Magnetic Mesoporous Silica Nanocomposites Research Articles

Design of thermosensitive polymer‐coated magnetic mesoporous silica nanocomposites with a core‐shell‐shell structure as a magnetic/temperature dual‐responsive drug delivery vehicle

AbstractA stimuli‐responsive nanocomposite with a core‐shell‐shell structure consisting of iron oxide (Fe3O4) nanoparticles as core, mesoporous silica as middle shell, and poly(N‐isopropyl acrylamide‐co‐acrylic acid) (P[NIPAAm‐co‐AAc]) as an exterior shell with thermo‐responsivity properties was synthesized to be used as a magnetic/temperature responsive drug delivery system. The structure, morphology, and size of P(NIPAAm‐co‐AAc)‐coated mesoporous silica embedded magnetite nanoparticles (P(NIPAAm‐co‐AAc)@mSiO2@Fe3O4) were characterized by XRD, FTIR, and TEM analyses. Also, the heating ability of mesoporous silica‐coated Fe3O4 nanoparticles, and P(NIPAAm‐co‐AAc)@mSiO2@Fe3O4 nanocomposites was investigated under the exposure of an alternating magnetic field (AMF). The results indicated that the prepared nanocomposites could generate enough heat for hyperthermia applications. Moreover, the magnetic/temperature‐responsive drug release behavior of P(NIPAAm‐co‐AAc)@mSiO2@Fe3O4 nanocomposites loaded with fluorouracil (5‐FU) was studied under the exposure of the AMF (frequency = 120 kHz, and amplitude = 22 kA m−1), as well as two different temperatures (37°C and 45°C). The results showed that only 7.8% of the drug could be released after 20 h at 37°C (below the LCST of the copolymer). In contrast, by increasing the temperature of release medium up to 45°C (above the LCST of the copolymer), the amount of released drug was increased up to 47%. Moreover, by exposing the prepared nanocomposite to a safe AMF, a burst release of drug was observed, indicating the excellent responsivity of the carrier to an external magnetic field. These results proved that the obtained nanocomposite has a great performance to be used as a magnetic/temperature‐sensitive drug carrier for advanced drug delivery applications.

Interfacially Super‐Assembled Asymmetric and H2O2 Sensitive Multilayer‐Sandwich Magnetic Mesoporous Silica Nanomotors for Detecting and Removing Heavy Metal Ions

AbstractAsymmetric hollow and magnetic mesoporous silica nanocomposites have great potential applications due to their unique structural–functional properties. Here, asymmetric multilayer‐sandwich magnetic mesoporous silica nanobottles (MMSNBs) are presented through an interfacial super‐assembly strategy. Asymmetric hollow silica nanobottles (SNBs) are first prepared, and Fe3O4 nanoparticles monolayers and mesoporous silica layers are uniformly super‐assembled on the surfaces of SNBs, respectively. The high Fe3O4 nanoparticles loading endows MMSNBs with a high magnetization (8.5 emu g−1), while the mesoporous silica layers exhibit high surface area (613.4 m2 g−1) and large pore size (3.6 nm). MMSNBs can be employed as a novel type of enzyme‐powered nanomotors by integrating catalase (Cat‐MMSNBs), which show an average speed of 7.59 µm s−1 (≈25 body lengths s−1) at 1.5 wt% H2O2. Accordingly, the water quality can be monitored by evaluating the movement speed of Cat‐MMSNBs. Moreover, MMSNBs act as a good adsorbent for removing more than 90% of the heavy metal ions with the advantage of the mesoporous structure. In addition, the good magnetic response enables the MMSNBs with precise directional control and is conducive to recycling for repeated operation. This bottom‐up interfacial super‐assembly construction strategy allows for a new understanding of the rational design and synthesis of multi‐functional nanomotors.

Magnetic mesoporous silica nanostructures: investigation of magnetic properties

Magnetic mesoporous silica (MS) nanocomposites provide the possibility of generating multi-functional objects for application in different technological areas. This paper focuses on the magnetic properties of nanocomposites constituted by spinel iron oxide nanoparticles (magnetic nanoparticles (MNPs), < D > ≈ 8–9 nm) embedded in an MS matrix. The mesoporous structure of the silica matrix and the presence of the nanoparticles inside clearly emerge from transmission electron microscopy (TEM) measurements. Low temperature (5 K) field-dependent magnetization measurements reveal saturation magnetization (MS) close to bulk value (MS bulk ∼ 90 emu g−1) for both MNPs and MNP/MS nanocomposites, indicating that the presence of silica does not affect the magnetic features of the single MNPs. Moreover, the dependence of the remanent magnetization on field (i.e. δM plots) at low temperature has shown a small but evident decrease of interaction in an MNP/MS sample with respect to MNP samples A m2 Kg–1. Finally, a partial orientation of the easy axis is observed when the MNPs are embedded in the silica matrix.

Magnetic mesoporous silica nanocomposites with binary metal oxides core-shell structure for the selective enrichment of endogenous phosphopeptides from human saliva

Developing an effective strategy for endogenous phosphopeptides enrichment and separation is necessary in phosphopeptidomics analysis due to the serious inference caused by chaotic biological environment. In this work, a size-exclusive magnetic binary metal mesoporous nanocomposites were synthesized to capture phosphorylated peptides for mass spectrometry analysis. The novel Fe3O4@TiO2–ZrO2@mSiO2 nanocomposites possessed the merits of ordered mesoporous channels, superparamagnetism and the integration of dual affinity of Zr–O and Ti–O. Compared with single-metal centered nanocomposites (Fe3O4@TiO2@mSiO2 and Fe3O4@ZrO2@mSiO2), Fe3O4@TiO2–ZrO2@mSiO2 showing much enhanced enrichment performance towards mono- and multi-phospho-peptides with better sensitivity. With all the advances, the Fe3O4@TiO2–ZrO2@mSiO2 was also successfully applied to capture endogenous phosphorylated peptides from human saliva. And consequently, a total of 30 phosphopeptides containing 2 multi- and 28 mono-phosphopeptides were identified efficiently. These results show that the novel materials have the great potential in peptidome analysis.

Development of a "Dual Gates" Locked, Target-Triggered Nanodevice for Point-of-Care Testing with a Glucometer Readout.

Developing a facile and sensitive sensing platform is of importance for point-of-care testing (POCT). Herein, a sensitive and portable POCT platform based on "dual gates" aminated magnetic mesoporous silica nanocomposites (AMMS) bearing polydopamine (PDA)-aptamer (Apt) two-tier shells, as a novel nanodevice, is designed for target detection through a target-triggered glucose (GO) release from AMMS with personal glucometer (PGM) readout. In the absence of target, GO can be firmly captured in pores by the designed "dual gates", which would decrease the high background signal of this system and ensure the accuracy of the detection results. Upon the introduction of the target molecules under acidic conditions (pH 5.5), the subsequent PDA self-degradation and the specific Apt-target reaction can cause the departure of "dual gates" and the opening of pores to release the loaded GO molecules, which could be quantitatively monitored by a portable PGM. It has been demonstrated that such POCT platform shows high sensitivity and excellent selectivity for aflatoxin B1 (AFB1) detection, accompanied by the well-presented reproducibility and stability. Importantly, this sensing platform was further validated by assaying contaminated samples, where the obtained results were well matched with that by HPLC. Regarding the features of portability, high sensitivity, and high throughput detection, the developed platform might find wide applications in POCT.

Photo-responsive magnetic mesoporous silica nanocomposites for magnetic targeted cancer therapy

A drug delivery platform for enhancing lung cancer treatment with controlled drug release, magnetic targeting and specific cancer cells targeting.

Recyclable Multifunctional Magnetic Mesoporous Silica Nanocomposite for Ratiometric Detection, Rapid Adsorption, and Efficient Removal of Hg(II)

In this paper, multifunctional inorganic–organic nanocomposites were fabricated through encapsulating CdTe quantum dots and Rhodamine 6G-deprived receptor into the nonporous and mesoporous shell of the magnetic mesoporous silica nanocomposites. The resultant nanomaterials display an obvious core–shell structure, superparamagnetic property, ordered mesoporous characteristics, and highly selective, sensitive, and regenerative ratiometric fluorescent sensing performance for determination of Hg2+. A good linearity is obtained between IRh6G/IQDs and Hg2+ concentration (0.7 to 90 × 10–8 mol·L–1), exhibiting a detection limit as low as 2.5 × 10–9 mol·L–1. Moreover, the multifunctional nanocomposites possess acceptable Hg2+ adsorption capacity and can be simply separated by magnet. Real water sample assays further verified its good mercury ion analysis and removal ability. Our results reveal that high sensitivity, selectivity, rapid adsorption, efficient removal ability, and good reusability as well as better acc...

Magnetic and pH dual-responsive mesoporous silica nanocomposites for effective and low-toxic photodynamic therapy.

Nonspecific targeting, large doses and phototoxicity severely hamper the clinical effect of photodynamic therapy (PDT). In this work, superparamagnetic Fe3O4 mesoporous silica nanoparticles grafted by pH-responsive block polymer polyethylene glycol-b-poly(aspartic acid) (PEG-b-PAsp) were fabricated to load the model photosensitizer rose bengal (RB) in the aim of enhancing the efficiency of PDT. Compared to free RB, the nanocomposites (polyethylene glycol-b-polyaspartate-modified rose bengal-loaded magnetic mesoporous silica [RB−MMSNs]) could greatly enhance the cellular uptake due to their effective endocytosis by mouse melanoma B16 cell and exhibited higher induced apoptosis although with little dark toxicity. RB−MMSNs had little dark toxicity and even much could be facilitated by magnetic field in vitro. RB−MMSNs demonstrated 10 times induced apoptosis efficiency than that of free RB at the same RB concentration, both by cell counting kit-8 (CCK-8) result and apoptosis detection. Furthermore, RB−MMSNs-mediated PDT in vivo on tumor-bearing mice showed steady physical targeting of RB−MMSNs to the tumor site; tumor volumes were significantly reduced in the magnetic field with green light irradiation. More importantly, the survival time of tumor-bearing mice treated with RB−MMSNs was much prolonged. Henceforth, polyethylene glycol-b-polyaspartate-modified magnetic mesoporous silica (MMSNs) probably have great potential in clinical cancer photodynamic treatment because of their effective and low-toxic performance as photosensitizers’ vesicles.

Chemo-photodynamic combined gene therapy and dual-modal cancer imaging achieved by pH-responsive alginate/chitosan multilayer-modified magnetic mesoporous silica nanocomposites.

Multifunctional theranostics have offered some interesting new opportunities for cancer therapy and diagnosis in the last decade. Herein, magnetic mesoporous silica nanoparticles (M-MSNs) were designed and synthesized, then the photosensitizer chlorin e6 (Ce6) and antitumor drug doxorubicin (Dox) were adsorbed onto the M-MSNs. Biocompatible alginate/chitosan polyelectrolyte multilayers (PEM) were assembled on the M-MSNs to achieve a pH-responsive drug delivery system and adsorb P-gp shRNA for reversing the multidrug resistance. The obtained M-MSN(Dox/Ce6)/PEM/P-gp shRNA nanocomposites were characterized using TEM, SEM, X-ray diffraction, BET, FTIR and electrophoresis. The nanocomposites with average diameter of 280 nm exhibited a pH-responsive drug release profile, and more singlet oxygen generation in cancer cells after laser illumination. CCK-8 assay and calcein-AM/PI co-staining showed that the multifunctional nanocomplexes significantly increased cell apoptosis in vitro. With tumor-bearing Balb/c mice employed as the animal model, combined photodynamic therapy and chemotherapy was carried out, also achieving synergistic anti-tumor effects in vivo. The cores of bifunctional Fe3O4-Au nanoparticles in the multifunctional nanocomposites enabled dual-modal MR and CT imaging, which illustrated strong tumor uptake of these nanocomposites after intravenous injection into tumor-bearing mice. This work highlights the great potential of magnetic mesoporous silica nanocomposites as a multifunctional delivery platform, which is promising for imaging-guided cancer combination therapy with high efficacy.

Solvent effects in the development of a drug delivery system for 5-fluorouracil using magnetic mesoporous silica nanoparticles

5-Fluorouracil (5-FU), an anticancer drug, was loaded into magnetic iron oxide/mesoporous silica nanocomposites (m-MCM-41) with and without aminopropyl functionalization using three different solvents (water, water/acetone, dimethyl sulfoxide). The parent and the drug-loaded samples were characterized using physicochemical techniques, such as powder X-Ray diffraction (pXRD), nitrogen adsorption-desorption isotherms and thermogravimetric analysis (TGA). Fourier Transform Infrared spectroscopy (FT-IR) and solid state Nuclear Magnetic Resonance (ssNMR) spectroscopy techniques were used to obtain molecular level insights into the loading of 5-FU into m-MCM-41 with different solvents and surface functionalization. The loading and release characteristics of 5-FU from m-MCM-41 depended on the solvent polarity and the surface functionalization of the host. The chemical insights provided by this study can be used in the future design and development of magnetic mesoporous silica nanocomposites for theranostic applications.

Removal of Lead(II), Copper(II) and Zinc(II) Ions from Aqueous Solutions Using Magnetic Amine-Functionalized Mesoporous Silica Nanocomposites

In this work, a batch adsorption study was conducted to investigate the removal efficiency of lead, copper and zinc ions from aqueous solutions. Magnetic amine-functionalized mesoporous silica nanoparticles were synthesized by grafting amine groups within the channels of magnetic mesoporous silica nanocomposites. Morphological and structural characterizations were made by X-ray powder diffraction, N2 adsorption-desorption, scanning and transmission electron microscopy, Fourier transform infrared spectroscopy and elemental analysis. Among different factors influencing the sorption process, solution pH, shaking time and mass of adsorbent were investigated. The removal efficiencies were higher than 98% under optimized experimental conditions. Maximum adsorption capacities calculated by the Langmuir model were 268, 93 and 82 mg g-1, for lead(II), copper(II) and zinc(II) ions, respectively. Accuracy and applicability of the synthesized adsorbent was estimated by analyzing spiked natural water samples and good recoveries (> 95%) were obtained with no matrix interferences.

Core-shell-type magnetic mesoporous silica nanocomposites for bioimaging and therapeutic agent delivery.

Advances in nanotechnology and nanomedicine offer great opportunities for the development of nanoscaled theranostic platforms. Among various multifunctional nanocarriers, magnetic mesoporous silica nanocomposites (M-MSNs) attract prominent research interest for their outstanding properties and potential biomedical applications. This Research News article highlights recent progress in the design of core-shell-type M-MSNs for both diagnostic and therapeutic applications. First, an overview of synthetic strategies for three representative core-shell-type M-MSNs with different morphologies and structures is presented. Then, the diagnostic functions of M-MSNs is illustrated for magnetic resonance imaging (MRI) applications. Next, magnetic targeted delivery and stimuli-responsive release of drugs, and effective package of DNA/siRNA inside mesopores using M-MSNs as therapeutic agent carriers are discussed. The article concludes with some important challenges that need to be overcome for further practical applications of M-MSNs in nanomedicine.

High-efficient mercury removal from environmental water samples using di-thio grafted on magnetic mesoporous silica nanoparticles.

In this work, magnetic di-thio functionalized mesoporous silica nanoparticles (DT-MCM-41) were prepared by grafting dithiocarbamate groups within the channels of magnetic mesoporous silica nanocomposites. The functionalized nanoparticles exhibited proper magnetic behavior. They were easily separated from the aqueous solution by applying an external magnetic field. The results indicated that the functionalized nanoparticles had a potential for high-efficient removal of Hg(2+) in environmental samples. The maximum adsorption capacity of the sorbent was 538.9 mg g(-1), and it took about 10 min to achieve the equilibrium adsorption. The resulted adsorption capacity was higher than similar works for adsorption of mercury. It can be due to the presence of di-thio and amine active groups in the structure of sorbent. The special properties of MCM-41 like large surface area and high porosity also provided a facile accessibility of the mercury ions into the ligand sites. The complete removal of mercury ions was attained with dithiocarbamate groups in a wide range of mercury concentrations. The recovery studies were also applied for the river water, seawater, and wastewater samples, and the values were over of 97 %.

Magnetic core-mesoporous shell nanocarriers with drug anchorages suspended in mesopore interior for cisplatin delivery

The synthesis of the core–shell magnetic mesoporous silica nanocomposites has recently attracted much attention, while it is highly desirable to modify the mesoporous shell with organic components for special interaction with guest molecules. Herein we propose a facile strategy to prepare novel magnetic mesoporous nanocomposites with superparamagnetic Fe3O4 core and mesoporous silica shell functionalized with pendant carboxylic groups in their mesopore interior. The successful deposition of organic–inorganic mesoporous layer on magnetic nanoparticles is verified by XRD, TEM and BET characterizations, and the integration of organic units is manifested by FT-IR and solid state NMR techniques. The inherent carboxylic units on the obtained nanocomposites serve as effective drug anchorages for coordinating with Pt atoms in the anti-cancer drug of cisplatin, resulting in increased drug loading amount and its sustained release. The obtained nanocomposites exhibit excellent water dispersity with well-defined size distribution (around 85nm), ordered mesoporous characteristics, superparamagnetism and high magnetization (37.0emug−1). The nanocomposites could not only effectively transport the encapsulated cisplatin into cancer cells but also mediate its sustained release in endosomes or lysosomes, leading to enhanced antitumor efficiency against both A549 and MCF-7 cell lines.

Multifunctional Mesoporous Nanocomposites with Magnetic, Optical, and Sensing Features: Synthesis, Characterization, and Their Oxygen-Sensing Performance

In this paper, the fabrication, characterization, and application in oxygen sensing are reported for a novel multifunctional nanomaterial of [Ru(bpy)(2)phen-MMS] (bpy, 2,2'-bipyridyl; phen, phenathrolin) which was simply prepared by covalently grafting the ruthenium(II) polypyridyl compounds into the channels of magnetic mesoporous silica nanocomposites (MMS). Scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, N(2) adsorption-desorption, a superconducting quantum interference device, UV-vis spectroscopy, and photoluminescence spectra were used to characterize the samples. The well-designed multifunctional nanocomposites show superparamagnetic behavior and ordered mesoporous characteristics and exhibit a strong red-orange metal-to-ligand charge transfer emission. In addition, the obtained nanocomposites give high performance in oxygen sensing with high sensitivity (I(0)/I(100) = 5.2), good Stern-Volmer characteristics (R(2) = 0.9995), and short response/recovery times (t↓ = 6 s and t↑ = 12 s). The magnetic, mesoporous, luminescent, and oxygen-sensing properties of this multifunctional nanostructure make it hold great promise as a novel multifunctional oxygen-sensing system for chemical/biosensor.

Targeted Delivery System Based on Magnetic Mesoporous Silica Nanocomposites with Light-Controlled Release Character

We report the facile synthesis and easy operation of a smart delivery system based on core-shell structured magnetic mesoporous silica nanocomposites covalently grafted with light-responsive azobenzene derivatives, which integrates magnetic targeting and stimuli-responsive release property. Irradiation with visible light triggers the release of guest molecules loaded in the mesopores.

Synthesis, characterization and biocompatibility evaluation of iron oxide incorporated magnetic mesoporous silica

On the basis of a thermal process, a facile, low cost, one-step approach for preparing iron oxide (Fe(2)O(3)) incorporated ordered magnetic mesoporous silica nanocomposites by a co-operative self-assembly approach is presented. Various mesostructured silica materials incorporated with different amounts of iron oxide (nSi/nFe = 1/1, 1/0.5, 1/0.25 and 1/0.123) at various pH (<1, 3, 5 and 7) were synthesized and characterized by electron microscopy and X-ray diffractometry. Further, the surface area and magnetic properties were evaluated using N(2)-sorption analyses, and a superconducting quantum interference device interfaced with a vibrating sample magnetometer (SQUID-VSM) respectively. The transmission electron micrographs and nitrogen sorption analysis indicated that most of the Fe(2)O(3) domains of several nanometers were embedded in the silica walls, rather than dispersed in the mesopores. The incorporation of iron oxide into the mesopores without compromising the structural and textural properties was achieved at pH < 1. These structures have great potential in diagnostics and therapeutics. However, the acceptance of this material by the biological host is a critical issue for such biomedical applications. In this study, we have also evaluated the in vivo biocompatibility of these magnetic mesoporous materials in a rat model. The histopathological results show that this magnetic material can be classified as a level 2 biomaterial that can be safely used for short term applications such as MRI imaging, hyperthermia, targeted drug delivery, etc.

Multifunctional Magnetic Mesoporous Silica Nanocomposites with Improved Sensing Performance and Effective Removal Ability toward Hg(II)

In the present work, a multifunctional inorganic-organic hybrid nanomaterial (MMS-Py) was prepared by the immobilization of a pyrene-based receptor (Py) within the channels of magnetic mesoporous silica nanocomposites (MMS), and characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, N(2) adsorption/desorption, superconducting quantum interference device, and photoluminescence spectra. This multifunctional nanomaterial exhibits superparamagnetic behavior, ordered mesoporous characteristics, and significantly improved fluorescence sensing properties that allow for highly sensitive and reproducible Hg(2+) detection. The fluorogenical responses of MMS-Py are stable over a broad pH range. A detection limit of 1.72 ppb is obtained, which is 2 orders of magnitude lower than that based on bulk mesoporous materials. Additionally, this nanomaterial shows high performance in convenient magnetic separability and efficient removal of Hg(2+). These results indicate that these multifunctional nanocomposites may find potential applications for simple detection and easy removal of Hg(2+) in biological, toxicological, and environmental areas.

Facile Synthesis of Boronic Acid-Functionalized Magnetic Mesoporous Silica Nanocomposites for Highly Specific Enrichment of Glycopeptides

In the work, aminophenylboronic acid (APB)-functionalized magnetic mesoporous silica, which holds the attractive features of high magnetic responsivity and large surface area, was developed to enrich glycopeptides. At first, magnetic mesoporous silica nanocomposites were prepared. And then, the nanocomposites were functioned with glycidoxypropyltrimethoxysilane (GLYMO) for boronic acid immobilization. Due to that the boronic acid group on the surface of magnetic mesoporous silica nanocomposites can form tight yet reversible covalent bond with glycopeptides containing cis-1,2-diols groups, the magnetic mesoporous silica nanocomposites were successfully applied to selective enrichment of glycopeptides. APB functionalized magnetic mesoporous silica was also demonstrated to have high selectivity for the glycopeptides in the presence of a 10-fold excess bovine serum albumin (BSA) over horseradish peroxidase (HRP) in the tryptic digest. We also find that magnetic mesoporous silica has better sensitivity in HRP digest compared with that of commercial aminophenylboronic acid-functionalized magnetic nanoparticles beads. The limit of detection for glycopeptides from glycoprotein HRP is about 0.01 ng/µL.