Functionalized Core Shell Research Articles

A facile fabrication of upconversion luminescent and mesoporous core-shell structured β-NaYF4:Yb3+, Er3+@mSiO2 nanocomposite spheres for anti-cancer drug delivery and cell imaging.

Upconversion luminescent β-NaYF4:Yb3+, Er3+ nanoparticles (UCNPs) were encapsulated with uniform mesoporous silica shells, which were further modified with poly(ethylene glycol) (PEG) and cancer-targeting ligand folic acid (FA), resulting in the formation of water-dispersible and biologically functionalized core-shell structured UCNPs@mSiO2 nanoparticles with an overall average size of around 80 nm. The obtained multifunctional nanocomposite spheres can be performed as an anti-cancer drug delivery carrier and applied for cell imaging. It is found that anti-cancer drug doxorubicin hydrochloride (DOX) can be absorbed into UCNPs@mSiO2-PEG/FA nanospheres and released in a pH-sensitive pattern. In vitro cell cytotoxicity tests on cancer cells verified that DOX-loaded UCNPs@mSiO2-PEG/FA nanospheres exhibited greater cytotoxicity with respect to free DOX and DOX-loaded UCNPs@mSiO2-PEG at the same concentrations, owing to the increase of cell uptake of anti-cancer drug delivery vehicles mediated by the FA receptor. Moreover, the upconversion luminescence image of UCNPs@mSiO2-PEG/FA taken up by cells shows green emission under 980 nm infrared laser excitation, making the UCNPs@mSiO2-PEG/FA nanocomposite spheres promising candidates as bioimaging agents. These findings highlight the promise of the highly versatile multifunctional nanoparticles for simultaneous imaging and therapeutic applications.

Au-ultrathin functionalized core–shell (Fe3O4@Au) monodispersed nanocubes for a combination of magnetic/plasmonic photothermal cancer cell killing

Download options Please wait... Supplementary files Supplementary information PDF (1013K) Article information DOI https://doi.org/10.1039/C3RA21479F Article type Paper Submitted 18 Jul 2012 Accepted 13 Mar 2013 First published 14 Mar 2013 Download Citation RSC Adv., 2013,3, 7816-7827 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Au-ultrathin functionalized core–shell (Fe3O4@Au) monodispersed nanocubes for a combination of magnetic/plasmonic photothermal cancer cell killing Md. Abdulla-Al-Mamun, Y. Kusumoto, T. Zannat, Y. Horie and H. Manaka, RSC Adv., 2013, 3, 7816 DOI: 10.1039/C3RA21479F To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Social activity Tweet Share Search articles by author Md. Abdulla-Al-Mamun Yoshihumi Kusumoto Tohfatul Zannat Yuji Horie Hirotaka Manaka

Phosphotungstic acid anchored to amino–functionalized core–shell magnetic mesoporous silica microspheres: A magnetically recoverable nanocomposite with enhanced photocatalytic activity

H3PW12O40 was successfully anchored to the surface of amino-functionalized Fe3O4@SiO2@meso-SiO2 microspheres by means of chemical bonding to aminosilane groups, aiming to remove unwanted organic compounds from aqueous media. The resultant multifunctional microspheres were thoroughly characterized by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, infrared spectroscopy, inductively coupled plasma, and N2 adsorption–desorption. The as-prepared microspheres possess unique properties including high magnetization (46.8emug−1), large BET surface area (135m2g−1), and highly open mesopores (∼5.0nm), and H3PW12O40 loading is calculated to be ∼16.8%; and as a result, the as-prepared microspheres exhibit enhanced performance in degrading dyes under UV irradiation compared with pure H3PW12O40. Additionally, the photocatalyst can be easily recycled using an external magnetic field without losing the photocatalytic activity.

Highly selective fluorescent chemosensor for detecting Hg(II) in water based on pyrene functionalized core–shell structured mesoporous silica

Novel pyrene functionalized mesoporous core–shell structured silica (denoted as SiO2@mSiO2/Py-Si) was designed and synthesized as a highly selective fluorescent chemosensor for detecting Hg2+ in water. The core–shell structured silica was prepared by a simple sol–gel process through coating SiO2 nanospheres with a layer of ordered mesoporous silica. The surface of outer mesoporous silica shell was then further functionalized by the fluorescent chromophore alkoxysilane modified pyrene (Py-Si). XRD data confirmed that the hexagonal ordered mesoporous structure was preserved after functionalization. The chemosensing material successfully exhibited a remarkable “turn on” response toward Hg2+ over miscellaneous metal ions. A good linear response towards Hg2+ in the concentration range of 10−8–10−4M was constructed with R2=0.9913. Most importantly, a satisfactory detection limit of 3.4×10−9gmL−1 (down to ppb level) was obtained, which is 100 times lower than our previous report of covalently grafted Py-OH to the bulk mesoporous silica SBA-15. These results indicated that SiO2@mSiO2/Py-Si can be used as a highly selective and sensitive fluorescence sensor for Hg2+.

Gain functionalized core–shell nanoparticles: the way to selectively compensate absorptive losses

We experimentally demonstrate that gain materials properly encapsulated into the shell surrounding metal nanoparticles (NPs) are responsible for the modification of the overall plasmon response of engineered nanostructures. A comparison between designed systems based on functionalized core–shell NPs having different encapsulated dye molecules is presented. Experimental observations of Rayleigh scattering enhancement, accompanied by an increase of transmission as a function of gain, reveal striking optical loss compensation effects. Fluorescence lifetime measurements demonstrate a quenching of dye photoluminescence in functionalized core–shell NP samples with respect to pure dye solutions, confirming the strong resonant coupling occurring between the gain medium and gold NPs. Experimental evidence of a selective modification of the gain functionalized core–shell Au NP extinction curve is found, in good agreement with the results of a simplified theoretical model. The model verifies the causality principle through Kramers–Kronig dispersion relations for the investigated gain functionalized plasmonic nanostructure.

Preparation and characterization of ellipsoidal-shaped thermosensitive microgel colloids with tailored aspect ratios

Prolate model colloids with defined properties can be obtained by the stretching of spherical polymeric particles, which is well-known for polystyrene and poly(methyl methacrylate) latices. The present study aims to extend this approach to functional core–shell particles in order to achieve a new class of anisotropic colloidal materials where both the aspect ratio and the effective volume fraction can be controlled by temperature. We describe the synthesis and characterization of these functional anisotropic core–shell particles consisting of a polystyrene (PS) core onto which a crosslinked thermoresponsive microgel shell of poly(N-isopropylmethacrylamide) (PNIPMAm) was grafted. Embedded into a film of polyvinylalcohol (PVA), the spherical composite microgels are heated above the glass transition temperature (Tg) of the polystyrene core and then stretched with different deformations γ. During the stretching, the particles adopt an elongated shape, that they retain after cooling to room temperature as confirmed by small-angle X-ray scattering performed on the films. Anisotropic composite microgels with aspect ratios ranging from 2.2 to 6.5 are recovered after dissolution of the PVA and purification, and are fully characterized by diverse methods such as transmission electron microscopy, confocal microscopy and light scattering. The temperature sensitivity of these anisotropic composite microgels is maintained as confirmed by dynamic light scattering and cryogenic electron microscopy performed below and above the volume phase transition of the shell.

One-pot synthesis of silica core–shell particles with double shells and different pore orientations from their nonporous counterparts

Silica core–shell particles (CSPs) have been successfully synthesized from their nonporous counterparts under basic conditions in the presence of the cationic surfactant cetyltrimethylammonium chloride and NH4F using a new one-pot templated dissolution and templated redeposition hybrid method. This method leads to high yield (∼85%) CSPs with an extremely narrow particle size distribution (no particle aggregation or fine particles) and allows us to vary reaction time to rapidly and conveniently control shell thickness up to the radius of the core particles. The resultant porous shells possess a unique double ordered pore arrangement with the inner and outer shells consisting of wormhole-like and radially oriented pores, respectively. To the best of our knowledge, this is the first report describing the fabrication of double shells in one step with the ability to manipulate the shell thickness from preformed silica particles in the presence of a surfactant. A mechanism to account for the formation of porous shells with different pore morphologies is presented. The resultant CSP particles have the combined characteristics of narrow particle distribution, narrow pore size distribution, unique double shells, and controlled shell thickness, surface area, and pore volume. These properties make them ideal candidates for fast and highly efficient chromatographic separation applications. The ability to control shell thickness while not dissolving the entire nonporous silica protective layer is particularly important to prepare functional core–shell particles (e.g., quantum dot core–nonporous silica shell–porous silica shell) for biomedical applications while avoiding toxic nanoparticles being directly exposed to the body. It is expected that this new hybrid synthesis method could be extended to generate a superficially porous silica layer with a controlled shell thickness and dual mesopore structure from any materials with a sol–gel silica coating.

One-step seeding growth of controllable Ag@Ni core–shell nanoparticles on skin collagen fiber with introduction of plant tannin and their application in high-performance microwave absorption

Controllable magnetic Ag@Ni core–shell nanoparticles (NPs) have been designed and constructed on the bayberry tannin (BT) grafted skin collagen fiber (SCF) though a simple one-step route. Due to the mild and naturally occurring reduction ability of BT, when the SCF-BT made contact with the mixture of Ag+/Ni2+ solution, BT was able to preferentially reduce Ag+ into Ag NPs, and subsequently, the formed Ag NPs served as in situ seeds for the over growth of magnetic Ni shell by the reduction of NaBH4. The systematic TEM and EDS analysis confirmed that the as-prepared Ag@Ni NPs on SCF-BT were a typical core–shell structure. Magnetic study of core–shell NPs indicated that their magnetic properties could be tuned by modulating their shell thickness with the change of Ag+/Ni2+ molar ratio. The diameter and size distribution of SCF-supported Ag@Ni core–shell NPs also can be controlled by varying the grafting degree of BT on SCF, as characterized by TEM. A novel and important application of these SCF-supported Ag@Ni core–shell NPs composites is use as high-performance microwave absorption materials in the whole X-band, C-band and some part of S-band with maximum reflection loss (RL) of −51 dB. The further analysis of electromagnetic parameters indicated that the enhancement of dielectric loss properties of SCF-supported Ag@Ni core–shell NPs is introduced by the multiple defective site polarization and interfacial polarization in bimetallic interface. In addition, owing to the combinated magnetic property on the nickel shell, the SCF-supported Ag@Ni core–shell NPs also exhibited a significant eddy current effect and anisotropic energy effect for the microwave absorption. To the best of our knowledge, this is the first time to explore tailoring the magnetic property, electromagnetic property and microwave absorption performance of functional core–shell NPs by tuning their core–shell microstructures. The present work has a significant potential for the development of novel, lightweight, low-cost, flexible and highly efficient microwave absorbing materials.

Multi-functional silicananotubes as a versatile nanoscale component for biology-driven sensing applications

Functional gold surfaces are of great interest in the field of biosensors, since reactions taking place at such surfaces are easily detected and can be applied in numerous applications. Nanotubes (NTs) have been explored as modifying nanostructuration agents for quartz crystal microbalance (QCM) electrodes. Two goals must be achieved in this study. First, preparation of functional NTs which are able to bind to the gold surface; second, these NTs should have an additional functional group which will bind biological markers. Functional silica nanotubes (SNTs) have great potential in various applications due to their biocompatibility and ability to bind functional groups in a covalent manner using various silica based linkers. Although many publications deal with the introduction of functional groups onto the SNT surface, at present there are no reports in the literature regarding core–shell morphology with a functional polymer shell, which is covalently linked to SNTs. Furthermore, such functional core–shell SNTs can be further modified by other functional groups like amines or thiols by a 2nd step functionalization. This fact gives rise to an orthogonal nanocomposite (NC) that can be used as the essential modification component of QCM electrodes for the detection of biological markers.

Functionalized shell-isolated nanoparticle-enhanced Raman spectroscopy for selective detection of trinitrotoluene

Shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS), which acts as the next generation of advanced spectroscopy, expands the versatility of surface-enhanced Raman spectroscopy (SERS). Here we present a facile one-step method to prepare functionalized core-shell nanoparticles for selective detection of trinitrotoluene (TNT) through the formation of Meisenheimer complexes. A well-designed type of tunable poly(2-aminothiophenol) (PAT) shells on gold nanoparticles was prepared for the first time and the shell thickness of 2 nm could be controlled by only adjusting the molar ratio of sodium dodecylsulfate (SDS) to 2-aminothiophenol. The polymer shells shows prominent advantages, including uniformity, better chemical stability, being free of pin-holes and amino-functionalized.

Highly sensitive thrombin detection by matrix assisted laser desorption ionization-time of flight mass spectrometry with aptamer functionalized core–shell Fe3O4@C@Au magnetic microspheres

Here, we describe a sensitive and specific method for thrombin detection with aptamer functionalized core–shell Fe3O4@C@Au magnetic microspheres (Au-MMPs). Firstly, Au-MMPs were synthesized through surface adsorption of gold nanoparticles onto PDDA functionalized Fe3O4@C magnetic microspheres. Then, the as-synthesized Au-MMPs were developed as new substrate for immobilization of thrombin binding aptamer (TBA) through easy formation of Au–S bond. After that, the prepared aptamer functionalized Au-MMPs (TBA@Au-MMPs) were used as effective magnetic absorbent to extract trace level of thrombin from dilute solutions. Finally, enriched thrombin was digested by trypsin and analyzed by matrix assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry. Taking advantage of the efficient affinity extraction ability of our TBA@Au-MMPs and the sensitive mass readout of MALDI-TOF, highly sensitive detection of thrombin was achieved. The limit of detection was as low as 18fmol, corresponding to 0.36nM thrombin in 50μL original solution. Linear relation was observed within a concentration range from 0.5nM to 10nM with linear correlation R2=0.998. Other proteins including human serum albumin (HSA), Ig G, transferrin, oval albumin (OVA) and fetal calf serum did not interfere with thrombin detection. This simple method holds great potential for analyzing, sensing, purification and preconcentration of proteins in biological fluids.

Probing the Structure of the Crystalline Core of Field-Aligned, Monodisperse, Cylindrical Polyisoprene-block-Polyferrocenylsilane Micelles in Solution Using Synchrotron Small- and Wide-Angle X-ray Scattering

The self-assembly of block copolymers in selective solvents represents a powerful approach to functional core-shell nanoparticles. Crystallization of the core can play a critical role in directing self-assembly toward desirable, nonspherical morphologies with low mean interfacial curvature. Moreover, epitaxial growth processes have been implicated in recent advances that permit access to monodisperse cylinders, cylindrical block comicelles with segmented cores and/or coronas, and complex hierarchical architectures. However, how the core-forming block crystallizes in an inherently curved nanoscopic environment has not been resolved. Herein we report the results of synchrotron small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) studies of well-defined, monodisperse crystalline-coil polyisoprene-block-polyferrocenylsilane cylindrical micelles aligned in an electric field. WAXS studies of the aligned cylinders have provided key structural information on the nature of the PFS micelle core together with insight into the role of polymer crystallinity in the self-assembly of these and potentially related crystalline-coil block copolymers.

Core/Shell Structured Hollow Mesoporous Nanocapsules: A Potential Platform for Simultaneous Cell Imaging and Anticancer Drug Delivery

A potential platform for simultaneous anticancer drug delivery and MRI cell imaging has been demonstrated by uniform hollow inorganic core/shell structured multifunctional mesoporous nanocapsules, which are composed of functional inorganic (Fe(3)O(4), Au, etc.) nanocrystals as cores, a thin mesoporous silica shell, and a huge cavity in between. The synthetic strategy for the creation of huge cavities between functional core and mesoporous silica shell is based on a structural difference based selective etching method, by which solid silica middle layer of Fe(2)O(3)@SiO(2)@mSiO(2) (or Au@SiO(2)@mSiO(2)) composite nanostructures was selectively etched away while the mesoporous silica shell could be kept relatively intact. The excellent biocompatibility of obtained multifunctional nanocapsules (Fe(3)O(4)@mSiO(2)) was demonstrated by very low cytotoxicity against various cell lines, low hemolyticity against human blood red cells and no significant coagulation effect against blood plasma. The cancer cell uptake and intracellular location of the nanocapsules were observed by confocal laser scanning microscopy and bio-TEM. Importantly, the prepared multifunctional inorganic mesoporous nanocapsules show both high loading capacity (20%) and efficiency (up to 100%) for doxorubicin simultaneously because of the formation of the cavity, enhanced surface area/pore volume and the electrostatic interaction between DOX molecules and mesoporous silica surface. Besides, the capability of Fe(3)O(4)@mSiO(2) nanocapsules as contrast agents of MRI was demonstrated both in vitro and in vivo, indicating the simultaneous imaging and therapeutic multifunctionalities of the composite nanocapsules. Moreover, the concept of multifunctional inorganic nanocapsules was extended to design and prepare Gd-Si-DTPA grafted Au@mSiO(2) nanocapsules for nanomedical applications, further demonstrating the generality of this strategy for the preparation of various multifunctional mesoporous nanocapsules.

Bifunctional magnetic nanoparticles for early detection and magnetic hyperthermia cancer therapy

Magnetic hyperthermia offers promise as cancer therapy. We have tested bimetallic core/shell Fe/Fe3O4 magnetic nanoparticles (MNP) for in vivo diagnosis and targeting of MNP to tumor tissue. We have received the MNP from NanoScale Corporation. These particles have a Dopamine‐PEG layer, to which a porphyrin 'A' is attached; another porhyrin 'B' is also attached to the MNP via a peptide that represents the urokinase cleavage site. MNP were tested in B16F10 melanoma cells and neural stem cells for loading using Ferrozine assay.. For in vivo tumor detection, the MNP were injected intravenously into tumor bearing mice and fluorescence was detected after one and two days. Heat distribution studies were conducted in live mice by injecting MNP into mouse leg; temperatures were measured using a fiber optic probe. Short exposure time hyperthermia studies were conducted by exposing tumor bearing mice to alternating magnetic field (AMF) for 10 min (336KHz frequency and 5KA/m amplitude) after injecting theMNP intratumorally. MNP loaded efficiently into mouse cells with little toxicity. We detected fluorescence in tumors during laser imaging of live mice. Mouse subcutaneous melanomas were markedly attenuated; we observed 76% tumor inhibition after short exposure to AMF. These data indicate that bi‐ functional core shell MNP are effective for hyperthermia therapy and detection of subcutaneous melanoma.

Synthesis and characterization of functionalized core–shell γFe 2O 3–SiO 2 nanoparticles

Amino and/or polyethyleneglycol (PEG) functionalized core–shell γFe 2O 3–SiO 2 magnetic nanoparticles were synthesized and characterized. Amino–PEG-functionalized core–shell nanoparticles have calibrated sizes and a good colloidal stability. These bi-functionalized core–shell nanoparticles are potentially useful as biocompatible particles for magnetically targeted chemotherapy.

Preparation of silica/polymer hybrid microspheres and the corresponding hollow polymer microspheres with functional groups

AbstractMonodisperse functional silica/polymer core–shell hybrid microspheres were prepared by a two‐stage reaction with silica grafting of 3‐(methacryloxy)propyl trimethoxysiliane (MPS) as core and polymer as shell having various functional groups such as chloromethyl, pyridyl, carboxylic acid, hydroxyl, and ester. MPS‐modified silica core was synthesized by the Stöber method and subsequently grafted with MPS as the first‐stage reaction. The functional polymer shell was then encapsulated over the MPS‐modified silica by distillation precipitation copolymerization of divinylbenzene (DVB) as a crosslinker and comonomers with different functional groups, including chloromethylstyrene (CMSt), vinyl pyridine (VPy), methacrylic acid (MAA), 2‐hydroxyethylmethacrylate (HEMA), ethyl methacrylate (EMA), ethyleneglycol dimethacrylate (EGDMA), and trimethylol propanetrimethacrylate (Trim), in neat acetonitrile with 2,2′‐azobisisobutyronitrile (AIBN) as an initiator. The encapsulation of the functional polymer shell onto the MPS‐modified silica core particles was driven by the capture of oligomer radicals the vinyl groups on the surface of the MPS‐modified silica cores during the second‐stage distillation precipitation copolymerization in the absence of any stabilizer or surfactant. The functionality and the shell thickness of the inorganic/polymer core–shell hybrid particles were controlled by the amount of DVB crosslinker and the functional comonomers during the copolymerization. The corresponding hollow polymer microspheres with various functional groups, including chloromethyl, pyridyl, carboxylic acid, and ester groups were further developed after the selective removal of silica core with hydrofluoric acid. The functional core–shell silica/polymer hybrid microspheres and the corresponding functional hollow polymer microspheres were characterized with transmission electron microscopy (TEM) and Fourier transform infrared spectra (FT‐IR). Copyright © 2008 John Wiley & Sons, Ltd.

A new strategy to prepare temperature-sensitive poly(N-isopropylacrylamide) microgels

In this study, a new method was developed to prepare temperature-sensitive poly(N-isopropylacrylamide) microgels by free radical precipitation polymerization using siloxane coupling agent as the new crosslinker. Ammonium persulfate acted as the initiator for the radical copolymerization as well as the catalyst for the hydrolysis/condensation of the siloxane groups. The particle diameter and polydispersity of the microgels were measured by photon correlation spectroscopy and the results display that the microgels are monodisperse. The microgels exhibit temperature sensitivity and the phase transition temperature is approximately 31 °C. Furthermore, the diameter of the microgels changes upon heating and cooling processes. These were observed to be reversible. The novel crosslinking method described herein is the condensation of siloxane groups, which is totally different from the traditional double-vinyl crosslinkers. This innovative approach offers an alternative path to prepare functional core–shell particles and inorganic/organic hybrid materials.

Preparation and Characterization of Core—Shell Structured Nanofibers by Coaxial Electrospinning

Functional core—shell structured composite nanofibers were prepared by electrospinning two polymer solutions in a coaxial system. The core—shell structured nanofibers were comprised of varying concentrations of polyurethane (PU, shell) and a Nylon-6 (core). The resultant nanofibers were characterized by means of scanning electron microscopy, transmission electron microscopy, fourier transform infrared spectroscopy and tensile mechanical test. Furthermore, water vapor transmission rate and pliability of cotton fabrics coated with non-woven mats of the core—shell structured nanofibers were also measured. The results indicated that it is feasible to attach composite nanofibers onto a textile substrate.

Hydrogel nanonetworks with functional core–shell structure

Nanohydrogel particles of poly(acrylonitrile-co- N-isopropylacrylamide (p(AN-c-NIPAM)) were synthesized using a microemulsion polymerization technique. Highly monodisperse nanohydrogel particles e.g. 50–150 nm, and various morphology such as core–shell and connected beads were obtained. It was shown that the shell thickness and the size of particles can be tuned by the monomer concentrations and their ratios as well as by the utilization of different crosslinkers. The hydrophobic core monomer, AN was converted to amidoxime groups to increase the hydrophilicity of the nanogels which provide more hydrophilic character and impart new functionality to the nanonetwork. Transmission electron microscopy (TEM), and dynamic light scattering (DLS) techniques were employed for the particle size characterizations. The amidoximation reaction was confirmed by FT-IR spectroscopy.

Nanostructured silica/polymer subcritical aerogels

The incorporation of functionalized core–shell polymer nanoparticles in a silica network, by the sol–gel process, yields a structure stiff enough to withstand capillary pressure upon subcritical drying. The resulting hybrid aerogels are machinable monoliths, stable under atmospheric conditions, and have improved mechanical performance. These combined properties make them strong candidates for insulation in high value applications.