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ABSTRACT: Intracellular glutathione-triggered doxorubicin release from silica nanotubes with hydrophobic labile cap was demonstrated for the drug-resistant cancer cell treatment.
Chemical Communications 02/2013; · 6.17 Impact Factor
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ABSTRACT: An electrical measurement known as Electric Cell-substrate Impedance Sensing (ECIS) has become increasingly applied to the study of cellular viability, proliferation and cytotoxicity with the advantages of label-free, non-invasion and real-time monitoring capability in comparison with other conventional methods (MTS, MTT). With this technique, cells are grown on the micro-sized gold electrodes where the micro-ampere alternative current is applied to measure the impedance changes due to the physiological changes caused by internal or external stimuli. In another field, Silica Nanotubes (SNTs) are a novel class of inorganic structures with promising potentials in bio-separation, drug delivery, imaging and other biomedical applications. In this study, by using ECIS-based self-fabricated cell chip, Cells were cultured on the working electrodes and separately exposure to the 0, 2 microm, 2 microm and 10 microm long at the varying concentrations of SNTs to evaluate the cellular responses such as viability, multiplication time and cytotoxicity. Final results were additionally compared with the MTS method as a reference to review the reliability
Journal of Biomedical Nanotechnology 02/2013; 9(2):286-90. · 4.22 Impact Factor
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ABSTRACT: We investigated the effect of arrayed nanostructures on the cell adhesion rate by forming nanopillars on a PMMA polymer surface, and demonstrated cell patterning tools for the polymer surface without biological or chemical reagents. Nanopillar arrayed structures with various heights (0, 50, 100, 150, and 200nm with 50nm of pitch size and 60nm of diameter) were formed on a PMMA surface by using nano-molding techniques with nanoporous AAO (Anodic Aluminum Oxide) as a template. The nanopillar arrayed structures providenegative effects on the cell adhesion on the non-treated PMMA (moderate hydrophobic, ≥ 80(o) of contact angle), whereas slightly positive and no effects were shown by nanopillar structures on plasma (hydrophilic, ≤ 20(o)) and silane-treated PMMA (moderate, 40(o)∼70(o)), respectively.The microstructure on the polymer surface showed a 20% positive effect on the cell adhesion rate. As a result, nano or micro patterning structures could control the cell adhesion rate (15 to 120%) and it enabled the formation of closed cell patterns on the PMMA surface without chemical or biological surface treatments.
Journal of biotechnology 01/2013; · 2.88 Impact Factor
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ABSTRACT: A simple and reliable drug screening method was developed using peptide hydrogel cell beads coded by quantum dot-embedded silica nanotubes. Very long silica nanotubes were fabricated upon a nanoporous alumina template using sol-gel techniques. The physical shapes of the nanotubes were measured by TEM (Transmission Electron Microscope). Green and red quantum dots embedded in silica nanotubes were applied to peptide hydrogel cell beads as coding materials. This was confirmed by confocal microscopy that examined fluorescence levels and quantum dot shapes. The peptide hydrogel cell beads coded with silica nanotubes were loaded into a PDMS single chamber in order to assess the effect of doxorubicin on HMEC and MCF-7 cells, which was measured in hydrogel cell beads by live and dead cell staining using coding materials. As a result, MCF-7 cancer cells were more affected by doxorubicin than HMEC; however, doxorubicin induced HMEC cell death at a relatively high concentration (> 5 microg/ml).
Journal of Nanoscience and Nanotechnology 05/2011; 11(5):4419-23. · 1.56 Impact Factor
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ABSTRACT: A silica based 3-D nanosurface was developed to enhance the signal intensity of a protein chip by increasing the surface density and reducing the aggregation of captured proteins immobilized on the nanosurface. The 3-D nanosurface was composed of silica nanopillar bundles formed from a nanoporous alumina template using the sol-gel method. The signal intensity of a protein spot increased exponentially when the capture probe was immobilized on a nanosurface with higher roughness and the amount of protein immobilized on the surface was proportional to the roughness of the nanosurface. To further investigate this nanosurface effect, changes in the nanosurface roughness before and after protein immobilization were investigated by AFM. The surface roughness was shown to increase after protein immobilization when the nanosurface initially had a relatively low surface roughness (Rq: 30-40nm); however, the surface roughness decreased after protein immobilization when it initially had a high roughness (Rq: 60-130nm). These results imply that a high nanosurface roughness decreases the overall aggregation of proteins on the surface. These findings were also confirmed by comparing the level of protein aggregation on nanosurfaces with high roughness and low roughness using AFM.
Ultramicroscopy 03/2010; 110(6):659-65. · 2.47 Impact Factor
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ABSTRACT: The recent development of 1D barcode arrays has proved their capabilities to be applicable to highly multiplexed bioassays. This article introduces two magnetic decoding protocols for suspension arrays of shape-coded silica nanotubes to process multiplexed assays rapidly and easily, which will benefit the minimization and automation of the arrays.
In the first protocol, the magnetic nanocrystals are incorporated into the inner voids of barcoded silica nanotubes in order to give the nanotubes magnetic properties. The second protocol is performed by trapping the barcoded silica nanotubes onto streptavidin-modified magnetic beads.
The rapid and easy decoding process was demonstrated by applying the above two protocols to multiplexed assays, resulting in high selectivity. Furthermore, the magnetic bead-trapped barcode nanotubes provided a great opportunity to exclude the use of dye molecules in multiplexed assays by using barcode nanotubes as signals.
The rapid and easy manipulation of encoded carriers using magnetic properties could be used to develop promising suspension arrays for portable bioassays.
Nanomedicine 01/2010; 5(1):77-88. · 5.05 Impact Factor
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ABSTRACT: Multifunctional silica nanotubes (SNTs) are being widely used for many biomedical applications due to their structural benefits. Controlling the structure of the open end of an SNT is a crucial step for drug/gene delivery and for fabrication of multifunctional SNTs. We developed a mechanical capsulation method to fabricate caps at the ends of SNTs. A thin layer of malleable capping materials (Au, Ag, PLGA) was deposited onto the surface of an SNT-grown AAO template. Capped SNTs were then obtained by hammering with alumina microbeads. For a proof-of-concept experiment, we demonstrated dye-encapsulated SNTs without any chemical functionalizations. Since a mechanical approach is free of the issue of chemical compatibility between cargo molecules and capping materials, the method can provide an effective platform for the preparation of smart multifunctional nanotubes for biomedical applications.
Journal of the American Chemical Society 10/2009; 131(43):15574-5. · 9.91 Impact Factor
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ABSTRACT: The neural basis of ambivalence has not yet been identified. We investigated the prefrontal cortical activations implicated in evaluative processing of ambivalent stimuli under the forced and non-forced response conditions. Cerebral blood flow was measured using H(2)(15)O positron emission tomography in twelve normal volunteers during a modified word-stem completion task that was designed to evoke different conditions of ambivalence. The prefrontal cortical activations were restricted to the orbitofrontal cortex during the non-forced ambivalent condition, whereas the ventrolateral prefrontal cortex and the frontopolar cortex were activated in addition to the orbitofrontal cortex during the forced ambivalent condition. It is remarkable that the orbitofrontal cortex and the ventrolateral prefrontal cortex demonstrated a reciprocal activation pattern, which might be linked to the evaluative attitude toward the ambivalent stimuli.
Brain research 11/2008; 1246:136-43. · 2.46 Impact Factor
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ABSTRACT: Nanotubes are fabricated by atomic layer deposition (ALD) into nanopore arrays created by anodic aluminum oxide (AAO). A transmission electron microscopy (TEM) methodology is developed and applied to quantify the ALD conformality in the nanopores (thickness as a function of depth), and the results are compared to existing models for ALD conformality. ALD HfO2 nanotubes formed in AAO templates are released by dissolution of the Al2O3, transferred to a grid, and imaged by TEM. An algorithm is devised to automate the quantification of nanotube wall thickness as a function of position along the central axis of the nanotube, by using a cylindrical model for the nanotube. Diffusion-limited depletion occurs in the lower portion of the nanotubes and is characterized by a linear slope of decreasing thickness. Experimentally recorded slopes match well with two simple models of ALD within nanopores presented in the literature. The TEM analysis technique provides a method for the rapid analysis of such nanostructures in general, and is also a means to efficiently quantify ALD profiles in nanostructures for a variety of nanodevice applications.
Small 08/2008; 4(8):1223-32. · 8.35 Impact Factor
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ABSTRACT: Arrays of gold nanocones have been fabricated by the nanotransfer printing (nTP) method and we have utilized these nanocones for field emission. By the nature of the printing, any shape of metal structure can be fabricated only at desired locations and a step-and-repeat process, which enables large-area fabrication, is possible. We demonstrate step-and-repeat printing with gold nanocone patterns occupying an area of 9 mm × 8 mm.
Nanotechnology 07/2008; 19(29):295302. · 3.98 Impact Factor
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ABSTRACT: Magnetic nanoparticles have been studied widely as MRI contrast agents to increase the sensitivity of this technique. This work describes the synthesis and characterization of magnetic nanotubes (MNTs) as a novel MRI contrast agent.
MNTs with high saturation magnetization were fabricated by the synthesis of superparamagnetic iron oxide nanoparticles (SPIONs) directly in the pores of silica nanotubes (SNTs). The MNTs were characterized by electron microscopy, superconducting quantum interference device and MRI. Preliminary studies on in vitro cytotoxicity and cell labeling were carried out.
The MNTs retained the superparamagnetic characteristics in bulk solutions with a considerably high saturation magnetization of 95 emu/gFe. The nuclear magnetic resonance (NMR) relaxivities for MNTs of 500 nm in length and of 60 nm in diameter were r(1) = 1.6 +/- 0.3 mM(-1)s(-1) and r(2) = 264 +/- 56 mM(-1)s(-1) and, for the MNTs of 2 microm in length and 70 nm in diameter, the r(1) and r(2) were 3.0 +/- 1.3 and 358 +/- 65 mM(-1)s(-1), respectively. In vitro cell labeling showed promising results with excellent labeling efficiency. No cellular toxicity was observed in vitro.
The integration of SPIONs with SNTs imparts the superparamagnetic characteristics of SPIONs onto the SNTs, creating unique magnetic nanoparticles with multifunctionality. The MNTs showed promising results as a MRI contrast agent with high NMR relaxivities, little cytotoxicity and high cell-labeling efficiency.
Nanomedicine 05/2008; 3(2):163-74. · 5.05 Impact Factor
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09/2007; , ISBN: 9783527610419
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ABSTRACT: Inorganic nanoparticles, such as carbon nanotubes, quantum dots and gold nanoshells, have been adopted for biomedical use, due to their unique optical and physical properties. Compared to conventional materials, inorganic nanomaterials have several advantages such as simple preparative processes and precise control over their shape, composition and size. In addition, inorganic porous nanomaterials are fundamentally advantageous for developing multifunctional nanomaterials, due to their distinctive inner and outer surfaces. In this review, we describe recent developments of hollow and porous inorganic nanomaterials in nanomedicine, especially for imaging/diagnosis and photothermal therapy.
Drug Discovery Today 09/2007; 12(15-16):657-63. · 6.83 Impact Factor
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ABSTRACT: Recent cytotoxicity studies on carbon nanotubes have shown that the biocompatibility of nanomaterial might be determined mainly by surface functionalization, rather than by size, shape, and material. Although the cytotoxicity for individual inorganic hollow nanomaterials should be extensively tested in vitro and in vivo, potential safety concerns about the use of inorganic nanomaterials in biomedical applications could be alleviated with proper surface treatment. Inorganic hollow nanoparticles and nanotubes have attracted great interest in nanomedicine because of the generic transporting ability of porous material and a wide range of functionality that arises from their unique optical, electrical, and physical properties. In this review, we describe recent developments of hollow and porous inorganic nanomaterials in nanomedicine, especially for drug/gene delivery.
Drug Discovery Today 09/2007; 12(15-16):650-6. · 6.83 Impact Factor
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ABSTRACT: A suspension array for multiplexed immunoassays has been developed using shape-coded silica nanotubes (SNTs) as coding materials. Fabricated by multistep anodization template synthesis, each shape-coded SNT has several segments with different reflectance values depending on their diameters and wall thicknesses. Therefore, the code of each SNT can be "read-out" under a conventional optical microscope. The suspension array with shape-coded SNTs has shown high stability and dispersibility in aqueous buffer media and high detection sensitivity. The SNTs have not shown any visible degradation while submerged in aqueous solution for 7 months, the tubular structure and silanol groups on the inner and outer surfaces allow SNTs to disperse evenly in buffer solution, and the detection limit of an IgG protein is about 6 pM with 1.5 x 10(6) SNTs per mL. We have demonstrated the high selectivity of the SNTs suspension array for the detection of multianalytes in the multiplexed immunoassay experiments.
Analytical Chemistry 08/2007; 79(14):5257-63. · 5.86 Impact Factor
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ABSTRACT: Multiplexed marker protein assay is critical in the diagnosis of complex diseases that cannot be diagnosed by detection of a single marker protein. Gold nanoparticle (Au NP) probes barcoded with reporter DNAs and magnetic microparticles functionalized with a capture antibody were developed for the multiplexed detection of three cancer marker proteins. Three types of Au NP probes were used and each Au NP probe was cofunctionalized with reporter (barcode) DNAs and a specific antibody for each corresponding target protein. Target proteins (antigens) were exposed to magnetic microparticles to form complexes and Au NP probes bound to the resulting target-magnetic microparticle complex through antigen-antibody interaction in a different region of the target protein. After magnetic separation of the complexes, barcode DNAs were released, hybridized with capture DNAs printed on a chip and then identified using a scanometric assay that involved silver amplification. Using this method, Mirkin and colleagues successfully demonstrated, for the first time, a highly selective and sensitive multiplexed protein assay against three cancer marker proteins at low picomolar concentration in a buffer of serum media.
Nanomedicine 03/2007; 2(1):79-82. · 5.05 Impact Factor
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ABSTRACT: Multifunctionality of nanotubes (NTs) is essential in biomedical and biotechnological applications, such as drug/gene delivery, bioseparation, and single-molecule detection. Each functionality should be located at optimal positions, depending on their roles such as targeting, tracking, and transporting. This enables avoidance of possible malfunctions or interference caused by having randomly distributed multiple groups (e.g., hydrophobic and hydrophilic) in the same space. In the aspect of multifunctionality, however, a general selective partial functionalization method of NT inner surfaces still remains a challenge. For this reason, we investigated a selective partial functionalization method of NTs using controlled gold nanoparticle (Au NP) diffusion in nanotubes and the preparation method of Au-capped silica nanotubes. Silica nanotubes (SNTs) were prepared using template sol-gel synthesis, and the inside of SNT was selectively modified with (3-trimethoxysilylpropyl) diethylenetriamine (DETA-silane). Au NPs of 2-nm size were then incubated with SNTs with DETA layer inside. Spontaneous diffusion of negatively charged Au NPs from bulk into the positively charged nanochannels of SNTs led trapped Au NPs onto the inner surface of SNTs. The degree of functionalization was controlled by the channel diameter, Au NP concentration, and solvent type. These SNTs partially modified with Au NPs were then used for localized selective chemical functionalization of SNTs. This was accomplished by the reaction between thionylated Au NPs trapped on the inside of SNTs and Alexa555-maleimide. Au-capped SNTs were prepared from SNTs with Au NPs inside by seed-mediated gold growth.
Journal of the American Chemical Society 01/2007; 128(50):15974-5. · 9.91 Impact Factor
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ABSTRACT: Shape-coded silica nanotubes (SNTs) were fabricated on the basis of template synthesis as a new dispersible microarray system. The template synthesis of shape-coded SNTs begins with the fabrication of a porous alumina film that has well-defined cylindrical pores with two or more different diameter segments by multistep anodization of an aluminum substrate. Then, SNTs were fabricated with a surface sol-gel method that can control the wall thickness of SNTs on the single-nanometer level. Attractively, the difference in optical reflectance between the segmented parts of individual silica nanotube makes it very convenient to identify each nanotube and enables these shape-coded SNTs to work as coding materials for biosensing.
Langmuir 10/2006; 22(20):8263-5. · 4.19 Impact Factor
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ABSTRACT: In the past few decades, nanoscale materials have been widely used for controlled release applications. Importantly, many researches have focused on multifunctional nanoparticles for targeted delivery of bioactive and imaging agents as therapeutics and diagnostics. Recent advances in nanotechnology have made possible the design and development of tubular nanoscale particles called nanotubes. The tubular shape of such particles is highly attractive since it is possible to differentially functionalize the inner and outer surfaces to facilitate drug loading, biocompatibility and biorecognition. Novel synthetic strategies allow the fabrication of tubular structures with well-defined diameters and lengths. This can have important implications in biodistribution, subcellular trafficking and drug release. In this article the biomedical applications of nanotubes will be discussed with emphasis on the template synthesis of composite nanotubes containing silica and iron oxide that have potential use in drug delivery, magnetic resonance imaging (MRI), and chemical and biochemical separations.
Journal of Controlled Release 09/2006; 114(2):143-52. · 5.73 Impact Factor
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ABSTRACT: The development of template-synthesized silica nanotubes has created a unique opportunity for studying confined fluids by providing nanometer-scale containers in which the inner diameter (i.d.) and surface chemistry can be systematically and independently varied. An interesting question to be answered is the following: do solvents wet nanometer-scale tubes in the same way they wet ordinary capillaries? To answer this question, we have conducted studies to explore the wettability of the hydrophobic interiors of individual nanotubes. In these studies, single nanotubes with i.d.'s of either 30 or 170 nm were investigated over a range of water/methanol mixtures. These studies provide a direct route for comparing wetting phenomena in nanotubes with conventional macroscopic theories of capillarity. Our observations reveal four important aspects of capillary wetting in the 30-170 nm regime, a size range where the application of the Young-Laplace theory has not been experimentally investigated for hydrophobic pores. They are (i) a sharp transition between wetting and nonwetting conditions induced by addition of a cosolvent, (ii) invariance of this transition between nanotubes of 30 and 170 nm pore diameter, (iii) failure of the Young-Laplace equation to accurately predict the cosolvent's (methanol) mol fraction where the transition occurs, and (iv) reversibility of the observed wetting. The first two aspects conform to conventional capillarity (Young-Laplace), but the latter two do not. These measurements were complemented with ensemble experiments. The difference between theory and experiment is likely due to reliance on macroscopic values of contact angles or to liquid-phase instability within the hydrophobic pore.
Journal of the American Chemical Society 01/2006; 127(49):17385-92. · 9.91 Impact Factor
