Colloidal Silica Nanoparticles Research Articles

A bioactive nanocomposite integrated specific TAMs target and synergistic TAMs repolarization for effective cancer immunotherapy

Reactive oxygen species (ROS) generated from photosensitizers exhibit great potential for repolarizing immunosuppressive tumor-associated macrophages (TAMs) toward the anti-tumor M1 phenotype, representing a promising cancer immunotherapy strategy. Nevertheless, their effectiveness in eliminating solid tumors is generally limited by the instability and inadequate TAMs-specific targeting of photosensitizers. Here, a novel core-shell integrated nano platform is proposed to achieve a coordinated strategy of repolarizing TAMs for potentiating cancer immunotherapy. Colloidal mesoporous silica nanoparticles (CMSN) are fabricated to encapsulate photosensitizer-Indocyanine Green (ICG) to improve their stability. Then ginseng-derived exosome (GsE) was coated on the surface of ICG/CMSN for targeting TAMs, as well as repolarizing TAMs concurrently, named ICG/CMSN@GsE. As expected, with the synergism of ICG and GsE, ICG/CMSN@GsE exhibited better stability, mild generation of ROS, favorable specificity toward M2-like macrophages, enhancing drug retention in tumors and superior TAMs repolarization potency, then exerted a potent antitumor effect. In vivo, experiment results also confirm the synergistic suppression of tumor growth accompanied by the increased presence of anti-tumor M1-like macrophages and maximal tumor damage. Taken together, by integrating the superiorities of TAMs targeting specificity and synergistic TAMs repolarization effect into a single nanoplatform, ICG/CMSN@GsE can readily serve as a safe and high-performance nanoplatform for enhanced cancer immunotherapy.

Mitigating CO2 emanations within the marine concrete industry with different structures of silica nanoparticles

The extensive utilization of marine concrete results in a significant consumption of cement, thereby leading to an increase in CO2 emanations. Enhancing the potency and longevity of marine concrete serves as an efficacious approach to mitigate CO2 emanations. The objective of this investigation was to introduce colloidal silica nanoparticles with distinct three-dimensional structures (MCM-41, SBA-15, and DFNS) for the purpose of enhancing the mechanical functionality and longevity of remarkable sulfate persistence Portland cement. Meantime, the incorporation of silica nanoparticles with distinct three-dimensional architectures (DFNS, MCM-41, and SBA-15) into marine cement mortar was carried out, and an investigation was conducted on the aggregation of silica nanoparticles, as well as the humidifying process and micro-process of the mortar. According to the findings, the addition of silica NPs improved the resilience, mechanical traits, and longevity of the marine cement cases. When the inclusion of silica nanoparticles with varying three-dimensional structures (DFNS, MCM-41, and SBA-15) was implemented, a decrease in both the chloride diffusion coefficient and porosity was observed. The compressive intensity of cement mortar was enhanced in the presence of DFNS, MCM-41, and SBA-15 when compared to control samples, following a rehabilitating period of 5, 15, and 30 days. These advancements in intensity and longevity suggest that DFNS exhibits considerable potential in mitigating CO2 emanations within the marine concrete industry.

Interactions of fluorescent surfactant micelles in solution with colloidal silica nanoparticles and their penetrant diffusion in hydrated fumed silica films

The preparation and properties of surfactant micelles labeled with the dye, Nile Red (NR), are described. Fluorescence emission and excitation spectroscopy establish the localization of NR in the hydrophobic core of nonionic Brij® S10, Brij® S20, and Triton X-100 micelles, and in ionic mixed micelles prepared from sodium dodecyl sulfate (SDS) and Triton X-100 mixtures of varying composition. Stokes diameter analysis of NR-micelles by fluorescence correlation spectroscopy (FCS) yields mean diameters ranging from 3.0 to 10.6 nm depending on the surfactant composition and its concentration used for micelle preparation. Adsorption of NR-micelles on a 20 nm, charged-stabilized, sol-gel silica nanoparticle is characterized by FCS. NR-micelle-nanoparticle solutions are analyzed as two-species mixtures of free and nanoparticle-bound NR-micelles allowing determinations of mean Stokes diameters and fractions of nanoparticle-bound NR-micelles. Incorporation of SDS into nonionic Triton X-100-NR-micelles progressively diminishes the adsorption of the mixed ionic NR-micelles on the nanoparticles with increasing SDS in the micelles. FCS analysis NR-micelle adsorption interactions with silica nanoparticles is shown to occur at the single NR-micelle level, providing a means for advancing the fundamental understanding of these interactions. The kinetics of a NR-micelle’s penetration into a hydrated fumed silica determined by FCS are shown to be a one-dimensional Fickian process and indicative of pores with low tortuosity. The use of NR-micelles as fluorescent diffusion probes in porous fumed silica films is concluded to be a viable general approach for the characterization of pore tortuosity in films composed of irregularly shaped (fractal) nanoparticles.

Nanopriming of Tomato (Solanum lycopersicum) Seeds Against Heavy Metal Stress During Germination and Seedling Formation

Abiotic stress can have a negative impact on plant growth. Heavy metal is one of the examples. One approach to overcome this issue is to use seed priming. The priming used in this study was nanopriming. We used colloidal silica nanoparticles (size of 10 nm) as the priming agent and copper (Cu) and barium (Ba) as the model heavy metals. This treatment was implemented for tomato (S. lycopersicum var. Momotaro) seed germination. The results showed that the presence of heavy metals during germination may lead to prolonging the germination time. The presence of Cu and Ba at 1 ppm could increase germination time by 28.38% and 26.9%, respectively, compared to control. When primed seeds were subjected to heavy metal stress, the use of silica nanopriming could reduce the germination time by 10.45% for Cu and 11.54% for Ba compared to the unprimed seeds. This evidence demonstrated that nanopriming could make seeds more resilient to heavy metal stress. We also found that heavy metal ions became less detectable in the seedlings when nanopriming was applied. This ion transport alteration essentially allowed seeds to cope with heavy metal stress. This method can be potentially used on various kinds of crops and heavy metals.

Thermoresponsive hollow polymeric shell nano/microparticles with interconnected nanoholes

AbstractPNIPAAm‐grafted thermoresponsive hollow nano‐holed polymeric‐shell (HHPS) particles were fabricated from surface‐modified colloidal silica (CS) with poly(ethylene glycol) methyl ether‐3‐(triethoxysilyl)propyl isocyanate (PEGME‐IPTES) and 3‐(trimethoxysilyl) propyl methacrylate (MPS) as templates. The polymeric shells were then synthesized through a “grafting‐through” approach via surface‐initiated polymerization of N‐isopropyl acrylamide (PNIPAAm) using potassium persulfate (KPS) as an initiator, followed by the etching of CS with hydrofluoric acid to remove the CS core templates. CS nanoparticles and PEGME‐IPTES were presynthesized using tetraethoxysilane (TEOS) and distilled water in methanol with ammonia solution as a catalyst by the sol–gel method and using 3‐(triethoxysilyl) propyl isocyanate (IPTES) with poly(ethylene glycol) methyl ether (PEGME) in the presence of dibutyltin dilaurate. The chemical structures of bare and modified CS, PNIPAAm, PNIPAAm‐CS, and HHPS particles were characterized by FT‐IR and NMR spectroscopies. SEM and TEM images confirmed that the resulting HHPS particles had a significant number of interconnected nanoholes. To evaluate the LCST behaviors of HHPS particles, the transition of transmittance and the changes in particle diameter according to the temperature change were measured through UV‐vis spectroscopy, DLS, and microscopy.

Comparative analysis of germination performance from several species of seeds under influence of silica nanoparticles

The first and most critical phase in growing crops is seed germination. Failure and slower germination process may have an impact on productivity. As a result, numerous strategies are needed to hasten germination and improving the quality of the seedlings. One possible strategy is the use of nanoparticles. This present study used colloidal silica nanoparticles (8 - 10 nm) with concentrations of 0 (control), 100, and 1000 mg/L. Seeds from six different species were used (Capsicum annuum, Capsicum frutescens, Cucumis sativus, Solanum melongena, Solanum lycopersicum, and Daucus carota). Seeds were germinated in dark condition for eight consecutive days. The result showed that the use of silica nanoparticles may shorten the germination time while increasing the germination index and coefficient of velocity of germination in C. annuum, C. frutescens, C. sativus, and S. lycopersicum. However, the observed effect was not very strong compared to the control. This could be due to the seeds utilized were not in dormant stage and had rather high viability. On the other hand, we found that silica nanoparticles could alter the structure of the seed coat, allowing for easier water imbibition for germination.

Measuring Solvent Exchange in Silica Nanoparticles with Rotor-Based Fluorophore.

Measuring the diffusivity of molecules is the first step toward understanding their dependence and controlling diffusion, but the challenge increases with the decrease of molecular size, particularly for non-fluorescent and non-reactive molecules such as solvents. Here, the capability to monitor the solvent exchange process within the micropores of silica with millisecond time resolution is demonstrated, by simply embedding a rotor-based fluorophore (thioflavin T) in colloidal silica nanoparticles. Basically, the silica provides an extreme case of viscous microenvironment, which is affected by the polarity of the solvents. The fluorescence intensity traces can be well fitted to the Fickian diffusion model, allowing analytical solution of the diffusion process, and revealing the diffusion coefficients. The validation experiments, involving the water-to-ethanol and ethanol-to-water solvent exchange, the comparison of different drying conditions, and the variation in the degree of cross-linking in silica, confirmed the effectiveness and sensitivity of this method for characterizing diffusion in silica micropores. This work focuses on the method development of measuring diffusivity and the high temporal resolution in tracking solvent exchange dynamics over a short distance (within 165nm) opens enormous possibilities for further studies.

Occurrence and behaviour of colloidal silica and silica-rich nanoparticles through stages of reverse osmosis treating coal seam gas associated water

Reverse Osmosis (RO) membrane filtration is a very common process for treating a wide range of groundwater types including produced water from coal seam gas (coalbed methane) wells. Mineral scaling limits water recovery for RO membranes and costs money in terms of treatment and downtime. Silica scaling can be particularly troublesome as it is often irreversible. Mitigating silica scaling requires an understanding of its occurrence, speciation mechanism and its interdependency with other operation factors. This study uses a range of techniques to show that silica colloids form during later stages of an RO process with very high recovery. This happens at silica concentrations above the solubility that would normally indicate high risk of silica scale. However, instead of scale, colloids preferentially formed which means the process can operate at high recoveries with RO performance maintained by regular cleaning cycles. The concentration of the colloidal silica through the RO stages was measured through the difference in total and dissolved silica. Once the existence was established with this technique, the particles were trapped and their size, morphology and composition were investigated with Scanning Electron Microscopy (SEM) in conjunction with Energy Dispersive X-Ray Spectroscopy (EDS). This revealed the particles to be predominantly silica with limited other elements involved.

Electro-cementation of calcareous sand using colloidal silica (CS) nanoparticles and alumina powder

The research investigates the effectiveness of a ground improvement technique that involves the electro-cementation of an onshore calcareous sand containing 95.3% calcium carbonate through a series of laboratory experiments. Colloidal silica (CS) nanoparticles and alumina powder were introduced as pozzolanic materials in the sand, and a direct current (DC) was passed through the sand-silica-alumina mix inside an electrokinetic (EK) cell. The method resulted in the electro-cementation of the calcareous sand through the formation of calcium silicate hydrates (C–S–Hs) and calcium aluminate hydrates (C–A–Hs) as products of the pozzolanic reactions between Ca(OH)2, SiO2 and Al2O3 after electrolysis occurred. Iron-rich cements were also formed by the degradation of anodes. These newly formed compounds changed the nature of the treated soil from a granular material into a rock. Results show that the compressive strength of the resulting rock formation is significantly improved. The treatment can be considered as an artificial lithification process through which the nature of the treated soil was changed from a granular material into a rock formation. The electro-cementation achieved by the treatment was further assessed by spectroscopic analyses including FE-SEM, EDX and XRD, which confirmed the formation of cementing agents within the structure of the treated sand. Potential applications of the technique include caissons, highway construction projects, dune fixation and erosion control, in addition to liquefaction mitigation due to electrolysis of pore water and plugging the pores with cementitious materials.

The study of the anti-icing performance of superhydrophobic silica-nanostructured metal substrates

Superhydrophobic surfaces have proven effective in mitigating ice formation on substrates. This study aimed to experimentally investigate the effects of the surface structure of selected metal substrates on the anti-icing performance. Superhydrophobic surfaces were fabricated on aluminum, copper, stainless steel, and titanium substrates using a spray coating technique with superhydrophobic tridecafluorooctyl triethoxy silane (FAS)-functionalized colloidal silica nanoparticles. The surface wettability, surface morphology, and chemical analysis of the coated surfaces were reported. The results demonstrated successful deposition of silica nanoparticles on all substrates, significantly improving the anti-icing property of the coated surfaces. When compared with uncoated surfaces, the droplet icing times of the coated aluminum plate (C-Al), of the coated copper plate (C-Cu), of the coated stainless steel plate (C-SS), and of the coated titanium plate (C-Ti) significantly enhanced by 751%, 795%, 830% and 1320%, respectively. Also, a heat transfer model was also developed to explain the anti-icing phenomenon.

Robotic pendant drop: containerless liquid for μs-resolved, AI-executable XPCS

The dynamics and structure of mixed phases in a complex fluid can significantly impact its material properties, such as viscoelasticity. Small-angle X-ray Photon Correlation Spectroscopy (SA-XPCS) can probe the spontaneous spatial fluctuations of the mixed phases under various in situ environments over wide spatiotemporal ranges (10−6–103 s /10−10–10−6 m). Tailored material design, however, requires searching through a massive number of sample compositions and experimental parameters, which is beyond the bandwidth of the current coherent X-ray beamline. Using 3.7-μs-resolved XPCS synchronized with the clock frequency at the Advanced Photon Source, we demonstrated the consistency between the Brownian dynamics of ~100 nm diameter colloidal silica nanoparticles measured from an enclosed pendant drop and a sealed capillary. The electronic pipette can also be mounted on a robotic arm to access different stock solutions and create complex fluids with highly-repeatable and precisely controlled composition profiles. This closed-loop, AI-executable protocol is applicable to light scattering techniques regardless of the light wavelength and optical coherence, and is a first step towards high-throughput, autonomous material discovery.

Key Role of Choline Head Groups in Large Unilamellar Phospholipid Vesicles for the Interaction with and Rupture by Silica Nanoparticles.

For highly abundant silica nanomaterials, detrimental effects on proteins and phospholipids are postulated as critical molecular initiating events that involve hydrogen-bonding, hydrophobic, and/or hydrophilic interactions. Here, large unilamellar vesicles with various well-defined phospholipid compositions are used as biomimetic models to recapitulate membranolysis, a process known to be induced by silica nanoparticles in human cells. Differential analysis of the dominant phospholipids determined in membranes of alveolar lung epithelial cells demonstrates that the quaternary ammonium head groups of phosphatidylcholine and sphingomyelin play a critical and dose-dependent role in vesicle binding and rupture by amorphous colloidal silica nanoparticles. Surface modification by either protein adsorption or by covalent coupling of carboxyl groups suppresses the disintegration of these lipid vesicles, as well as membranolysis in human A549 lung epithelial cells by the silica nanoparticles. Furthermore, molecular modeling suggests a preferential affinity of silanol groups for choline head groups, which is also modulated by the pH value. Biomimetic lipid vesicles can thus be used to better understand specific phospholipid-nanoparticle interactions at the molecular level to support the rational design of safe advanced materials.

Stabilisation of acrylic latexes containing silica nanoparticles for dirt repellent coating applications

This study examines the feasibility of using colloidal silica nanoparticles as active agents in high concentration waterborne polymer latex formulations. We showed that distributing the silica throughout the waterborne emulsion formed a composite coating material with a hydrophilic surface that consequently reduced exterior dirt pickup. Two grades of silica nanoparticles were studied, one using sodium stabilisation and another using epoxysilane modification to introduce glycidoxypropyltrimethoxysilane surface functionality. Rheological study of the waterborne latex on mixing showed that there was an immediate pH responsive interaction between the silica sols and the polymer latex. Once loading of sodium charge stabilised silica NPs exceeded the volume required for heteroflocculation to occur the mixture demonstrated the potential to gel on standing – a process which took weeks, or months, to occur depending on the pH and relative concentrations used. At least fifty percent silane modification to the NP surface was found to be necessary to maintain a stable colloidal dispersion for long term storage of the waterborne latex. Despite this both grades of silica were found to imbue reductions in dirt pickup when applied to exterior masonry concrete studies over a 3-month weathering test.

An ultralow-friction, low-temperature-lubrication, anti-volatilization and anti-corrosion organohydrogel merely containing nanosilica gelator

Although hydrogel lubricants are effective in eliminating problems caused by creeping or leakage of conventional liquid lubricants, they are easy to encounter issues such as solvent evaporation, electrochemical corrosions to metallic materials and freezing at sub-zero temperatures during the lubrication process. Here we created an organohydrogel lubricant with effective anti-freezing, anti-volatile and anti-corrosive performances using a ternary mixture of colloidal silica nanoparticles, glycerol and water. The hydrogel could attain a very low coefficient of friction at room temperature and could maintain its lubricity even when the environmental temperature reached as low as − 80 °C. Its lubrication mechanism was a synergistic effect between the formation of a physically protective film of glycerol/water mixture and the rolling and repairing actions of silica particles. The presence of glycerol endowed the hydrogel excellent resistance to water volatilization and electrochemical corrosions. Our study is anticipated to find applications in mechanical engineering, metal processing and aerospace industry.

Strength, Durability and Permeability Studies on Cement Concrete with and without Nano-Silica

The application of nanomaterials in cement/concrete has resulted in the development of smart materials which are durable, sustainable and high performance oriented apart from being eco-friendly. Several types of nanomaterials are being used by researchers all over the world to improve the properties of cementitious system, amongst them silica nanoparticles (SNPs) have been credited with high pozzolanic reactivity and pore filling effects. It is also very well known that permeability is the major factor for deteriorations of concrete structures in the long term thus affecting its durability. A thorough study was performed on cement mortar composites and standard grade concrete with the additions of colloidal silica nanoparticles(SNPs) in various dosages starting from 0.5%,0.75%,1.0%,1.25% and 1.5% by weight of cement(b.w.c.) to understand the impact from micro-structure improvement to macro-level property enhancement. The results show that in presence of colloidal SNPs (Indian branded) having 35-40% active nano content with 5-40nm particle size the strength increase at 28 days is 32% increasing to 59% at 90 days. An influence on durability is also observed with strength increasing from 4% to 8% with the addition of more SNPs from 0.75% to 1.0% b.w.c. The microstructural investigations reveal that silica nanoparticles refines the pore structure due to accelerated hydrated mechanisms leading to the creation of more hydration products and thus to a more denser microstructure. A M-40 grade standard concrete was prepared as per IS:10262 with the addition of optimized SNPs as found for cement mortar composites strength results at 28 days maximum strength keeping the water-cement(w/c) ratio fixed at 0.4. Tests were conducted on concrete to find out the compressive strength and permeability of concrete. The compressive strength of concrete containing nano materials were found to be 24% more than that of normal cement concrete (NCC) of M-40 grade. The permeability values were found to be decreased by 57% with the addition of nano silica particles to concrete.

Oral spatial-to-point cascade targeting “sugar-coated bullets” for precise and safe chemotherapy by intervention Warburg effect

Glycolysis plays a vital role in the development and progression of tumors. Inhibiting glycolysis via smart and safe methods serves as a promising target for cancer therapy. Here, an oral “sugar-coated bullet” aiming at intervening Warburg effect is designed by coating colloidal mesoporous silica nanoparticles (CMS) encapsulating glycolysis inhibitor shikonin (SHK) with dextran, namely DCMS/SHK. The solubility and drug-loading capacity of SHK were enhanced by the special structure of CMS. Besides, the tempting bullets possess the spatial-to-point cascade targeting ability in delivering SHK from the colonic lumen to colon cancer cells and finally to PKM2. After DCMS/SHK reaches the colon, the dextran is hydrolyzed by dextranase especially existing in the colon site to glucose and the carriers become glucose-coated nanoparticles. The glucose-cloak nanoparticles would be largely endocytosed by tumor cells and complete the efficient delivery of SHK. The encapsulated SHK can prevent the glycolysis of cancer cells and thus inhibit tumor growth effectively. This work presents an ingenious cascade colon-targeting strategy to treat colon cancer by destroying cell energy metabolism.

Noninvasive Multiplexed Analysis of Bladder Cancer-Derived Urine Exosomes via Janus Magnetic Microspheres.

Bladder cancer greatly endangers human health, and its early diagnosis is of vital importance. Exosomes, which contain proteins and nucleic acids related to their source cells, are expected to be an emerging biomarker for bladder cancer detection. Here, we propose a novel system for multiplexed analysis of bladder cancer-derived urine exosomes based on Janus magnetic microspheres as barcoded microcarriers. The microcarriers are constructed by droplet-templated coassembly of colloidal silica nanoparticles and magnetic nanoparticles under a magnetic field. The microcarriers possess one hemisphere with structural color and the other hemisphere with magneto-responsiveness. Benefiting from the unique structure, these Janus microcarriers could serve as barcodes and could move controllably in a sample solution, thus realizing the multiplex detection of exosomes with high sensitivity. Notably, the present platform is noninvasive since a urine specimen, as an ideal source of bladder cancer-derived exosomes, is employed as the sample solution. This feature, together with the good sensitivity, specificity, low sample consumption, and easy operation, indicates the great potential of the platform for bladder cancer diagnosis in clinical applications.

Complex destruction of textured water-repellent coatings under the influence of UV and water flow

The resistance of micro- and nanotextured coatings to aggressive factors of ultraviolet radiation, immersion in water and water flow has been studied. These coatings were obtained using calcium carbonate microparticles modified with stearic acid and colloidal silica nanoparticles treated with dimethyldichlorosilane. The inherent aging rate of polymeric materials under UV radiation is compared with the treated surface layer of hydrophobized particles. The influence of immersion in water and friction of the water flow on the Cassie state stability have been established. А mechanism for the destruction of organo-mineral coatings based on the balance of the rates of UV degradation, detachment of particles in water, degradation of the polymer and the treated surface layer of particles is proposed.

Surface morphology regulation of colloidal Nanoparticles: A convenient Kinetically-Controlled seeded growth strategy

HypothesisExcept for chemical composition, surface morphology may endue colloidal nanoparticles with special interfacial behaviors, which is highly desired in certain scenarios, for example, ultra-stable Pickering emulsion for pharmaceutical applications where only limited chemicals are allowed. Herein, silica colloidal nanoparticle was chosen as a demo to illustrate a kinetically-controlled seeded growth strategy for the surface morphology regulation of colloidal nanoparticles. ExperimentsSurface chemical heterogeneity was primarily introduced to the silica seed nanoparticles by a seeded growth process in the presence of mixed silicate moieties with thermodynamical incompatibility. Then a further kinetically-controlled seeded growth step was performed to regulate the surface morphology of silica nanoparticles by promoting the selective condensation of tetraethoxysilane on the hydrophilic microdomains. FindingsUpon reducing the growing rate, tetraethoxysilane hydrolysates tend to condensate on silica microdomains, resulting in the formation of raspberry-like nanoparticles. The generality of the kinetically-controlled seeded growth strategy was validated by its success on differently-sized silica seeds modified with a range of silane coupling agents. This established strategy is facile and effective for massive production of raspberry-like silica colloidal nanoparticles with precisely-designed surface morphology and size, offering an ideal platform for the investigation on the exclusive contribution of morphology to the interfacial behaviors of nanoparticles.

Plasmon induced quantified agglomeration of SiO2 nanoparticles to improve in efficiency in solar cell

The impact of plasmonic confinement induced by the SiO2 nanosphere utilized as a photonic absorber in a solar cell is investigated in this paper. The modified Stober technique is utilized for irradiation experiments using the size and shape of colloidal silica nanoparticles at two dosages of 0.485mg/ml and 0.693mg/ml solutions. The agglomerated silica is placed as an absorbent layer on a solar cell, and the J-V characteristics are studied under solar irradiation. The enhancement in efficiency and Jsc is far greater than predicted induced in photon injection caused by silica nanoparticle coating under coverage limit.