Silica Nanostructures Research Articles

Fe/Au galvanic nanocells to generate self-sustained Fenton reactions without additives at neutral pH.

The generation of reactive oxygen species (ROS) via the Fenton reaction has received significant attention for widespread applications. This reaction can be triggered by zero-valent metal nanoparticles by converting externally added H2O2 into hydroxyl radicals (˙OH) in acidic media. To avoid the addition of external additives or energy supply, developing self-sustained catalytic systems enabling onsite production of H2O2 at a neutral pH is crucial. Here, we present novel galvanic nanocells (GNCs) based on metallic Fe/Au bilayers on arrays of nanoporous silica nanostructures for the generation of self-sustained Fenton reactions. These GNCs exploit the large electrochemical potential difference between the Fe and Au layers to enable direct H2O2 production and efficient release of Fe2+ in water at neutral pH, thereby triggering the Fenton reaction. Additionally, the GNCs promote Fe2+/Fe3+ circulation and minimize side reactions that passivate the iron surface to enhance their reactivity. The capability to directly trigger the Fenton reaction in water at pH 7 is demonstrated by the fast degradation and mineralization of organic pollutants, by using tiny amounts of catalyst. The self-generated H2O2 and its transformation into ˙OH in a neutral environment provide a promising route not only in environmental remediation but also to produce therapeutic ROS and address the limitations of Fenton catalytic nanostructures.

Comparison of the antimicrobial photocatalytic activities of SiO2 and Au@SiO2 nanostructures in water decontamination.

Photocatalytic disinfection of Escherichia coli suspension by silicon dioxide nanoparticles and silicon dioxide/gold nanocomposite in a batch reactor is investigated experimentally and results are compared. Silica nanoparticles were synthesized by Stöber method and pulsed laser ablation method was employed to prepare gold nanoparticles in distilled water. Composition of two nanoparticles species was carried out, using the second harmonic pulse of Nd:YAG laser, whose wavelength is in the absorption spectra of gold nanoparticles. Results confirm a decrease in the bandgap energy of silica nanoparticles after composition. Escherichia coli were selected as an indicator of the microbial water contamination. Disk diffusion method was used to evaluate the antimicrobial potential of SiO2 and Au@SiO2 nanostructures. Photocatalytic activities of both nanostructures were examined in dark, and under the irradiation of UV and visible light. In all conditions, the performance of Au@SiO2 nanocomposites was higher than SiO2 nanoparticles. In dark condition the higher biocidal nature and activity of Au nanoparticles and for the case of UV radiation, decreasing the bandgap energy and recombination rate of SiO2 nanoparticles after composition with Au increased the efficiency. For the case of visible light radiation, surface plasmon resonances effects, and local heat of Au nanoparticles were responsible for increasing the efficiency. RESEARCH HIGHLIGHTS: Doping large bandgap semiconductors nanostructures, such as silica with metal nanoparticles, such as gold will improve their photocatalytic activity to work in visible light. In this mechanism, gold nanoparticles act as effective traps to prevent the recombination of photogenerated electron-hole pairs. Other mechanisms, such as Schottky barrier formation, surface plasmon resonance absorption of gold nanoparticles, and biocidal nature of the gold nanoparticles are effective in increasing the efficiency of Au doped silica nanostructures.

Sustainable SiO2 Nanostructures from Different Diatom Species As Anode Material for Future Generation Lithium-Ion Batteries

Energy harvesting and storage devices occupy a more prominent place in the 21st century than at any time in the past. Intensive efforts have been devoted to next-generation energy storage devices such as rechargeable lithium-ion batteries (LIBs) to develop high energy density and long cycle life electrode materials from sustainable sources. In the present anode, graphite is severely restricted by capacity and unavoidable solid electrolyte interface (SEI) formation. Besides, it has been listed as a critical material by the European Commission. Recently, silicon-based electrodes have been pinpointed as promising anode candidates due to their high theoretical capacity (~4200 mAhg-1 for Li4.4Si), low operating voltage (0.4V/Li/Li+), abundant resources, and environmental friendliness. Interestingly, nanostructures of Silica (SiO2) can be extracted from the frustules (exoskeletons) of a type of microalgae called diatoms. In this current work, SiO2 frustules were grown from two different diatom species, constituting a sustainable source for producing nanostructured Si-based materials. Scanning electron microscopy (SEM) images confirmed the highly nanoporous structure of diatom silica, which was retained even after ball-milling. The electrochemical performance of SiO2 was investigated as an anode material for LIBs. Herein, we have tested both species A & B milled and un-milled samples (denoted as SPAUM, SPAM, SPBUM, and SPBM). The diatom SiO2 un-milled species A (SPAUM) exhibited a high specific capacity of ~ 810 mAhg-1 with remarkable capacity retention and coulombic efficiency even after 100 cycles at 0.1 Ag-1 and delivered a high specific capacity of ~ 400 mAhg-1 even at high current density 3 Ag-1. For comparison and understanding, commercially available diatomaceous earth milled, and un-milled silica (denoted as EDAM & EDAUM) has been subjected to the same cycling protocol. Results clearly showed species A & B milled and un-milled displaying better electrochemical performance than diatomaceous earth milled and un-milled silica. Such improved electrochemical properties like cycle life, and rate capability of SPAUM are mainly ascribed to their highly porous nature which significantly facilitates fast Li ion diffusion, its unique morphology, which favors a faster kinetics and its complete lithiation/de-lithiation after the initial activation cycle. In view of the superior electrochemical properties, such sustainably sourced SiO2 materials can be considered a potential anode material for future LIBs. Figure 1

Microwave-assisted sol-gel synthesis of mesoporous NiO-decorated silica nanostructures utilizing biogenic silica source for supercapacitor applications

Developing efficient and sustainable energy storage materials is essential for supercapacitor technology. This study presents a microwave-assisted sol-gel synthesis of nickel oxide-decorated SiO2 nanostructures employing rice husk as a silica source for supercapacitor application. Rice husk, an abundant agricultural waste, was utilized as a cost-effective and environmentally friendly precursor for silica synthesis. Sol-gel synthesis assisted by microwaves allowed rapid and controlled formation of the silica nanostructure via alkaline extraction with NaOH, acidification with acetic acid, and capping with PEG. Likewise, nickel precursor with an appropriate concentration was introduced during the formation of silica nanostructures, leading to NiO-decorated silica nanostructures. XRD, FTIR, BET, FESEM, EDS, and HRTEM analysis demonstrated that NiO was decorated on the silica nanostructure distinctly depending on the concentration of nickel precursor. The electrochemical studies using 2 M KOH electrolyte revealed that the maximum specific capacitance of RH-SiO2, NiO@RH-SiO2-1, and NiO@RH-SiO2-2 was found to be 102 F/g, 405 F/g, and 506 F/g at a current density of 0.5 A/g with superior energy density and power density. It is also found that the electrode exhibits high-capacitance retention and good cycle stability after 5000 cycles. The obtained result revealed that when the nickel precursor concentration was increased, the specific capacitance was also increased because high nickel precursor concentration leads to the formation of NiO species which can serve as reactive surfaces for carrier transport. Moreover, the asymmetric supercapacitor (ASC) was fabricated using NiO@RH-SiO2-2 and it provides an excellent energy density of 31.25 Wh kg−1 at a power density of 745 W kg−1 with long-term cyclic stability (96.4% specific capacitance retention after 10,000 cycles). Based on these results, NiO-decorated silica nanostructures can be a promising electrode material for supercapacitor applications.

Facile fabrication of diatomite biosilica-based nasal drug delivery vehicle for enhanced treatment of allergic rhinitis

Nanostructured silica-based materials have great potential as drug delivery vehicles for precise and personalized medical applications. As natural nanostructured silica, diatomite biosilica (DB) is recognized as a novel carrier to construct oral/parenteral smart drug delivery systems due to high surface area, biocompatibility, and applicability at low cost, yet the related studies on its use in local delivery routes are still scarce. Herein, we proposed a novel strategy to develop multifunctional nasal drug delivery vehicles based on DB, and demonstrated their versatile performance for enhanced treatment of allergic rhinitis (AR). As a proof of concept, the purified DB microparticles were loaded with budesonide as an anti-inflammatory model drug, and further processed via surface modification to graft polydopamine and carboxymethyl chitosan layers. The synthesized microcapsules exhibited remarkable mucin binding capacity and antibacterial activity against Staphylococcus aureus. Besides, toxicity evaluation with human skin fibroblast cells and hemolysis tests indicated their high biocompatibility. Moreover, in vitro drug release results demonstrated pH-responsive release performance of the microcapsules under simulated AR environment (pH 5.0, 35 °C). Hence, this study provides a facile and reliable approach to construct DB-based mucoadhesive nasal drug delivery vehicles, showing great potential for treatment of allergic airway inflammatory diseases.

The Exploitation of pH-Responsive Eudragit-Coated Mesoporous Silica Nanostructures in the Repurposing of Terbinafine Hydrochloride for Targeted Colon Cancer Inhibition: Design Optimization, In Vitro Characterization, and Cytotoxicity Assessment.

Targeted drug delivery is achieving great success in cancer therapy due to its potential to deliver drugs directly to the action site. Terbinafine hydrochloride (TER) is a broad-spectrum anti-fungal drug that has been found to have some potential anti-tumor effects in the treatment of colon cancer. We aimed here to design and develop pH-sensitive Eudragit (Eud)-coated mesoporous silica nanostructures (MSNs) to control drug release in response to changes in pH. The diffusion-supported loading (DiSupLo) technique was applied for loading TER into the MSNs. The formulation was optimized by a D-optimal design, which permits the concurrent assessment of the influence of drug/MSN%, coat concentration, and MSN type on the drug entrapment efficiency (EE) and its release performance. The optimal formula displayed a high EE of 96.49%, minimizing the release in pH 1.2 to 16.15% and maximizing the release in pH 7.4 to 78.09%. The cytotoxicity of the optimal formula on the colon cancer cells HT-29 was higher than it was with TER alone by 2.8-fold. Apoptosis in cancer cells exposed to the optimum formula was boosted as compared to what it was with the plain TER by 1.2-fold and it was more efficient in arresting cells during the G0/G1 and S stages of the cell cycle. Accordingly, the repurposing of TER utilizing Eud/MSNs is a promising technique for targeted colon cancer therapy.

Preparation of Chiral Silica Nanostructures with Radial Pores through Single-templating Approach

Preparation of Chiral Silica Nanostructures with Radial Pores through Single-templating Approach

Biopolymer assisted synthesis of metal–silica hybrid nanoflowers as a medium for the photocatalytic degradation of dye pollutants

This report presents an ecofriendly synthesis and characterization of biopolymer (sodium alginate)-capped silver nanoparticle-silicon dioxide (Ag-SiO2) hybrid nanoflowers and their efficiency for the plasmon-mediated dye degradation of methylene blue. The reducing and capping agents for the initial silver nanoparticles (AgNPs) synthesis were glucose and sodium alginate, respectively. The mesoporous silica nanostructures were introduced using two-step hydrolysis followed by a polycondensation process. Detailed structural and morphological characterizations of the as-prepared hybrid nanostructures were done using various techniques. The results revealed the formation of nanoflower-like hybrid alginate-capped Ag-SiO2 nanostructures with a size range of approximately 523 ± 56 nm. The BET surface area analysis showed that the hybrid nanostructure has a surface area of 15.6 m2/g together with a pore diameter of 18.2 nm. The hybrid Ag-SiO2 nanoflowers showed excellent catalytic properties for the visible light photodegradation of methylene blue dye after 1 min exposure compared to silver nanoparticles at the same condition. The synergistic effect of SiO2 and Ag nanoparticles improved the catalytic property of the hybrid nanostructure. This study demonstrated a simple and effective model for the efficiency of designed hybrid nanostructures for degradation of industrial dyes.

Design, fabrication, and evaluation of green mesoporous hollow magnetic spheres with antibacterial activity

Hollow silica nanostructures are receiving more attention due to their special features such as low density and very high surface-to-volume ratio compared to other types of nanoparticles. In this research, an efficient method for the synthesis of hollow magnetic spheres with antibacterial properties is investigated. These hollow magnetic spheres are prepared in several steps and identified by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EDS), Elemental mapping, High-resolution transmission electron microscopy (HRTEM), and vibrating-sample magnetometer (VSM) techniques. Also, the antibacterial property of magnetic hollow spheres is investigated by the agar diffusion method on the Acinetobacter baumannii, Staphylococcus epidermidis, Proteus mirabilis, Staphylococcus aureus, and Pseudomonas aeruginosa. Due to the high surface-to-volume ratio, their contact level with the surrounding environment is extremely high, which increases the effectiveness of their antibacterial properties. The results of FTIR bond analysis show that TEOS precursor particles established surface bonds with CTAB activators during the synthesis process, and the presence of SiOSi bonds in the range (600–1320 cm−1) indicates the formation of silicate chains. The size of the nanoparticles based on the HRTEM images was estimated to be approximately 40 nm. FESEM images confirmed the spherical shape of nanoparticles with an average size of 350 nm. The antibacterial feature, porous walls and empty space inside the spheres made it possible to facilitate and control the drug release and use it in medicine, especially for wound healing. Also, due to the magnetic properties of the manufactured nanospheres, they can be used in many ways in medical fields, especially in the treatment of cancer. In the continuation of the work, it is suggested to use Ag/Fe3O4@@ magnetic hollow mesoporous spheres (HMS) as a suitable drug carrier due to increasing the efficiency and control of drug delivery with the capabilities of targeting/responding to stimuli, increasing the speed and effect of the drug.

Polysaccharide/Silica Microcapsules Prepared via Ionic Gelation Combined with Spray Drying: Application in the Release of Hydrophilic Substances and Catalysis.

Polysaccharide/silica hybrid microcapsules were prepared using ionic gelation followed by spray-drying. Chitosan and alginate were used as biopolymer matrices, and in situ prepared silica was used as a structuring additive. The prepared microparticles were used in two very different applications: the encapsulation of hydrophilic molecules, and as a support for palladium nanoparticles used as catalysts for a model organic reaction, namely the reduction of p-nitrophenol by sodium borhydride. In the first application, erioglaucine disodium salt, taken as a model hydrophilic substance, was encapsulated in situ during the preparation of the microparticles. The results indicate that the presence of silica nanostructures, integrated within the polymer matrix, affect the morphology and the stability of the particles, retarding the release of the encapsulated substance. In the second application, chloropalladate was complexed on the surface of chitosan microparticles, and palladium(II) was subsequently reduced to palladium(0) to obtain heterogeneous catalysts with an excellent performance.

Incorporation of phosphated tin oxide in mesoporous silica nanostructure for high-performance wastewater treatment and synthesis of pharmaceutically significant 14-aryl-14-alkyl-14-H-dibenzoxanthene

Purifying wastewater is critical for mitigating the expected clean water shortage and climate change. Herein, phosphated-SnO2/mesoporous silica nanostructure (SnP2O7/MCM-41) was prepared by skillfully interacting pyrophosphate (P2O7-4) with Sn(OH)4 in the mesopores of MCM-41 via a simple sol-gel approach. TGA and XRD analysis revealed the high thermal stability and crystallinity of the SnP2O7/MCM-41 mesostructure. More importantly, the TEM images and acidity measurements indicated that the SnP2O7 species are homogeneously distributed over the MCM-41 surface, and the acid strength is maximized when the surface is saturated with 35 wt% SnP2O7/MCM-41. Benefiting from the high acidity and plenty of active sites, SnP2O7/MCM-41 catalyzed the conversion of benzaldehyde and β-naphthol to pharmaceutical-significant 14-Aryl-14-alkyl-14-H-dibenzoxanthene with an excellent yield of 97% after 2 h reaction progress under a gentle and solvent-free environment. Moreover, the zeta potential of SnP2O7/MCM-41 catalyst was measured at different pH values and the point of zero charges (PZC) were investigated to determine the best circumstances and make water purification more practicable. The PZC of SnP2O7/MCM-41 was found to be around pH 5.4, and SnP2O7/MCM-41 exhibits 96 % removal of 100 ppm BG dye, which is far higher than SnO2/MCM-41 under the same conditions of pH 8, adsorption contact time (1 h), and adsorbent dosage (0.05 g). The experimental data follows a pseudo-second-order model, providing a good correlation coefficient (R2 = 0.998). In terms of chemical stability, SnP2O7/MCM-41 was reused for 10 cycles without significant performance loss. From the application perspective, our results demonstrate that SnP2O7/MCM-41 has the desired chemical composition for wastewater purification and catalysis applications.

Combined Electrospinning-Electrospraying for High-Performance Bipolar Membranes with Incorporated MCM-41 as Water Dissociation Catalysts.

Electrospinning has been demonstrated as a very promising method to create bipolar membranes (BPMs), especially as it allows three-dimensional (3D) junctions of entangled anion exchange and cation exchange nanofibers. These newly developed BPMs are relevant to demanding applications, including acid and base production, fuel cells, flow batteries, ammonia removal, concentration of carbon dioxide, and hydrogen generation. However, these applications require the introduction of catalysts into the BPM to allow accelerated water dissociation, and this remains a challenge. Here, we demonstrate a versatile strategy to produce very efficient BPMs through a combined electrospinning-electrospraying approach. Moreover, this work applies the newly investigated water dissociation catalyst of nanostructured silica MCM-41. Several BPMs were produced by electrospraying MCM-41 nanoparticles into the layers directly adjacent to the main BPM 3D junction. BPMs with various loadings of MCM-41 nanoparticles and BPMs with different catalyst positions relative to the junction were investigated. The membranes were carefully characterized for their structure and performance. Interestingly, the water dissociation performance of BPMs showed a clear optimal MCM-41 loading where the performance outpaced that of a commercial BPM, recording a transmembrane voltage of approximately 1.11 V at 1000 A/m2. Such an excellent performance is very relevant to fuel cell and flow battery applications, but our results also shed light on the exact function of the catalyst in this mode of operation. Overall, we demonstrate clearly that introducing a novel BPM architecture through a novel hybrid electrospinning-electrospraying method allows the uptake of promising new catalysts (i.e., MCM-41) and the production of very relevant BPMs.

Osmolytes as Cryoprotectants under Salt Stress.

Cryoprotecting agent (CPA)-guided preservation is essential for effective protection of cells from cryoinjuries. However, current cryoprotecting technologies practiced to cryopreserve cells for biomedical applications are met with extreme challenges due to the associated toxicity of CPAs. Because of these limitations of present CPAs, the quest for nontoxic alternatives for useful application in cell-based biomedicines has been attracting growing interest. Toward this end, here, we investigate naturally occurring osmolytes' scope as biocompatible cryoprotectants under cold stress conditions in high-saline medium. Via a combination of the simulation and experiment on charged silica nanostructures, we render first-hand evidence that a pair of archetypal osmolytes, glycine and betaine, would act as a cryoprotectant by restoring the indigenous intersurface electrostatic interaction, which had been a priori screened due to the cold effect under salt stress. While these osmolytes' individual modes of action are sensitive to subtle chemical variation, a uniform augmentation in the extent of osmolytic activity is observed with an increase in temperature to counter the proportionately enhanced salt screening. The trend as noted in inorganic nanostructures is found to be recurrent and robustly transferable in a charged protein interface. In hindsight, our observation justifies the sufficiency of the reduced requirement of osmolytes in cells during critical cold conditions and encourages their direct usage and biomimicry for cryopreservation.

Nanostructured N/S doped carbon dots/mesoporous silica nanoparticles and PVA composite hydrogel fabrication for anti-microbial and anti-biofilm application

Regarding the convergence of the worldwide epidemic, the appearance of bacterial infection has occasioned in a melodramatic upsurge in bacterial pathogens with confrontation against one or numerous antibiotics. The implementation of engineered nanostructured particles as a delivery vehicle for antimicrobial agent is one promising approach that could theoretically battle the setbacks mentioned. Among all nanoparticles, silica nanoparticles have been found to provide functional features that are advantageous for combatting bacterial contagion. Apart from that, carbon dots, a zero-dimension nanomaterial, have recently exhibited their photo-responsive property to generate reactive oxygen species facilitating to enhance microorganism suppression and inactivation ability. In this study, potentials of core/shell mesoporous silica nanostructures (MSN) in conjugation with carbon dots (CDs) toward antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli have been investigated. Nitrogen and sulfur doped CDs (NS/CDs) conjugated with MSN which were cost effective nanoparticles exhibited much superior antimicrobial activity for 4 times as much as silver nanoparticles against all bacteria tested. Among all nanoparticles tested, 0.40 M NS/CDs@MSN showed the greatest minimal biofilm inhibitory at very low concentration (< 0.125 mg mL−1), followed by 0.20 M NS/CDs@MSN (0.5 mg mL−1), CD@MSN (25 mg mL−1), and MSN (50 mg mL−1), respectively. Immobilization of NS/CDs@MSN in polyvinyl alcohol (PVA) hydrogel was performed and its effect on antimicrobial activity, biofilm controlling efficiency, and cytotoxicity toward fibroblast (NIH/3 T3 and L-929) cells was additionally studied for further biomedical applications. The results demonstrated that 0.40 M NS/CDs-MSN@PVA hydrogel exhibited the highest inhibitory effect on S. aureus > P. aeruginosa > E. coli. In addition, MTT assay revealed some degree of toxicity of 0.40 M NS/CDs-MSN@PVA hydrogel against L-929 cells by a slight reduction of cell viability from 100% to 81.6% when incubated in the extract from 0.40 M NS/CDs-MSN@PVA hydrogel, while no toxicity of the same hydrogel extract was detected toward NIH/3 T3 cells.

Electronic and Structural Properties of Core-Shell Amino-Silica Nanoparticles: DFT And SCC-DFTB Calculation

Introduction: Silica nanoparticles (SNP) are extremely promising tools in nanotechnology and nano medicine. In most of applications such as capture and release of bacteriophage viruses the nano-structures of silica are coated by bio-compatible groups such as amine compounds. The presence of amino groups on the surface of the biosensors enables the installation of analyte receptors and antifouling agents such as oligo (ethylene oxide). Therefore, in this study, the electronic and structural properties of Core-Shell amino- Silica Nanoparticles are investigated.Material and Methods: In this investigation, we aim at obtaining the optimized structures and evaluate the geometries of the ground state for (SiO2) n (n=16, 20) nanoclusters. The electronic properties computed by density functional theory with GGA approximation and SCC-DFTB with hybrid Slater-Koster files are investigated and the effect of functionalization on such properties is discussed.Results: Solvolysis of studied structures is examined and it is shown that the highest occupied and lowest unoccupied molecular orbital states shift to obviously higher energy levels, which lead to more stable hydrogenated nanoclusters. The stability of nanoclusters rises by functionalization with amino and methylamine groups. Charge analysis of functionalized systems indicates the reactivity of nanoclusters. The results obtained in this paper are useful for chemical and biochemical applications of silica nanostructures.Conclusion: Results show that the length of amine hydrocarbon chain can control the electronic and magnetic properties of studied silica nanocluster (SNP) with different number of SiO2 unit. Pure ultra-small nanocluster shows the impressive spin splitting around the Fermi level, which is due to the spin splitting of outer silicon atoms. This feature of silica nanoclusters may be notable for applications in electronics.

Nanosilica Extraction from Grumusol Soil

Grumusol soil is a type of soil that contains significant amounts of silica. Silica content in grumusol soil can reach up to 90%. The aim of this research was to determine the characteristics of silica nanostructures in Grumusol soil. The stages of the research were carried out including the preparation of raw materials, silica extraction, and XRD analysis. The raw material preparation stage is carried out by cleaning the grumusol soil from dirt. The second stage was carried out by synthesizing silica with the base extraction method and followed by acid deposition. The final stage is X-Ray Diffracion (XRD) analysis. The results of the research that has been carried out is the FWHM value of 0.0900 (&lt;0.1) which indicates that the crystals produced have very good crystals with a very regular structure. The crystal size which includes nanosilica is 39.5076-48.6633 nm for 3M NaOH with 1 and 3 hours extraction time and 5M NaOH with 1 hour extraction time

Internally bridged nanosilica for loadings and release of sparsely soluble compounds

The engineering of a new monodisperse colloid with a sea urchin-like structure with a large complex internal structure is reported, in which silica surfaces are bridged by an aromatic organic cross-linker to serve as a nanocarrier host for drugs such as doxorubicin (DOX) against breast cancer cells. While dendritic fibrous nanosilica (DFNS) was employed and we do not observe a dendritic structure, these particles are referred to as sea urchin-like nanostructured silica (SNS). Since the structure of SNS consists of many silica fibrils protruding from the core, similar to the hairs of a sea urchin. For the aromatic structured cross-linker, bis(propyliminomethyl)benzene (b(PIM)B-S or silanated terephtaldehyde) were employed, which are prepared with terephtaldehyde and 3-aminopropyltriethoxy-silane (APTES) through a simple Schiff base reaction. b(PIM)B-S bridges were introduced into SNS under open vessel reflux conditions. SPS refers to the product obtained by incorporating the cross-linker b(PIM)B-S in ultra-small colloidal SNS particles. In-situ incorporation of DOX molecules resulted in SPS-DOX. The pH-responsive SPS nanocomposites were tested as biocompatible nanocarriers for controllable doxorubicin (DOX) delivery. We conclude that SPS is a unique colloid which has promising potential for technological applications such as advanced drug delivery systems, wastewater remediation and as a catalyst for green organic reactions in water.

Laccase catalytic activity shielded by SiO2 nanostructured materials: an in vitro and in silico approach

This study investigates the enhancement of enzymatic catalytic performance by immobilizing laccase on various nanostructured mesoporous silica materials (SBA-15, MCF, and MSU-F). The activity of immobilized laccase was evaluated under different hydrothermal, pH, and solvent conditions, with laccase@MSU-F showing a three-fold increase in stability. Laccase immobilized on these materials demonstrated stability in a pH range of 4.5 to 10.0, while free laccase was inactivated at pH higher than 7. Molecular dynamics simulations revealed that electrostatic interactions and protective confinement effects contribute to the improved stability of immobilized laccase. Overall, the findings suggest that nanomaterials can enhance the operational stability and recovery of enzymes. Communicated by Ramaswamy H. Sarma

Sol–Gel Silica Coatings for Corrosion Protection of Aluminum Parts Manufactured by Selective Laser Melting (SLM) Technology

Metal additive manufacturing is a rapidly growing field based on the fabrication of complex parts with improved performance. The advantages of using this technology include the production of shapes that cannot be produced by traditional machining technologies, the possibility of using trabecular reinforcing structures, and the ability to make parts with topological optimization that allow for increased performance and decreased mass of the parts produced. Metal parts produced by selective laser melting technology exhibit high surface roughness, which limits their direct implementation. Corrosion protection of these surfaces is difficult, especially for galvanic processes. This paper analyzes the possibility of using sol–gel silica (silicon oxide) coatings to effectively protect various surfaces of aluminum alloys produced by selective laser melting technology. Silicon oxide sol–gel protective coatings have demonstrated excellent chemical stability and corrosion resistance, being able to be applied in very thin layers. These properties make them excellent candidates for protecting additive-manufactured metal parts, especially as-built surfaces with a high surface roughness. Nanostructured silica sol–gel protective coatings have demonstrated excellent corrosion resistance and have the potential to replace the highly toxic chromium-based galvanic treatments. Using nanostructured silica sol–gel coatings, aluminum parts can be seamlessly integrated into circular-economy cycles.

A sinterless, low-temperature route to 3D print nanoscale optical-grade glass.

Three-dimensional (3D) printing of silica glass is dominated by techniques that rely on traditional particle sintering. At the nanoscale, this limits their adoption within microsystem technology, which prevents technological breakthroughs. We introduce the sinterless, two-photon polymerization 3D printing of free-form fused silica nanostructures from a polyhedral oligomeric silsesquioxane (POSS) resin. Contrary to particle-loaded sacrificial binders, our POSS resin itself constitutes a continuous silicon-oxygen molecular network that forms transparent fused silica at only 650°C. This temperature is 500°C lower than the sintering temperatures for fusing discrete silica particles to a continuum, which brings silica 3D printing below the melting points of essential microsystem materials. Simultaneously, we achieve a fourfold resolution enhancement, which enables visible light nanophotonics. By demonstrating excellent optical quality, mechanical resilience, ease of processing, and coverable size scale, our material sets a benchmark for micro- and nano-3D printing of inorganic solids.