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gold nanoparticles

Lichao Sun, Qingfeng Zhang, Guangfang Grace Li, Esteban Villarreal, Xiaoqi Fu, Hui Wang
Kinetically controlled, seed-mediated coreduction provides a robust and versatile synthetic approach to multimetallic nanoparticles with precisely controlled geometries and compositions. Here we demonstrate that single-crystalline cylindrical Au nanorods selectively transform into a series of structurally distinct Au@Au-Pd alloy core-shell bimetallic nanorods with exotic multifaceted geometries enclosed by specific types of facets upon seed-mediated Au-Pd coreduction under diffusion controlled conditions. By adjusting several key synthetic parameters, such as the Pd/Au precursor ratio, the reducing agent concentration, the capping surfactant concentration, and foreign metal ion additives, we have been able to simultaneously fine-tailor the atomic-level surface structures and fine-tune the compositional stoichiometries of the multifaceted Au-Pd bimetallic nanorods...
February 23, 2017: ACS Nano
Miguel Sison, Sabyasachi Chakrabortty, Jérôme Extermann, Amir Nahas, Paul James Marchand, Antonio Lopez, Tanja Weil, Theo Lasser
We present a 3D time-lapse imaging method for monitoring mitochondrial dynamics in living HeLa cells based on photothermal optical coherence microscopy and using novel surface functionalization of gold nanoparticles. The biocompatible protein-based biopolymer coating contains multiple functional groups which impart better cellular uptake and mitochondria targeting efficiency. The high stability of the gold nanoparticles allows continuous imaging over an extended time up to 3000 seconds without significant cell damage...
February 23, 2017: Scientific Reports
Wenqian Wang, Yaya Cheng, Yansheng Li, Hao Zhou, Li-Ping Xu, Yongqiang Wen, Liang Zhao, Xueji Zhang
The formation and metastatic colonization of circulating tumor cells (CTCs) are responsible for the vast majority of cancer-related deaths. Over the last decade, drug delivery system (DDS) has been rapidly developed with nanotechnology arising, however, most of the reported tumor-targeting DDSs were just able to deliver drugs to the solid tumor cells but not CTCs. In here, a novel drug delivery system was constructed with composite nanofiber film to inhibit the viability of circulating tumor cells (CTCs). In this system, gold nanoparticles (Au NPs) were functionalized with doxorubicin (DOX) through an acid-responsive cleavable linker to get the Au-DOX NPs...
February 23, 2017: ChemMedChem
Peter Hermansen, Scott MacKay, David Wishart, Jie Chen, Peter Hermansen, Scott MacKay, David Wishart, Jie Chen, David Wishart, Peter Hermansen, Scott MacKay, Jie Chen
Microfabricated interdigitated electrode chips have been designed for use in a unique gold-nanoparticle based biosensor system. The use of these electrodes will allow for simple, accurate, inexpensive, and portable biosensing, with potential applications in diagnostics, medical research, and environmental testing. To determine the optimal design for these electrodes, finite element analysis simulations were carried out using COMSOL Multiphysics software. The results of these simulations determined some of the optimal design parameters for microfabricating interdigitated electrodes as well as predicting the effects of different electrode materials...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Hao Shen, Li Chen, Lorenzo Ferrari, Meng-Hsien Lin, N Asger Mortensen, Shangjr Gwo, Zhaowei Liu
The advances in recent nanofabrication techniques have facilitated explorations of metal structures into nanometer scales, where the traditional local-response Drude model with hard-wall boundary conditions fails to accurately describe their optical responses. The emerging nonlocal effects in single ultrasmall silver nanoparticles have been experimentally observed in single-particle spectroscopy enabled by the unprecedented high spatial resolution of electron energy loss spectroscopy (EELS). However, unambiguous optical observation of such new effects in gold nanoparticles has yet not been reported, due to the extremely weak scattering and the obscuring fingerprint of strong interband transitions...
February 22, 2017: Nano Letters
Yan Wu, Fubing Xiao, Zhaoyang Wu, Ruqin Yu
A novel aptasensor platform has been developed for quantitative detection of adenosine triphosphate (ATP) based on a ratiometric surface-enhanced Raman scattering (SERS) strategy. The thiolated 3'-Rox-labeled complementary DNA (cDNA) is first immobilized on the gold nanoparticle (AuNP) surface and then hybridizes with the 3'-Cy5-labeled ATP-binding aptamer probe (Cy5-aptamer) to form a rigid double-stranded DNA (dsDNA), in which the Cy5 and Rox Raman labels are used to produce the ratiometric Raman signals...
February 22, 2017: Analytical Chemistry
Hilary L Byrne, Yaser Gholami, Zdenka Kuncic
The addition of gold nanoparticles within target tissue (i.e. a tumour) to enhance the delivered radiation dose is a well studied radiotherapy treatment strategy, despite not yet having been translated into standard clinical practice. While several studies have used Monte Carlo simulations to investigate radiation dose enhancement by Auger electrons emitted from irradiated gold nanoparticles, none have yet considered the effects due to escaping fluorescence photons. Geant4 was used to simulate a water phantom containing 10 mg/mL uniformly dispersed gold (1% by mass) at 5cm depth...
February 22, 2017: Physics in Medicine and Biology
Maria Sanroman-Iglesias, Charles Lawrie, Luis M Liz-Marzán, Marek Grzelczak
Circulating DNA (ctDNA) and specifically the detection cancer-associated mutations in liquid biopsies promises to revolutionize cancer detection. The main difficulty however is that the length of typical ctDNA fragments (~150 bases) can form secondary structures potentially obscuring the mutated fragment from detection. We show that an assay based on gold nanoparticles (65 nm) stabilized with DNA (Au@DNA) can discriminate single nucleotide polymorphism in clinically-relevant DNA sequences (70-140 bases). The preincubation step was crucial to this process, allowing sequential bridging of Au@DNA, so that single base mutation can be discriminated, down to 100 pM concentration...
February 22, 2017: Bioconjugate Chemistry
Gaosong Chen, Jun Hai, Hao Wang, Weisheng Liu, Fengjuan Chen, Baodui Wang
Nowadays, the development of a multifunction system for the simultaneous multiple signal amplification detection and fast removal of Hg(2+) remains a major challenge. Herein, we for the first time used gold nanoparticles (Au NPs) and the corresponding filter membrane as chemosensors and adsorbents for dual signal amplification detection and fast removal of Hg(2+). Such a system was based on the formation of gold amalgam and a gold amalgam-based reaction between rhodamine B (RhB) and NaBH4 with fluorescence and colorimetric sensing functions...
February 22, 2017: Nanoscale
Syed Baker, Azmath Pasha, Sreedharamurthy Satish
The present study emphasizes on synthesis of bimetallic silver-gold nanoparticles from cell free supernatant of Pseudomonas veronii strain AS41G inhabiting Annona squamosa L. The synthesized nanoparticles were characterized using hyphenated techniques with UV-Visible spectra ascertained absorbance peak between 400 and 800 nm. Possible interaction of biomolecules in mediating and stabilization of nanoparticles was depicted with Fourier transform infrared spectroscopy (FTIR). X-ray diffraction (XRD) displayed Bragg's peak conferring the 1 0 0, 1 1 1, 2 0 0, and 2 2 0 facets of the face centered cubic symmetry of nanoparticles suggesting that these nanoparticles were crystalline in nature...
January 2017: Saudi Pharmaceutical Journal: SPJ: the Official Publication of the Saudi Pharmaceutical Society
Ahmed Alalaiwe, Georgia Roberts, Paul Carpinone, John Munson, Stephen Roberts
Metallic nanoparticles can be produced in a variety of shapes, sizes, and surface chemistries, making them promising potential tools for drug delivery. Most studies to date have evaluated uptake of metallic nanoparticles from the GI tract with methods that are at best semi-quantitative. This study used the classical method of comparing blood concentration area under the curve (AUC) following intravenous and oral doses to determine the oral bioavailability of 1, 2 and 5 kDa PEG-coated 5 nm gold nanoparticles (AuNPs)...
November 2017: Drug Delivery
Si-Jing Ding, Da-Jie Yang, Jin-Ling Li, Gui-Ming Pan, Liang Ma, Yong-Jie Lin, Jia-Hong Wang, Li Zhou, Min Feng, Hongxing Xu, Shiwu Gao, Qu-Quan Wang
The surface plasmon resonance (SPR) of metal nanoparticles exhibits quantum behaviors as the size decreases owing to the transitions of quantized conduction electrons, but most studies are limited to the monotonous SPR blue-shift caused by off-resonant transitions. Here, we demonstrate the nonmonotonous SPR red-shift caused by resonant electron transitions and photocatalytic activity enhanced by the quantum plasmon resonance of colloidal gold nanoparticles. A maximal SPR wavelength and the largest photocatalytic activity are observed in the quantum regime for the first time for the gold nanoparticles with a diameter of 3...
February 21, 2017: Nanoscale
M Decker, T Pertsch, I Staude
We study resonant photonic-plasmonic coupling between a gold dipole nanoantenna and a silicon nanodisc supporting electric and magnetic dipolar Mie-type resonances. Specifically, we consider two different cases for the mode structure of the silicon nanodisc, namely spectrally separate and spectrally matching electric and magnetic dipolar Mie-type resonances. In the latter case, the dielectric nanoparticle scatters the far fields of a unidirectional Huygens' source. Our results reveal an anticrossing of the plasmonic dipole resonance and the magnetic Mie-type dipole resonance of the silicon nanodisc, accompanied by a clear signature of photonic-plasmonic mode hybridization in the corresponding mode profiles...
March 28, 2017: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
Raja Chinnappan, Sana Al Attas, Gerrit Koop, Tine van Werven, Wendy E Kaman, Floris J Bikker, Mohammed Zourob
Mastitis in dairy cattle is an inflammatory reaction of the udder tissue. Mastitis increases plasmin levels, leading to an increased proteolysis of milk proteins such as casein, resulting in a significant decrease in milk quality and related dairy products. Due to its key-role in mastitis, we used plasmin proteolytic activity as a biomarker for the detection of mastitis in bovine mastitic milk. Inspired by earlier studies on protease activity using mastitic milk samples, we developed a simple colorimetric assay to distinguish mastitic milk from milk derived from healthy animals...
February 17, 2017: Analytical Biochemistry
Teng Cui, Juan-Juan Liang, Huan Chen, Dong-Dong Geng, Lei Jiao, Jian-Yong Yang, Hai Qian, Can Zhang, Ya Ding
Drug-conjugated gold nanoparticles (GNPs), which are generally constructed with many molecules of thiol-terminated polyethylene glycol (PEG)-drug decorated on their surfaces via a thiol-Au covalent bond, are promising and efficient nanoprodrugs. However, due to the exposure of the hydrophobic drug molecules on the surface of the conjugate, in vivo stability, opsonization, and subsequent inefficient therapy become the main issues of this system. To solve these problems without complicating the structures of gold conjugates, herein we propose a method to change the relative position of PEG and the drug...
February 20, 2017: ACS Applied Materials & Interfaces
Sang Bong Lee, Sang-Woo Lee, Shin Young Jeong, GhilSuk Yoon, Sung Jin Cho, Sang Kyoon Kim, In-Kyu Lee, Byeong-Cheol Ahn, Jaetae Lee, Yong Hyun Jeon
The development of highly sensitive, stable, and biocompatible imaging agents allowing visualization of dendritic cell (DC) migration is one of the essential factors for effective DC-based immunotherapy. Here, we used a novel and efficient synthesis approach to develop Radioiodine-124-labeled Tannic Acid Gold Core-Shell Nanoparticles (124I-TA-Au@AuNPs) for DC labeling and in vivo tracking of their migration using positron emission tomography (PET). 124I-TA-Au@AuNPs were produced within 40 min in high yield via straightforward tannic acid-mediated radiolabeling chemistry and incorporation of Au shell, which resulted in high radio-sensitivity and excellent chemical stability of nanoparticles in DCs and living mice...
February 20, 2017: ACS Applied Materials & Interfaces
Chenqi Shen, Xiang Lan, Chenggan Zhu, Wei Zhang, Leyu Wang, Qiangbin Wang
Plasmonic motifs with precise surface recognition sites are crucial for assembling defined nanostructures with novel functionalities and properties. In this work, a unique and effective strategy is successfully developed to pattern DNA recognition sites in a helical arrangement around a gold nanorod (AuNR), and a new set of heterogeneous AuNR@AuNP plasmonic helices is fabricated by attaching complementary-DNA-modified gold nanoparticles (AuNPs) to the predesigned sites on the AuNR surface. AuNR is first assembled to one side of a bifacial rectangular DNA origami, where eight groups of capture strands are selectively patterned on the other side...
February 20, 2017: Advanced Materials
Xinghua Xia, Chen Wang, Yi Shi, Xing-Guo Nie, Yuan-Yuan Dan, Jian Li
Enzyme mimics have been widely used as alternatives to natural enzymes. However, the catalytic performances of enzyme mimics are often decreased due to different spatial structures or absence of functional groups compared to natural enzymes. Herein, we report a highly efficient enzyme-like catalytic performance of gold nanoparticles (AuNPs) by visible light stimulation. The enzyme-like reaction is evaluated by the catalytic reaction of AuNPs oxidizing a typical chromogenic substrate 3, 3', 5, 5'-tetramethylbenzydine (TMB) with hydrogen peroxide as an oxidant...
February 20, 2017: Chemistry: a European Journal
S Khabbaz Abkenar, A Tufani, G Ozaydin Ince, H Kurt, A Turak, C W Ow-Yang
For the transfer of 2-D gold nanoparticle arrays between different substrates, we have developed a new method using thermo-responsive poly-N-isopropylacrylamide (pNIPAAm). By tuning the degree of surface hydrophilicity of pNIPAAm between 5 °C and 50 °C, we demonstrate the transfer of arrays extending over micron-scale areas with preservation of array properties.
February 20, 2017: Nanoscale
Xiaohua Huang, Ryan O'Connor, Elyahb Allie Kwizera
Detection of cancer-related circulating biomarkers in body fluids has become a cutting-edge technology that has the potential to noninvasively screen cancer, diagnose cancer at early stage, monitor tumor progression, and evaluate therapy responses. Traditional molecular and cellular detection methods are either insensitive for early cancer intervention or technically costly and complicated making them impractical for typical clinical settings. Due to their exceptional structural and functional properties that are not available from bulk materials or discrete molecules, nanotechnology is opening new horizons for low cost, rapid, highly sensitive, and highly specific detection of circulating cancer markers...
2017: Nanotheranostics (Syd)
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