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https://www.readbyqxmd.com/read/28650660/ph-triggered-recovery-and-reuse-of-thiolated-poly-acryl-acid-functionalized-gold-nanoparticles-with-applications-in-colloidal-catalysis
#1
Siyam M Ansar, Benjamin D Fellows, Patrick Mispireta, O Thompson Mefford, Christopher L Kitchens
Thiolated poly(acrylic acid) (PAA-SH) functionalized gold nanoparticles were explored as a colloidal catalyst with potential application as a recoverable catalyst where the PAA provides pH-responsive dispersibility and phase transfer capability between aqueous and organic media. This system demonstrates complete nanoparticle recovery and redispersion over multiple reaction cycles without changes in nanoparticle morphology or reduction in conversion. The catalytic activity (rate constant) was reduced in subsequent reactions when recovery by aggregation was employed, despite unobservable changes in morphology or dispersability...
June 26, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28650641/a-discovery-of-strong-metal-support-bonding-in-nano-engineered-au-fe3o4-dumbbell-like-nanoparticles-by-in-situ-transmission-electron-microscopy
#2
Chang Wan Han, Tej Choksi, Cory Adam Milligan, Paulami Majumdar, Michael J Manto, Yanran Cui, Xiahan Sang, Raymond R Unocic, Dmitry Y Zemlyanov, Chao Wang, Fabio H Ribeiro, Jeffrey Greeley, Volkan Ortalan
The strength of metal-support bonding in heterogeneous catalysts determines their thermal stability, therefore, a tremendous amount of effort has been expended to understand metal-support interactions. Herein, we report the discovery of an anomalous "strong metal-support bonding" between gold nanoparticles and "nano-engineered" Fe3O4 substrates by in-situ microscopy. During in-situ vacuum annealing of Au-Fe3O4 dumbbell-like nanoparticles, synthesized by the epitaxial growth of nano-Fe3O4 on Au nanoparticles, the gold nanoparticles transform into the gold thinfilms and wet the surface of nano-Fe3O4, as the surface reduction of nano-Fe3O4 proceeds...
June 26, 2017: Nano Letters
https://www.readbyqxmd.com/read/28650507/stabilisation-of-gold-nanoparticles-by-n-heterocyclic-thiones
#3
Leonardo C Moraes, Bertrand Lacroix, Rute C Figueiredo, Patricia Lara, Javier Rojo, Salvador Conejero
Gold nanoparticles (Au-NPs) have been prepared using N-heterocyclic thiones (NHTs) as ligand stabilisers. These Au-NPs have been shown to be very stable, even in air, and have been characterized by a combination of several techniques (TEM, HR-TEM, STEM-HAADF, EDX, DLS, elemental analysis and (1)H NMR). These nanoparticles are active in the catalytic reduction of nitroarenes to anilines.
June 26, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28650053/in-situ-crystal-growth-of-gold-nanocrystals-on-upconversion-nanoparticles-for-synergistic-chemo-photothermal-therapy
#4
Ruoyan Wei, Wensong Xi, Haifang Wang, Jinliang Liu, Torsten Mayr, Liyi Shi, Lining Sun
A multifunctional cancer therapy nanocomposite was proposed and synthesized by linking the pH-responsive SH-PEG-DOX prodrug onto gold nanocrystals that were grown in situ on the surface of upconversion nanoparticles (UCNPs). In the structure of the SH-PEG-DOX prodrug, a hydrazone bond was utilized for subsequent pH-responsive drug release in the intracellular acidic microenvironment of cancer cells. This innovative assembly method is facile and mild, and can be used to obtain nanocomposites of UCNPs and gold, which show excellent photostability and biocompatibility...
June 26, 2017: Nanoscale
https://www.readbyqxmd.com/read/28650026/the-effect-of-pegylated-hollow-gold-nanoparticles-on-stem-cell-migration-potential-application-in-tissue-regeneration
#5
Maria Del Mar Encabo-Berzosa, Maria Sancho-Albero, Alejandra Crespo, Vanesa Andreu, Victor Sebastian, Silvia Irusta, Manuel Arruebo, Pilar Martín-Duque, Jesus Santamaria
Mesenchymal stem cells (MSCs) not only can be differentiated into different cell types but also have tropism towards injured or inflamed tissues serving as repair cells. Here we have demonstrated that MSCs containing gold nanoparticles (GNPs) whose surface has been functionalized with PEG show accelerated cell migration, successful scaffold colonization and regeneration. We report the impact of GNPs on the migration (by the wound healing assay), and proliferation (by flow cytometry analysis and by the detection of metabolic mitochondrial activity) on the behaviour of different cell lines including MSCs, HeLa cells, and human dermal fibroblasts...
June 26, 2017: Nanoscale
https://www.readbyqxmd.com/read/28650007/dual-channel-signals-for-intracellular-mrna-detection-via-a-pret-nanosensor
#6
Tao Xie, Meng Li, Yi-Tao Long
An intracellular nanosensor was designed and developed to accurately sense mRNA in living cells without false positive results. This nanosensor consists of gold nanoparticles assembled with recognition sequences and dye-labelled nanoflares. By analyzing both the wavelength shifts and intensity recovery of the scattering spectra, this dual-channel nanosensor could efficiently distinguish and avoid the interference induced by other common substances. This novel dual-channel nanosensor would precisely recognize the target mRNA, and it is promising for further cancer diagnoses...
June 26, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28649960/gold-nanoparticles-decorated-electrospun-poly-n-vinyl-2-pyrrolidone-nanofibers-with-tunable-size-and-coverage-density-for-nanomolar-detection-of-single-and-binary-component-dyes-by-surface-enhanced-raman-spectroscopy
#7
Alfin Kurniawan, Meng-Jiy Wang
The application of the electrospun nanomaterials to surface-enhanced Raman spectroscopy (SERS) is a rapidly evolving field which holds potential for future developments in the generation of portable plasmonic-based detection platforms. In this study, a simple approach to fabricate electrospun poly(N-vinylpyrrolidone) (PVP) mats decorated with gold nanoparticles (AuNPs) by combining electrospinning and calcination was presented. AuNPs were decorated on the fiber mat surface through electrostatic interactions between positively charged aminosilane groups and negatively charged AuNPs...
June 26, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28649829/photoelectrochemical-bioanalysis-platform-of-gold-nanoparticles-equipped-perovskite-bi4nbo8cl
#8
Yi-Fan Ruan, Nan Zhang, Yuan-Cheng Zhu, Wei-Wei Zhao, Jing-Juan Xu, Hong-Yuan Chen
We have developed sensitive photoelectrochemical (PEC) detection of cysteine using the gold nanoparticles (Au NPs) equipped perovskite Bi4NbO8Cl heterostructure. The Bi4NbO8Cl was prepared by a solid-state reaction, and the Au NPs/Bi4NbO8Cl electrode was made through electrostatic layer-by-layer self-assembly technique. The Au NPs/Bi4NbO8Cl electrode provided much enhanced photocurrent with great increase compared to the bare Bi4NbO8Cl electrode and allow for the plasmon-enhanced PEC detection of cysteine with good performance...
June 26, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28649026/proximity-hybridization-regulated-electrogenerated-chemiluminescence-bioassay-of-%C3%AE-fetoprotein-via-target-induced-quenching-mechanism
#9
Hongfang Gao, Xiaofei Wang, Man Li, Honglan Qi, Qiang Gao, Chengxiao Zhang
A proximity hybridization-regulated electrogenerated chemiluminescence (PLA-ECL) bioassay was developed for the detection of α-fetoprotein (AFP) on basis of the sensitization of gold nanoparticles (AuNPs) and target-induced quenching mechanism. Ru(bpy)3(2+) was used as ECL signal while ferrocene (Fc) was used as ECL quencher. Ru(bpy)3(2+) was electrostatically adsorbed into the AuNPs/Nafion film prepared by casting the mixture of Nafion and AuNPs onto the surface of glassy carbon electrode (GCE) to form an ECL platform (Ru(bpy)3(2+)/AuNPs/Nafion/GCE), which displayed strong ECL emissions...
June 21, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28649024/microfluidic-platform-integrated-with-graphene-gold-nano-composite-aptasensor-for-one-step-detection-of-norovirus
#10
Rohit Chand, Suresh Neethirajan
Noroviruses are a foremost cause of gastroenteritis outbreaks throughout the world. On-site sample processing and detection of the viral clinical samples has always been a problem. This study reports an all-polydimethylsiloxane microfluidic chip integrated with screen-printed carbon electrode for the electrochemical detection of norovirus. The microfluidic chip contained packed silica microbeads zones to filter and enrich the norovirus infected clinical sample. Selective detection of norovirus was accomplished by functionalizing the graphene-gold nanoparticles composite modified carbon electrode with the viral capsid-specific aptamer...
June 17, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28648622/a-novel-antimicrobial-therapy-for-the-control-of-aeromonas-hydrophila-infection-in-aquaculture-using-marine-polysaccharide-coated-gold-nanoparticle
#11
Sekar Vijayakumar, Baskaralingam Vaseeharan, Balasubramanian Malaikozhundan, Narayanan Gobi, Samuthirapandian Ravichandran, Sellamuthu Karthi, Balasubramaniem Ashok Kumar, Natesan Sivakumar
In the present study, we prepared fucoidan coated Au-NPs, known as gold nanoparticles of fucoidan (Fu-AuNPs), and examined its effect on the antimicrobial activity against Aeromonas hydrophila. The green synthesized Fu-AuNPs were bio-physically characterized by Ultraviolet-visible (UV-Vis) spectroscopy, X-ray Diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), Higher Transmission Electron Microscopy (HR-TEM), Zeta potential analysis and Energy Dispersive X-ray spectroscopy (EDX). Fu-AuNPs were crystalline in nature, spherical to triangular in shape, with particle size ranging within 10-100 nm...
June 22, 2017: Microbial Pathogenesis
https://www.readbyqxmd.com/read/28648075/synergistic-effects-of-gold-palladium-nanoalloys-and-reducible-supports-on-the-catalytic-reduction-of-4-nitrophenol
#12
Ndzondelelo Bingwa, Rapelang Patala, Jihyang Noh, Matumuene Joe Ndolomingo, Siyamthanda Tetyana, Semakaleng Bewana, Reinout Meijboom
Herein we report on the catalytic activity of mesoporous nickel, iron, cerium, cobalt and manganese oxides prepared using KIT-6 as a hard-template via evaporation assisted precipitation. The mesoporous metal oxides (MMOs) were characterized and used as heterogeneous catalysts in the reduction of 4-nitrophenol (4-Nip) by sodium borohydride (〖BH〗_4^-). Furthermore, polyamidoamide (PAMAM) dendrimers were used to synthesize Gold-Palladium nanoalloy particles. The size of AuPd/PAMAM was found to be 3.5 ± 0...
June 24, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28644401/the-investigation-of-electrochemistry-behaviors-of-tyrosinase-based-on-directly-electrodeposited-grapheneon-choline-gold-nanoparticles
#13
Yaping He, Xiaohui Yang, Quan Han, Jianbin Zheng
A novel catechol (CA) biosensor was developed by embedding tyrosinase (Tyr) onto in situ electrochemical reduction graphene (EGR) on choline-functionalized gold nanoparticle (AuNPs-Ch) film. The results of UV-Vis spectra indicated that Tyr retained its original structure in the film, and an electrochemical investigation of the biosensor showed a pair of well-defined, quasi-reversible redox peaks with Epa = -0.0744 V and Epc = -0.114 V (vs. SCE) in 0.1 M, pH 7.0 sodium phosphate-buffered saline at a scan rate of 100 mV/s...
June 23, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28644380/adenosine-triphosphate-encapsulated-liposomes-with-plasmonic-nanoparticles-for-surface-enhanced-raman-scattering-based-immunoassays
#14
Xuan-Hung Pham, Eunil Hahm, Tae Han Kim, Hyung-Mo Kim, Sang Hun Lee, Yoon-Sik Lee, Dae Hong Jeong, Bong-Hyun Jun
In this study, we prepared adenosine triphosphate (ATP) encapsulated liposomes, and assessed their applicability for the surface enhanced Raman scattering (SERS)-based assays with gold-silver alloy (Au@Ag)-assembled silica nanoparticles (NPs; SiO₂@Au@Ag). The liposomes were prepared by the thin film hydration method from a mixture of l-α-phosphatidylcholine, cholesterol, and PE-PEG2000 in chloroform; evaporating the solvent, followed by hydration of the resulting thin film with ATP in phosphate-buffered saline (PBS)...
June 23, 2017: Sensors
https://www.readbyqxmd.com/read/28640995/colloidal-gold-nanoparticles-induce-changes-in-cellular-and-subcellular-morphology
#15
Xiaowei Ma, Raimo Hartmann, Dorleta Jimenez de Aberasturi, Fang Yang, Stefaan J H Soenen, Bella B Manshian, Jonas Franz, Daniel Valdeperez, Beatriz Pelaz, Neus Feliu, Norbert Hampp, Christoph Riethmüller, Henning Vieker, Natalie Frese, Armin Gölzhäuser, Michael Simonich, Robert L Tanguay, Xing-Jie Liang, Wolfgang J Parak
Exposure of cells to colloidal nanoparticles (NPs) can have concentration-dependent harmful effects. Mostly, such effects are monitored with biochemical assays or probes from molecular biology, i.e. viability assays, gene expression profiles, etc., neglecting that the presence of NPs can also drastically affect cellular morphology. In the case of polymer-coated Au NPs we demonstrate that upon NP internalization, cells undergo lysosomal swelling, alterations in mitochondrial morphology, disturbances in actin and tubulin cytoskeleton and associated signaling, and reduction of focal adhesion contact area and number of filopodia...
June 22, 2017: ACS Nano
https://www.readbyqxmd.com/read/28640589/ru-bpy-32-incorporated-luminescent-polymer-dots-double-enhanced-electrochemiluminescence-for-detection-of-single-nucleotide-polymorphism
#16
Yaqiang Feng, Feng Sun, Ningning Wang, Jianping Lei, Huangxian Ju
Encapsulating a large amount of electrochemiluminescence (ECL) active molecules into one nanoparticle for single target recognition can greatly improve the sensitivity of ECL assay. This work used luminescent conjugated polymer as a carrier to synthesize Ru(bpy)32+ doped polymer dots (RuPdots). The RuPdots with an average size of 20 nm and encapsulation of about 1354 Ru(bpy)32+ showed greatly enhanced ECL emission. Using tripropylamine as a co-reactant, the resonance energy transfer from the excited polymer dots to the encapsulated Ru(bpy)32+ was demonstrated, which led to 15...
June 22, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28639680/anticancer-luminescent-gold-quantum-clusters-for-in-situ-cancer-selective-marking-imaging-targeting
#17
Jeong-Hwan Kim, Haruki Eguchi, Yoshihiro Ishikawa
Ultrafine Au quantum clusters (QCs) were synthesized by etching host Au nanoparticles in the presence of ethylenediamine (en) and exhibited both strong photoluminescence (PL) and specific anticancer activity. The cutting-edge feature of this QC compound comprises subnanometer-size rhombohedral Au8, which consists of 8 units of the anticancer motif, namely, an Au(+)(en) complex (Au(en)QCs), which contributes to photo- and physicochemical stability as well as subcellular theranostic activity in intracellular PL imaging and in situ targeting...
June 22, 2017: Nanoscale
https://www.readbyqxmd.com/read/28639677/detection-of-single-metal-nanoparticle-collision-events-in-non-aqueous-media
#18
Benjamin H Meekins
In this work, the detection of metal nanoparticle collision events in a non-aqueous solvent-here, toluene and acetonitrile-using gold nanoparticles and a platinum ultramicroelectrode (UME) is reported. The collisions were monitored by the oxidation of tri-n-propylamine (TPrA) under diffusion-dominated conditions. Based on the current response, it was observed that the current steps were indicative of a mediated Faradaic reaction. Current steps as small as 1-2 pA could be clearly observed. Larger current steps were caused by agglomeration of the nanoparticles attributed to the polarity of the mixed solvent...
June 22, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28638474/self-assembly-of-gold-nanoparticles-shows-microenvironment-mediated-dynamic-switching-and-enhanced-brain-tumor-targeting
#19
Qishuai Feng, Yajing Shen, Yingjie Fu, Megan E Muroski, Peng Zhang, Qiaoyue Wang, Chang Xu, Maciej S Lesniak, Gang Li, Yu Cheng
Inorganic nanoparticles with unique physical properties have been explored as nanomedicines for brain tumor treatment. However, the clinical applications of the inorganic formulations are often hindered by the biological barriers and failure to be bioeliminated. The size of the nanoparticle is an essential design parameter which plays a significant role to affect the tumor targeting and biodistribution. Here, we report a feasible approach for the assembly of gold nanoparticles into ~80 nm nanospheres as a drug delivery platform for enhanced retention in brain tumors with the ability to be dynamically switched into the single formulation for excretion...
2017: Theranostics
https://www.readbyqxmd.com/read/28638065/colorimetric-detection-of-magnesium-ii-ions-using-tryptophan-functionalized-gold-nanoparticles
#20
Dae-Young Kim, Surendra Shinde, Gajanan Ghodake
The functional nanoparticles with specific molecular probe appear to be a promising approach for developing colorimetric nanosensor. In this work, we have synthesized tryptophan capped gold nanoparticles (AuNPs) and used to establish colorimetric detection of magnesium (Mg(2+)). The colorimetric response of the AuNPs toward Mg(2+) was noticed with naked eyes, and spectral changes were monitored by using UV-Vis spectrophotometer. The detection response was rapid (less than 1 min), with a detection limit (LOD) about 0...
June 21, 2017: Scientific Reports
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