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https://www.readbyqxmd.com/read/28813601/platinum-decorated-gold-nanoparticles-with-dual-functionalities-for-ultrasensitive-colorimetric-in-vitro-diagnostics
#1
Zhuangqiang Gao, Haihang Ye, Dianyong Tang, Jing Tao, Sanaz Habibi, Adriene Minerick, Dianping Tang, Xiaohu Xia
Au nanoparticles (AuNPs) as signal reporters have been utilized in colorimetric in vitro diagnostics (IVDs) for decades. Nevertheless, it remains a grand challenge to substantially enhance the detection sensitivity of AuNP-based IVDs as confined by the inherent plasmonics of AuNPs. In this work, we circumvent this confinement by developing a unique dual-functional AuNPs that were engineered by coating conventional AuNPs with ultrathin Pt skins of sub-10 atomic layers (i.e., Au@Pt NPs). The Au@Pt NPs retain the plasmonic activity of initial AuNPs, while possess ultrahigh catalytic activity enabled by Pt skins...
August 16, 2017: Nano Letters
https://www.readbyqxmd.com/read/28812746/redox-titration-of-gold-and-platinum-surface-oxides-at-porous-microelectrodes
#2
Mareike Haensch, Julian Behnken, Luis Balboa, Alexander Dyck, Gunther Wittstock
The extension of the surface interrogation mode of scanning electrochemical microscopy (SI-SECM) is demonstrated for porous electrode materials. These materials are often high surface area powders which are very important electrocatalysts for instance in fuel cells or water electrolyzers. The powdered electrocatalyst material is filled into a cavity-microelectrode which is then operated as the sample electrode in SECM. After a surface oxide generation step, the oxides on the porous sample are reduced by [Ru(NH3)6](2+) formed at the microelectrode probe of the SECM while the sample is at open circuit potential...
August 16, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28811023/agnps-3d-nanostructure-enhanced-electrochemiluminescence-of-cdse-quantum-dot-coupled-with-strand-displacement-amplification-for-sensitive-biosensing-of-dna
#3
Meng Jiao, Guifen Jie, Lu Tan, Shuyan Niu
A novel strategy using Ag nanoparticles-3D (AgNPs-3D) nanostructure enhanced electrochemiluminescence (ECL) of CdSe quantum dots (QDs) coupled with strand displacement amplification (SDA) for sensitive biosensing of DNA was successfully designed. The prepared CdSe QDs with intense ECL were assembled on the poly (diallyldimethylammonium chloride) (PDDA) graphene oxide (GO) nanocomposites modified electrode, then gold nanoparticles (NPs) as the quenching probe was conjugated to the QDs, ECL signal was efficiently quenched...
August 29, 2017: Analytica Chimica Acta
https://www.readbyqxmd.com/read/28810178/distance-dependent-fluorescence-quenching-and-enhancement-of-gold-nanoclusters-by-gold-nanoparticles
#4
Haiyan Qin, Diao Ma, Jianxiu Du
The interaction between fluorescent gold nanoclusters (AuNCs) and gold nanoparticles (AuNPs) has been investigated. It was observed that the fluorescence of AuNCs was remarkably quenched when direct contact with AuNPs. The fluorescence quenching of AuNCs by AuNPs was dynamic quenching and exhibited size-dependent property. A larger size of AuNPs displayed a stronger quenching effect and gave a larger quenching constant. When a silica spacer shell was introduced between AuNPs and AuNCs, a fluorescence enhancement of AuNCs by Au@SiO2 NPs was observed...
August 10, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28810054/dynamic-self-assembly-of-gold-polymer-nanocomposites-ph-encoded-switching-between-1d-nanowires-and-3d-nanosponges
#5
Da-Hui Qu, Qi Zhang, Tian-Yi Xu, Cai-Xin Zhao, Wei-Hang Jin, Qian Wang
The design of tunable dynamic self-assembly of nanoparticles with switchable assembled dimensions and morphologies is a challenging goal whose realization is vital for the evolution of smart nanomaterials. Herein we show the chitosan polymer as an effective supramolecular "glue" for aldehyde-modified Au nanoparticles to reversibly modulate the states of self-assembled nanocomposites. By simultaneous integration of dynamic covalent Schiff base interactions and noncovalent hydrogen bonds, the chitosan/Au nanocomposites could reversibly transform their assembled morphologies from one-dimensional nanowires to three-dimensional nanosponges in response to the variation of pH value...
August 15, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28809887/fano-resonance-based-mode-matching-hybrid-metasurface-for-enhanced-second-harmonic-generation
#6
Zhi Li, Wenwei Liu, Zhancheng Li, Hua Cheng, Shuqi Chen, Jianguo Tian
Plasmonic nanostructures have been considered as potential candidates for enhancing the nonlinear upconversion rate at nanoscale levels due to their strong near-field enhancement. Here, we propose a Fano-resonance-based mode-matching hybrid metasurface that combines the advantages of Fano resonances and mode-matching for boosting second-harmonic conversion. A confined and strong near-field intensity is generated by gold nanoantennas within the volume of polycrystalline zinc sulfide nanoparticles, thus resulting in a larger effective second-harmonic coefficient...
August 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28809545/plasmonic-nanoprobe-of-gold-triangular-nanoprism-core-polyaniline-shell-for-real-time-three-dimensional-ph-imaging-of-anterior-chamber
#7
Peijun Tang, Xueqin Jiang, Yangyang Wang, Huanjun Chen, Yu Shrike Zhang, Panpan Gao, Hao Wang, Xuemeng Li, Jianhua Zhou
Three-dimensional (3D) molecular imaging enables the study of biological processes in both living and nonviable systems at the molecular level and has a high potential on early diagnosis. In conjunction with specific molecular probes, optical coherent tomography (OCT) is a promising imaging modality to provide 3D molecular features at the tissue level. In this study, we introduced (gold-triangular-nanoprism-core)/(polyaniline-shell nanoparticles) (GTNPs@PANI) as an OCT contrast agent and pH-responsive nanoprobe for 3D imaging of pH distribution...
August 15, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28809475/a-dna-fueled-and-catalytic-molecule-machine-lights-up-trace-under-expressed-micrornas-in-living-cells
#8
Daxiu Li, Wenjiao Zhou, Ruo Yuan, Yun Xiang
The detection of specific intracellular microRNAs (miRNAs) in living cells can potentially provide insight into the causal mechanism of cancer metastasis and invasion. However, due to the characteristic nature of miRNAs in terms of small sizes, low abundance and similarity among family members, it is of great challenge to monitor miRNAs in living cells, especially those with much lower expression levels. In this work, we describe the establishment of a DNA-fueled and catalytic molecule machinery in cell signal amplification approach for monitoring trace and under-expressed miRNAs in living cells...
August 15, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28809413/tumor-targeted-nanoprobes-for-enhanced-multimodal-imaging-and-synergistic-photothermal-therapy-core-shell-and-dumbbell-gd-tailored-gold-nanorods
#9
Jinchang Yin, Deqi Chen, Shuangshuang Wu, Chaorui Li, Lizhi Liu, Yuanzhi Shao
Multifunctional nanoprobes, due to their unique nanocomposite structures, have prominent advantages that combine multimodal imaging of a tumor with photothermal therapy. However, they remain a challenge for constructing nanostructures via conventional approaches due to the peculiar environmental sensitivity of each component. Here, we report the design and synthesis of Gd-based nanoparticle-tailored gold nanorods with distinctive core-shell and dumbbell nanoarchitectures (NAs) by a specific synthesis technology...
August 15, 2017: Nanoscale
https://www.readbyqxmd.com/read/28806685/ecofriendly-gold-nanoparticles-lysozyme-interaction-thermodynamical-perspectives
#10
Swarup Roy, Shailendra K Saxena, Suryakant Mishra, Priyanka Yogi, P R Sagdeo, Rajesh Kumar
In the featured work interaction between biosynthesized gold nanoparticles (GNP) and lysozyme (Lys) has been studied using multi-spectroscopic approach. A moderate association constant (Kapp) of 2.66×10(4)L/mol has been observed indicative of interactive nature. The binding constant (Kb) was 1.99, 6.30 and 31.6×10(4)L/mol at 291, 298 and 305K respectively and the number of binding sites (n) was found to be approximately one. Estimated values of thermodynamic parameters (Enthalpy change, ΔH=141.99kJ/mol, entropy change, ΔS=570J/mol/K, Gibbs free energy change, ΔG=-27...
August 8, 2017: Journal of Photochemistry and Photobiology. B, Biology
https://www.readbyqxmd.com/read/28806669/griess-reaction-based-paper-strip-for-colorimetric-fluorescent-sers-triple-sensing-of-nitrite
#11
Dan Li, Yadan Ma, Huazhen Duan, Wei Deng, Dawei Li
This study demonstrates a novel strategy for colorimetric/fluorescent/surface enhanced Raman scattering (SERS) triple-mode sensing of nitrite based on Griess reaction modulated gold nanorods (GNRs)-Azo-gold nanoparticles (GNPs) (GNRs-Azo-GNPs) assembly. The p-aminothiophenol (PATP)-capped GNRs (GNRs@PATP) and 1,8-diaminonaphthalene (DAP)-modified GNPs (GNPs@DAP) are first synthesized through Au-S and Au-N bonds, respectively. Upon being excited at 365nm, the dispersion of GNRs-GNPs (GNRs@PATP and GNPs@DAP) emits cyan fluorescence...
August 8, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28806668/combination-of-electrochemical-biosensor-and-textile-threads-a-microfluidic-device-for-phenol-determination-in-tap-water
#12
F R Caetano, E A Carneiro, D Agustini, L C S Figueiredo-Filho, C E Banks, M F Bergamini, L H Marcolino-Junior
Microfluidic devices constructed using low cost materials presents as alternative for conventional flow analysis systems because they provide advantages as low consumption of reagents and samples, high speed of analysis, possibility of portability and the easiness of construction and maintenance. Herein, is described for the first time the use of an electrochemical biosensor for phenol detection combined with a very simple and efficient microfluidic device based on commercial textile threads. Taking advantages of capillary phenomena and gravity forces, the solution transportation is promoted without any external forces or injection pump...
July 29, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28806557/a-highly-sensitive-and-selective-aptamer-based-colorimetric-sensor-for-the-rapid-detection-of-pcb-77
#13
Ruojie Cheng, Siyao Liu, Huijie Shi, Guohua Zhao
A highly sensitive, specific and simple colorimetric sensor based on aptamer was established for the detection of polychlorinated biphenyls (PCB 77). The use of unmodified gold nanoparticles as a colorimetric probe for aptamer sensors enabled the highly sensitive and selective detection of polychlorinated biphenyls (PCB 77). A linear range of 0.5nM to 900nM was obtained for the colorimetric assay with a minimum detection limit of 0.05nM. In addition, by the methods of circular dichroism, UV and naked eyes, we found that the 35 base fragments retained after cutting 5 bases from the 5 'end of aptamer plays the most significant role in the PCB 77 specific recognition process...
July 25, 2017: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/28806528/surface-adaptive-gold-nanoparticles-with-effective-adherence-and-enhanced-photothermal-ablation-of-methicillin-resistant-staphylococcus-aureus-biofilm
#14
Dengfeng Hu, Huan Li, Bailiang Wang, Zi Ye, Wenxi Lei, Fan Jia, Qiao Jin, Ke-Feng Ren, Jian Ji
Biofilms which contribute to the persistent bacterial infections pose serious threats to global public health, mainly due to their resistance to antibiotics penetration and escaping innate immune attacks by phagocytes. Here, we report a kind of surface-adaptive gold nanoparticles (AuNPs) exhibiting (1) self-adaptive target to the acidic microenvironment of biofilm, (2) enhanced photothermal ablation of methicillin-resistant Staphylococcus aureus (MRSA) biofilm under near-infrared (NIR) light irradiation and (3) no damage to the healthy tissues around biofilm...
August 14, 2017: ACS Nano
https://www.readbyqxmd.com/read/28806065/synthesis-characterization-and-selective-delivery-of-darpin-gold-nanoparticle-conjugates-to-cancer-cells
#15
Sergey Deyev, Galina Proshkina, Anastasiya Ryabova, Francesco Tavanti, Maria Cristina Menziani, Gennady Eidelshtein, Gabriel Avishai, Alexander B Kotlyar
We demonstrate that the designed ankyril repeat protein (DARPin) _9-29, which specifically targets human epidermal growth factor receptor 2 (HER 2), binds tightly to gold nanoparticles (GNPs). Binding of the protein strongly increases the colloidal stability of the particles. The results of experimental analysis and molecular dynamics simulations show that approximately 35 DARPin _9-29 molecules are bound to the surface of a 5 nm GNP and that the binding does not involve the receptor-binding domain of the protein...
August 14, 2017: Bioconjugate Chemistry
https://www.readbyqxmd.com/read/28806061/construction-of-a-polyhedral-dna-12-arm-junction-for-self-assembly-of-wireframe-dna-lattices
#16
Ilenia Manuguerra, Guido Grossi, Rasmus P Thomsen, Jeppe Lyngsø, Jan Skov Pedersen, Jørgen Kjems, Ebbe Sloth Andersen, Kurt Vesterager Gothelf
A variety of different tiles for the construction of DNA lattices have been developed since the structural DNA nanotechnology field was born. The majority of these are designed for the realization of close-packed structures where DNA helices are arranged in parallel and tiles are connected through sticky ends. Assembly of such structures requires to the use of cation rich buffers to minimize repulsion between parallel helices, which poses limits to the application of DNA nanostructures. Wireframe structures on the other hand are less susceptible to salt concentration, but the assembly of wireframe lattices is limited by the availability of tiles and 2 motifs...
August 14, 2017: ACS Nano
https://www.readbyqxmd.com/read/28805153/investigating-the-susceptibility-of-mice-to-a-bacterial-challenge-after-intravenous-exposure-to-durable-nanoparticles
#17
Saeed Khan, Qin Zhang, Bernard S Marasa, Kidon Sung, Carl E Cerniglia, Taylor Ingle, Margie Yvonne Jones, Angel M Paredes, Grainne A Tobin, Simona Bancos, James L Weaver, Peter L Goering, Paul C Howard, Anil K Patri, Katherine M Tyner
AIM: The goal of this study was to determine whether bacterial clearance in a rodent model would be impaired upon exposure to gold, silver or silica nanoparticles (NPs). MATERIALS & METHODS: Mice received weekly injections of NPs followed by a challenge of Listeria monocytogenes (LM). On days 3 and 10 after LM injections, the animals were sacrificed and their tissues were collected for elemental analysis, electron microscopy and LM count determination. RESULTS: The untreated and NP-treated animals cleared LM at the same rate suggesting that bioaccumulation of NPs did not increase the animals' susceptibility to bacterial infection...
August 14, 2017: Nanomedicine
https://www.readbyqxmd.com/read/28804578/using-nanoparticles-in-medicine-for-liver-cancer-imaging
#18
REVIEW
Farideh Farokhi Moghadam
One of the most important types of liver cancer is hepatocellular carcinoma (HCC). HCC is the fifth most common cancer, and its correct diagnosis is very important. For the quick diagnosis of HCC, the use of nanoparticles is helpful. The major applications of nanoparticles are in medicine for organ imaging. Two methods of liver imaging are X-ray computed tomography (CT) and magnetic resonance imaging (MRI). In this review, we attempt to summarize some of the contrast agents used in imaging such as superparamagnetic iron oxide nanoparticles (SPIONs) and iron oxide nanoparticles (IONPs), various types of enhanced MRI for the liver, and nanoparticles like gold (AuNPs), which is used to develop novel CT imaging agents...
July 2017: Oman Medical Journal
https://www.readbyqxmd.com/read/28804527/synthesis-and-characterisation-of-cross-linked-chitosan-composites-functionalised-with-silver-and-gold-nanoparticles-for-antimicrobial-applications
#19
Catherine Ryan, Emma Alcock, Finbarr Buttimer, Michael Schmidt, David Clarke, Martyn Pemble, Maria Bardosova
We present a study of a range of cross-linked chitosan composites with potential antimicrobial applications. They were formed by cross-linking chitosan and siloxane networks and by introducing silver and gold nanoparticles (NPs). The aim was to investigate whether adding the metal NPs to the chitosan-siloxane composite would lead to a material with enhanced antimicrobial ability as compared to chitosan itself. The composites were synthesised in hydrogel form with the metal NPs embedded in the cross-linked chitosan network...
2017: Science and Technology of Advanced Materials
https://www.readbyqxmd.com/read/28802850/thermo-sensitive-chitosan-copolymer-gold-hybrid-nanoparticles-as-a-nanocarrier-for-delivery-of-erlotinib
#20
Marziyeh Fathi, Parham Sahandi Zangabad, Jaleh Barar, Ayuob Aghanejad, Hamid Erfan-Niya, Yadollah Omidi
Here, using (poly(N-isopropylacrylamide)-co-oleic acid)-g-chitosan ((PNIPAAm-co-OA)-g-CS), CS copolymer-gold hybrid nanoparticles (CGH NPs) were synthesized by autoreduction of auric cations (HAuCl4) in aqueous solution in the absence of any other reducing agent. The engineered thermo-sensitive CS copolymer with free amino groups could reduce auric cations and stabilized the resultant NPs. CGH NPs were prepared using different concentrations of CS copolymer (0.1-1% w/v) and HAuCl4 (50-500μL, 0.2% w/v). They were characterized in terms of structure, surface Plasmon band, zeta potential, atomic absorption, stability, size and size distribution...
August 9, 2017: International Journal of Biological Macromolecules
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