Evaluation of biocompatible alginate- and deferoxamine-coated ternary composites for magnetic resonance imaging and gene delivery into glioblastoma cells.

BACKGROUND: This paper describes comparative studies in cytotoxicities, magnetic resonance imaging (MRI), and gene delivery into glioblastoma U87MG or U138MG cells with ternary composites that are consist of superparamagnetic iron oxide (SPIO) nanoparticles (NPs) (size: 8-10 nm) with different surface coatings, circular plasmid DNA (pDNA) (~4 kb) equipped with fluorescent/luminescent probe, and branched polyethylenimine (25 kDa, PDI 2.5). METHODS: Three types of SPIO-NPs were used, including: (I) naked iron oxide NPs with Fe-OH surface group (Bare-NP); (II) iron oxide NPs with a coating of alginate (Alg-NPs); and (III) iron oxide NPs with a coating of deferoxamine (Def-NPs). By tuning the polyethylenimine (PEI)/NP ratios and with a fixed DNA amount, different ternary composites were employed for NP/gene transfection into glioblastoma U87MG or U138MG cells, which were then characterized by Prussian blue staining, in vitro MRI, green fluorescence protein (GFP) fluorescence and luciferase assay. RESULTS: Among the composites prepared, 0.2 ng PEI/0.5 µg DNA/1.0 µg Bare-NP ternary composite possessed the best cellular uptake efficiency of NP to the cytoplasm, following the trend Bare-NP > Alg-NP > Def-NP. This observation was consistent to the MRI assessments with in vitro T 2 relaxivity (r 2) values of 46.0, 35.5, and 23.7 s(-1)·µM(-1)·Fe, respectively. For cellular uptake efficiency of the pDNA, all variations of PEI/NP ratios of the composites did not yield significant differences. However, cellular uptake efficiencies of pDNA in the ternary composites in U138MG cells were generally higher than that of U87MG cells by an order of magnitude. Exceptionally, the ternary composite 0.2 ng PEI/0.5 µg DNA/1.0 µg Bare-NP possessed a lowered luciferase activity RLU for gene expression in U138MG cells. A total of 0.2 ng PEI/0.5 µg DNA/0.1 µg Bare-NP would be uptaken to the cell nucleus with the highest luciferase activity. A working concentration range of PEI with at least 15% higher cell viabilities than lipofectamine was 0.1 to 0.2 ng/well. The cytotoxicities became significant when 0.5 ng/well PEI was present in the ternary composites. CONCLUSIONS: The as-prepared composites offer potential biomedical applications in simultaneous gene delivery, imaging contrast enhancement, and metabolism study.

Improving brush polymer infrared one-dimensional photonic crystals via linear polymer additives.

Brush block copolymers (BBCPs) enable the rapid fabrication of self-assembled one-dimensional photonic crystals with photonic band gaps that are tunable in the UV-vis-IR, where the peak wavelength of reflection scales with the molecular weight of the BBCPs. Due to the difficulty in synthesizing very large BBCPs, the fidelity of the assembled lamellar nanostructures drastically erodes as the domains become large enough to reflect IR light, severely limiting their performance as optical filters. To overcome this challenge, short linear homopolymers are used to swell the arrays to ∼180% of the initial domain spacing, allowing for photonic band gaps up to ∼1410 nm without significant opacity in the visible, demonstrating improved ordering of the arrays. Additionally, blending BBCPs with random copolymers enables functional groups to be incorporated into the BBCP array without attaching them directly to the BBCPs. The addition of short linear polymers to the BBCP arrays thus offers a facile means of improving the self-assembly and optical properties of these materials, as well as adding a route to achieving films with greater functionality and tailorability, without the need to develop or optimize the processing conditions for each new brush polymer synthesized.

Crystalline phosphorus fibers: controllable synthesis and visible-light-driven photocatalytic activity.

An efficient method is developed for the synthesis of single crystalline fibrous phosphorus submicron materials. Via the chemical vapor deposition (CVD) technique, fibrous phosphorus fibers with diameters from ∼150 nm to 2 µm were prepared directly from amorphous red phosphorus. The as-prepared fibrous phosphorus exhibited interesting photocatalytic properties.

Nanoparticle-encapsulated chlorhexidine against oral bacterial biofilms.

BACKGROUND: Chlorhexidine (CHX) is a widely used antimicrobial agent in dentistry. Herein, we report the synthesis of a novel mesoporous silica nanoparticle-encapsulated pure CHX (Nano-CHX), and its mechanical profile and antimicrobial properties against oral biofilms. METHODOLOGY/PRINCIPAL FINDINGS: The release of CHX from the Nano-CHX was characterized by UV/visible absorption spectroscopy. The antimicrobial properties of Nano-CHX were evaluated in both planktonic and biofilm modes of representative oral pathogenic bacteria. The Nano-CHX demonstrated potent antibacterial effects on planktonic bacteria and mono-species biofilms at the concentrations of 50-200 µg/mL against Streptococcus mutans, Streptococcus sobrinus, Fusobacterium nucleatum, Aggregatibacter actinomycetemcomitans and Enterococccus faecalis. Moreover, Nano-CHX effectively suppressed multi-species biofilms such as S. mutans, F. nucleatum, A. actinomycetemcomitans and Porphyromonas gingivalis up to 72 h. CONCLUSIONS/SIGNIFICANCE: This pioneering study demonstrates the potent antibacterial effects of the Nano-CHX on oral biofilms, and it may be developed as a novel and promising anti-biofilm agent for clinical use.

Surface molecular tailoring using pH-switchable supramolecular dendron-ligand assemblies.

The rational design of materials with tailored properties is of paramount importance for a wide variety of biological, medical, electronic and optical applications. Here we report molecular level control over the spatial distribution of functional groups on surfaces utilizing self-assembled monolayers (SAMs) of pH-switchable surface-appended pseudorotaxanes. The supramolecular systems were constructed from a poly(aryl ether) dendron-containing a dibenzo[24]crown-8 (DB24C8) macrocycle and a thiol ligand-containing a dibenzylammonium recognition site and a fluorine end group. The dendron establishes the space (dendritic effect) that each pseudorotaxane occupies on the SAM. Following SAM formation, the dendron is released from the surface by switching off the noncovalent interactions upon pH stimulation, generating surface materials with tailored physical and chemical properties.

Type III-B rotaxane dendrimers.

Type III-B first generation [3]rotaxane and second generation [4]rotaxane dendrimers have been synthesized via (1) a modified copper-catalyzed alkyne-azide cycloaddition (CuAAC), (2) Glaser-Hay's acetylenic oxidative homo-coupling, and (3) amide formation. The dendron does not reveal obvious cytotoxicities in L929 fibroblast cells. The rotaxane dendrimers can capture ammonia and are switchable both in solution and on surfaces.

Nanoparticle-DNA-polymer composites for hepatocellular carcinoma cell labeling, sensing, and magnetic resonance imaging.

This paper describes comparative studies and protocols in (1) self-assembling of ultrasmall superparamagnetic iron oxide nanoparticle (NP), circular plasmid DNA, and branched polyethylenimine (PEI) composites; (2) magnetofection; (3) gene delivery, (4) magnetic resonance imaging (MRI), and (5) cytotoxicity of the composites toward hepatocellular carcinoma HepG2 cells.

Ultrasound, pH, and magnetically responsive crown-ether-coated core/shell nanoparticles as drug encapsulation and release systems.

Core@shell nanoparticles with superparamagnetic iron oxide core, mesoporous silica shell, and crown ether periphery were fabricated toward drug delivery and tumor cell imaging. By the concept of nanovalve based on supramolecular gatekeeper, stimuli-responsive drug delivery nanosystems Fe3O4@SiO2@meso-SiO2@crown ethers were synthesized by (i) modified solvothermal reaction; (ii) sol-gel reaction; and (iii) amide coupling reaction. The successful coupling of the dibenzo-crown ethers onto the mesoporous silica shell was confirmed by thermogravimetric analysis and Infrared spectroscopy. In this system, the "ON/OFF" switching of the gatekeeper supramolecules can be controlled by pH-sensitive intramolecular hydrogen bonding or electrostatic interaction (such as metal chelating). Biological evaluation of the nanoparticles renders them noncytotoxic and can be uptaken by L929 cells. In this work, the antitumor drug (doxorubicin) loading and release profiles which were studied by the UV/visible absorption spectroscopy. The mechanism involves the best-fit binding of crown ethers with cesium or sodium ions at different pH values with ultrasonic wave in phosphate buffered saline (PBS). Magnetic resonance imaging analysis of the particles reveals a high relaxivity, rendering them potentially useful theranostic agents.

Enhanced cellular uptake and gene delivery of glioblastoma with deferoxamine-coated nanoparticle/plasmid DNA/branched polyethylenimine composites.

Ternary composite nanomaterials based on deferoxamine-coated superparamagnetic iron oxide nanoparticles (8-10 nm), circular plasmid DNA (~4 kb) with fluorescent/luminescent reporter group, and branched polyethylenimine (25 kDa, PDI = 2.5) were prepared and compared in terms of their efficiencies in transfecting brain tumor cells at low concentration.

Folate-conjugated Fe3O4@SiO2@gold nanorods@mesoporous SiO2 hybrid nanomaterial: a theranostic agent for magnetic resonance imaging and photothermal therapy.

In this paper, we investigated the functional imaging and targeted therapeutic properties of core@multi-shell nanoparticles composed of a superparamagnetic iron oxide (SPIO) core and gold nanorods (GNRs) in the mesoporous silica shells functionalized with folic acid (Fe3O4@SiO2@GNRs@mSiO2-FA). The as-synthesized five-component hybrid nanocomposite was revealed to have insignificant cytotoxicity. Intracellular uptake of the nanoparticles was studied in the folate receptor over-expressing human epidermoid carcinoma of the nasopharynx (KB) cells. Due to their magnetic/optical properties as well as the folate targeting potential, compared with Fe3O4@SiO2@GNRs@mSiO2 nanoparticles, higher cellular uptake efficiency was observed for Fe3O4@SiO2@GNRs@mSiO2-FA nanoparticles in KB cells. Characterizations were achieved using both dark field and magnetic resonance (MR) imaging techniques. The hyperthermia induced by Fe3O4@SiO2@GNRs@mSiO2-FA nanoparticles resulted in a higher cytotoxicity in KB cells. Thus, the Fe3O4@SiO2@GNRs@mSiO2-FA hybrid nanomaterial is an effective and promising MR imaging and photothermal therapy agent for folate-receptor over-expressing cancer cells.

Ternary hybrid nanocomposites for gene delivery and magnetic resonance imaging of hepatocellular carcinoma cells.

This paper describes comparative studies in magnetic resonance imaging (MRI) and gene deliveries toward hepatocellular carcinoma (HCC) HepG2 cells with ternary composites that consist of superparamagnetic iron oxide (SPIO) nanoparticles (NPs) (8-10 nm) with deferoxamine coating, circular plasmid DNA (~4 kb) equipped with green fluorescent probe, and branched polyethylenimine (PEI) (25 kDa, PDI 2.5). The packaging of the ternary complexes has been characterized by agarose gel retardation assay. By tuning the PEI/NP ratios and with a fixed DNA amount, different ternary composites have been employed for NP/gene transfection towards HepG2 cells, which have been characterized by in vitro MRI and green fluorescence protein (GFP) fluorescence.

Hollow superparamagnetic iron oxide nanoshells as a hydrophobic anticancer drug carrier: intracelluar pH-dependent drug release and enhanced cytotoxicity.

With curcumin and doxorubicin (DOX) base as model drugs, intracellular delivery of hydrophobic anticancer drugs by hollow structured superparamagnetic iron oxide (SPIO) nanoshells (hydrodynamic diameter: 191.9 ± 2.6 nm) was studied in glioblastoma U-87 MG cells. SPIO nanoshell-based encapsulation provided a stable aqueous dispersion of the curcumin. After the SPIO nanoshells were internalized by U-87 MG cells, they localized at the acidic compartments of endosomes and lysosomes. In endosome/lysosome-mimicking buffers with a pH of 4.5-5.5, pH-dependent drug release was observed from curcumin or DOX loaded SPIO nanoshells (curcumin/SPIO or DOX/SPIO). Compared with the free drug, the intracellular curcumin content delivered via curcumin/SPIO was 30 fold higher. Increased intracellular drug content for DOX base delivered via DOX/SPIO was also confirmed, along with a fast intracellular DOX release that was attributed to its protonation in the acidic environment. DOX/SPIO enhanced caspase-3 activity by twofold compared with free DOX base. The concentration that induced 50% cytotoxic effect (CC(50)) was 0.05 ± 0.03 µg ml(-1) for DOX/SPIO, while it was 0.13 ± 0.02 µg ml(-1) for free DOX base. These results suggested SPIO nanoshells might be a promising intracellular carrier for hydrophobic anticancer drugs.

Photocytotoxicity and magnetic relaxivity responses of dual-porous γ-Fe2O3@meso-SiO2 microspheres.

Novel high magnetization microspheres with porous γ-Fe(2)O(3) core and porous SiO(2) shell were synthesized using a templating method, whereas the size of the magnetic core and the thickness of the porous shell can be controlled by tuning the experimental parameters. By way of an example, as-prepared γ-Fe(2)O(3)@meso-SiO(2) microspheres (170 nm) display excellent water-dispersity and show photonic characteristics under externally applied a magnetic field. The magnetic property of the γ-Fe(2)O(3) porous core enables the microspheres to be used as a contrast agent in magnetic resonance imaging with a high r(2) (76.5 s(-1) mM(-1) Fe) relaxivity. The biocompatible composites possess a large BET surface area (222.3 m(2)/g), demonstrating that they can be used as a bifunctional agent for both MRI and drug carrier. Because of the high substrate loading of the magnetic, dual-porous materials, only a low dosage of the substrate will be acquired for potential practical applications. Hydrophobic zinc(II) phthalocyanine (ZnPC) photosensitizing molecules have been encapsulated into the dual-porous microspheres to form γ-Fe(2)O(3)@meso-SiO(2)-ZnPC microspheres. Biosafety, cellular uptake in HT29 cells, and in vitro MRI of these nanoparticles have been demonstrated. Photocytotoxicity (λ > 610 nm) of the HT29 cells uptaken with γ-Fe(2)O(3)@meso-SiO(2)-ZnPC microspheres has been demonstrated for 20 min illumination.

Enhanced cellular uptake of aminosilane-coated superparamagnetic iron oxide nanoparticles in mammalian cell lines.

PURPOSE: To compare the cellular uptake efficiency and cytotoxicity of aminosilane (SiO(2)-NH(2))-coated superparamagnetic iron oxide (SPIO@SiO(2)-NH(2)) nanoparticles with three other types of SPIO nanoparticles coated with SiO(2) (SPIO@SiO(2)), dextran (SPIO@dextran), or bare SPIO in mammalian cell lines. MATERIALS AND METHODS: Four types of monodispersed SPIO nanoparticles with a SPIO core size of 7 nm and an overall size in a range of 7-15 nm were synthesized. The mammalian cell lines of MCF-7, MDA-MB-231, HT-29, RAW264.7, L929, HepG2, PC-3, U-87 MG, and mouse mesenchymal stem cells (MSCs) were incubated with four types of SPIO nanoparticles for 24 hours in the serum-free culture medium Dulbecco's modified Eagle's medium (DMEM) with 4.5 µg/mL iron concentration. The cellular uptake efficiencies of SPIO nanoparticles were compared by Prussian blue staining and intracellular iron quantification. In vitro magnetic resonance imaging of MSC pellets after SPIO labeling was performed at 3 T. The effect of each SPIO nanoparticle on the cell viability of RAW 264.7 (mouse monocyte/macrophage) cells was also evaluated. RESULTS: Transmission electron microscopy demonstrated surface coating with SiO(2)-NH(2), SiO(2), and dextran prevented SPIO nanoparticle aggregation in DMEM culture medium. MCF-7, MDA-MB-231, and HT-29 cells failed to show notable iron uptake. For all the remaining six cell lines, Prussian blue staining and intracellular iron quantification demonstrated that SPIO@ SiO(2)-NH(2) nanoparticles had the highest cellular uptake efficiency. SPIO@SiO(2)-NH(2), bare SPIO, and SPIO@dextran nanoparticles did not affect RAW 264.7 cell viability up to 200 µg Fe/mL, while SPIO@SiO(2) reduced RAW 264.7 cell viability from 10 to 200 µg Fe/mL in a dose-dependent manner. CONCLUSION: Cellular uptake efficiency of SPIO nanoparticles depends on both the cell type and SPIO surface characteristics. Aminosilane surface coating enhanced the cellular uptake efficiency without inducing cytotoxicity in a number of cell lines.

Gold and iron oxide hybrid nanocomposite materials.

This critical review provides an overview of current research activities that focused on the synthesis and application of multi-functional gold and iron oxide (Au-Fe(x)O(y)) hybrid nanoparticles and nanocomposites. An introduction of synthetic strategies that have been developed for generating Au-Fe(x)O(y) nanocomposites with different nanostructures is presented. Surface functionalisation and bioconjugation of these hybrid nanoparticles and nanocomposites are also reviewed. A variety of applications such as theranostics, gene delivery, biosensing, cell sorting, bio-separation, and catalysis is discussed and highlighted. Finally, future trends and perspectives of these sophisticated nanocomposites are outlined. Underpinning the fundamental requirements for effectively forming Au-Fe(x)O(y) hybrid nanocomposite materials would shed light on future development of nanotheranostics, nanomedicines, and chemical technologies. It would be interesting to investigate such multi-component composite nanomaterials with different novel morphologies in the near future to advance chemistry, biology, medicine, and engineering multi-disciplinary research (120 references).

Synthesis of biocompatible, mesoporous Fe(3)O(4) nano/microspheres with large surface area for magnetic resonance imaging and therapeutic applications.

This article reports the fabrication of mesoporous Fe(3)O(4) nano/microspheres with a high surface area value (163 m(2)/g, Brunauer-Emmett-Teller) and demonstrates their use for drug loading, release, and magnetic resonance imaging (MRI). These monodispersed, mesoporous Fe(3)O(4) nano/microspheres with controllable average sizes ranging from 50 to 200 nm were synthesized using a Fe(3)O(4)/poly(acrylic acid) hybrid sphere template and subsequent silica shell formation and removal. We found that the SiO(2) coating is a crucial step for the successful synthesis of uniform mesoporous Fe(3)O(4) nano/microspheres. The as-synthesized mesoporous Fe(3)O(4) nanospheres show a high magnetic saturation value (M(s) = 48.6 emu/g) and could be used as MRI contrast agents (r(2) = 36.3 s(-1) mM(-1)). Trypan blue exclusion and MTT assay (see Supporting Information ) cytotoxicity analyses of the nanospheres based on HepG2 and MDCK cells showed that the products were biocompatible, with a lower toxicity than lipofectamine (positive control). Hydrophilic ibuprofen and hydrophobic zinc(II) phthalocyanine drug loading into mesoporous Fe(3)O(4) nanospheres and selected release experiments were successfully achieved. The potential use of mesoporous Fe(3)O(4) nanospheres in biomedical applications, in light of the nano/microspheres' efficient drug loading and release, MRI, and low cytotoxicity, has been demonstrated. It is envisaged that mesoporous Fe(3)O(4) nanospheres can be used as drug carriers and MRI contrast agents for the reticuloendothelial system; they can also be delivered locally, such as via a selective catheter.

Efficacy and Durability in Direct Labeling of Mesenchymal Stem Cells Using Ultrasmall Superparamagnetic Iron Oxide Nanoparticles with Organosilica, Dextran, and PEG Coatings.

We herein report a comparative study of mesenchymal stem cell (MSC) labeling using spherical superparamagnetic iron oxide (SPIO) nanoparticles containing different coatings, namely, organosilica, dextran, and poly(ethylene glycol) (PEG). These nanomaterials possess a similar SPIO core size of 6-7 nm. Together with their coatings, the overall sizes are 10-15 nm for all SPIO@SiO2, SPIO@dextran, and SPIO@PEG nanoparticles. These nanoparticles were investigated for their efficacies to be uptaken by rabbit bone marrow-derived MSCs without any transfecting agent. Experimentally, both SPIO@SiO2 and SPIO@PEG nanoparticles could be successfully uptaken by MSCs while the SPIO@dextran nanoparticles demonstrated limited labeling efficiency. The labeling durability of SPIO@SiO2 and SPIO@PEG nanoparticles in MSCs after three weeks of culture were compared by Prussian blue staining tests. SPIO@SiO2 nanoparticles demonstrated more blue staining than SPIO@PEG nanoparticles, rendering them better materials for MSCs labeling by direct uptake when durable intracellullar retention of SPIO is desired.