Mesoporous Silica Layer Research Articles

Mesoporous Silica Nanosheets with Tunable Pore Lengths Supporting Metal Nanoparticles for Enhanced Hydrogenation Reactions

The channel lengths of mesoporous materials have a crucial impact on the catalytic performances of as-loaded active components. However, it remains a challenge to precisely tune the mesochannel length in a wide range from ≤50 nm to 200 nm. In this paper, we developed a top-down strategy, that is to say, crushing hollow microspheres, for preparing mesoporous silica nanosheets (MSSs) with perpendicular mesochannels and tunable thicknesses. Owing to the heterogeneous growth of the mesoporous silica layer on the surfaces of polystyrene microspheres (hard template), it was achieved to regulate the mesochannel length continuously in the range of 20–200 nm. The obtained materials were characterized by X-ray diffraction (XRD), nitrogen sorption, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The effect of channel lengths on the catalytic activity of metal nanoparticles was then investigated in the selective hydrogenation reaction of nitroarenes. It was found that a short channel not only favored dispersing metal nanoparticles uniformly and then avoiding pore blocking, but also improved the accessibility of metal nanoparticles largely during reactions.

Nanomedicine-Enabled Photonic Thermogaseous Cancer Therapy.

Local photothermal hyperthermia for tumor ablation and specific stimuliresponsive gas therapy feature the merits of remote operation, noninvasive intervention, and in situ tumor‐specific activation in cancer‐therapeutic biomedicine. Inspired by synergistic/sequential therapeutic modality, herein a novel therapeutic modality is reported based on the construction of two‐dimensional (2D) core/shell‐structured Nb2C–MSNs–SNO composite nanosheets for photonic thermogaseous therapy. A phototriggered thermogas‐generating nanoreactor is designed via mesoporous silica layer coating on the surface of Nb2C MXene nanosheets, where the mesopores provide the reservoirs for NO donor (S‐nitrosothiol (RSNO)), and the core of Nb2C produces heat shock upon second near‐infrared biowindow (NIR‐II) laser irradiation. The Nb2C–MSNs–SNO‐enabled photonic thermogaseous therapy undergoes a sequential process of phototriggered heat production from the core of Nb2C and thermotriggered NO generation, together with photoacoustic‐imaging (PAI) guidance and monitoring. The constructed Nb2C–MSNs–SNO nanoreactors exhibit high‐NIR‐induced photothermal effect, intense NIR‐controlled NO release, and desirable PAI performance. Based on these unique theranostic properties of Nb2C–MSNs–SNO nanocomposites, sequential photonic thermogaseous therapy with limited systematic toxicity on efficiently suppressing tumor growth is achieved by PAI‐guided NIR‐controlled NO release as well as heat generation. Such a thermogaseous approach representes a stimuli‐selective strategy for synergistic/sequential cancer treatment.

Coating of Pt-Loaded Mesoporous Silica Layers on Ceramics Scaffolds for Practical Preservation System for Greengrocery.

To enhance the decomposition properties of ethylene, Pt-loaded mesoporous silica (SiO2) was coated onto the scaffolds of cordierite (Mg2Al4Si5O18) membranes (CM) and glass fibers (GF). The surface areas of the mesostructured SiO2 layers coated on CM (CM/meso-SiO2) and GF (GF/meso-SiO2) were, respectively, 118 and 323 times higher than those of the CM and GF. In addition, Pt nanoparticles were homogeneously loaded in the mesopores, which acted as a catalyst. The prepared CM/Pt@meso-SiO2 and GF/Pt@meso-SiO2 showed an efficient and high-performing ethylene decomposition. In particular, the flowers, fruits, and vegetables were well stored with the use of CM/Pt@meso-SiO2 and GF/Pt@meso-SiO2, which effectively decomposed ethylene gas they generated. As a result, Pt@meso-SiO2 with scaffolds (CM and GF) are expected to be effective in commercial application for a practical system of preservation.

Synthesis, characterization, and luminescence properties of BiVO4:Eu3+ embedded Fe3O4@mSiO2 nanoparticles

Magnetic Fe3O4 nanospheres with high dispersion, high saturation magnetization and narrow particle size distribution were synthesized by a CaF2 mediated solvothermal method. Next, a nonporous silica layer and a mesoporous silica (mSiO2) layer were uniformly coated on the surface of the magnetic nanospheres sequentially to form Fe3O4@mSiO2 nanoparticles. It was shown that the pore size and thickness of the mSiO2 shell could be fine-tuned by adjusting the composition of the double-template micelle system consisting of a partially fluorinated short-chain anionic fluorocarbon surfactant and cetyltrimethylammonium bromide. Finally, Eu3+ in the BiVO4 host was embedded on the surface of Fe3O4@mSiO2 nanoparticles with the Pechini sol-gel process, thus to form magnetic fluorescent nanoparticles. It was found that the fluorescence of the inorganic nanoparticles can be further enhanced by the complexation of 2-thenoyltrifluoroaceate (TTA) to the Eu3+ on the surface of the nanoparticles. The as-prepared nanoparticles were well characterized and the preparation process was optimized in order to establish a robust preparation method for the multiple functionalized luminescent nanoparticles.

A composite consisting of sulfo-functionalized magnetic graphene and mesoporous silica for extraction of metformin and glimepiride prior to their determination by liquid chromatography tandem mass spectrometry.

A new sorbent was synthesized for restricted-access matrix solid phase extraction (RAM-SPE) of the diabetes drugs metformin (MET) and glimepiride (Glim). Mesoporous silica layers were placed on Fe3O4-magnetized graphene modified with sulfo-functionalized pore walls (denoted as magG@mSiO2-SO3H composites). The composites have a large specific surface (173m2·g-1), appropriate pore sizes (typically 3.7nm), and sulfo-functionalized pore walls. Magnetic separation can be accomplished within 10s. The unique properties of the composites allow both MET and Glim to be selectively and quickly extracted from plasma sample. Following magnetic separation and elution by 50% aqueous acetonitrile with 4% ammonium solution, the two drugs were quantified by LC-MS/MS analysis. The assay has high selectivity, good linearity (2.5-4000ng•mL-1 for MET and 0.02-1600ng•mL-1 for Glim), a low detection limit (as low as 60pg•mL-1 for MET and 1pg•mL-1 for Glim), excellent recovery (above 92.2%), and good precision (RSDs <12%). The method was successfully applied in a pharmacokinetic study in beagle dogs. Graphical abstract Schematic representation of the synthesis of sulfo-functionalized magnetic graphene/mesoporous silica composites, giving a material of type magG@mSiO2-SO3H. Results showed its great potential as a feasible and alternative adsorbent for the selective extraction of MET and Glim from complicated biological samples.

Hydrogel-Encapsulated Mesoporous Silica-Coated Gold Nanoshells for Smart Drug Delivery.

A “smart” core@shell composite nanoparticle (NP) having dual-response mechanisms (i.e., temperature and light) was synthesized, and its efficacy in the loading and release of small molecules was explored. These core@shell NPs are composed of an optically active gold nanoshell (GNS) core and a mesoporous (m-) silica layer (m-SiO2). The GNS@m-SiO2 nanoparticles are further encapsulated within a thermo-responsive poly(N-isopropylacrylamide-co-acrylic acid) hydrogel (PNIPAM-co-AA). The multi-responsive composite NPs were designed to create thermally and optically modulated drug-delivery vehicles with a m-SiO2 layer providing additional non-collapsible space for drug storage. The influence of the m-SiO2 layer on the efficacy of loading and release of methylene blue, which serves as a model for a small-molecule therapeutic drug, was evaluated. The “smart” core@shell composite NPs having a m-SiO2 layer demonstrated an improved capacity to load and release small molecules compared to the corresponding NPs with no m-SiO2 shell. Additionally, an efficient response by the composite NPs was successfully induced by the thermal energy generated from the gold nanoshell core upon exposure to near infrared (NIR) stimulation.

Functionalization of the magnetite nanoparticles with polysilsesquioxane-bearing N- and S-complexing groups to create solid-phase adsorbents

Sol–gel method based on the reaction of hydrolytic co-polycondensation of alkoxysilanes was applied to obtain composites of magnetite and silica with amino and mercapto functional groups of core–shell structure. Magnetite core ensures easy removal of materials from solutions in a quick and effective way with a help of a magnet. Using 1,2-bis(triethoxysilyl)ethane as a structure-forming agent (instead of traditional tetraethoxysilane) allowed synthesis of mesoporous samples with well-developed porous structure (specific surface area values of 400–800 m2/g). In combination with high content of available functional groups, introduced to the process of one-pot synthesis using 3-aminopropyltriethoxysilane and 3-mercaptopropyltriethoxysilane as functionalyzing agents, it endowed the synthesized composites with high sorption capacities to silver(I), copper(II), and lead(II) ions. Meanwhile, the affinity to the molecules of dyes (Acid Red 88 and Methylene Blue) was shown to be in direct correlation with the composites’ surface charges and uptake can reach 118 mg/g and 88 mg/g, respectively. These results indicate the possibility of magnetite nanoparticles’ one-step functionalization with mesoporous silica layers and simultaneous introduction of different functional groups. Such properties make them very attractive for application in adsorption technologies as effective adsorbents of metal ions as well as organic pollutants.

Guar gum modified upconversion nanocomposites for colorectal cancer treatment through enzyme-responsive drug release and NIR-triggered photodynamic therapy

Multimodal therapeutic approach towards colorectal cancer (CRC) holds great promise. There is, however, no convincing strategy reported to date that employs a multimodal strategy in CRC treatment. The present study reports an intense green-emitting core–shell photoluminescent upconversion (CSGU) nanocrystal engineered to synergistically perform photodynamic and enzyme-triggered delivery of the chemotherapeutic agent for an enhanced therapeutic outcome on HT-29 colon carcinoma cells in vitro. The photodynamic activity is achieved by the energy transfer between CSGU and the chemically conjugated Rose Bengal (RB) molecules that are further protected by a mesoporous silica (MS) layer. The chemical assay demonstrates a remarkable FRET mediated generation of 1O2 under NIR (980 nm) excitation. The outermost MS layer of the nanoplatform is utilized for the loading of the 5FU anticancer drug, which is further capped with a guar gum (GG) polysaccharide polymer. The release of the 5FU is specifically triggered by the degradation of the GG cap by specific enzymes secreted from colonic microflora, which otherwise showed ‘zero-release behavior’ in the absence of any enzymatic trigger in various simulated gastro-intestinal (GI) conditions. Furthermore, the enhanced therapeutic efficacy of the nanoplatform (CSGUR-MSGG/5FU) was evaluated through in vitro studies using HT-29 CRC cell lines by various biochemical and microscopic assays by the simultaneous triggering effect of colonic enzyme and 980 nm laser excitation. In addition, the strong visible emission from the nanoplatform has been utilized for NIR-induced cellular bioimaging.

Influence of embedded inhibitors on the corrosion resistance of zinc coated with mesoporous silica layers

The aim of this work was to prepare and investigate the corrosion behavior of mesoporous silica layers hosting inhibitor molecules (1H-benzotriazole, BTA and cetyltrimethylammonium bromide, CTAB), which were impregnated into the porous coatings from their aqueous solutions. The mesoporous silica layers were prepared by sol–gel dip-coating method on zinc and (for comparison) on glass substrates using two different pore-forming agents (CTAB and Pluronic PE 10,300). The permeability of one (mono-) and two (bi-) deposited layers was studied by measuring the refractive indices of impregnated samples using optical spectroscopy method. Coatings showed significant permeability to CTAB molecules regardless of the template used. Surface morphology of the samples on zinc substrates was investigated by scanning electron microscopy. The pore structure of the coatings developed with two different surfactants was studied by high resolution transmission electron microscopy. In some cases, the inhibitors were trapped in the impregnated samples by hydrophobizing the layers with dimethyldichlorosilane. Wettability of the silylated coatings was investigated by the sessile drop method. For water and an aqueous solution of Na2SO4 were obtained contact angles above 90°, which confirm the hydrophobic character of the samples. The corrosion behavior of the samples was monitored by electrochemical methods. It was found that the inhibitor containing coatings show higher corrosion inhibiting effect than the native porous silica layers. Moreover, the corrosion current densities decrease by one order of magnitude by rendering the surfaces of the inhibitor containing samples hydrophobic. Interestingly, BTA did not significantly accumulate in the pores, but its presence in the coatings caused increased protection against corrosion.

Chromatographic study of the structural properties of mesoporous silica layers deposited on radially elongated pillars

We report on the ability to change the layer properties of porous layered radially elongated pillar (PLREP) array columns and its relevance to the separation efficiency. The adjustment of the preparation condition resulted in the formation of a 1.2-fold thicker layer than the layer produced in the preceding study. The mesoporosity of the layer was controlled by changing the hydrothermal treatment temperature from 105 °C to 80 °C. Chromatographic characterization was performed on a commercial nano-LC system using the octadecylsilylated PLREP columns having the aforementioned characteristics, i.e. (1) different layer thickness (df = 180–220 nm) and (2) different mesoporosity (dp = 7.6–11.2 nm, Pore volume (Vp) = 0.733‒0.838 cc/g and Surface area (SA) = 364‒611 m2/g). For isocratic separations of an alkylphenone mixture, the change in both the layer thickness and the mesoporosity caused no significant difference in the column efficiency, while the thicker layer and the reduction of mesopore size resulted in a 1.3-fold increase and a 1.4-fold increase in the retention capacity, respectively. Based on the result of the examination using scanning electron microscopy and argon physisorption technique, the formar enhancement was in agreement with the increase in the layer thickness, and the latter one was attributed to the larger surface area. When applying a column with 16.5 cm long to gradient separations, the combination of the thicker layer and the smaller mesopores provided the peak capacity of 365 for the alkylphenone mixture at a 180 min gradient, while the combination of the thinner layer and the larger mesopores provided the peak capacity of 315. For peptide separations, it appeared that the thicker layer was still favorable, however, the lager mesopores were more advantageous for MWs of larger than 1000, providing a conditional peak capacity of 245 for a commercially available peptide mixture because of less content of small pores which hinder the diffusion of large molecules in pores in the layer.

Synthesis and photocatalytic performance of recyclable core-shell mesoporous Fe3O4@Bi2WO6 nanoparticles

Composite photocatalysts composed of semiconductor and magnetic matters are of great concern due to their excellent catalytic and recyclable performances. In this work, Fe3O4 nanoparticles are modified by a fibrous mesoporous silica layer (F-SiO2), on which a mesoporous Bi2WO6 shell is grown in situ through hydrothermal reaction. Along with the formation of Bi2WO6 shell, the F-SiO2 layer fades away by the acid etching. As a result, novel spherical core-shell mesoporous Fe3O4@Bi2WO6 nanoparticles with a high BET surface area of 127.3 m2/g are fabricated. The photocatalytic decomposition of methylene blue (MB) under visible light irradiation reveals that the mesoporous Fe3O4@Bi2WO6 nanoparticles show excellent physisorption and photocatalytic performances. The total removal ratio of MB can be achieved as high as 98%. Furthermore, the mesoporous Fe3O4@Bi2WO6 nanoparticles maintain high photocatalytic activity after five cycles. This work provides a new way to construct recyclable mesoporous Bi2WO6-based nanomaterials with high performance to remove organic pollutants.

Hypoxia-Irrelevant Photonic Thermodynamic Cancer Nanomedicine.

The hypoxic tumor microenvironment severely lowers the therapeutic efficacy of oxygen-dependent anticancer modalities because tumor hypoxia hinders the generation of toxic reactive oxygen species. Here we report a thermodynamic cancer-therapeutic modality that employs oxygen-irrelevant free radicals generated from thermo-labile initiators for inducing cancer cell death. A free radical nanogenerator was engineered via direct growth of mesoporous silica layer onto the surface of two-dimensional Nb2C MXene nanosheets toward multifunctionality, where the mesopore provided the reservoirs for initiators and the MXene core acted as the photonic-thermal trigger at the near-infrared-II biowindow (NIR-II). Upon illumination by a 1064 nm NIR-II laser, the photothermal-conversion effect of Nb2C MXene induced the fast release and quick decomposition of the encapsulated initiators (AIPH) to produce free radicals, which promoted cancer cell apoptosis in both normoxic and hypoxic microenvironment. Systematic in vitro and in vivo evaluations have demonstrated the synergistic-therapeutic outcome of this intriguing photonic nanoplatform-enabled thermodynamic cancer therapy for completely eradicating the 4T1 tumors without recurrence by NIR-II laser irradiation. This work pioneers the thermodynamic therapy for oxygen-independent cancer treatment by photonic triggering at the NIR-II biowindow.

Sensing of airborne molecular contaminants based on microfiber coupler with mesoporous silica coating

Airborne molecular contaminants (AMCs) are critical issues for the performance of optics in high power lasers (HPLs). In this work we demonstrate an AMCs sensor based on an optical microfiber coupler (OMC) with mesoporous silica coating experimentally. AMCs adhered on the mesoporous silica coating modifies the surrounding refractive index (RI). Using Beam Propagation Method (BPM), the proposed structure was analyzed to demonstrate the feasibility of AMCs sensing. By coating a mesoporous silica layer on the surface of sensing area, the proposed structure was able to operate as an AMCs sensor. By monitoring the spectral shift in the wavelength domain, the sensor was shown to be capable of detecting concentration of AMCs. The experimental results show that the sensitivity of the sensor is concentration-dependent. The maximum sensitivity of 0.541nm/(mg/m3) is achieved. The detected signal is found to be proportional to AMCs present.

Smart Hydrophilic Modification of Magnetic Mesoporous Silica with Zwitterionic l-Cysteine for Endogenous Glycopeptides Recognition

There are still few reports about endogenous glycosylated peptides although the significance of the study of them has been confirmed since they may provide higher sensitivity and specificity in clinical practice. In this work, magnetic mesoporous silica microspheres were endowed with strong hydrophilicity by a simple and smart modification way to l-cysteine, which was attributed to the bond formation of Fe–S. The microsphere (denoted as l-Cys-Fe3O4@mSiO2) was composed of Fe3O4 core, mesoporous silica layer, and innumerable perpendicularly aligned mesopores, as well as abundant l-cysteine in the mesopores. Thanks to the excellent hydrophilicity of l-cysteine probe, the l-Cys-Fe3O4@mSiO2 microspheres showed strong recognition ability toward glycopeptides. Owing to the superparamagnetic cores well encapsulated in microspheres, the whole process is quite time-saving by magnetic separation. Also, due to the appropriate pore size of the l-Cys-Fe3O4@mSiO2 microspheres, the extraction method exhibited good size-e...

Mesoporous Silica-gold Films for Straightforward, Highly Reproducible Monitoring of Mercury Traces in Water.

Trace-level detection of mercury in waters is connected with several complications including complex multistep analysis routines, applying additional, harmful reagents increasing the risk of contamination, and the need for expensive analysis equipment. Here, we present a straightforward reagent-free approach for mercury trace determination using a novel thin film sampling stick for passive sampling based on gold nanoparticles. The nanoparticles supported on a silicon wafer and further covered with a thin layer of mesoporous silica. The mesoporous silica layer is acting as a protection layer preventing gold desorption upon exposure to water. The gold nanoparticles are created by thermal treatment of a homogenous gold layer on silicon wafer prepared by vacuum evaporation. This gold-covered substrate is subsequently covered by a layer of mesoporous silica through dip-coating. Dissolved mercury ions are extracted from a water sample, e.g., river water, by incorporation into the gold matrix in a diffusion-controlled manner. Thus, the amount of mercury accumulated during sampling depends on the mercury concentration of the water sample, the accumulation time, as well as the size of the substrate. Therefore, the experimental conditions can be chosen to fit any given mercury concentration level without loss of sensitivity. Determination of the mercury amount collected on the stick is performed after thermal desorption of mercury in the gas phase using atomic fluorescence spectrometry. Furthermore, the substrates can be re-used several tens of times without any loss of performance, and the batch-to-batch variations are minimal. Therefore, the nanogold-mesoporous silica sampling substrates allow for highly sensitive, simple, and reagent-free determination of mercury trace concentrations in waters, which should also be applicable for on-site analysis. Successful validation of the method was shown by measurement of mercury concentration in the certified reference material ORMS-5, a river water.

Synthesis of high-quality carbon nanotubes by using monodisperse spherical mesoporous silica encapsulating iron oxide nanoparticles

Well-graphitized carbon nanotubes (CNTs) were grown by using monodisperse spherical mesoporous silica encapsulating single iron oxide (Fe3O4) nanoparticles (MSEINPs) as catalytic templates by chemical vapor deposition (CVD) and using acetylene as carbon source. The catalytic templates were synthesized by a sol-gel method. The MSEINPs exhibited better activity and selectivity in CNT synthesis than bare Fe3O4 catalysts. The synthesized multiwall carbon nanotubes (MWCNTs) were analyzed by powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Raman spectroscopy. The carbon deposits are rich in MWCNTs, as confirmed by FESEM and TGA. The wall thickness of the MWCNTs is controlled primarily by the size of the spherical mesoporous silica layer encapsulating the Fe3O4 NPs, while the inner diameter of the CNTs is determined by the size of the Fe3O4 NPs at the center of the MSEINPs. The average diameter of the MWCNTs increased significantly with increases in the growth temperature and acetylene flow rate. The analytical results show that the CNTs prepared on MSEINPs are well graphitized with a narrow size distribution in thickness, and straight and longer tubes are obtained without major defects as compared to the CNTs grown on bare Fe3O4 NPs.

Mesoporous silica modified luminescent Gd2O3:Eu nanoparticles: physicochemical and luminescence properties

Highly colloidal Gd2O3:Eu nanoparticles (core-NPs) were synthesized by thermal decomposition via weak base at low temperature. The sol–gel chemical process was employed for silica layer surface coating to increase solubility, colloidal stability, biocompatibility, and non-toxicity at the ambient conditions. XRD results indicate the highly purified, crystalline, single phase, and cubic phase Gd2O3 nanocrystals. TEM image shows that the mesoporous thick silica layer was effectively coated on the core nanocrystals, which have irregular size with nearly spherical shape and grain size about 10–30 nm. An absorption spectra and zeta potential results in aqueous media revealed that solubility, colloidal stability, and biocompatibility character were enhanced from core to core–shell structure because of silica layer surface encapsulation. The samples, demonstrated excellent photoluminescence properties (dominant emission 5D0 → 7F2 transition in the red region at 610 nm), indicated to be used in optical bio-detection, bio-labeling, etc. The photoluminescence intensity of the silica shell modified core/shell NPs was suppressed relatively core-NPs; it indicates the multi-photon relaxation pathways arising from the surface coated high vibrational energy molecules of the silanol groups. The core/nSiO2/mSiO2 nanocrystals display strong emission (5D0 → 7F2) transition along with excellent solubility and biocompatibility, which may find promising applications in the photonic based biomedical field.

Mesoporous multi-silica layer-coated Y2O3:Eu core-shell nanoparticles: Synthesis, luminescent properties and cytotoxicity evaluation

Mesoporous multi-layered silica-coated luminescent Y2O3:Eu nanoparticles (NPs) were prepared by a urea-based decomposition process, and their surfaces were gradually modified with nanoporous and mesoporous silica layers using modified sol-gel methods. The synthesized luminescent core-shell NPs were characterized thoroughly to investigate their structural, morphological, thermal, optical, photo luminescent properties and their surface chemistry. The morphology of the core NPs were nearly spherical in shape and were nano-sized grains. The observed luminescent efficiency of the mesoporous multi-layered silica-coated luminescent core NPs was gradually reduced because of bond formation between the Y2O3:Eu core and the amorphous silica shell via YOSiOH bridges on the surface of the NPs; the bonds suppressed the non-radiative transition pathways. Biocompatibility tests on Human breast cancer cells using the 3‑(4,5‑Dimethylthiazol‑2‑yl)‑2,5‑diphenyltetrazolium bromide and lactate dehydrogenase assays indicated that the core-shell NPs were non-toxic even at high concentrations. The mesoporous SiO2 layer played a key role in perfecting the solubility, biocompatibility, and non-toxicity of the NPs. The zeta potential, surface chemistry (Fourier transform infrared spectroscopy), and optical absorption spectral analyses revealed the high hydrophilicity of the as-prepared core-shell NPs because of the active surface-functionalized silanol (SiOH) groups, which could potentially offer many exciting opportunities in photonic-based biomedical applications.

Vertically aligned porous silica thin films functionalized by nickel chloride incorporated in walls

Abstract The article concerns a novel functional material in the form of thin film: vertically aligned mesoporous silica layer precisely functionalized by nickel chloride molecules. The functional units are placed exclusively inside silica walls, where they are chelated by cyclam (1,4,8,11-tetraazacyclotetradecane) molecules. The synthesis routes, based on a self-assembly approach, resulted in materials with the assumed molecular structure. The microscopic studies of the silica matrices structure confirmed that tetrasilylated cyclam did not perturb the formation of porous silica films. Vibrational spectroscopy showed incorporation of the cyclam inside silica structure. In turn, the EPR spectroscopy confirmed, that nickel dichloride was chelated by cyclam molecules, which resulted in a homogeneous distribution of functional nickel-containing groups.

Research on design, fabrication, and properties of Fe2O3@SiO2/CDs/PEG@nSiO2 nanocomposites

Multimodal imaging, which can combine information from different imaging modalities, offers huge advantages. Among various multifunctional images, magnetic resonance imaging (MRI) combination with fluorescence imaging has attracted considerable attention for their potential biomedical applications. In this study, we present a facile method for fabrication of core-shell-structured nanocomposite particles. First, Fe2O3 nanoparticles were synthesized as the magnetic core. Then, the Fe2O3 nanoparticles were covered with a silica shell. Carbon dots and PEG could be absorbed into the mesoporous silica layer and then sealed by a dense silica layer (denoted as Fe2O3@SiO2/CDs/PEG@nSiO2). The results show that the as-prepared nanocomposite has a uniform size, strong magnetization and good fluorescence properties, which has application as a bioimaging probe.