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Gold nanoparticle

Liyan Kong, Jiaming Zhu, Wen Wang, Lehe Jin, Yanjiao Fu, Bohui Duan, Liang Tan
As an integral glycoprotein on the surface of endothelial cells, thrombomodulin (TM) has very high affinity for thrombin. TM has been regarded to be a marker of endothelial damage since it can be released during endothelial cell injury. In this work, a highly sensitive fluorescence method for the quantitative detection of TM was developed. TM antibody (Ab) and bovine serum albumin (BSA) were bound on gold nanoparticles (AuNPs) to construct BSA-AuNPs-Ab nanocomposites and they were characterized by transmission electron microscope and UV-vis spectrophotometry...
October 17, 2016: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Sujin Ahn, Peng Zhang, Hyunung Yu, Seungah Lee, Seong Ho Kang
Super-localization of immunoplasmonic nanotags on antibody-bound gold-nanoislands (GNIs) along the x, y coordinates was determined using total internal reflection scattering-based super-resolution microscopy (TIRS-SRM) at subdiffraction limit resolu-tion. Individual immunoplasmonic nanotags (20-nm silver nanoparticles) and 100-nm GNIs were selectively acquired in the eva-nescent field layer by wavelength-dependent plasmonic scattering using two illumination lasers (405 nm and 635 nm, respectively). Alpha-fetoprotein (AFP), a liver cancer-related model protein, was immobilized as a target molecule on the GNI arrays...
October 25, 2016: Analytical Chemistry
Sean Murphy, Sarah Jaber, Cameron Ritchie, Matthias Karg, Paul Mulvaney
Hydrophobic forces play a key role in the processes of collapse and re-swelling of thermoresponsive polymers. However little is known about the dynamics of these processes. Here, thermoresponsive poly(N-isopropylacrylamide) encapsulated gold nanoparticles (Au-PNIPAM) are heated via nanosecond laser flash photolysis. Photothermal heating via excitation of the localized surface plasmon resonance of the Au nanoparticle cores results in rapid PNIPAM shell collapse within the 10 ns pulse width of the laser. Remarkably, re-swelling of the polymer shell takes place in less than 100 nanoseconds...
October 25, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Tzu-Heng Wu, Chia-Chen Chang, Julien Vaillant, Aurélien Bruyant, Chii-Wann Lin
Smartphone camera based gold nanoparticle colorimetry (SCB-AuNP colorimetry) has shown good potential for point-of-care applications. However, due to the use of a camera as a photo-detector, there are major limitations to this technique such as a low bit resolution (∼8 bits mainstream) and a low data acquisition rate. These issues have limited the ultimate sensitivity of smartphone based colorimetry as well as the possibility to integrate efficiently a more sensitive approach such as detection based on a lock-in amplifier (LIA)...
October 25, 2016: Lab on a Chip
Kamlesh Shrivas, Pathik Maji, Khemchand Dewangan
We report a simple, selective and sensitive colorimetric assay for onsite determination of Ni(II) and Ba(II) from river, pond and tap water samples using the localized surface plasmon resonance (LSPR) of malonate capped gold nanoparticles (AuNPs) as a chemical sensor. The method is based on the color change and red shift of LSPR absorption band in visible region that caused by the aggregation of NPs because of the coordination complex between Ba(II) and Ni(II) with carboxylate ions of malonate capped AuNPs...
October 17, 2016: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Tae Soup Shim, Zaki G Estephan, Zhaoxia Qian, Jacob H Prosser, Su Yeon Lee, David M Chenoweth, Daeyeon Lee, So-Jung Park, John C Crocker
Active materials that respond to physical and chemical stimuli can be used to build dynamic micromachines that lie at the interface between biological systems and engineered devices. In principle, the specific hybridization of DNA can be used to form a library of independent, chemically driven actuators for use in such microrobotic applications and could lead to device capabilities that are not possible with polymer- or metal-layer-based approaches. Here, we report shape changing films that are powered by DNA strand exchange reactions with two different domains that can respond to distinct chemical signals...
October 24, 2016: Nature Nanotechnology
Selvaraj Naveenraj, Ramalinga Viswanathan Mangalaraja, Jerry J Wu, Abdullah M Asiri, Sambandam Anandan
Gold triangular nanoprisms and nanodecahedra (pentagonal bipyramids) were synthesized in the absence and presence of nanoseeds by a simple solvothermal synthesis through the reduction of Auric Chloride (HAuCl4) with poly(vinylpyrrolidone) (PVP) in N,N-dimethylformamide (DMF), respectively. These gold nanoparticles exhibit two plasmon resonance bands. The interaction of these gold nanoparticles with luminol was investigated using UV-vis and fluorescence spectroscopy since hefty number of environmental and biological sensors are based on the combination of luminol and gold nanoparticles...
October 24, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Safaa Al-Rehili, Karim Fhayli, Mohamed Amen Hammami, Basem Moosa, Sachin Patil, Daliang Zhang, Ohoud Alharbi, Mohamed Nejib Hedhili, Helmuth Möhwald, Niveen M Khashab
Toroidal structures based on self-assembly of predesigned building blocks are well established in literature however, spontaneous self-organization to prepare such structures has never been reported thus far. Here, organic-inorganic hybrid microtoroids synthesized by simultaneous coordination-driven assembly of amphiphilic molecules and hydrophilic polymers are reported. Mixing amphiphilic molecules with iron(III) chloride and hydrophilic polymers in water leads, within minutes, to the formation of star-like nanostructures...
October 24, 2016: Journal of the American Chemical Society
Jie Chen, Hong Liang, Lin Lin, Zhaopei Guo, Pingjie Sun, Meiwan Chen, Huayu Tian, MingXiao Deng, Xuesi Chen
Multifunctional nanoparticles with high gene transfection activity, low cytotoxicity, photoacoustic imaging ability, and photothermal therapeutic properties were prepared by conjugating low-molecular-weight polyethylenimine onto the surfaces of gold nanorods through the formation of stable S-Au bonded conjugates. Results revealed that the gene transfection efficiency of the prepared polyethylenimine-modified gold nanorods (GNRs-PEI1.8k) was higher and their cytotoxicity was less than those of the commercial reagent PEI25k...
October 24, 2016: ACS Applied Materials & Interfaces
Xueling Feng, Kaihuan Zhang, Peng Chen, Xiaofeng Sui, Mark A Hempenius, Bo Liedberg, G Julius Vancso
Highly swellable, dual-responsive hydrogels, consisting of thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) and redox-responsive poly(ferrocenylsilane) (PFS) based poly(ionic liquid)s (PILs) are formed by photo-polymerization. PFS chains bearing cross-linkable vinylimidazolium (VIm) side groups are copolymerized with NIPAM in aqueous solutions under ultraviolet light (λ = 365 nm) in the presence of a photoinitiator. The PFS-PILs serve as a macro-cross-linker and also provide redox responsiveness. The swelling ratio, morphology, and lower critical solution temperature (LCST) of the hydrogels are studied as a function of the PNIPAM/PFS ratio...
October 24, 2016: Macromolecular Rapid Communications
Y Lu, K Wang, F-R Chen, W Zhang, M L Sui
It has been fundamentally important and technologically challenging to elucidate the migration behavior of solute atoms in solvents, which can help to understand the growth of nanoparticles. Recently, ascribed to the booming development of start-of-the-art liquid environmental transmission electron microscopes (LETEMs), it has become possible to disclose, in situ, the phase segregation mechanism of elementary units in a solvent at the nanoscale. In addition, bombardment with an electron beam can induce a locally positive potential, with the application of low-conductive Si3N4 and water in LETEMs...
October 24, 2016: Physical Chemistry Chemical Physics: PCCP
X R Zhang, Y Zhang, F T Chen, Y Li, S S Zhang
A novel biosensor was developed based on the cation-exchange of CuS nanoparticles (NPs) and Cu(i)-based click chemistry of functionalized gold nanoparticles (AuNPs). As a proof-of-principle, novel applications of this method as a versatile biosensor for single-nucleotide polymorphisms (SNPs) and DNA methyltransferase (MTase) were presented.
October 24, 2016: Chemical Communications: Chem Comm
Meng Zhou, Chenjie Zeng, Yuxiang Chen, Shuo Zhao, Matthew Y Sfeir, Manzhou Zhu, Rongchao Jin
The evolution from the metallic (or plasmonic) to molecular state in metal nanoparticles constitutes a central question in nanoscience research because of its importance in revealing the origin of metallic bonding and offering fundamental insights into the birth of surface plasmon resonance. Previous research has not been able to probe the transition due to the unavailability of atomically precise nanoparticles in the 1-3 nm size regime. Herein, we investigate the transition by performing ultrafast spectroscopic studies on atomically precise thiolate-protected Au25, Au38, Au144, Au333, Au∼520 and Au∼940 nanoparticles...
October 24, 2016: Nature Communications
Nivethaa E A K, Dhanavel S, Narayanan V, Stephen A
Fluorescent CS/Ag-Au (chitosan/silver-gold) nanocomposite containing different weight percentage of Ag and Au was synthesized using the chemical reduction method. 5-Fluorouracil (5-FU) encapsulated nanocomposite was also synthesized and its cytotoxicity towards breast cancer cell lines (MCF-7) studied. The XRD pattern of the nanocomposite shows peaks of chitosan, silver and gold. The peaks corresponding to gold and silver indicate the face centered cubic structure of silver and gold nanoparticles. The polymer matrix nanocomposite structure with chitosan as the matrix and silver-gold as the filler phase is evident from the high resolution transmission electron microscopy (HRTEM) images and an increase in particle size from∼5nm to about 12nm is noticeable on encapsulation of 5-Fluorouracil (5-FU)...
October 20, 2016: International Journal of Biological Macromolecules
Ahmad Shanei, Mohammad Mahdi Shanei
When a liquid is irradiated with high intensities of ultrasound irradiation, acoustic cavitation occurs. Acoustic cavitation generates free radicals from the breakdown of water and other molecules. Cavitation can be fatal to cells and is utilized to destroy cancer tumors. The existence of particles in liquid provides nucleation sites for cavitation bubbles and leads to decrease the ultrasonic intensity threshold needed for cavitation onset. In the present investigation, the effect of gold nanoparticles with appropriate amount and size on the acoustic cavitation activity has been shown by determining hydroxyl radicals in terephthalic acid solutions containing 15, 20, 28 and 35nm gold nanoparticles sizes by using 1MHz low level ultrasound...
January 2017: Ultrasonics Sonochemistry
Zhicheng Huang, Biwu Liu, Juewen Liu
DNA-functionalized gold nanoparticles (AuNPs) have been extensively used in sensing, drug delivery, and materials science. A key step is to attach DNA to AuNPs forming a stable and functional conjugate. While the traditional salt-aging method takes a full day or longer, a recent low-pH method allows DNA conjugation in a few minutes. The effect of low pH was attributed to protonation of adenine (A) and cytosine (C), resulting in an overall lower negative charge density on DNA. In this work, the effect of DNA conformation at low pH is studied...
October 24, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Tao Le, Yong Xie, Liqian Zhu, Lei Zhang
To monitor the levels of furazolidone in edible animal tissues, a fluorescent sensor was developed for the determination of 3-amino-2-oxazolidinone (AOZ), the metabolite of furazolidone, featuring an immunochromatographic test strip assay (ITSA) integrated with a quantum dot (QD) label. The optimal QD-based ITSA sensor exhibits good dynamic linear detection for AOZ over the range of 0.1 to 100 μg/L, with a 50% inhibitory concentration (IC50) of 1.06 μg/L. The decision limit and the detection capability were 0...
October 22, 2016: Journal of Agricultural and Food Chemistry
Satadru Jha, Federico Ramadori, Santina Quarta, Alessandra Biasiolo, Enrica Fabris, Paola Baldan, Gaetano Guarino, Mariagrazia Ruvoletto, Gianmarco Villano, Cristian Turato, Angelo Gatta, Fabrizio Mancin, Patrizia Pontisso, Paolo Scrimin
One of the most daunting challenges of nanomedicine is the finding of appropriate targeting agents to deliver suitable payloads precisely to cells affected by malignancies. Even more complex is to achieve the ability to ensure the nanosystems enter those cells. Here we use 2 nm (metal core) gold nanoparticles to target human hepatocellular carcinoma (HepG2) cells stably transfected with the SERPINB3 (SB3) protein. The nanoparticles were coated with a 85:15 mixture of thiols featuring, respectively, a phosphoryl choline, to ensure water solubility and biocompatibility, and a 28-mer peptide corresponding to the amino acid sequence 21-47 of the hepatitis B virus-PreS1 protein (PreS1(21-47))...
October 22, 2016: Bioconjugate Chemistry
Bharat Baruah, Toni-Ann Miller
This article reports a surface modification of gold nanoparticles with water soluble polyoxometalate, V10O28(6-) (decavanadate, V10). Two sizes of citrate-capped gold nanoparticles AuNP-Citrate-S (∼11nm) and AuNP-Citrate-L (∼46nm) were modified with V10 in aqueous media to form AuNP-V10-S and AuNP-V10-L, respectively. Both AuNP-V10-S and AuNP-V10-L were found to be significantly better than their citrate counterparts in strengthening Raman vibrational signals of analyte molecule. All the nanoparticles were characterized by UV-visible and Fourier transform infrared (FTIR) spectroscopies, dynamic light scattering (DLS), transmission electron microscopy (TEM) and energy dispersive X-ray (EDX) line analysis...
October 17, 2016: Journal of Colloid and Interface Science
Seyedeh Fatemeh Hosseini, Mahdi Sadeghi, Mohammad Reza Aboudzadeh, Morteza Mohseni
Gold has two medically useful radioactive isotopes, (198)Au and (199)Au, for locally irradiating and killing tumor cells. (198)Au radionuclide has been produced through the irradiation of the pure gold via (197)Au(n,γ)(198)Au reaction in the Tehran Research Reactor at a thermal neutron flux of 4.5×10(13)ncm(-2)s(-1) for the different irradiation times. In this paper, the activity of (198)Au radionuclide has been determined using MCNPX-2.6 and TALYS-1.6 codes and also the theoretical approach. The calculated results were compared with the corresponding experimental values...
October 5, 2016: Applied Radiation and Isotopes
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