Mesoporous Silica Template Research Articles

Lychee-shaped magneto-gold nanohybrid with highly retained magnetic-plasmonic activity for ultrasensitive and multiplex immunochromatographic assay

Utilizing nanomaterials with magnetic and plasmonic properties can significantly enhance the sensitivity of immunochromatographic assay (ICA) through magnetic enrichment, and signal amplification. Herein, we successfully synthesized a lychee-shaped magneto-gold nanohybrid (designated as MSiAuTA). This nanohybrid comprises a magnetic nanoparticle core, a flesh-fiber-like mesoporous silica template hosting numerous gold nanoparticles (AuNPs), and a lychee-exocarp-like tannic acid layer. The resultant MSiAuTA exhibits rapid magnetic response, strong plasmonic activity, and excellent biocompatibility. We further developed a multiplex ICA (mICA) platform utilizing MSiAuTA as labels for target enrichment and colorimetric signal amplification. This platform enables simultaneous and quantitative detection of Escherichia coli O157:H7 and Salmonella typhimurium. The MSiAuTA-mICA supports portable strip reader and smartphone readout and demonstrates exceptional sensitivity, achieving detection limits of 9.8 × 102 CFU/mL for E. coli O157:H7 and 4.9 × 102 CFU/mL for S. typhimurium. Additionally, we validated the accuracy, robustness, and practicality of MSiAuTA-mICA in detecting both spiked and naturally contaminated samples, including water, lettuce, chicken, apple juice, and milk. In conclusion, the lychee-shaped MSiAuTA nanohybrid shows significant promise as a versatile label for enhancing ICA’s detection capabilities in complex sample matrices.

Synthesis and up-conversion luminescence of erbium-doped yttrium silicate single crystal nanoparticles tailored by the mesoporous silica template

Erbium-activated yttrium silicate nanoparticles were tailored using a mesoporous silica template. Transmission electron microscopy (TEM) revealed that the synthesized particles are single crystals of yttrium pyrosilicate (α−Y2Si2O7:Er), possessing a spherical shape (with an average size of about 210 nm) and a narrow size distribution. Up-conversion luminescence of the synthesized particles was investigated in the green spectral region under excitation by a laser diode operating at a wavelength of 808 nm. In the range of 510-580 nm, intense narrow lines with a Lorentzian shape were observed, attributed to radiative transitions from two thermally coupled energy levels of the Er3+ ion [2H11/2→4I15/2 (520–540 nm) and 4S3/2→4I15/2 (545–570 nm)]. It was experimentally demonstrated that within the temperature range of 250–520 K, the equilibrium populations of the 2H11/2 and 4S3/2 levels follow the Boltzmann distribution. This result provides a basis for the potential use of the synthesized particles as temperature sensors in various applications, including biomedical ones.

Protocrystallinity of Monodispersed Ultra-Small Templated Mesoporous Silica Nanoparticles.

Monodisperse and semi-faceted ultra-small templated mesoporous silica nanoparticles (US-MSNs) of 20-25 nm were synthesized using short-time hydrolysis of tetraethoxysilane (TEOS) at room temperature, followed by a dilution for nucleation quenching. According to dynamic light scattering (DLS), a two-step pH adjustment was necessary for growth termination and colloidal stabilization. The pore size was controlled by cetyltrimethylammonium bromide (CTAB), and a tiny amount of neutral surfactant F127 was added to minimize the coalescence between US-MSNs and to favor the transition towards internal ordering. Flocculation eventually occurred, allowing us to harvest a powder by centrifugation (~60% silica yield after one month). Scanning transmission electron microscopy (STEM) and 3D high-resolution transmission electron microscopy (3D HR-TEM) images revealed that the US-MSNs are partially ordered. The 2D FT transform images provide evidence for the coexistence of four-, five-, and sixfold patterns characterizing an "on-the-edge" crystallization step between amorphous raspberry and hexagonal pore array morphologies, typical of a protocrystalline state. Calcination preserved this state and yielded a powder characterized by packing, developing a hierarchical porosity centered at 3.9 ± 0.2 (internal pores) and 68 ± 7 nm (packing voids) of high potential for support for separation and catalysis.

The existence of a strongly bonded layer in associating liquids within silica pores - a spectral and molecular dynamics study.

The properties of confined materials are assumed to be governed by the phenomena occurring at the interface, especially the formation of an irreversible adsorption layer (IAL), which has been widely discussed and detected in the case of thin polymer films and silica nanoparticles. In this paper, we present a novel experimental approach allowing us to reveal the formation of an IAL in two phenyl alcohols infiltrated into various mesoporous silica templates. The proposed methodology (based on evaporation) allowed us to detect the alterations in the OH and aromatic CH stretching vibration bands in infrared spectra, which were considered as evidence of the existence of IAL in constrained systems. Such interpretation was also confirmed by complementary molecular dynamics (MD) simulations that indicated the creation of much stronger hydrogen bonds between alcohols and silanol units than between alcohols themselves. Moreover, computation allowed us to identify additional enormously strong π-stacking interactions between phenyl rings stabilizing the interfacial layer. MD simulations also shed new light on the clustering process of both alcohols under confinement. Simulation and experimental data presented in this paper allowed a much deeper understanding of the processes occurring at the interface-formation of IAL and the association phenomenon at the nanoscale level.

Study on morphology and N-doping effects of carbon cathodes for zinc-ion hybrid supercapacitors

Aqueous zinc-ion hybrid supercapacitors (ZHSCs) are spotlighted as next-generation energy storage devices; however, the carbon cathodes usually dictate their performance. Herein, we aim to optimize the electrochemical performance of the carbon cathodes through particle morphology control along with porosity and surface-active site control. N-doped spherical mesocelluler carbon foam (S-MCF-N) is synthesized using a mesoporous silica template, and spherical mesocelluler carbon foam (S-MCF) and irregularly shaped mesocellular carbon foam (MSUF-C) are synthesized as control samples. Consequently, S-MCF-N shows the best ion storage capability with its large surface area, with active sites that cause redox reactions and high electrical conductivity. In particular, the spherical morphology of S-MCF-N achieves a higher tap density and can reduce the electrode thickness, which decreases the diffusion length for electrolyte migration and electrode resistance. Therefore, S-MCF-N as the cathode materials deliver a specific capacitance of 208 F g−1 at 0.2 A g−1 and superb cycling stability of up to 7000 cycles at 5 A g−1 without capacity decay. Furthermore, benefiting from the reduced electrode thickness, S-MCF-N has a 112 % higher volumetric energy density than MSUF-C while showing a 42 % higher gravimetric energy density.

An Evaluation of Urease A Subunit Nanocapsules as a Vaccine in a Mouse Model of Helicobacter pylori Infection.

Using removable silica templates, protein nanocapsules comprising the A subunit of Helicobacter pylori urease (UreA) were synthesised. The templates were of two sizes, with solid core mesoporous shell (SC/MS) silica templates giving rise to nanocapsules of average diameter 510 nm and mesoporous (MS) silica templates giving rise to nanocapsules of average diameter 47 nm. Both were shown to be highly monodispersed and relatively homogenous in structure. Various combinations of the nanocapsules in formulation were assessed as vaccines in a mouse model of H. pylori infection. Immune responses were evaluated and protective efficacy assessed. It was demonstrated that vaccination of mice with the larger nanocapsules combined with an adjuvant was able to significantly reduce colonisation.

Mesoporous Single Crystal NiS2 Microparticles with FeS Clusters Decorated on the Pore Walls for Efficient Electrocatalytic Oxygen Evolution

AbstractAbundant active sites and their easy accessibility in a stable and conductive structure are of great importance for efficient electrocatalysts. In principle, activated mesoporous single‐crystal microparticles can meet these desired requirements. Here, the Fe‐doped NiS2 mesoporous single crystal microparticles decorated with FeS clusters on the pore walls (FeS@MSC‐NiS2:Fe) are constructed via a pre‐decorated and sequentially seeded mesoporous silica template. Throughout the external and internal surfaces, the Fe‐doped NiS2 modulated by the adjacent FeS clusters induces favorable charge distributions and promotes the crucial formation of the active Fe/Ni (oxy)hydroxide. Combined with the spatial enrichment effect of the intermediates in the holey space and the boosted charge transfer within the continuous single‐crystalline framework, the dually regulated FeS@MSC‐NiS2:Fe as ideal integral microreactors show efficient performances in oxygen evolution reaction. In electrochemical tests, the particulate FeS@MSC‐NiS2:Fe requires an overpotential of only 236 mV to reach a current density of 10 mA cm−2 and displays fast reaction kinetics with a Tafel slope of 32.4 mV dec−1. This study provides an important strategy to construct electrocatalysts with highly active sites and good accessibility.

Nanostructured germanium synthesized by high-pressure chemical vapor deposition in mesoporous silica templates

Nanostructured germanium synthesized by high-pressure chemical vapor deposition in mesoporous silica templates

The construction of high efficient visible-light-driven 3D porous g-C3N4/Fe3O4 photocatalyst: A new photo-induced bacterial inactivation material enhanced by cascade photo-Fenton reaction

Photocatalytic disinfection is considered a promising method for eliminating the hazards of pathogenic bacteria. Graphitic carbon nitride (g-C3N4) is an ideal photocatalytic bacterial inactivation material for its advantage of tunable band structure, good stability and easy preparation. This work has constructed a novel defective 3D porous g-C3N4 by cyanamide carbonation using dendritic mesoporous silica template. The direct loading of Fe3O4 nanoparticles provided an excellent pg–C3N4–Fe3O4 photocatalyst suitable for water disinfection. Compared to pristine g-C3N4, the prepared 3D porous defective g–C3N4–Fe3O4 exhibited the enhanced visible light absorbance as indicated by the band gap decreasing of 0.66 eV, and about 3 and 10 fold increase of photo-induced current response and O2 adsorption respectively. The pg–C3N4–Fe3O4 showed excellent visible-light-driven photocatalytic bactericidal activity. It could kill 1 × 107 cfu mL−1Escherichia coli completely within 1 h under visible-light illumination (100 mW cm−2) with good reusability, its logarithmic bacterial inactivation efficiency was about 2.5 fold higher than pg-C3N4. The enhanced bactericidal performance is mainly ascribed to the Fe3O4 involved cascade photo-Fenton reaction.

Accurate design of porous g-C3N4+x with greatly extended visible-light response for enhanced photocatalytic performance and mechanism insight for environmental remediation

Nitrogen-rich graphite carbon nitride has attracted considerable attention due to its low band gap and widespread potential application. Herein, a series of porous g-C3N4+x materials are developed by pyrolysis of 3-amino-1, 2, 4-triazole (C2H4N4) and mesoporous silica template (KIT-6). The pore diameters can be precisely tuned by controlling the proportion of C2H4N4 and KIT-6. A variety of characterizations were conducted to analyze the correlation between structure and photocatalytic performance toward the degradation of rhodamine B. It was found that, the synthesized porous g-C3N4+x exhibited a narrower band gap of 1.43 eV, which significantly extended its visible-light responsive range. Moreover, the enhanced N content and adjustable porous diameter effectively increased the separation efficiency of photogenerated electron–hole pairs. Therefore, remarkably improved photocatalytic activity was achieved, which was 5.2 times higher than that of bulk g-C3N4+x , and presented super stability as well. Additionally, the possible photocatalytic mechanism was proposed and verified. These findings shed light on a new facile way to fabricate high-performance photocatalytic materials and provided new opportunities for environmental remediation.

Nanocasting nanoporous nickel oxides from mesoporous silicas and their comparative catalytic applications for the reduction of p-nitrophenol

Herein, nanoporous nickel oxides were prepared through nanocasting using ordered- and less-ordered mesoporous silica templates, i.e., MCM-41 and KCC-1, respectively. The products resembled the replica of the inner architecture of each template. NiO-MCM-41 (nanocasted in MCM-41) possessed a highly ordered structure originating from the arrangement of nanorods resulting in a large specific surface area of 53 m2 g−1. On the other hand, NiO-KCC-1 (nanocasted in KCC-1) exhibited the combination of ordered nanorod and non-ordered foam-like structures with a less specific surface area of 23 m2 g−1. Ultimately, the catalytic tests in the reduction of p-nitrophenol (p-NP) with sodium borohydride (NaBH4) demonstrated that NiO-MCM-41 had significantly higher activity (kobs = 0.25 min−1) and better reusability (p-NP conversion of 92% after 3 times reactions) than those of NiO-KCC-1 (kobs = 0.14 min−1 and a 35% p-NP conversion after 3 times reactions) due to the more improved molecular diffusion within a highly ordered structure. The preferred mechanism was found to follow the Langmuir–Hinshelwood route in which both reactants (p-NP and [BH4]−) were initially adsorbed onto the surface of the catalyst.

Template-Assisted Crystallization Behavior in Stirred Solutions of the Monoclonal Antibody Anti-CD20: Probability Distributions of Induction Times.

We present a method to determine the template crystallization behavior of proteins. This method is a statistical approach that accounts for the stochastic nature of nucleation. It makes use of batch-wise experiments under stirring conditions in volumes smaller than 0.3 mL to save material while mimicking larger-scale processes. To validate our method, it was applied to the crystallization of a monoclonal antibody of pharmaceutical interest, Anti-CD20. First, we determined the Anti-CD20 phase diagram in a PEG-400/Na2SO4/water system using the batch method, as, to date, no such data on Anti-CD20 solubility have been reported. Then, the probability distribution of induction times was determined experimentally, in the presence of various mesoporous silica template particles, and crystallization of Anti-CD20 in the absence of templates was compared to template-assisted crystallization. The probability distribution of induction times is shown to be a suitable method to determine the effect of template particles on protein crystallization. The induction time distribution allows for the determination of two key parameters of nucleation, the nucleation rate and the growth time. This study shows that the use of silica particles leads to faster crystallization and a higher nucleation rate. The template particle characteristics are shown to be critical parameters to efficiently promote protein crystallization.

Deposition of poly(furfuryl alcohol) in mesoporous silica template controlled by solvent polarity: A cornerstone of facile and versatile synthesis of high-quality CMK-type carbon replicas. Nanocasting of SBA-15, SBA-16, and KIT-6

Six CMK-n replicas (n = 3, 5, 6, 7, 8, and 9) were synthesized using a new, facile and versatile method based on a surface-selective deposition of poly(furfuryl alcohol) onto the silica matrix. The concept of the synthesis relies on the in situ polycondensation of the carbon precursor in a toluene suspension of the hard template. Preferential pre-adsorption of the monomer onto silica provides even coverage of its surface with polymer, which is a prerequisite to the formation of highly ordered carbon negative structures (either hollow- or rod-type). The procedure is operated under ambient pressure and at moderate temperature, and a preliminary modification of silica and vacuo carbonization are no longer needed. A systematic study on materials (SEM, TEM, XRD, N2, and Ar adsorption) evidenced that the proposed pathway offers the preparation of carbon mesostructures featuring excellent structural and textural parameters while maintaining the morphology of the mother silica. CO2 adsorption revealed inhomogeneous porosity of the carbonaceous material itself. The rod-type replicas showed a core-shell structure, in which each carbon rod was built of the outer nonporous shell enveloping the microporous core. In contrast, the hollow-type carbons were constituted of non-microporous turbostratic carbon.

Pore structure of ordered mesoporous Pt-CeO2 probed by CO via VT-DRIFTS

CeO2-supported Pt (1 wt%) catalysts have been synthesized using three ordered mesoporous silica templates, SBA-15, KIT-6, and COK-19, with the representative pore structures listed as 2D hexagonal, bicontinuous cubic and face-centered cubic structures. The effect of pore structure on surface and adsorption properties of those ordered mesoprous CeO2-supported Pt catalysts have been studied by in situ variable temperature diffuse reflectance infrared Fourier transform spectroscopy (VT-DRIFTS) using carbon monoxide (CO) as the probing molecule to study the Pt – COads and carbonate/formate surface species. VT-DRIFT spectra demonstrate that the mesoporous Pt-CeO2 catalyst synthesized from the SBA-15 template shows the largest amount of Pt – COads, indicating that mesoporous Pt-CeO2 synthesized from SBA-15 possesses the largest number of active metal sites, due to its larger pore volume and pore size, compared to the ones synthesized from KIT-6 and COK-19. The VT-DRIFT results of CO adsorption and desorption from ordered mesoporous CeO2-supported Pt catalysts will assist in understanding the surface chemistry of reactions with CO as a reactant, such as water–gas shift reaction; and help design effective mesoporous catalysts for CO reactions, under operando conditions.

Bioresponsive Polyphenol-Based Nanoparticles as Thrombolytic Drug Carriers.

Thrombolytic (clot-busting) therapies with plasminogen activators (PAs) are first-line treatments against acute thrombosis and ischemic stroke. However, limitations such as narrow therapeutic windows, low success rates, and bleeding complications hinder their clinical use. Drug-loaded polyphenol-based nanoparticles (NPs) could address these shortfalls by delivering a more targeted and safer thrombolysis, coupled with advantages such as improved biocompatibility and higher stability in vivo. Herein, a template-mediated polyphenol-based supramolecular assembly strategy is used to prepare nanocarriers of thrombolytic drugs. A thrombin-dependent drug release mechanism is integrated using tannic acid (TA) to cross-link urokinase-type PA (uPA) and a thrombin-cleavable peptide on a sacrificial mesoporous silica template via noncovalent interactions. Following drug loading and template removal, the resulting NPs retain active uPA and demonstrate enhanced plasminogen activation in the presence of thrombin (1.14-fold; p < 0.05). Additionally, they display lower association with macrophage (RAW 264.7) and monocytic (THP-1) cell lines (43 and 7% reduction, respectively), reduced hepatic accumulation, and delayed blood clearance in vivo (90% clearance at 60 min vs 5 min) compared with the template-containing NPs. Our thrombin-responsive, polyphenol-based NPs represent a promising platform for advanced drug delivery applications, with potential to improve thrombolytic therapies.

Charge Storage and Solar Rechargeable Battery Devices Based on Electrodes Electrochemically Modified with Conducting Polymer Nanowires.

In this work, the use of nanostructured conducting polymer deposits on energy-storing devices is described. The cathode and the anode are electrochemically modified with nanowires of polypyrrole and poly(3,4-ethylenedioxythiophene), respectively, prepared after the use of a mesoporous silica template. The effect of aqueous or ionic liquid medium is assayed during battery characterization studies. The nanostructured device greatly surpasses the performance of the bulk configuration in terms of specific capacity, energy, and power. Moreover, compared with devices found in the literature with similar designs, the nanostructured device prepared here shows better battery characteristics, including cyclability. Finally, considering the semi-conducting properties of the components, the device was adapted to the design of a solar-rechargeable device by the inclusion of a titanium oxide layer and cis-bis(isothiocyanate)-bis(2,2′-bipyridyl-4,4′-dicarboxylate) ruthenium (II) dye. The device proved that the nanostructured design is also appropriate for the implementation of solar-rechargeable battery, although its performance still requires further optimization.

Glycerol acetalization over highly ordered mesoporous molybdenum dioxide: Excellent catalytic performance, recyclability and water-tolerance

Highly ordered mesoporous molybdenum dioxide (meso-MoO2) was successfully synthesized by a nano-replication method using a mesoporous silica template with 3D cubic Ia3d mesostructure. Structural analyses using X-ray diffraction, N2 sorption, and electron microscopy indicated that the meso-MoO2 material exhibited high surface area (106 m2/g), large pore volume (0.66 cm3/g), and well-defined mesopores. Under the optimized reaction conditions, the meso-MoO2 catalyst showed excellent catalytic performances for the acetalization of glycerol with acetone (95.8% of glycerol conversion, and 97.8% of solketal selectivity) at 20 °C, due to its high surface area with large number of acid sites. During recycling, the meso-MoO2 catalyst exhibited a slight decrease in activity; and after a simple regeneration at 350 °C, the catalytic performances could be completely recovered. More importantly, a partial hydrophobic treatment of the meso-MoO2 catalyst dramatically enhanced the water-tolerance during the catalytic reaction.

Controlled template removal from nanocast La0.8Sr0.2FeO3 for enhanced CO2 conversion by reverse water gas shift chemical looping

This study addresses an enhanced CO2 conversion of mesoporous La0.8Sr0.2FeO3 (LSF) perovskite synthesized using a nanocasting method in reverse water gas shift chemical looping (RWGS-CL) process. The effects of controlled template removal from the nanocast LSF on its textural property and resulting redox reactivity were thoroughly investigated. LSF was first impregnated on SBA-15 (a mesoporous silica template), which was removed by NaOH etching to monitor the residual Si content. Specific surface area, total pore volume, and metal dispersion of the nanocast LSF were dramatically enhanced as the residual Si content decreased, but Si contents of < 5 wt% caused the mesoporous structure to collapse. Temperature-programmed experiments revealed that both the reactivity and capacity of reducible oxygen were maximized by optimizing residual Si content at 10 wt%. XPS analyses showed that the atomic ratio of surface oxygen to lattice oxygen, a key indicator of CO productivity, was also maximized at a Si content of 10 wt%. The mesoporous LSF with this Si content achieved the highest average CO yield of 2.80 mmol/g for RWGS-CL at 600 °C, which was 5.9 fold-higher than that achieved by bulk LSF.

High-performance asymmetric supercapacitor achieved by CoS2 nanoparticles decorated polyaniline functionalized SBA-15-derived mesoporous nitrogen-doped carbon with rod-like architectures

The promising candidates for high-performance electrode materials, transition metal species@N-doped mesoporous carbon composites (M/MO/M(OH)2@NDMCs), were synthesized by carbonization of metal ion-doped polyaniline (PANI) functionalized mesoporous silica SBA-15, followed by etching the mesoporous silica template. The yielded M/MO/M(OH)2@NDMC can be further converted into sulfide via a simple hydrothermal sulfidization treatment. The mesoporous structure, large amount of the accessible electrochemically active nitrogen species, partially graphitic structure, and transition metal compounds of transition metal species@NDMC composites will increase the electronic and ionic conductivity by reducing the internal and ion diffusion resistances resulting in fast diffusion of ions in the electrolyte to the electrode surface. These endowed them good electrochemical performance characteristics for use in supercapacitor electrodes. Correspondingly, NiO/Ni(OH)2@NDMC, Co/Co(OH)2@NDMC, and CoS2@NDMC as the electrodes in 2 M KOH showed specific capacitance of 337, 589, and 1178 F g–1 at 2.0 A g–1, respectively. Furthermore, the assembled asymmetric supercapacitor device utilizing CoS2@NDMC as a cathode exhibited a satisfactory energy storage capability (50 Wh kg–1 at 750 W kg–1) with an admirable cyclic life (retaining ~99% initial capacitance over 6000 repeated cycles). This finding gives these transition metal species@NDMC composites, especially CoS2@NDMC, prospective applications as high-performance supercapacitor electrode materials, where a fast charge/discharge is required.

Hybrid Inorganic-Organic Visible-Light-Driven Microrobots Based on Donor-Acceptor Organic Polymer for Degradation of Toxic Psychoactive Substances.

Light-driven microrobots based on organic semiconductors have received tremendous attention in the past few years due to their unique properties, such as ease of reactivity tunability, band-gap modulation, and low cost. However, their fabrication with defined morphologies is a very challenging task that results in amorphous microrobots with poor motion efficiencies. Herein, we present hybrid inorganic-organic photoactive microrobots with a tubular shape and based on the combination of a mesoporous silica template with an active polymer containing thiophene and triazine units (named as Tz-Th microrobots). Owing to their well-defined tubular structure, such Tz-Th microrobots showed efficient directional motion under fuel-free conditions. Depending on the accumulation of the polymer coating, these microdevices also exhibited stand-up and rotation motion. As a proof-of-concept, we use these hybrid microrobots for the capture and degradation of toxic psychoactive drugs commonly found in wastewater effluents such as methamphetamine derivatives. We found that the microrobots were able to decompose the drug into small organic fragments after 20 min of visible light irradiation, reaching total intermediates removal after 2 h. Therefore, this approach represents a versatile and low-cost strategy to fabricate structured organic microrobots with efficient directional motion by using inorganic materials as the robot chassis, thereby maintaining the superior photocatalytic performance usually associated with such organic polymers.