Multifunctional uniform nanoparticles composed of a magnetite nanocrystal core and a mesoporous silica shell for magnetic resonance and fluorescence imaging and for drug delivery

Fluorescent-magnetic hybrid nanoparticles induce a dose-dependent increase in proinflammatory response in lung cells in vitro correlated with intracellular localization

Iron-platinum nanoparticles embedded in a poly(methacrylic acid) (PMA) polymer shell and fluorescently labeled with the dye ATTO 590 (FePt-PMA-ATTO-2%) are investigated in terms of their intracellular localization in lung cells and potential to induce a proinflammatory response dependent on concentration and incubation time. A gold core coated with the same polymer shell (Au-PMA-ATTO-2%) is also included. Using laser scanning and electron microscopy techniques, it is shown that the FePt-PMA-ATTO-2% particles penetrate all three types of cell investigated but to a higher extent in macrophages and dendritic cells than epithelial cells. In both cell types of the defense system but not in epithelial cells, a particle-dose-dependent increase of the cytokine tumor necrosis factor alpha (TNFalpha) is found. By comparing the different nanoparticles and the mere polymer shell, it is shown that the cores combined with the shells are responsible for the induction of proinflammatory effects and not the shells alone. It is concluded that the uptake behavior and the proinflammatory response upon particle exposure are dependent on the time, cell type, and cell culture.

Novel multifunctional nanocomposites: magnetic mesoporous silica nanospheres covalently bonded with near-infrared luminescent lanthanide complexes

In this paper, we report the fabrication and characterization of magnetic mesoporous silica nanospheres covalently bonded with near-infrared (NIR) luminescent lanthanide complexes [denoted as Ln(DBM)(3)phen-MMS (Ln = Nd, Yb)]. Ln(DBM)(3)phen-MMS (Ln = Nd, Yb) nanospheres with an average size of 80-130 nm were synthesized via incorporation of the chelate ligand 5-[N,N-bis-3-(triethoxysilyl)propyl]ureyl-1,10-phenanthroline (phen-Si) into the framework of magnetic mesoporous silica (denoted as phen-MMS), followed by introduction of the Ln(DBM)(3)(H(2)O)(2) (Ln = Nd, Yb) complexes into the nanocomposites via a ligand exchange reaction. The morphological, structural, textural, magnetic, and NIR luminescent properties were well-characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), N(2) adsorption-desorption, a superconducting quantum interference device (SQUID), and photoluminescence spectra. These nanocomposites, which possess high surface area, high pore volume, and well-defined pore size, exhibit two-dimensional hexagonal (P6mm) mesostructures. After ligand-mediated excitation, Ln(DBM)(3)phen-MMS (Ln = Nd, Yb) nanocomposites exhibit the characteristic NIR emission of Nd(3+) and Yb(3+), respectively. Magnetic measurements reveal that these mulfunctional nanocomposites possess superparamagnetic properties at 300 K. The high magnetization values make the nanocomposites respond to the external magnetic field quickly. Additionally, the results indicate that Nd(DBM)(3)phen-MMS nanocomposites may have potential applications for laser systems or the optical amplifiers operating at 1.3 microm and Yb(DBM)(3)phen-MMS nanocomposites have several advantages for potential applications in drug delivery or optical imaging.

Boronic acid functionalized core-satellite composite nanoparticles for advanced enrichment of glycopeptides and glycoproteins

A core-satellite-structured composite material has been successfully synthesized for capturing glycosylated peptides or proteins. This novel hybrid material is composed of a silica-coated ferrite "core" and numerous "satellites" of gold nanoparticles with lots of "anchors". The anchor, 3-aminophenylboronic acid, designed for capturing target molecules, is highly specific toward glycosylated species. The long organic chains bridging the gold surface and the anchors could reduce the steric hindrance among the bound molecules and suppress nonspecific bindings. Due to the excellent structure of the current material, the trap-and-release enrichment of glycosylated samples is quite simple, specific, and effective. Indeed, the composite nanoparticles could be used for enriching glycosylated peptides and proteins with very low concentrations, and the enriched samples can be easily separated from bulk solution by a magnet. By using this strategy, the recovery of glycopeptides and glycoproteins after enrichment were found to be 85.9 and 71.6% separately, whereas the adsorption capacity of the composite nanoparticles was proven to be more than 79 mg of glycoproteins per gram of the material. Moreover, the new composite nanoparticles were applied to enrich glycosylated proteins from human colorectal cancer tissues for identification of N-glycosylation sites. In all, 194 unique glycosylation sites mapped to 155 different glycoproteins have been identified, of which 165 sites (85.1%) were newly identified.

Gold nanoparticles functionalized by gadolinium-DTPA conjugate of cysteine as a multimodal bioimaging agent

The synthesis and characterization of gold nanoparticles coated with Gd-chelate (Au@GdL), where L is a conjugate of DTPA and cysteine, is described. These particles are obtained by the replacement of citrate from the gold nanoparticle surfaces with gadolinium chelate (GdL). The average size of Au@GdL is 14 nm with a loading of GdL reaching up to 2.9x10(3) per particles, and they demonstrate very high R1 relaxivity (approximately 10(5) mM(-1) s(-1)) as well as X-ray attenuation. The R1 relaxivity per [Gd] is 17.9 mM(-1) s(-1). The present system also exhibits macrophage-specific property, as demonstrated by histological and TEM images as well as CT and MR, rendering itself as a new class of T1 multimodal CT/MR contrast agent.

Water-dispersible, multifunctional, magnetic, luminescent silica-encapsulated composite nanotubes

A multifunctional one-dimensional nanostructure incorporating both CdSe quantum dots (QDs) and Fe(3)O(4) nanoparticles (NPs) within a SiO(2)-nanotube matrix is successfully synthesized based on the self-assembly of preformed functional NPs, allowing for control over the size and amount of NPs contained within the composite nanostructures. This specific nanostructure is distinctive because both the favorable photoluminescent and magnetic properties of QD and NP building blocks are incorporated and retained within the final silica-based composite, thus rendering it susceptible to both magnetic guidance and optical tracking. Moreover, the resulting hydrophilic nanocomposites are found to easily enter into the interiors of HeLa cells without damage, thereby highlighting their capability not only as fluorescent probes but also as possible drug-delivery vehicles of interest in nanobiotechnology.

HER2 targeting as a two-sided strategy for breast cancer diagnosis and treatment: Outlook and recent implications in nanomedical approaches

At present, mammary carcinoma is the second most common type of malignant tumor in adult women after lung cancer, as more than one million women are diagnosed with breast cancer every year. Despite advances in diagnosis and treatment, which have resulted in a decrease in mortality in recent decades, breast cancer remains a major public health problem. One of the most significant unresolved clinical and scientific problems is the occurrence of resistance to clinical treatments and their toxicity (and how to predict, prevent and overcome them). However, the heterogeneity of human breast cancer in terms of genetic features, molecular profiles and clinical behavior represents a constraint obstructing the discovery of a solution to the disease. It is currently considered that the chances of success of therapy may increase if the tumor cells are selectively removed before they can evolve to their mature stages up to metastases production. Therefore, novel and more sensitive diagnostic tools are being developed, with the aim of improving the early and noninvasive detection of rising malignancies and the accuracy of tumor tissue localization. Meanwhile, there is an emerging use of targeted therapies in oncology, depending on the expression of specific proteins or genes present in tumor cells. Among the molecular targets considered for the treatment of breast cancer cells so far, we chose to focus on examples involving overexpression and/or gene amplification of "Human Epidermal growth factor Receptor 2" (HER2) protein. In current studies, various types of nanoparticles conjugated with the anti-HER2 monoclonal antibody, the so-called "trastuzumab", are investigated extensively due to promising results in biological and preclinical applications aimed at improving the treatment of breast cancer. In this paper, we present a critical review of the preparation and use of different kinds of trastuzumab-functionalized nanoparticles, with an emphasis on the therapeutic and diagnostic (theranostic) potential of this generation of hybrid nanoparticles, exploiting the multifaceted mechanisms of action of trastuzumab against malignant cells.

Cu2+-labeled, SPION loaded porous silica nanoparticles for cell labeling and multifunctional imaging probes

We have developed an ion-sensing nanoparticle that is comprised of a superparamagnetic iron oxide (SPIO) core encapsulated with a porous silica shell. The latter can be readily anchored with ligands capable of coordinating with positron-emitting metal. Evidently, this nanoparticle has a great potential for use in cell tracking with magnetic resonance (MR) imaging and positron emission tomography (PET). Herein we report the synthesis, surface functionalization and characterization of the magnetic nanoparticle-based probes and evaluate their cell-labeling efficacy, cytotoxicity and relaxivity in comparison to one of the most commonly utilized MRI contrast agents, Feridex.

Optical imaging-guided cancer therapy with fluorescent nanoparticles

The diagnosis and treatment of cancer have been greatly improved with the recent developments in nanotechnology. One of the promising nanoscale tools for cancer diagnosis is fluorescent nanoparticles (NPs), such as organic dye-doped NPs, quantum dots and upconversion NPs that enable highly sensitive optical imaging of cancer at cellular and animal level. Furthermore, the emerging development of novel multi-functional NPs, which can be conjugated with several functional molecules simultaneously including targeting moieties, therapeutic agents and imaging probes, provides new potentials for clinical therapies and diagnostics and undoubtedly will play a critical role in cancer therapy. In this article, we review the types and characteristics of fluorescent NPs, in vitro and in vivo imaging of cancer using fluorescent NPs and multi-functional NPs for imaging-guided cancer therapy.

Multifunctional magnetoplasmonic nanoparticle assemblies for cancer therapy and diagnostics (theranostics)

In this work, we describe the preparation and biomedical functionalities of complex nanoparticle assemblies with magnetoplasmonic properties suitable for simultaneous cancer therapy and diagnostics (theranostics). Most commonly magnetoplasmonic nanostructures are made by careful adaptation of metal reduction protocols which is both tedious and restrictive. Here we apply the strategy of nanoscale assemblies to prepare such systems from individual building blocks. The prepared superstructures are based on magnetic Fe(3) O(4) nanoparticles encapsulated in silica shell representing the magnetic module. The cores are surrounded in a corona-like fashion by gold nanoparticles representing the plasmonic module. As additional functionality they were also coated by poly(ethyleneglycol) chains as a cloaking agent to extend the blood circulation time. The preparation is exceptionally simple and allows one to vary the contribution of each function. Both modules can carry drugs and, in this study, they were loaded with the potential anticancer drug curcumin. A comprehensive set of microscopy, spectroscopy and biochemical methods were applied to characterize both imaging and therapeutic function of the nanoparticle assemblies against leukemia HL-60 cells. High contrast magnetic resonance images and high apoptosis rates demonstrate the success of assembly approach for the preparation of magnetoplasmonic nanoparticles. This technology allows one to easily "dial in" the functionalities in the clinical setting for personalized theranostic regiments.

Polyethyleneimine coating enhances the cellular uptake of mesoporous silica nanoparticles and allows safe delivery of siRNA and DNA constructs

Surface-functionalized mesoporous silica nanoparticles (MSNP) can be used as an efficient and safe carrier for bioactive molecules. In order to make the MSNP a more efficient delivery system, we modified the surface of the particles by a functional group that enhances cellular uptake and allows nucleic acid delivery in addition to traditional drug delivery. Noncovalent attachment of polyethyleneimine (PEI) polymers to the surface not only increases MSNP cellular uptake but also generates a cationic surface to which DNA and siRNA constructs could be attached. While efficient for intracellular delivery of these nucleic acids, the 25 kD PEI polymer unfortunately changes the safety profile of the MSNP that is otherwise very safe. By experimenting with several different polymer molecular weights, it was possible to retain high cellular uptake and transfection efficiency while reducing or even eliminating cationic MSNP cytotoxicity. The particles coated with the 10 kD PEI polymer were particularly efficient for transducing HEPA-1 cells with a siRNA construct that was capable of knocking down GFP expression. Similarly, transfection of a GFP plasmid induced effective expression of the fluorescent protein in >70% cells in the population. These outcomes were quantitatively assessed by confocal microscopy and flow cytometry. We also demonstrated that the enhanced cellular uptake of the nontoxic cationic MSNP enhances the delivery of the hydrophobic anticancer drug, paclitaxel, to pancreatic cancer cells. In summary, we demonstrate that, by a careful selection of PEI size, it is possible to construct cationic MSNP that are capable of nucleotide and enhanced drug delivery with minimal or no cytotoxicity. This novel use of a cationic MSNP extends its therapeutic use potential.

Mechanised nanoparticles for drug delivery

Time and time again humanity is faced with a unifying global crisis that crosses the many great divides in different societies and serves to bring once segregated communities back together as a collective whole. This global community instinctively turns to science to develop the means of addressing its most pressing problems. More often than not, these forces dictate the direction that scientific research takes. This influence is no more apparent than in the field of supramolecular chemistry where, for decades now, its responsibility to tackle such issues has been put on the back burner as a consequence of a lack of platforms with which to deliver this contemporary brand of chemistry to meaningful applications. However, the tide is slowly turning as new materials emerge from the field of nanotechnology that are poised to host the many attractive attributes that are inherent in the chemistry of these supermolecules and also in the mechanostereochemistry of mechanically interlocked molecules (MIMs), which can be reused as a sequel to supramolecular chemistry. Mesoporous silica nanoparticles (SNPs) have proven to be supremely effective solid supports as their surfaces are easily functionalised with either supermolecules or MIMs. In turn, the blending of supramolecular chemistry and mechanostereochemistry with mesoporous SNPs has led to a new class of materials - namely, mechanised SNPs that are effectively biological nanoscale 'bombs' that have the potential to infiltrate cells and then, upon the pulling of a chemical trigger, explode! The development of these materials has been driven by the need to devise new therapies for the treatment of cancer. Recent progress in research promises not only to control the acuteness of this widespread and insidious disease, but also to make the harsh treatment less debilitating to patients. This global scourge is the unifying force that has brought together supramolecular chemistry, mechanostereochemistry and nanotechnology, uniting these three communities for the common good. At the nanoscale level, the mechanism for the release of cargos from the confines of the nanopores in the SNPs is accomplished by way of mechanical modifications made on the surface of these functionalised supports. These mechanical motions rely on both supramolecular, i.e., host-guest complexes, and mechanostereochemical phenomena (e.g., bistable rotaxanes), which are often stimulated by changes in pH, light and redox potentials, in addition to enzymatic catalysis. The future of this field lies in the development of 'smart bombs' wherein the loaded mechanised SNPs are endocytosed selectively by cancer cells, whereupon an intracellular trigger causes release of a cytotoxin, effectively leading to apoptosis. This review serves to highlight (1) the evolution of surface-functionalisation of SNPs with supermolecules and also with MIMs, (2) the mechanisms through which controlled-release of cargo from mechanised SNPs occurs, and (3) results from the in vitro application of these mechanised SNPs.

Multifunctional core-shell nanoparticles as highly efficient imaging and photosensitizing agents

Here we report the preparation of a novel multifunctional core-shell nanocomposite material that contains a nonporous dye-doped silica core and a mesoporous silica shell containing photosensitizer molecules, hematoporphyrin (HP). This architecture allows simultaneous fluorescence imaging and photosensitization treatment. The photosensitizer molecules are covalently linked to the mesoporous silica shell and exhibit excellent photo-oxidation efficiency. The efficiency of photo-oxidation of the core-shell hybrid nanoparticles was demonstrated to be significantly improved over that in the homogeneous solution. The mesoporous silica nanovehicle acts not only as a carrier for the photosensitizers but also as a nanoreactor to facilitate the photo-oxidation reaction. The doping of fluorescence dyes into the nonporous core endows the imaging capability, which has been demonstrated with cell imaging experiments. This approach could be easily extended to conjugate other functional regents if necessary. These multifunctional nanovehicles possess unique advantages in acting as nanocarriers in photodynamic therapy to allow simultaneous high-resolution targeting and treatment.

Stable and functionable mesoporous silica-coated gold nanorods as sensitive localized surface plasmon resonance (LSPR) nanosensors

Core-shell structured Au NRs with a surface-exposed gold core and a mesoporous silica shell (MS Au NRs) were demonstrated as a promising platform for localized surface plasmon resonance (LSPR) based molecular sensing. Mesoporous silica shell not only allows the Au NRs core to be directly exposed to their surrounding environment but also stabilizes Au NRs dispersion in various water-organic mixtures and pure organic solvents. The LSPR band of MS Au NRS displays a stable and linear response in spectral shift to the changes in their surrounding refractive index with a sensitivity of 325 nm/RIU. To demonstrate the application of MS Au NRs as LSPR nanosensors in molecular sensing, the plasmon response to molecular adsorbates (GSH) was demonstrated. MS Au NRs provide a more stable and sensitive response than CTAB-capped Au NRs in GSH sensing. In addition, we have also demonstrated that the LSPR response of Au NRs is highly sensitive to changes of local refractive index in mesoporous silica shell, which renders the feasibility of using MS Au NRs as effective molecule-sensing platforms when mesoporous silica shells were functionalized with various chemical and biological ligands.

Preparation of P(NIPAM-co-AA) microcontainers surface-anchored with magnetic nanoparticles

P(NIPAM-co-AA) microcontainers surface-anchored with magnetic nanoparticles were prepared using PSt/P(NIPAM-co-AA) core/shell microspheres and amino-modified Fe(3)O(4)@SiO(2) particles as building blocks. At first, the PSt/P(NIPAM-co-AA) core/shell microspheres were prepared by seeded emulsion polymerization, and the amino-modified Fe(3)O(4)@SiO(2) particles were prepared by a modified Stober method followed by functionalized by 3-aminopropyltriethoxysilane. Then, the smaller amino-modified Fe(3)O(4)@SiO(2) particles were assembled onto the surface of PSt/P(NIPAM-co-AA) core/shell microspheres by electrostatic interaction. Subsequently, the two particles were permanently combined through amidation reaction between carboxylic groups and amino groups under the catalysis of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide. By dissolving the PSt core with tetrahydrofuran, novel triple-functional microcontainers with superparamagnetism and pH and temperature sensitivity were obtained.

A magnetic, luminescent and mesoporous core-shell structured composite material as drug carrier

In this paper, hydrothermal synthesized Fe3O4 microspheres have been encapsulated with nonporous silica and a further layer of ordered mesoporous silica through a simple sol-gel process. The surface of the outer silica shell was further functionalized by the deposition of YVO4:Eu3+ phosphors, realizing a sandwich structured material with mesoporous, magnetic and luminescent properties. The multifunctional system was used as drug carrier to investigate the storage and release properties using ibuprofen (IBU) as model drug by the surface modification. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS), Fourier transform infrared spectroscopy (FT-IR), N2 adsorption/desorption, photoluminescence (PL) spectra, and superconducting quantum interference device (SQUID) were used to characterized the samples. The results reveal that the material shows typical ordered mesoporous characteristics, and have monodisperse spherical morphology with smooth surface and narrow size distribution. Additionally, the multifunctional system shows the characteristic emission of Eu3+ (5D0-7F(1-4)) even after the loading of drug molecules. Magnetism measurement reveals the superparamagnetic feature of the samples. Drug release test indicates that the multifunctional system shows drug sustained properties. Moreover, the emission intensities of Eu3+ in the drug carrier system increase with the released amount of drug, thus making the drug release be easily tracked and monitored by the change of the luminescence intensity.

Magnetic Nanoparticles for Early Detection of Cancer by Magnetic Resonance Imaging

This article provides a brief overview of recent progress in the synthesis and functionalization of magnetic nanoparticles and their applications in the early detection of malignant tumors by magnetic resonance imaging (MRI). The intrinsic low sensitivity of MRI necessitates the use of large quantities of exogenous contrast agents in many imaging studies. Magnetic nanoparticles have recently emerged as highly efficient MRI contrast agents because these nanometer-scale materials can carry high payloads while maintaining the ability to move through physiological systems. Superparamagnetic ferrite nanoparticles (such as iron oxide) provide excellent negative contrast enhancement. Recent refinement of synthetic methodologies has led to ferrite nanoparticles with narrow size distributions and high crystallinity. Target-specific tumor imaging becomes possible through functionalization of ferrite nanoparticles with targeting agents to allow for site-specific accumulation. Nanoparticulate contrast agents capable of positive contrast enhancement have recently been developed in order to overcome the drawbacks of negative contrast enhancement afforded by ferrite nanoparticles. These newly developed magnetic nanoparticles have the potential to enable physicians to diagnose cancer at the earliest stage possible and thus can have an enormous impact on more effective cancer treatment.

Encapsulation of single quantum dots with mesoporous silica

A new generation of silica encapsulated single quantum dots (QDs) was synthesized based on recent breakthroughs made in coating magnetic nanoparticles and their clusters. In comparison with the traditional Stöber sol-gel method, this new approach is significantly simpler, resulting in QDs with excellent luminescence, stability, size monodispersity, and tunable silica shell thickness. An important finding was that unlike previous reported magnetic and metallic nanoparticles, the QDs coated with only a layer of surfactant molecules were highly unstable and sensitive to the environment. As a consequence, the surfactant stabilized QDs must be prepared fresh and stored in dark before silica coating. The QDs became stable once silica shell formed on their surface and excess surfactants were removed. Further development of this technology particularly by incorporating drugs into the mesosized silica pores will open exciting opportunities in traceable delivery and controlled release of therapeutic agents.

Syndecan-1 mediates the coupling of positively charged submicrometer amorphous silica particles with actin filaments across the alveolar epithelial cell membrane

The cellular interactions and pathways of engineered submicro- and nano-scale particles dictate the cellular response and ultimately determine the level of toxicity or biocompatibility of the particles. Positive surface charge can increase particle internalization, and in some cases can also increase particle toxicity, but the underlying mechanisms are largely unknown. Here we identify the cellular interaction and pathway of positively charged submicrometer synthetic amorphous silica particles, which are used extensively in a wide range of industrial applications, and are explored for drug delivery and medical imaging and sensing. Using time lapse fluorescence imaging in living cells and other quantitative imaging approaches, it is found that heparan sulfate proteoglycans play a critical role in the attachment and internalization of the particles in alveolar type II epithelial cell line (C10), a potential target cell type bearing apical microvilli. Specifically, the transmembrane heparan sulfate proteoglycan, syndecan-1, is found to mediate the initial interactions of the particles at the cell surface, their coupling with actin filaments across the cell membrane, and their subsequent internalization via macropinocytosis. The observed interaction of syndecan molecules with the particle prior to their engagement with actin filaments suggests that the particles initiate their own internalization by facilitating the clustering of the molecules, which is required for the actin coupling and subsequent internalization of syndecan. Our observations identify a new role for syndecan-1 in mediating the cellular interactions and fate of positively charged submicrometer amorphous silica particles in the alveolar type II epithelial cell, a target cell for inhaled particles.