Silica Template Research Articles

Surface imprinted upconversion nanoparticles for selective albumin recognition

Upconversion nanoparticles (UCNPs) have attracted researchers’ attention because these particles transform two or more low-energy infrared (IR) photons into high-energy visible photons via a sequential absorption process. The molecular imprinting method, one of the biomimicking approaches, has remarkable advantages for creating synthetic receptors for molecules of interest. In this study, we have focused our attention on developing novel selective materials simultaneously having upconversion and biorecognition abilities to form a supramolecular complex. We proposed a new approach to synthesize silica-based UCNPs via surface imprinting of albumin that was chosen as a model biomolecule. In the first step, synthesis of surface imprinted upconversion silica nanoparticles and template removal processes were performed. FTIR, SEM, fluorimetry / UV-Vis spectrophotometry, zeta-size / potential measurements and BET (surface area measurements) were performed for the characterization. Biorecognition conditions were optimized and the optimum BSA recognition conditions were determined as BSA initial concentration, interaction time, pH, and temperature as 0.5 mg/mL, 15 min, 4.5, and 25 oC, respectively. The relative selectivity coefficients, designating the selectivity gained by the imprinting process for BSA/hemoglobin, BSA/ovalbumin, and BSA/γ-globulin pairs were calculated as 4.69, 38.37, and 9.66, respectively. In the second step, the synthesis of the magnetic nanoparticles and antibody immobilization onto these particles were investigated. At the final step, sandwich-like supramolecular complex with magnetic nanoparticles (MNPs) and upconversion silica nanoparticles (UC-SiNPs) were done and characterized with UV-Vis spectroscopy, fluorescent spectrometry, and zeta size and potential measurements. In a conclusion, developed molecular imprinted upconversion supramolecular complex will be an alternative and intriguing approach where sandwich-like recognition, detection, and selective adsorption properties are simultaneously required.

Dual-template strategy synthesis of hierarchically porous electrocatalysts for oxygen reduction reaction

Metal organic frameworks derived M-N-C catalysts have been discovered as promising alternatives to Pt-based catalysts in oxygen reduction reaction (ORR). However, the dominated micropores in their porous structures strongly restrain the mass transfer and lead to insufficient utilization of active sites. Here, we proposed a dual-template strategy to improve the catalytic performance of ZIF-8 derived M-N-C catalysts. Both the silica and sodium chloride templates created mesopores, which may intensified the mass transfer. Moreover, the molten sodium chloride connected the individual ZIF-8 crystals form highly graphitized carbon structure which had better stability and conductivity. The as-synthesized (FeCo)HPNC@NaCl catalyst exhibited similar ORR activity to commercial Pt/C under acidic conditions with half-wave potential of 0.808 V. The catalyst expressed high stability with 12 mV decrease of half-wave potential after 5000 cycles and 80% remained activity after 100000 s operation. Moreover, we tested the catalyst in fuel cell for practical application, achieving a high peak power density of 427 mW cm−2.

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.

Preparation of Biocompatible Poly(2-(methacryloyloxy)ethyl phosphorylcholine) Hollow Particles Using Silica Particles as a Template.

Hydrophilic poly(2-(methacryloyloxy)ethyl phosphorylcholine) (PMPC) shows biocompatibility because the pendant phosphorylcholine group has the same chemical structure as the hydrophilic part of phospholipids that form cell membranes. Hollow particles can be used in various fields, such as a carrier in drug delivery systems because they can encapsulate hydrophilic drugs. In this study, vinyl group-decorated silica particles with a radius of 150 nm were covered with cross-linked PMPC based on the graft-through method. The radius of PMPC-coated silica particles increased compared to that of the original silica particles. The PMPC-coated silica particles were immersed in a hydrogen fluoride aqueous solution to remove template silica particles to prepare the hollow particles. The PMPC hollow particles were characterized by dynamic light scattering, infrared spectroscopy, thermogravimetric analysis, and transmission electron microscopy observations. The thickness of the hollow particle shell can be controlled by the polymerization solvent quality. When a poor solvent for PMPC was used for the polymerization, PMPC hollow particles with thick shells can be obtained. The PMPC hollow particles can encapsulate hydrophilic guest molecules by immersing the hollow particles in a high-concentration guest molecule solution. The biocompatible PMPC hollow particles can be used in a drug carrier.

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.

Hydrogen-rich syngas production by the three-dimensional structure of LaNiO3 catalyst from a blend of acetic acid and acetone as a bio-oil model compound

Converting biomass bio-oil to hydrogen is valuable strategy. In this study, a blend of acetic acid and acetone has been utilized as a bio-oil model compound, where perovskite in a three-dimensional structure (3D-LaNiO 3 ) synthesized by a silica template method used as a catalyst. The result shows that the main phase of perovskite at 3D-LaNiO 3 catalyst has lower crystal size, resulting in decrease possibility of agglomeration. The amount of oxygen vacancies and higher ratio of Ni 3+ /Ni 2+ are produced, enhancing the redox of catalyst. The stronger basic site and lager surface indicated the ability of improving coke deposition resistance. These results explained great activity of 3D-LaNiO 3 catalyst in producing hydrogen-rich syngas. The different steam/carbon mole ratios (S/C) have been discussed at 1 to 4, and the gas yield of H 2 (93.5%) shows highest at 600 °C and S/C = 3. Meanwhile, under this condition, the H 2 gas yield was stable and over 90% throughout 15 h of reaction. By analysis of spent 3D-LaNiO 3 catalyst, the result indicated that it has ability to resist the production of graphite coke deposition which is one of reasons for keeping catalyst activity. On the other hand, the stable of perovskite structure help in produce lattice oxygen for oxidizing coke deposited. • Acetic acid and acetone as a bio-oil model compound has been used for H 2 production. • Three-structure of LaNiO 3 has been used as a catalyst and compared with LaNiO 3 . • Three-structure of LaNiO 3 catalyst showed better catalytic performance. • The key factors of the high catalytic activity are oxygen vacancies, crystal size, coke deposition resistance. • Over 90% H 2 yield achieved with three structure -LaNiO 3 catalyst throughout 15 h.

Flower‐like Mesoporous Carbon with Cobalt Sulfide Nanocrystalline as Efficient Bifunctional Electrocatalysts for Zn‐Air Batteries

AbstractTransition‐metal sulfides have gained considerable attention for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in rechargeable Zn‐air batteries owing to their natural abundance, chemical stability, and efficient activity. Here, cobalt sulfide nanocrystalline supported on the 3D hierarchically flower‐like porous nanocarbon (mC‐CoSx‐50) electrocatalysts have been synthesized through a combination of metal‐organic complexation and porous silica templates for efficient bifunctional oxygen catalysis. With the high specific surface area, high nitrogen content and heteroatom doping, the as‐synthesized mC‐CoSx‐50 exhibits an excellent bifunctional oxygen catalytic performance. Remarkably, the rechargeable Zn‐air batteries assembled with the cobalt sulfide‐based hierarchically porous electrocatalysts reveal a high peak power density and excellent cycling stability in comparison with Pt/C+RuO2 owing to the synergistic effects between cobalt sulfide nanocrystallines and hierarchically porous carbon. We envision that this work not only offers high‐performance metal sulfide for future clean energy conversion but also provides a facial strategy for constructing hierarchically porous carbon‐supported catalyst.

Graphene anchored mesoporous MnO2 nanostructures as stable and high-performance anode materials for Li-ion batteries

Among various transition metal oxides, MnO2 is a promising anode material for Li-ion battery applications due to its lower discharge potential, good capacity and high abundance. However, poor electronic conductivity hampers its practical applications. Herein we report two unique mesoporous MnO2–graphene composites, M1-MnO2-G and M8-MnO2-G, where M1 and M8 represent the use of specific silica template, MCM-41 and MCM-48 respectively in deriving these phases. Our results show that as anode materials for Li-ion battery application, both the composites exhibit good cycling stability, high discharge capacity, and superior rate performance. For instance, M1-MnO2-G and M8-MnO2-G deliver stable discharge capacity of 1112 mA h g−1 and 1494 mA h g−1 at C/5 rate. The high specific capacities and superior rate performance of the composites are due to the synergistic effects of graphene integrated mesoporous MnO2. The mesoporous architecture with nano-size wall thickness provides shorter diffusion paths for Li+ ion conduction in addition to facilitating uniform electrolyte infiltration throughout the electrode, while the graphene enhances the electronic conductivity and mechanical strength of the composite electrode. Full cell studies using mesoporous MnO2-Graphene composites anode against LiNi0.8Mn0.1Co0.1O2 cathode (M8-MnO2-G║LiNMC811) indicate very stable capacity (200 cycles at 0.1C) and high rate (5C) performance.

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.

Varied Morphological Study of Albite Nanomaterials at Low Temperature with Co-effect of Single Walled Nanotubes and Graphene Oxide for Kevlar Fabric Strength

A comprehensive study of synthesizing zeolite nanoparticles, with the addition of organic template, by reflux method has been chalked out to form crystals. The method is effectivly for the synthesis of zeolite nanocrystals, incorporating alkali metals, silica and organic template. The organic templates tetra-propyl ammonium hydroxide (TPAOH), tetra-propyl ammonium bromide (TPABr) or (TPABr, N,N,N-tripropyl-1-propanaminiumbromide), tetraethyl orthosilicate (TEOS) were added to assist the formation of zeolite (Albite) crystals. A cross linker tetraethyl orthosilicate (TEOS) was also mixed. Addition of carbon nanotubes (CNTs) and graphene oxide (GO) resulted into a unique nano morphology of Albite (when the time of reaction was less than 240 h). Effect of additives on morphology, particle size, crystal geometry, surface area, and particle shapes was characterized with FT-IR, X-ray diffraction, BET, EDX and SEM. For the practical point of view, Kevlar supported polymer membrane with the Zeolite as catalyst is used. Results show that polymeric supported fabric and catalyst supported fabric have same result with response to mechanical testing. This suggest that the Kevlar supported polymer membrane has potential application in industrial cables, asbestos replacement brake lining, under water applications, tyres, and body armors.

Polyaniline nanowire arrays generated through oriented mesoporous silica films: effect of pore size and spectroelectrochemical response.

Indium-tin oxide electrodes modified with vertically aligned silica nanochannel membranes have been produced by electrochemically assisted self-assembly of cationic surfactants (cetyl- or octadecyl-trimethylammonium bromide) and concomitant polycondensation of the silica precursors (tetraethoxysilane). They exhibited pore diameters in the 2-3 nm range depending on the surfactant used. After surfactant removal, the bottom of mesopores was derivatized with aminophenyl groups via electrografting (i.e., electrochemical reduction of in situ generated aminophenyl monodiazonium salt). These species covalently bonded to the ITO substrate were then exploited to grow polyaniline nanofilaments by electropolymerization of aniline through the nanochannels. Under potentiostatic conditions, the length of polyaniline wires is controllable by tuning the electropolymerization time. From cyclic voltammetry characterization performed either before or after dissolution of the silica template, it appeared that both the polyaniline/silica composite and the free polyaniline nanowire arrays were electroactive, yet with much larger peak currents in the latter case as a result of larger effective surface area offered to the electrolyte solution. At identical electropolymerization time, the amount of deposited polyaniline was larger when using the silica membrane with larger pore diameter. All polyaniline deposits exhibited electrochromic properties. However, the spectroelectrochemical data indicated more complete interconversion between the coloured oxidized form and colourless reduced polyaniline for the arrays of nanofilaments in comparison to bulky films. In addition, the template-free nanowire arrays (i.e., after silica dissolution) were characterized by faster electrochromic behaviour than the polyaniline/silica hybrid, confirming the potential interest of such polyaniline nano-brushes for practical applications.

Reinforcement of ultrahigh thermoresistant polybenzimidazole films by hard craters

Ultrahigh thermoresistant polybenzimidazole films with uniform pores and hard craters on the surface were prepared by a silica template method. The pore and crater formation enhanced elongation and Young's modulus.

Assessing the Electrochemical Performance of Different Nanostructured CeO2 Samples as Anodes for Lithium-Ion Batteries

In this work, six samples of CeO2 are successfully prepared by diverse synthesis routes leading to different microstructures regarding both morphology and particle size. The structural and microstructural characteristics presented by the samples and their influence on the electrochemical response of the prepared anodes are analyzed. In particular, the Ce-CMK3 sample, synthesized from a mesoporous carbon obtained through a CMK3 silica template, displays an enhanced electrochemical response. Thus, capacity values of ~220 mA h g−1 are obtained at a current rate of 0.155 A g−1 after 50 cycles and an excellent cyclability at intermediate current densities. On the other hand, it is observed that the capacity values are satisfactorily recovered at 0.31 A g−1, displaying ~100 mA h g−1 after 550 cycles and efficiencies close to 100%. The electrochemical performance is interpreted considering the microstructural peculiarities of this anode, which are deeply analyzed.

Synthesis of double-layered hollow carbon spheres with large interlayer space as sulfur hosts for Li-S batteries

Double-layered hollow carbon spheres (DLHC) were widely used as sulfur matrix for Li-S batteries. However, DLHC with 20–30 nm interlayer distances between carbon shells were reported due to the difficult controllable synthesis of monodisperse silica template (<200 nm) in the Stöber method, leading to low sulfur utilization. Here, DLHC with the interlayer space up to 50 nm (DLHC-50) is synthesized by controlling hydrolysis rate of tetraethyl orthosilicate (TEOS) using ammonia/LiOH as catalysts. DLHC-50 based sulfur cathode contains high sulfur content of 82%, and exhibits excellent cycling and rate performances. This research provides guidance for synthesis of DLHC with high sulfur utilization.

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.

A single step solid NH4F-assisted method for the removal of hard silica template to obtain microporous carbon for electrochemical applications

A new method for removing silica templates to prepare high surface area porous carbons is reported. In this method solid NH4F is used as a sacrificial agent to remove silica as SiF4 in a single step process, thus eliminating the corrosive methods by using HF/NaOH in multi-step processes. This method is versatile to enhance the surface area and porous-network of carbons at higher calcination temperatures. The carbon sample prepared at 900 °C exhibits high surface area (861 m2 g−1) among others and shows specific capacitance of 240 F g−1 at current density 0.5 A g−1.

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.