential cytotoxicity of these very small inorganic nanocarriers has raised great consideration. Thus, it becomes of utmost importance to conduct the intracellular trace of nanocarriers. Among many analytical techniques, surface enhanced Raman scattering (SERS) method is one of the current state-of-the-art techniques for cell visualization and trace. In this work, a novel stellate porous silica based gene delivery system has been designed for SERS trace purpose. A stellate porous silica nanoparticle modified with many small Au nanoparticles is designed to replace common metallic SERS tags. The results show that the designed system not only could deliver siRNA into cells for therapy, but also could realize SERS trace with high sensitivity and non-invasive features. The constructed delivery system has considerable potential to trace the dynamic gene delivery in living cells.

Silica nanoparticles were synthesized using the aqueous extract of orange peels by the green chemistry approach and simple method. The physicochemical properties such as optical and chemical banding of as-synthesized silica nanoparticles were analyzed with UV–visible spectroscopy and Fourier transform infrared spectroscopy. Scanning Electron Microscopy with Energy Dispersive X-Ray Analysis and X-ray diffraction analysis were employed to confirm the shape, size and elemental purities of the silica nanoparticles. The thermal stability and mass loss of the silica nanoparticles was examined using thermogravimetric analysis and zeta potential analysis. The surface plasmon resonance band of the silica nanoparticle was obtained in the wavelength of 292 nm. Silica nanoparticles with a spherical and amorphous nature and an average size of 20 nm were produced and confirmed by X-ray diffraction and Scanning Electron Microscopy. The zeta potential of the silica nanoparticles was −25.00 mV. The strong and broad bands were located at 457, 642 and 796 cm−1 in the Fourier transform infrared spectra of the silica nanoparticles, associated with the Si–O bond. All the results of the present investigation confirmed and proved that the green synthesized silica nanoparticles were highly stable, pure and spherical in nature. In addition, the antioxidant activity of the green synthesized orange peel extract mediated by the silica nanoparticles was investigated with a DPPH assay. The antioxidant assay revealed that the synthesized silica nanoparticles had good antioxidant activity. In the future, green synthesized silica nanoparticles may be used for the production of nano-medicine.

Commercially available oxygen scavengers used to prevent lipid autoxidation, microbial growth and enzymatic browning in food products present several issues, which include the usage of metals and their moisture dependence to work properly. We present the synthesis and characterization of a moisture-independent oil-based oxygen scavenging system comprised of linseed oil and silica nanoparticles. The system was synthesized via sol-gel chemistry and was characterized using morphological analysis (SEM, AFM, TEM, and N2 adsorption/desorption), oil-loading analysis (TGA), and surface analysis (ζ-potential and ATR-FTIR). Performance of the system was evaluated through headspace measurements and reproducibility of synthetic procedure was verified using six replicates. Nanoparticles showed the desired spherical shape with a diameter of (122.7 ± 42.7 nm) and mesoporosity (pore diameter = 3.66 ± 0.08 nm), with an encapsulation efficiency of 33.9 ± 1.5% and a highly negative ζ-potential (−56.1 ± 1.2 mV) in basic solution. Performance of the system showed a promising high value for oxygen absorption of 25.8 ± 4.5 mL O2/g of encapsulated oil (8.3 ± 1.5 mL O2/g of nanocapsules) through a moisture independent mechanism, which suggests that the synthesized system can be used as an oxygen scavenger in dry atmosphere conditions.

In this study, oil-in-water Pickering emulsions (PEs) were prepared by modified silica nanoparticles (MSNs) with cetyltrimethylammonium bromide (CTAB) using the Taguchi approach. The surface modification of SiO2 nanoparticles (NPs) was performed in different conditions, temperatures, pH levels, and amounts of CTAB as a coating agent, followed by an evaluation of their physicochemical properties. After treatment of the SiO2 NPs, the relationship of the MSNs’ surface properties and their efficiency in stabilizing Pickering emulsions was investigated by considering the zeta potential (ZP) and emulsion physical stability as main responses, respectively. Results disclosed were then supported by additional characterization, such as thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, contact angle (CA), and scanning electron microscopy. Results demonstrated that temperature has the most important role in the treatment of SiO2 nanoparticles, and allows for the identification of the best experimental conditions, i.e., range of zeta potential of MSNs to produce more efficient NPs, as well as the best stabilization of PEs.

We measure the center-of-mass diffusion of silica nanoparticles (NPs) in entangled poly(2-vinylpyridine) (P2VP) melts using Rutherford backscattering spectrometry. While these NPs are well within the size regime where enhanced, nonhydrodynamic NP transport is theoretically predicted and has been observed experimentally (2RNP/dtube ≈ 3, where 2RNP is the NP diameter and dtube is the tube diameter), we find that the diffusion of these NPs in P2VP is in fact well-described by the hydrodynamic Stokes–Einstein relation. The effective NP diameter 2Reff is significantly larger than 2RNP and strongly dependent on P2VP molecular weight, consistent with the presence of a bound polymer layer on the NP surface with thickness heff ≈ 1.1Rg. Our results show that the bound polymer layer significantly augments the NP hydrodynamic size in polymer melts with attractive polymer–NP interactions and effectively transitions the mechanism of NP diffusion from the nonhydrodynamic to hydrodynamic regime, particularly at high mole...

We investigate the crystallization-induced ordering of C18 grafted 14 nm diameter spherical silica nanoparticles (NPs) in a short chain (Mw = 4 kDa, ĐM ≈ 2.3) polyethylene and a commercial high-den...

Theranostic nanoparticles hold the potential to greatly improve cancer management by providing personalized medicine. Although many theranostic nanoconstructs have been successful in preclinical studies, clinical translation is still hampered by their limited targeting capability and lack of successful therapeutic efficacy. We report the use of novel ultrasmall porous silica nanoparticles (UPSN) with enhanced in vivo pharmacokinetics such as high target tissue accumulation (12% ID/g in the tumor) and evasion from the reticuloendothelial system (RES) organs. Herein, UPSN is conjugated with the isotopic pair (90/86)Y, enabling both noninvasive imaging as well as internal radiotherapy. In vivo PET imaging demonstrates prolonged blood circulation and excellent tumor contrast with (86)Y-DOTA-UPSN. Tumor-to-muscle and tumor-to-liver uptake values were significantly high (12.4 ± 1.7 and 1.5 ± 0.5, respectively), unprecedented for inorganic nanomaterials. (90)Y-DOTA-UPSN significantly inhibits tumor growth and increases overall survival, indicating the promise of UPSN for future clinical translation as a cancer theranostic agent.

This article describes about feasibility of silica modified Candelilla wax (CW)/thermoplastic polyurethane (TPU) coating for hydrophobic textiles. CW/TPU blend solutions at different ratio (10:1, 1...