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Find video protocols related to scientific articles indexed in Pubmed.
Interactions of Skin with Gold Nanoparticles of Different Surface Charge, Shape, and Functionality.
Small
PUBLISHED: 06-30-2014
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The interactions between skin and colloidal gold nanoparticles of different physicochemical characteristics are investigated. By systematically varying the charge, shape, and functionality of gold nanoparticles, the nanoparticle penetration through the different skin layers is assessed. The penetration is evaluated both qualitatively and quantitatively using a variety of complementary techniques. Inductively coupled plasma optical emission spectrometry (ICP-OES) is used to quantify the total number of particles which penetrate the skin structure. Transmission electron microscopy (TEM) and two photon photoluminescence microscopy (TPPL) on skin cross sections provide a direct visualization of nanoparticle migration within the different skin substructures. These studies reveal that gold nanoparticles functionalized with cell penetrating peptides (CPPs) TAT and R7 are found in the skin in larger quantities than polyethylene glycol-functionalized nanoparticles, and are able to enter deep into the skin structure. The systematic studies presented in this work may be of strong interest for developments in transdermal administration of drugs and therapy.
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Hyperspectral darkfield microscopy of single hollow gold nanoparticles for biomedical applications.
Phys Chem Chem Phys
PUBLISHED: 09-04-2013
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Hyperspectral microscopy is a versatile method for simultaneous spatial and spectroscopic characterization of nonfluorescent samples. Here we present a hyperspectral darkfield imaging system for spectral imaging of single nanoparticles over an area of 150 × 150 ?m(2) and at illumination intensities compatible with live cell imaging. The capabilities of the system are demonstrated using correlated transmission electron microscopy and single-particle optical studies of colloidal hollow gold nanoparticles. The potential of the system for characterizing the interactions between nanoparticles and cells has also been demonstrated. In this case, the spectral information proves a useful improvement to standard darkfield imaging as it enables differentiation between light scattered from nanoparticles and light scattered from other sources in the cellular environment. The combination of low illumination power and fast integration times makes the system highly suitable for nanoparticle tracking and spectroscopy in live-cell experiments.
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Gold nanoparticles and fluorescently-labelled DNA as a platform for biological sensing.
Nanoscale
PUBLISHED: 08-29-2013
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In the past decade gold nanoparticle-nucleic acid conjugates became progressively important for biomedical applications. Fluorophores attached to nucleic acid-gold nanoparticle conjugates have opened up a new era of biological sensing. The most promising advancement in this field was the invention of the so-called nano-flare systems. These systems are capable of detecting specific endocellular targets such as mRNAs, microRNAs or small molecules in real time. In this minireview, we discuss the current progress in the field of DNA-nanoparticles as sensors, their properties, stability, cellular uptake and cytotoxicity.
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Interaction of stable colloidal nanoparticles with cellular membranes.
Biotechnol. Adv.
PUBLISHED: 08-05-2013
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Due to their ultra-small size, inorganic nanoparticles (NPs) have distinct properties compared to the bulk form. The unique characteristics of NPs are broadly exploited in biomedical sciences in order to develop various methods of targeted drug delivery, novel biosensors and new therapeutic pathways. However, relatively little is known in the negotiation of NPs with complex biological environments. Cell membranes (CMs) in eukaryotes have dynamic structures, which is a key property for cellular responses to NPs. In this review, we discuss the current knowledge of various interactions between advanced types of NPs and CMs.
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Copper-free click chemistry as an emerging tool for the programmed ligation of DNA-functionalised gold nanoparticles.
Nanoscale
PUBLISHED: 07-04-2013
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We demonstrate a new method to program the ligation of single stranded DNA-modified gold nanoparticles using copper-free click chemistry. Gold nanoparticles functionalized with a discrete number of 3-azide or 5-alkyne modified oligonucleotides, can be brought together via a splint strand and covalently clicked, in a simple one-pot reaction. This new approach to the assembly of gold nanoparticles is inherently advantageous in comparison to the traditional enzymatic ligation. The chemical ligation is specific and takes place at room temperature by simply mixing the particles without the need for special enzymatic conditions. The yield of clicked nanoparticles can be as high as 92%. The ease of the copper-free, click-ligation method allows for its universal applicability and opens up new avenues in programmed nanoparticle organization.
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Manipulation of in vitro angiogenesis using peptide-coated gold nanoparticles.
ACS Nano
PUBLISHED: 05-28-2013
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We demonstrate the deliberate activation or inhibition of invitro angiogenesis using functional peptide coated gold nanoparticles. The peptides, anchored to oligo-ethylene glycol capped gold nanospheres, were designed to selectively interact with cell receptors responsible for activation or inhibition of angiogenesis. The functional particles are shown to influence significantly the extent and morphology of vascular structures, without causing toxicity. Mechanistic studies show that the nanoparticles have the ability to alter the balance between naturally secreted pro- and anti-angiogenic factors, under various biological conditions. Nanoparticle-induced control over angiogenesis opens up new directions in targeted drug delivery and therapy.
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Colloidal branched semiconductor nanocrystals: state of the art and perspectives.
Acc. Chem. Res.
PUBLISHED: 01-31-2013
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Colloidal inorganic nanocrystals are versatile nanoscale building blocks. Advances in their synthesis have yielded nanocrystals with various morphologies including spheres, polyhedra, rods, disks, sheets, wires, and a wide range of branched shapes. Recent developments in chemical methods have allowed the synthesis of colloidal nanocrystals made of sections of different inorganic materials connected together. Many research groups are investigating these nanocrystals structural and photophysical properties experimentally and theoretically, and many have examined their prospects for commercial applications. Branched nanocrystals, in particular, are gaining attention, in part for their potential applications in solar cells or electronic devices. In this Account, we review recent developments in synthesis and controlled assembly of colloidal branched nanocrystals. Synthesis of branched nanocrystals builds on previous work with spherical nanocrystals and nanorods, but a unique factor is the need to control the branching event. Multiple arms can branch from a nucleus, or secondary branches can form from a growing arm. Branching can be governed by mechanisms including twinning, crystal splitting, polymorphism, oriented attachment, and others. One of the most relevant parameters is the choice of appropriate surfactant molecules, which can bind selectively to certain crystal facets or can even promote specific crystallographic phases during nucleation and growth. Also, seeded growth approaches recently have allowed great progress in the synthesis of nanocrystals with elaborate shapes. In this approach, nanocrystals with a specified chemical composition, size, shape, crystalline habit, and phase act as seeds on which multiple branches of a second material nucleate and grow. These approaches yield nanostructures with improved homogeneity in distribution of branch length and cross section. Ion exchange reactions allow further manipulation of branched nanocrystals by transforming crystals of one material into crystals with the same size, shape, and anion sublattice but with a new cation. Combining seeded growth with ion exchange provides a method for greatly expanding the library of branched nanocrystals. Assembly of morphologically complex nanocrystals is evolving in parallel to developments in chemical synthesis. While researchers have made many advances in the past decade in controlled assembly of nanocrystals with simple polyhedral shapes, modeling and experimental realization of ordered superstructures of branched nanocrystals are still in their infancy. In the only case of ordered superstructure reported so far, the assembly proceeds by steps in a hierarchical fashion, in analogy to several examples of assembly found in nature. Meanwhile, disordered assemblies of branched nanocrystals are also interesting and may find applications in various fields.
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Preparation of peptide-functionalized gold nanoparticles using one pot EDC/sulfo-NHS coupling.
Langmuir
PUBLISHED: 07-14-2011
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Although carbodiimides and succinimides are broadly employed for the formation of amide bonds (i.e., in amino acid coupling), their use in the coupling of peptides to water-soluble carboxylic-terminated colloidal gold nanoparticles remains challenging. In this article, we present an optimization study for the successful coupling of the KPQPRPLS peptide to spherical and rodlike colloidal gold nanoparticles. We show that the concentration, reaction time, and chemical environment are all critical to achieving the formation of robust, peptide-coated colloidal nanoparticles. Agarose gel electrophoresis was used for the characterization of conjugates.
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Interactions of human endothelial cells with gold nanoparticles of different morphologies.
Small
PUBLISHED: 07-13-2011
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The interactions between noncancerous, primary endothelial cells and gold nanoparticles with different morphologies but the same ligand capping are investigated. The endothelial cells are incubated with gold nanospheres, nanorods, hollow gold spheres, and core/shell silica/gold nanocrystals, which are coated with monocarboxy (1-mercaptoundec-11-yl) hexaethylene glycol (OEG). Cell viability studies show that all types of gold particles are noncytotoxic. The number of particles taken up by the cells is estimated using inductively coupled plasma (ICP), and are found to differ depending on particle morphology. The above results are discussed with respect to heating efficiency. Using experimental data reported earlier and theoretical model calculations which take into account the physical properties and distribution of particles in the cellular microenvironment, it is found that collective heating effects of several cells loaded with nanoparticles must be included to explain the observed viability of the endothelial cells.
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Laser-induced damage and recovery of plasmonically targeted human endothelial cells.
Nano Lett.
PUBLISHED: 02-15-2011
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Laser-induced techniques that employ the surface plasmon resonances of nanoparticles have recently been introduced as an effective therapeutic tool for destroying tumor cells. Here, we adopt a low-intensity laser-induced technique to manipulate the damage and repair of a vital category of noncancerous cells, human endothelial cells. Endothelial cells construct the interior of blood vessels and play a pivotal role in angiogenesis. The degree of damage and repair of the cells is shown to be influenced by laser illumination in the presence of gold nanoparticles of different morphologies, which either target the cellular membrane or are endocytosed. A pronounced influence of the plasmonic nanoparticle laser treatment on the expression of critical angiogenic genes is shown. Our results show that plasmon-mediated mild laser treatment, combined with specific targeting of cellular membranes, enables new routes for controlling cell permeability and gene regulation in endothelial cells.
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Receptor-mediated interactions between colloidal gold nanoparticles and human umbilical vein endothelial cells.
Small
PUBLISHED: 10-13-2010
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A new strategy to manipulate cell operations is demonstrated, based on membrane-receptor-specific interactions between colloidal peptide-capped gold nanoparticles and human umbilical vein endothelial cells. It is shown that colloidal gold nanoparticles of similar charge and size but capped with different peptide sequences can deliberately trigger specific cell functions related to the important biological process of blood vessel growth known as angiogenesis. Specific binding of the peptide-capped particles to two endothelial-expressed receptors (VEGFR-1, NRP-1), which control angiogenesis, is achieved. The cellular fate of the functional nanoparticles is imaged and the influence of the different peptide-coated nanoparticles on the gene expression profile of hypoxia-related and angiogenic genes is monitored. The findings open up new avenues towards the deliberate biological control of cellular functions using strategically designed nanoparticles.
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Ligand-mediated self-assembly of polymer-enveloped gold nanoparticle chains and networks.
Chem. Commun. (Camb.)
PUBLISHED: 09-13-2010
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We demonstrate a universal approach to assemble gold nanoparticles (AuNPs) into ordered robust nanostructures. Colloidal AuNPs are partially coated by thiol-containing ligands and then destabilised into anisotropic superstructures. In situ polymerization of the surface attached ligands produces enveloped nanoparticle networks with retained nanoplasmonic properties and enhanced stability.
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Enzymatic activity of lipase-nanoparticle conjugates and the digestion of lipid liquid crystalline assemblies.
Langmuir
PUBLISHED: 08-11-2010
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Variants of lipase were attached to gold nanoparticles (NPs) and their enzymatic activity was studied. The two bioengineered lipase variants have been prepared with biotin groups attached to different residues on the protein outer surface. The biotinylation was evidenced by denaturing polyacrylamide gel electrophoresis and quantified by the ([2-(4-hydroxyazobenzene)]benzoic acid spectrophotometric test. NPs of 14 +/- 1 nm diameter coated with thiolated-polyethylene glycol ligands containing controlled proportions of biotin moieties have been prepared and characterized by transmission electron microscopy, UV-vis spectroscopy, small angle neutron scattering, and elemental analysis. These biotin-functionalized NPs were conjugated to lipase using streptavidin as a linker molecule. Enzyme activity assays on the lipase-nanoparticle conjugates show that the lipase loading and activity of the NPs can be controlled by varying the percentage of biotin groups in the particle protecting coat. The lipase-NP conjugates prepared using one variant display higher activity than those prepared using the other variant, demonstrating orientation-dependent enzyme activity. Cryogenic transmission electron microscopy was used to visualize the enzymatic activity of lipase-NP on well-defined lipid substrates. It was found that lipase-coated NPs are able to digest the substrates in a different manner in comparison to the free lipase.
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Programmed assembly of peptide-functionalized gold nanoparticles on DNA templates.
Langmuir
PUBLISHED: 08-03-2010
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We present a novel nanoparticle building block system based on the interactions between short synthetic oligonucleotides and peptides. Gold nanoparticles coated with DNA-binding peptides can be attached to self-organized oligonucleotide templates to formulate well-ordered structures of nanoparticles. By regulating the amount of DNA-binding peptide attached to the nanoparticle surface and using specifically designed oligonucleotides, the nanoparticle assembly can be controlled to form dimers, trimers, and adjustable-length nanoparticle chains as well as more complex structures.
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Diacetylene-containing ligand as a new capping agent for the preparation of water-soluble colloidal nanoparticles of remarkable stability.
Langmuir
PUBLISHED: 01-19-2010
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A new type of strategically designed functional ligands was used to cap gold nanocrystals and form robust colloidal nanoparticles, resistant to pH changes, temperature, and ionic strength variations as well as ligand-exchange reactions. The nanoparticles are coated with ligands that polymerize upon UV-irradiation, consequently embedding the particles in a stable organic shell. The ligand consists of an anchoring thiol group, which binds directly to the nanocrystal surface and two units, one hydrophobic and one hydrophilic. The hydrophobic alkyl unit contains a diacetylene group, which undergoes a 1,4-topochemical polymerization leading to a poly(enyne) structure during UV-irradiation. The hydrophilic unit contains an oligo-ethylene glycol chain, which ensures water solubility, and a terminal carboxylic group. Derived particles were characterized by transmission electron microscopy, surface enhanced Raman spectroscopy, and visible spectroscopy. Their stability was investigated and compared to particles capped with nonpolymerized ligands.
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Directed organization of gold nanoparticles in polymer coatings through infrared-assisted evaporative lithography.
Chem. Commun. (Camb.)
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Infrared-assisted evaporative lithography (IRAEL) is presented as an emerging technology to direct the assembly of gold nanospheres (AuNSs) into large-scale superstructures within colloidal polymeric coatings. The organization of gold nanoparticle arrays within the superstructures can be tuned over length scales, ranging from micrometers up to several millimetres, giving rise to intrinsic plasmonic properties.
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Exocytosis of peptide functionalized gold nanoparticles in endothelial cells.
Nanoscale
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We present the exocytosis profile of two types of peptide-coated nanoparticles, which have similar charge and size but different functionality. While one kind of particles appears to progressively exocytose, the other one has a more complex profile, suggesting that some of the particles are re-uptaken by the cells. Both types of particles retain their colloidal stability after exocytosis.
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Formation and plasmonic response of self-assembled layers of colloidal gold nanorods and branched gold nanoparticles.
Langmuir
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The plasmonic properties of self-assembled layers of rod- and branched-shaped gold nanoparticles were investigated using optical techniques. Nanoparticles were synthesized by a surfactant-guided, seed-mediated growth method. The layers were obtained by gradual assembly of nanoparticles at the interface between a polar and a nonpolar solvent and were transferred to a glass slide. Polarization and angle-dependent extinction measurements showed that the layers made of gold nanorods were governed by an effective medium response. The response of the layers made by branched gold particles was characterized by random light scattering. Microscopic mapping of the spatial mode structure demonstrates a uniform optical response of the nanoparticle layers down to a submicrometer length scale.
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JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.

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In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.