High Surface Area Mesoporous Silica Nanoparticles with Tunable Size in the Sub-Micrometer Regime: Insights on the Size and Porosity Control Mechanisms

Advancing Adsorption and Separation with Modified SBA-15: A Comprehensive Review and Future Perspectives

Mesoporous silica SBA-15 has emerged as a promising adsorbent and separation material due to its unique structural and physicochemical properties. To further enhance its performance, various surface modification strategies, including metal oxide and noble metal incorporation for improved catalytic activity and stability, organic functionalization with amino and thiol groups for enhanced adsorption capacity and selectivity, and inorganic-organic composite modification for synergistic effects, have been extensively explored. This review provides a comprehensive overview of the recent advances in the surface modification of SBA-15 for adsorption and separation applications. The synthesis methods, structural properties, and advantages of SBA-15 are discussed, followed by a detailed analysis of the different modification strategies and their structure-performance relationships. The adsorption and separation performance of functionalized SBA-15 materials in the removal of organic pollutants, heavy metal ions, gases, and biomolecules, as well as in chromatographic and solid-liquid separation, is critically evaluated. Despite the significant progress, challenges and opportunities for future research are identified, including the development of low-cost and sustainable synthesis routes, rational design of SBA-15-based materials with tailored properties, and integration into practical applications. This review aims to guide future research efforts in developing advanced SBA-15-based materials for sustainable environmental and industrial applications, with an emphasis on green and scalable modification strategies.

Porous protein crystals: synthesis and applications

Large-pore protein crystals (LPCs) are an emerging class of biomaterials. The inherent diversity of proteins translates to a diversity of crystal lattice structures, many of which display large pores and solvent channels. These pores can, in turn, be functionalized via directed evolution and rational redesign based on the known crystal structures. LPCs possess extremely high solvent content, as well as extremely high surface area to volume ratios. Because of these characteristics, LPCs continue to be explored in diverse applications including catalysis, targeted therapeutic delivery, templating of nanostructures, structural biology. This Feature review article will describe several of the existing platforms in detail, with particular focus on LPC synthesis approaches and reported applications.

Fluorine-free nanoparticle coatings on cotton fabric: comparing the UV-protective and hydrophobic capabilities of silica vs. silica-ZnO nanostructures

Robust, hydrophobic woven cotton fabrics were obtained through the sol-gel dip coating of two different nanoparticle (NP) architectures; silica and silica-ZnO. Water repellency values as high as 148° and relatively low tilt angles for fibrous fabrics (12°) were observed, without the need for fluorinated components. In all cases, this enhanced functionality was achieved with the broad retention of water vapor permeability characteristics, i.e., less than 10% decrease. NP formation routes indicated direct bonding interactions in both the silica and silica-ZnO structures. The physico-chemical effects of NP-compatibilizer (i.e., polydimethoxysilane (PDMS) and n-octyltriethoxysilane (OTES) at different ratios) coatings on cotton fibres indicate that compatibilizer-NP interactions are predominantly physical. Whenever photoactive ZnO-containing additives were used, there was a minor decrease in hydrophobic character, but order of magnitude increases in UV-protective capability (i.e., UPF > 384); properties which were absent in non-ZnO-containing samples. Such water repellency and UPF capabilities were stable to both laundering and UV-exposure, resisting the commonly encountered UV-induced wettability transitions associated with photoactive ZnO. These results suggest that ZnO-containing silica NP coatings on cotton can confer both excellent and persistent surface hydrophobicity as well as UV-protective capability, with potential uses in wearables and functional textiles applications.

Effect of silica-based mesoporous nanomaterials on human blood cells

Different mesoporous nanomaterials (MSNs) are constantly being developed for a range of therapeutic purposes, but they invariably interact with blood components and may cause hazardous side effects. Therefore, when designing and developing nanoparticles for biomedical applications, hemocompatibility should be one of the primary goals to assess their toxicity at the cellular level of all blood components. The aim of this study was to evaluate the compatibility of human blood cells (erythrocytes, platelets, and leukocytes) after exposure to silica-based mesoporous nanomaterials that had been manufactured using the sol-gel method, with Ca and Ce as doping elements. The viability of lymphocytes and monocytes was unaffected by the presence of MSNs at any concentration. However, it was found that all nanomaterials, at all concentrations, reduced the viability of granulocytes. P-selectin expression of all MSNs at all concentrations was statistically significantly higher in platelet incubation on the first day of storage (day 1) compared to the control. When incubated with MSNs, preserved platelets displayed higher levels of iROS at all MSNs types and concentrations examined. Ce-containing MSNs presented a slightly better hemocompatibility, although it was also dose dependent. Further research is required to determine how the unique characteristics of MSNs may affect various blood components in order to design safe and effective MSNs for various biomedical applications.

Contact Lens with pH Sensitivity for On-Demand Drug Release in Wearing Situation

Drug-releasing contact lenses are emerging therapeutic systems for treating ocular diseases. However, their applicability is limited by the burst release of drugs during lens wear and premature drug leakage during packaging, rendering the precise control of release duration or dose difficult. Here, we introduce a pH-sensitive contact lens exhibiting on-demand drug release only during lens wear and negligible premature drug leakage during packaging and transportation, which is accomplished by incorporating drug-loaded mesoporous silica nanoparticles (MSNs) coated with a pH-sensitive polymer into the contact lens. The compositionally optimized pH-sensitive polymer has a lower critical solution temperature (LCST) at >45 °C at pH 7.4, whereas its LCST decreases to <35 °C under acidic conditions (pH ∼ 6.5). Consequently, the MSN-incorporated contact lens sustainably releases the loaded drugs only in the acidic state at 35 °C, which corresponds to lens-wear conditions, through the MSN pores that open because of the shrinkage of polymer chains. Conversely, negligible drug leakage is observed from the contact lens under low-temperature or neutral-pH conditions corresponding to packaging and transportation. Furthermore, compared with the plain contact lens, the pH-sensitive contact lens exhibits good biocompatibility and unchanged bulk characteristics, such as optical (transmittance in the visible-light region), mechanical (elastic modulus and tensile strength), and physical (surface roughness, oxygen permeability, and water content) properties. These findings suggest that the pH-sensitive contact lens can be potentially applied in ocular disease treatment.

Tuning Mesoporous Silica Nanoparticles in Novel Avenues of Cancer Therapy

The global menace of cancer has led to an increased death toll in recent years. The constant evolution of cancer therapeutics with novel delivery systems has paved the way for translation of innovative therapeutics from bench to bedside. This review explains the significance of mesoporous silica nanoparticles (MSNs) as delivery vehicles with particular emphasis on cancer therapy, including novel opportunities for biomimetic therapeutics and vaccine delivery. Parameters governing MSN synthesis, therapeutic agent loading characteristics, along with tuning of MSN toward cancer cell specificity have been explained. The advent of MSN in nanotheranostics and its potential in forming nanocomposites for imaging purposes have been illustrated. Additionally, various hurdles encountered during the bench to bedside translation have been explained along with potential avenues to circumvent them. This also opens up new horizons in drug delivery, which could be useful to researchers in the years to come.

Au/Ti Synergistically Modified Supports Based on SiO2 with Different Pore Geometries and Architectures

New photocatalysts were obtained by immobilization of titanium and gold species on zeolite Y, hierarchical zeolite Y, MCM-48 and KIT-6 supports with microporous, hierarchical and mesoporous cubic structure. The obtained samples were characterized by X-ray diffraction (XRD), N2-physisorption, scanning and transmission electron microscopy (SEM/TEM), diffuse reflectance UV–Vis spectroscopy (DRUV-Vis), X-ray photoelectron spectroscopy (XPS), Raman and photoluminescence spectroscopy. The photocatalytic properties were evaluated in degradation of amoxicillin (AMX) from water, under UV (254 nm) and visible light (532 nm) irradiation. The higher degradation efficiency and best apparent rate constant were obtained under UV irradiation for Au-TiO2-KIT-6, while in the visible condition for the Au-TiO2-MCM-48 sample containing anatase, rutile and the greatest percent of Au metallic clusters were found (evidenced by XPS). Although significant values of amoxicillin degradation were obtained, total mineralization was not achieved. These results were explained by different reaction mechanisms, in which Au species act as e− trap in UV and e− generator in visible light.

NIR-Absorbing Mesoporous Silica-Coated Copper Sulphide Nanostructures for Light-to-Thermal Energy Conversion

Plasmonic nanostructures, featuring near infrared (NIR)-absorption, are rising as efficient nanosystems for in vitro photothermal (PT) studies and in vivo PT treatment of cancer diseases. Among the different materials, new plasmonic nanostructures based on Cu_2−xS nanocrystals (NCs) are emerging as valuable alternatives to Au nanorods, nanostars and nanoshells, largely exploited as NIR absorbing nanoheaters. Even though Cu_2−xS plasmonic properties are not linked to geometry, the role played by their size, shape and surface chemistry is expected to be fundamental for an efficient PT process. Here, Cu_2−xS NCs coated with a hydrophilic mesoporous silica shell (MSS) are synthesized by solution-phase strategies, tuning the core geometry, MSS thickness and texture. Besides their loading capability, the silica shell has been widely reported to provide a more robust plasmonic core protection than organic molecular/polymeric coatings, and improved heat flow from the NC to the environment due to a reduced interfacial thermal resistance and direct electron–phonon coupling through the interface. Systematic structural and morphological analysis of the core-shell nanoparticles and an in-depth thermoplasmonic characterization by using a pump beam 808 nm laser, are carried out. The results suggest that large triangular nanoplates (NPLs) coated by a few tens of nanometers thick MSS, show good photostability under laser light irradiation and provide a temperature increase above 38 °C and a 20% PT efficiency upon short irradiation time (60 s) at 6 W/cm² power density.

A Comparison of Environmental Impact of Various Silicas Using a Green Chemistry Evaluator

To answer questions surrounding the sustainability of silica production, MilliporeSigma's DOZN 2.0 Green Chemistry Evaluator was employed as it provides quantitative values based on the 12 principles of Green Chemistry. As a first study using DOZN 2.0 to evaluate the greenness of nanomaterials, a range of silica types were considered and their greenness scores compared. These included low- and high-value silicas, both commercial and emerging, such as precipitated, gel, fumed, colloidal, mesoporous, and bioinspired silicas. When surveying these different types of silicas, it became clear that while low value silicas have excellent greenness scores, high-value silicas perform poorly on this scale. This highlighted the tension between high-value silicas that are desired for emerging markets and the sustainability of their synthesis. The calculations were able to quantify the issues pertaining to the energy-intensive reactions and subsequent removal of soft templates for the sol-gel processes. The importance of avoiding problematic solvents during processes and particularly releasing them as waste was identified. The calculations were also able to compare the amount of waste generated as well as their hazardous nature. The effects of synthesis conditions on greenness scores were also investigated in order to better understand the relationship between the production process and their sustainability.

Immunomodulatory and Antioxidant Potential of Biogenic Functionalized Polymeric Nutmeg Oil/Polyurethane/ZnO Bionanocomposite

The current study is focused on the biosynthesis of nutmeg oil/ polyurethane/ZnONPs bionanocomposite film for immunomodulatory and antioxidant activities. The fabricated film was prepared by using naturally extracted nutmeg oil functionalized with ZnONPs in the presence of polyutherane (PU) medium. The bionanocomposite film was obtained by incorporating dropwise 10 % (w/v) of nutmeg oil to the PU solution/ZnONPs blend. The active constituents of nutmeg oil were determined by gas chromatography coupled with mass spectrometry (GC-MS). The morphological characteristics of the resulting bionanocomposite film were confirmed using various microscopic and spectroscopic methods. Immunomodulatory potential of bionanocomposite was evaluated for RAW 264.7 macrophages. The results exhibited an excellent reduction in inflammatory cytokines (IL-6, IL-10, and TNFα) secretions after the treatment with bionanocomposite. The bionanocomposite exerted the highest inhibitory effects on certain cell signaling constituents that influence the initiation of expression of proinflammatory cytokines. The bionanocomposite was also tested for DPPH and ABTS free radicals scavenging assays and showed excellent antioxidant potential with IC₅₀ values (0.28 ± 0.22 and 0.49 ± 0.36), respectively. The outcomes suggested promising immunomodulatory and antioxidant potentials for the biogenic synthesized nutmeg oil/PU/ZnONPs polymeric bionanocomposite.

Enhancement of Temperature Fluorescence Brightness of Zn@Si Core-Shell Quantum Dots Produced via a Unified Strategy

Despite many dedicated efforts, the fabrication of high-quality ZnO-incorporated Zinc@Silicon (Zn@Si) core–shell quantum dots (ZnSiQDs) with customized properties remains challenging. In this study, we report a new record for the brightness enhancement of ZnSiQDs prepared via a unified top-down and bottom-up strategy. The top-down approach was used to produce ZnSiQDs with uniform sizes and shapes, followed by the bottom-up method for their re-growth. The influence of various NH₄OH contents (15 to 25 µL) on the morphology and optical characteristics of ZnSiQDs was investigated. The ZnSiQDs were obtained from the electrochemically etched porous Si (PSi) with Zn inclusion (ZnPSi), followed by the electropolishing and sonication in acetone. EFTEM micrographs of the samples prepared without and with NH₄OH revealed the existence of spherical ZnSiQDs with a mean diameter of 1.22 to 7.4 nm, respectively. The emission spectra of the ZnSiQDs (excited by 365 nm) exhibited bright blue, green, orange-yellow, and red luminescence, indicating the uniform morphology related to the strong quantum confinement ZnSiQDs. In addition, the absorption and emission of the ZnSiQDs prepared with NH₄OH were enhanced by 198.8% and 132.6%, respectively. The bandgap of the ZnSiQDs conditioned without and with NH₄OH was approximately 3.6 and 2.3 eV, respectively.

Method for High-Yield Hydrothermal Growth of Silica Shells on Nanoparticles

Coating processes are commonly used in materials science to protect a core or modify material properties. We describe a hydrothermal coating process using TEOS (tetraethyl orthosilicate), a widely used precursor for silica coatings, on three representative template materials (carbon nanotubes, silica, and polystyrene nanoparticles) with different properties and shapes. We compare the efficiency of previously published protocols for silica coatings at room temperature and atmospheric pressure with the hydrothermal process at 160 °C and 3 bar. The hydrothermal method achieves higher yields and thicker silica coatings with the same amount of precursor when compared to the conventional way, thus offering higher effectiveness. Furthermore, the hydrothermal coating process yields more homogeneous shells with a higher density, making hydrothermal coating the method of choice when mechanical integrity and low permeability of the coating are required.

Innovative Silver-Based Capping System for Mesoporous Silica Nanocarriers Able to Exploit a Twofold Anticorrosive Mechanism in Composite Polymer Coatings: Tailoring Benzotriazole Release and Capturing Chloride Ions

In this work, engineered stimuli-responsive mesoporous silica nanoparticles (MSNs) were developed and exploited in polymer coatings as multifunctional carriers of a typical corrosion inhibitor, benzotriazole (BTA). In detail, a new capping system based on a BTA-silver coordination complex, able to dissolve in acid and alkaline conditions and to simultaneously tailor the BTA release and the capture of chloride ions, was properly designed and realized. Acrylic coatings embedding the engineered MSNs were deposited onto iron rebar samples and tested for their protective capability in acid and alkaline environments. Results highlighted the high potential of the proposed system for the protection of metals, due to the synergistic effect of the mesoporous structure and the capping system, which guaranteed both the sequestration of chloride ions and the on-demand release of the effective amount of anticorrosive agents able to ensure the enhanced protection of the substrate.