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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.

Efficient drug delivery to target tissue is a major challenge in many cancer treatment modalities. Silica nanoparticles (SiNPs) have been identified as an ideal drug carrier due to their unique properties. In Photodynamic therapy (PDT), one of the key challenges in utilizing photosensitizers (PS) lies in effectively delivering the PS to the targeted tissue. Using Silica nanoparticles encapsulation will effectively prevent the leakage of entrapped PS from the particles, protects against reduction by the retinal endothelial system, and reduces PS toxicity. In this study, Silica nanoparticles (SiNPs) were used as carriers for Safranin (SF) as a photosensitizer agent to treat MCF-7 breast cancer cells in vitro. The SiNPs nanoparticles were synthesized, and their size and shape were measured using Transmission Electron Microscopy (TEM). Cytotoxicity was evaluated for different concentrations of encapsulated and naked SF. The optimal concentrations and exposure times required to eliminate the MCF-7 under light (Intensity ~110 mW/cm2, red laser) were determined. The results indicated that encapsulated SF by SiNPs exhibited higher efficacy than naked SF with a +50% concentration efficacy and +78% exposure time efficacy. This confirmed the superior ability of encapsulated SF to eliminate MCF-7 cells compared to naked SF. The use of synthesized silica nanoparticles loaded with SF improved photodynamic therapy by increasing the bioavailability of SF in the target cells. Our results demonstrate that SiNP encapsulation significantly improves the efficacy of SF in eliminating MCF-7 cells compared to bare SF. This study underscores the potential of SiNPs as a drug delivery system for photodynamic therapy and could pave the way for developing more effective cancer treatments.

Silica nanoparticles (nano-silica) were used as synergistic agents with ammonium polyphosphate (APP) and pentaerythritol (PER) to enhance flame retardancy of polypropylene (PP) in this research. The composites were prepared using a melt-mixing method. The influences of nano-silica on the fire performance of composites were thoroughly discussed, which promotes understanding of nano-silica on the flame-retardant performance of polypropylene composite. Scanning electron microscope (SEM) and energy-dispersive spectrometer (EDS) results indicated that the nano-silica with a diameter of about 95 ± 3.9 nm were dispersed favorably in the composite matrix, which might elevate its synergistic effect with intumescent flame retardant and improve the flame retardancy of polypropylene composite. The synergistic effects between nano-silica and intumescent flame retardant on PP composites were studied using the limiting oxygen index (LOI), UL-94 test, and cone calorimeter test (CCT). The total amount of flame retardant was maintained at 30%. When the dosage of nano-silica was 1 wt.%, the LOI value of PP/IFR/Si1.0 composite reached 27.3% and its UL-94 classification reached V-1. Based on the parameters of the CCT, the introduction of nano-silica induced composites with depressed heat release rate (HRR) and peak heat release rate (PHRR). The PHRR of PP/IFR/Si0.5 was only 295.8 kW/m2, which was 17% lower than that of PP/IFR. Moreover, the time to PHRR of PP/IFR/Si0.5 was delayed to 396 s, which was about 36 s later than that without nano-silica. EDS was used to quantitatively analyze the distribution of silica in charred residue. The EDS results indicated that the silica tended to accumulate on the surface during the fire. The surface accumulation characteristic of silica endows it with the enhanced flame-retardant properties of polypropylene composite at a very small dosage (as low as 1 wt.%).

Although promising for biomedicine, the clinical translation of inorganic nanoparticles (NPs) is limited by low biocompatibility and stability in biological fluids. A common strategy to circumvent this drawback consists in disguising the active inorganic core with a lipid bilayer coating, reminiscent of the structure of the cell membrane to redefine the chemical and biological identity of NPs. While recent reports introduced membrane-coating procedures for NPs, a robust and accessible method to quantify the integrity of the bilayer coverage is not yet available. To fill this gap, we prepared SiO2 nanoparticles (SiO2NPs) with different membrane coverage degrees and monitored their interaction with AuNPs by combining microscopic, scattering, and optical techniques. The membrane-coating on SiO2NPs induces spontaneous clustering of AuNPs, whose extent depends on the coating integrity. Remarkably, we discovered a linear correlation between the membrane coverage and a spectral descriptor for the AuNPs’ plasmonic resonance, spanning a wide range of coating yields. These results provide a fast and cost-effective assay to monitor the compatibilization of NPs with biological environments, essential for bench tests and scale-up. In addition, we introduce a robust and scalable method to prepare SiO2NPs/AuNPs hybrids through spontaneous self-assembly, with a high-fidelity structural control mediated by a lipid bilayer.

This study presents preparing and characterization of polyacrylonitrile (PAN) fibers containing various content of tetraethoxysilane (TEOS) incorporated via mutual spinning solution or emulsion using wet and mechanotropic spinning methods. It was shown that the presence of TEOS in dopes does not affect their rheological properties. The coagulation kinetics of complex PAN solution was investigated by optical methods on the solution drop. It was shown that during the interdiffusion process phase separation occurs and TEOS droplets form and move in the middle of the dope’s drop. Mechanotropic spinning induces the TEOS droplets to move to the fiber periphery. The morphology and structure of the fibers obtained were investigated by scanning and transmission electron microscopy, as well as X-ray diffraction methods. It was shown that during fiber spinning stages the transformation of the TEOS drops into solid silica particles takes place as a result of hydrolytic polycondensation. This process can be characterized as the sol-gel synthesis. The formation of nano-sized (3–30 nm) silica particles proceeds without particles aggregation, but in a mode of the distribution gradient along the fiber cross-section leading to the accumulation of the silica particles either in the fiber center (wet spinning) or in the fiber periphery (mechanotropic spinning). The prepared composite fibers were carbonized and according to XRD analysis of carbon fibers, the clear peaks corresponding to SiC were observed. These findings indicate the useful role of TEOS as a precursor agent for both, silica in PAN fibers and silicon carbide in carbon fibers that has potential applications in some advanced materials with high thermal properties.

Dengue hemorrhagic fever (DHF) is a severe form of dengue virus (DENV) infection that can lead to abnormal immune responses, endothelial vascular dysfunction, and hemorrhage pathogenesis. The virion-associated envelope protein domain III (EIII) is thought to play a role in the virulence of DENV by damaging endothelial cells. However, it is unclear whether EIII-coated nanoparticles simulating DENV virus particles could cause a more severe pathogenesis than soluble EIII alone. This study aimed to investigate whether EIII-coated silica nanoparticles (EIII-SNPs) could elicit greater cytotoxicity in endothelial cells and hemorrhage pathogenesis in mice compared to EIII or silica nanoparticles alone. The main methods included in vitro assays to assess cytotoxicity and in vivo experiments to examine hemorrhage pathogenesis in mice. EIII-SNPs induced greater endothelial cytotoxicity in vitro than EIII or silica nanoparticles alone. Two-hit combined treatment with EIII-SNPs and antiplatelet antibodies to simulate DHF hemorrhage pathogenesis during secondary DENV infections resulted in higher endothelial cytotoxicity than either treatment alone. In mouse experiments, two-hit combined treatment with EIII-SNPs and antiplatelet antibodies resulted in more severe hemorrhage pathogenesis compared to single treatments of EIII, EIII-SNPs, or antiplatelet antibodies alone. These findings suggest that EIII-coated nanoparticles are more cytotoxic than soluble EIII and could be used to develop a tentative dengue two-hit hemorrhage pathogenesis model in mice. Additionally, our results indicated that EIII-containing DENV particles could potentially exacerbate hemorrhage pathogenesis in DHF patients who have antiplatelet antibodies, highlighting the need for further research on the potential role of EIII in DHF pathogenesis.

Zdravljenje okužb z mikroorganizmi, predvsem bakterijskih okužb, predstavlja velik izziv, saj uporaba protimikrobnih učinkovin povzroča vse večjo odpornost. Najbolj pomemben mehanizem odpornosti bakterij je tvorba biofilmov. Bakterije se na površinah združujejo v organizirane tridimenzionalne strukture, ki jih varujejo pred škodljivimi vplivi okolice. Znotraj biofilmov so bakterije lahko do tisočkrat bolj odporne na zunanje vplive kot planktonske bakterije približno 80 % kroničnih okužb je povezanih s pojavom biofilmov. Magistrska naloga je vsebinsko vezana na ARRS projekt “Baktericidna nanorezila: preizkus bimodalnega mehanokemijskega odstranjevanja trdovratnih biofilmov”. Eden od ciljev omenjenega projekta je priprava nanodelcev v obliki paličic, ki so odzivni na magnetno polje, površino pa imajo prevlečeno z lipofilnimi spojinami s pozitivnim nabojem, ki naj bi delovale biocidno. Poleg tega želimo te nanodelce tudi spremljati s fluorescenčnim mikroskopom v ta namen bi nanodelce označili s fluorofori in tako lažje opazovali interakcije z bakterijskim biofilmom. V magistrski nalogi smo pripravili fluorofore, primerne za vgradnjo v plast silike na površini nanodelcev in na primeru nanodelcev silike preverili kako se v le-to vgrajujejo. V ta namen smo sintetizirali lantanoidne komplekse izmed vseh pripravljenih fluoroforov se je za najbolj primernega za vgradnjo v nanodelce silike izkazal evropijev kompleks (spojina 4). Pri pripravi spojin z biocidnim delovanjem smo sintetizirali nekaj pozitivno nabitih kvaternih amonijevih spojin z azidno oz. alkinsko skupino, ki smo jo želeli nadalje pripeti na komplementarni sililni reagent s kemijo klik. Pri sintezi sililnih reagentov smo preizkušali predvsem različne pristope za vpeljavo alkinske skupine na te reagente, pri tem smo ugotovili, da so sililni etri obstojni tudi pri povišani temperaturi. Žal vezave teh spojin na nanodelce nismo izvedli, saj v času nastajanja naloge nismo imeli na razpolago ustreznih materialov za pripravo biocidnih površin. V sklopu naloge smo uspeli pripraviti stabilno suspenzijo nanodelcev silike z vgrajenim evropijevim kompleksom, ki so primerni za opazovanje delcev z optičnimi metodami v prihodnosti pa bodo na zunanjo površino silike na nanodelcih vezali tudi pripravljene pozitivno nabite sililne reagente. Treatment of bacterial infections is a major challenge due to the overuse of antimicrobial agents, which in turn leads to resistance. One of the common mechanisms of bacterial resistance is biofilm formation. Bacteria clump together on surfaces to form organized three-dimensional structures that protect them from harmful environmental agents. Bacteria protected by biofilms can be up to a thousand times more resistant to external influences than planktonic bacteria approximately 80% of chronic infections are attributed to biofilms. This Master’s thesis’ content is linked to an ARRS project named: “Bactericidal nanoblades: a proof-of-concept approach for bimodal chemo-mechanical eradication of persistent biofilms”. One of the goals of this project is preparation of nanoparticles shaped as blades that respond to magnetic field, and coating of their surface with lipophilic compounds with positive charge that are supposedly biocidal. Besides that, we want to monitor these nanoparticles with a fluorescent microscope for this purpose, we would like to mark them with fluorophores which would allow us to more easily observe their reaction with bacterial biofilms. In this work we prepared fluorophores that are suitable for binding to silica-based surfaces of nanoparticles we observed said fluorophores’ binding to silica nanoparticles. For this purpose, we synthesized lanthanide complexes and among all prepared compounds we found that the most suitable for binding to silica nanoparticles is an europium complex (compound 4). For the preparation of compounds with biocidal effect, we synthesized positively charged quaternary ammonium compounds with azide or alkyne groups that we intended to further bind to a complementary silyl reagent using click chemistry. For the synthesis of silyl reagents, we tried different approaches for the introduction of alkyne groups to these reagents and we discovered that silyl ethers are resistant to higher temperatures. Unfortunately, we did not perform their binding to nanoparticles because at the time we did not have the appropriate nanomaterial for the preparation of biocidal surfaces. In this work, we have succeeded in preparing a stable suspension of silica nanoparticles labeled with europium complex and suitable for observation with fluorescent microscope. In the future, we also hope to bind positively charged silyl reagents to the surface of nanoparticles.

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.

The objective of this study was to assess the effectiveness of functionalized bionanocompounds with ice nucleation protein (INP) as a novel approach for freezing applications in terms of how much energy is used during each step of freezing when water bionanocompound solutions were compared with pure water. According to the results of the manufacturing analysis, water required 28 times less energy than the silica + INA bionanocompound and 14 times less than the magnetite + INA bionanocompound. These findings showed that water used the least energy during the manufacturing process. In order to determine the associated environmental implications, an analysis of the operating stage was also conducted, taking the defrosting time of each bionanocompound during a 4 h work cycle into account. Our results showed that bionanocompounds may substantially reduce the environmental effects by achieving a 91% reduction in the impact after their use during all four work cycles in the operation stage. Additionally, given the energy and raw materials needed in this process, this improvement was more significant than at the manufacturing stage. The results from both stages indicated that, when compared with water, the magnetite + INA bionanocompound and the silica + INA bionanocompound would save an estimated 7% and 47% of total energy, respectively. The study’s findings also demonstrated the great potential for using bionanocompounds in freezing applications to reduce the effects on the environment and human health.

In this study, hydrophobic functionalized carbon nanotubes (fCNTs) and silica nanoparticles (fSiO2NPs) were incorporated into polyvinylidene fluoride (PVDF) flat-sheet membranes to improve their performance in membrane distillation (MD). The performance of the as-synthesized membranes was evaluated against commercial reference polytetrafluoroethylene (PTFE) flat-sheet membranes. The water contact angle (WCA) and liquid entry pressure (LEP) of the PVDF membrane were compromised after incorporation of hydrophilic pore forming polyvinylpyrrolidone (PVP). These parameters were key in ensuring high salt rejections in MD processes. Upon incorporation of fCNTS and fSiO2NPs, WCA and LEP improved to 103.61° and 590 kPa, respectively. Moreover, the NP additives enhanced membrane surface roughness. Thus, an increase in membrane roughness improved WCA and resistance to membrane wetting. High salt rejection (>99%) and stable fluxes (39.77 kg m−2 h−1) were recorded throughout a 3 h process evaluation where 3.5 wt% NaCl solution was used as feed. These findings were recorded at feed temperature of 60 (Formula presented.). Evidently, this study substantiated the necessity of high feed temperatures towards high rates of water recovery.

Although silica nanoparticles (SNPs) are generally thought to be biocompatible and safe, the adverse effects of SNPs were also reported in previous studies. SNPs cause follicular atresia via the induction of ovarian granulosa cell apoptosis. However, the mechanisms for this phenomenon are not well understood. This study focuses on exploring the relationship between autophagy and apoptosis induced by SNPs in ovarian granulosa cells. Our results showed that 25.0 mg/kg body weight (b.w.)/intratracheal instillation of 110 nm in diameter spherical Stöber SNPs caused ovarian granulosa cell apoptosis in follicles in vivo. We also found that SNPs mainly internalized into the lumens of the lysosomes in primary cultured ovarian granulosa cells in vitro. SNPs induced cytotoxicity via a decrease in viability and an increase in apoptosis in a dose-dependent manner. SNPs increased BECLIN-1 and LC3-II levels, leading to the activation of autophagy and increased P62 level, resulting in the blockage of autophagic flux. SNPs increased the BAX/BCL-2 ratio and cleaved the caspase-3 level, resulting in the activation of the mitochondrial-mediated caspase-dependent apoptotic signaling pathway. SNPs enlarged the LysoTracker Red-positive compartments, decreased the CTSD level, and increased the acidity of lysosomes, leading to lysosomal impairment. Our results reveal that SNPs cause autophagy dysfunction via lysosomal impairment, resulting in follicular atresia via the enhancement of apoptosis in ovarian granulosa cells.

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.

Silica nanoparticles (SNPs) have shown great applicability potential in a number of fields like chemical, biomedical, biotechnology, agriculture, environmental remediation and even wastewater purification. With remarkably instinctive properties like mesoporous structure, high surface area, tunable pore size/diameter, biocompatibility, modifiability and polymeric hybridizability, the SNPs are growing in their applicable potential even further. These particles are shown to be non-toxic in nature, hence safe to be used in biomedical research. Moreover, the molecular mobilizability onto the internal and external surface of the particles makes them excellent carriers for biotic and non-biotic compounds. In this respect, the present study comprehensively reviews the most important and recent applications of SNPs in a number of fields along with synthetic approaches. Moreover, despite versatile contributions, the applicable potential of SNPs is still a tip of the iceberg waiting to be exploited more, hence, the last section of the review presents the future prospects containing only few of the many gaps/research extensions regarding SNPs that need to be addressed in future work.

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.

Silica nanoparticles (SiNPs) are one of the most widely used nanomaterials. SiNPs can encounter erythrocytes and hypertension is strongly linked to abnormalities in the functional and structural characteristics of erythrocytes. As little is known about the combinatorial effect of SiNP-hypertension interactions on erythrocytes, the aim of this work was to study the effects triggered by hypertension on SiNPs induced hemolysis and the pathophysiological mechanism underlying it. We compared the interaction of amorphous 50 nm SiNPs at various concentrations (0.2, 1, 5 and 25 µg/mL) with erythrocytes of normotensive (NT) and hypertensive (HT) rats in vitro. Following incubation of the erythrocytes, SiNPs induced significant and dose-dependent increase in hemolysis. Transmission electron microscopy revealed erythrocyte deformity in addition to SiNPs taken up by erythrocytes. The erythrocyte susceptibility to lipid peroxidation was significantly increased. The concentration of reduced glutathione, and activities of superoxide dismutase, and catalase were significantly increased. SiNPs significantly increased intracellular Ca2+. Likewise, the concentration of the cellular protein annexin V and calpain activity was enhanced by SiNPs. Concerningly, all the tested parameters were significantly enhanced in erythrocytes from HT rats compared to NT rats. Our results collectively demonstrate that hypertension can potentially exacerbate the in vitro effect induced by SiNPs.

Silica nanoparticles (SiNPs) are a promising material for nanomedicine technology. SiNPs are considered a powerful tool for drug delivery, functional coatings and films, and biomolecule separation due to their stability, biocompatibility, and accessible surface modification. Herein, the synthesis of SiNPs and SiNPs nylon 6 (SiNPs-Nylon) coated nanocomposites was proposed. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) were used for morphology, size, and stability analysis. Anticancer drug doxorubicin (DOX) loading to the nanocomposites and pH-dependent release experiments are presented. DOX-loaded nanocomposites with high drug capacities of up to 258 μg/mg (DOX/SiNPs) and 493 μg/mg (DOX/SiNPs-Nylon) show effective inhibition of A549 and HEK 293FT cell lines. The IC50 values were 0.08 ± 0.01 µM in terms of DOX amount and recalculated as 0.31 ± 0.04 µg/mL in terms of the concentration of SiNPs for the HEK 293FT cells. Therefore, silica nanocomposites have a high potential for cancer treatment.

Superhydrophobic coatings are gaining popularity because of their low maintenance requirements, high durability, and wide range of potential uses. Such coatings, for instance, may provide beneficial resistance to fouling, icing, smear, and corrosion, and can separate oil from water. Therefore, the creation of superhydrophobic materials is a topic of great interest to academics all around the world. In this paper, a spray-coating deposition technique is used to deposit silica nanoparticles on glass while using a sol–gel as a base. The applied coating increased the transmittance to 99% at 600 nm. Water contact angle (WCA) and scanning electron microscopy (SEM) observations of the coated layer’s grade index and induced porousness led to superhydrophobic behavior with a water contact angle that was higher than 158°.

Drug Delivery and Translational Research 13, 1195-1211 (2023). doi:10.1007/s13346-022-01204-8 special issue: "A Global Perspective of Research in Local Chapters of the Controlled Release Society / Guest Editors: Yu-Kyoung Oh, Avi Schroeder and Bruno Sarmento", Published by Springer, New York, NY [u.a.]

Plasticized nanocomposites based on poly(lactic acid) have been prepared by melt mixing following a two-step approach, adding two different oligomeric esters of lactic acid (OLAs) as plasticizers and fumed silica nanoparticles. The nanocomposites maintained a remarkable elongation at break in the presence of the nanoparticles, with no strong effects on modulus and strength. Measuring thermo-mechanical properties as a function of aging time revealed a progressive deterioration of properties, with the buildup of phase separation, related to the nature of the plasticizer. Materials containing hydroxyl-terminated OLA showed a higher stability of properties upon aging. On the contrary, a synergistic effect of the acid-terminated plasticizer and silica nanoparticles was pointed out, inducing an accelerated hydrolytic degradation of PLA: materials at high silica content exhibited a marked brittleness and a dramatic decrease of molecular weight after 16 weeks of aging.

Electrochromic (EC) technology allows control of the transmission of visible light and solar radiation through thin-film devices. When applied to “smart” windows, EC technology can significantly diminish energy use for cooling and air conditioning of buildings and simultaneously provide good indoor comfort for the buildings’ occupants through reduced glare. EC “smart” windows are available on the market, but it is nevertheless important that their degradation under operating conditions be better understood and, ideally, prevented. In the present work, we investigated EC properties, voltammetric cycling durability, and potentiostatic rejuvenation of sputter-deposited WO3 thin films immersed in LiClO4–propylene carbonate electrolytes containing up to 3.0 wt% of ∼7-nm-diameter SiO2 nanoparticles. Adding about 1 wt% SiO2 led to a significant improvement in cycling durability in the commonly used potential range of 2.0–4.0 V vs. Li/Li+. Furthermore, X-ray photoemission spectroscopy indicated that O–Si bonds were associated with enhanced durability in the presence of SiO2 nanoparticles.

Otsubo, M., Terao, K. Kinetics of the complex formation of silica nanoparticles with collagen. Polym J 53, 1481–1484 (2021). https://doi.org/10.1038/s41428-021-00553-4., Time-resolved small-angle X-ray scattering measurements were made for a mixed solution of negatively charged silica nanoparticles (SiNPs) and positively charged atelocollagen (AC) in buffers at pH = 3 and 4 at 25 °C, in which the scattering intensity from the AC molecules was very weak in the investigated q (magnitude of the scattering vector) range. The scattering intensity from the SiNPs at the low q end and middle q range gradually increased and decreased, respectively, and reached asymptotic values approximately 5–20 min after rapid mixing of the two solutions of SiNPs and AC. This clearly shows that the structural formation of the SiNP–AC complex is on the time scale of minutes. Furthermore, the structure factor at 30 min after mixing is consistent with the previously investigated data for SiNPs and triple helical AC at 15 °C. The obtained time scale to form the complex can be important information to control the aggregating structure of SiNPs with the aid of collagen molecules.

Nanoparticles have shown great potential in many sectors of the oil and gas industry, including enhanced oil recovery (EOR). They can be used to improve water flooding by altering the wettability of the porous medium, reducing the interfacial tension, blocking pores, or preventing asphaltene precipitation. Ensuring the stability of nanofluids injected into reservoirs is essential and a great challenge. However, high temperature favors particle collisions and high salinity (ionic strength) decreases electrostatic repulsion between particles. Therefore, nanofluids are extremely unstable at reservoir conditions. In this paper, we investigated the effects of electrolytes (brine and seawater) and temperature (up to 80 °C) on the stability of silica nanofluids. The nanofluids are characterized by dynamic light scattering (size), turbidity (stability), and zeta potential (electrostatic repulsions). One solution to increase the stability is to compensate for the loss of repulsive forces due to salts in the solution through increased electrostatic and/or steric repulsions by changing the pH of the base fluid. At high ionic strength (42 g/L NaCl and seawater), the stability of 0.1 and 0.5 wt% silica nanofluids at basic pH is about one day, regardless of temperature. In contrast, at pH 1.5, the nanofluids have a stability of at least three weeks at 80 °C. The results obtained with base fluids containing divalent cations confirmed their more destabilizing effect. This study confirmed that it is possible to stabilize silica nanofluids beyond one month at reservoir conditions just by lowering the pH near the isoelectric point.

The growth and development of rice face many issues, including its exposure to high soil salinity. This issue can be alleviated using new approaches to overwhelm the factors that restrict rice productivity. The objective of our investigation was the usage of the rhizobacteria (Pseudomonas koreensis and Bacillus coagulans) as plant growth-promoting rhizobacteria (PGPRs) and nano-silicon, which could be a positive technology to cope with the problems raised by soil salinity in addition to improvement the morpho-physiological properties, and productivity of two rice varieties (i.e., Giza 177 as salt-sensitive and Giza 179 as salt-tolerant). The findings stated that the application of combined PGPRs and nano-Si resulted in the highest soil enzymes activity (dehydrogenase and urease), root length, leaf area index, photosynthesis pigments, K+ ions, relative water content (RWC), and stomatal conductance (gs) while resulted in the reduction of Na+, electrolyte leakage (EL), and proline content. All these improvements are due to increased antioxidant enzymes activity such as catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD), which decreased hydrogen peroxide (H2O2) and malondialdehyde (MDA) under soil salinity in rice plants compared to the other treatments. Combined application of PGPRs and nano-Si to Giza 177 significantly surpassed Giza 179, which was neither treated with PGPR nor nano-Si in the main yield components (number of grains/panicles, 1000 grain weight, and grain yield as well as nutrient uptake. In conclusion, both PGPRs and nano-Si had stimulating effects that mitigated the salinity-deleterious effects and encouraged plant growth, and, therefore, enhanced the grain yield.

Improvements to fluoropolymer processing techniques by way of utilizing nanoparticles as drop-in processing aids have pronounced effects on bulk composite properties. In this work, we prepared fluoroalkyl-silanized silica nanoparticles (F-SiNPs, ca. 200 nm) that were solvent-blended with polyvinylenedifluoride (PVDF) in order to prepare composites with varying weight fractions. We demonstrated that the ability to functionalize SiNPs with long fluoroalkylchains that induced co-crystallization with the PVDF matrix, resulting in uniform particle dispersion and improved interlaminate adhesion. This was quantitatively investigated using calorimetry and thermogravimetric analysis, which showed a decrease in the bulk crystallinity of the virgin PVDF from 37% to 10% with minimal 10 wt % F-SiNP loading, rendering a nearly amorphous PVDF. Additional discussions in this work include the effects of various bare and fluoroalkyl-functionalized SiNP loadings on the amorphous and crystalline domains of the PVDF matrix, as well as thermal decomposition.

Dental nanocomposite resins have been proposed as potential restorative materials that are inevitably challenged with dynamic oral conditions. This investigation focused on the contribution of miscellaneous silane blends, used as coupling agents, to the ultimate performance of dental nanocomposite dimethacrylate resins. Herein, silica nanoparticles were initially silanized with functional/functional or functional/non-fuctional silane mixtures (50/50 wt/wt). Fourier transforms infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA) verified the modification of nanosilica. The organomodified nanoparticles were then inserted into Bis-GMA/TEGDMA based resins by hand spatulation process. Scanning electron microscopy (SEM) findings revealed a broad distribution of fillers in the polymer network when reactive silanes and their corresponding blends were used. Furthermore, optical profilometry results showed that the presence of functional/non-functional mixtures can produce relatively smooth composite surfaces. Polymerization shrinkage was found to be limited upon the decrease of the degree of conversion regarding all the tested silane mixtures. The functional/functional silane blend assured the highest flexural properties and the lowest solubility after the storage of the nanocomposite in water for 1 week at 37 °C. The above experimental data could contribute to the proper designing of dental nanocomposite resins which may fit the modern clinical applications.

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.

We describe an in situ facile synthetic approach to prepare carbon quantum dot (CQD) fluorescent markers (FMs) for polyethylene (PE) in the presence of agglomerated silica nanoparticles (SiO2 NPs) under mild reaction conditions. First SiO2 NPs, prepared by the Stöber method, were dispersed in toluene. This dispersion was added to a PE solution in toluene. After heating (either in air or under Ar) a fluorescent mixture was obtained. After drying, PE films were obtained by compression molding, which showed strong blue fluorescence, attributed to CQDs. SiO2 NPs loading values varied between 0.5 and 4 wt %. Subsequent to isolation, the fluorescent CQDs were characterized by TEM, UV-vis, and fluorescence spectroscopy. TEM imaging unveiled a lattice spacing value of 0.21 nm of the isolated fluorescent particles which is typical for (100) graphite plane lattice spacing in CQDs. UV spectroscopy and fluorescence measurements show characteristic absorption and excitation spectra for the aromatic core and oxidized surface defects typically observed for CQDs. The emission maximum for PE/CQD samples increased from 394 to 408 nm when the reaction temperature was decreased from 110 to 90 °C, which is attributed to increasing oxygen content in the reaction mixture upon decreasing the reaction temperature. When the reaction was performed under Ar, the PE/CQD samples emitted in the ultraviolet region (286 nm). Finally, we demonstrated that PE samples marked with CQDs can be easily visually identified upon irradiating with 367 nm light. Thus, the marked PE can be used, for example, as a labeling ingredient in master batches for component identification and in recycling.

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...

With the rapid development of nanotechnology, new types of fluorescent nanomaterials (FNMs) have been springing up in the past two decades. The nanometer scale endows FNMs with unique optical properties which play a critical role in their applications in bioimaging and fluorescence-dependent detections. However, since low selectivity as well as low photoluminescence efficiency of fluorescent nanomaterials hinders their applications in imaging and detection to some extent, scientists are still in search of synthesizing new FNMs with better properties. In this review, a variety of fluorescent nanoparticles are summarized including semiconductor quantum dots, carbon dots, carbon nanoparticles, carbon nanotubes, graphene-based nanomaterials, noble metal nanoparticles, silica nanoparticles, phosphors and organic frameworks. We highlight the recent advances of the latest developments in the synthesis of FNMs and their applications in the biomedical field in recent years. Furthermore, the main theories, methods, and limitations of the synthesis and applications of FNMs have been reviewed and discussed. In addition, challenges in synthesis and biomedical applications are systematically summarized as well. The future directions and perspectives of FNMs in clinical applications are also presented.

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.

This work is a continuance to our previous findings on silica nanoparticles (NPs) modified with diamine polymer, carboxymethyl-β-cyclodextrin (CM-β-CD) and folic acid (FA), respectively. When four different polymer lengths (D230, D400, D2000 and D4000) were analyzed, the release rate of anticancer agents was inversely related to the polymer length while the cell toxicity was directly related to the length. We investigate here the effect of polymer length on the extent of cellular interaction with HeLa cells. The mean particle size, the polydispersity (PD) and the zeta potential of the NPs were measured using dynamic light scattering (DLS), the quantitative analysis of the extent of NPs' interaction was studied using fluorescence microscopy and transmission electron microscopy (TEM) was used to qualitatively visualize them. The particle size increased by increasing the polymer length, the PD values were within the acceptable ranges (0.3−0.5) and the zeta potential was in the range of (−16 to −20 mV). A direct relation was observed between the fluorescence intensity and the length. All modified NPs were capable of entering the cells, however a greater number of NPs with long polymers was observed compared to short polymers. Thus, the direct relation of polymer length to the cell toxicity is due to the release rate behavior and the enhanced interaction of NPs which possess long polymers.

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.