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Gold nanoparticle

Xuan Cao, Gang Lei, Jingjing Feng, Qi Pan, Xiaodong Wen, Yan He
Creating color difference and improving the color resolution in digital imaging is crucial for better application of color analy-sis. Herein, a novel color modulation analysis strategy was developed by using a homemade tunable multiband laser illumi-nation device, in which the portions of R, G, and B components of the illumination light are discretionarily adjustable, and hence the sample color could be visually modulated continuously in the RGB color space. Through this strategy, the color appearance of single gold nanorods (AuNRs) under dark-field microscopy, was migrated from the spectrally insensitive red region to the spectrally sensitive green-yellow-red region...
January 15, 2018: Analytical Chemistry
Zhao-Hua Miao, Kai Li, Pei-Ying Liu, Zhenglin Li, Huanjie Yang, Qingliang Zhao, Manli Chang, Qingzhu Yang, Liang Zhen, Cheng-Yan Xu
Humic acids, a major constituent of natural organic carbon resources, are naturally formed through the microbial biodegradation of animal and plant residues. Due to numerous physiologically active groups (phenol, carboxyl, and quinone), the biomedical applications of humic acid have been already investigated across different cultures for several centuries or even longer. In this work, sodium humate, the sodium salt of humic acid, is explored as phototheranostic agent for light-induced photoacoustic imaging and photothermal therapy based on intrinsic absorption in the near-infrared region...
January 15, 2018: Advanced Healthcare Materials
Debasree Burman, Sumita Santra, Panchanan Pramanik, Prasanta Kumar Guha
In this work, we report the fabrication of a low power, humidity sensor where platinum nanoparticles (NPs) decorated few-layered Molybdenum disulphide (MoS<sub>2</sub>) nanoflakes have been used as the sensing layer. A mixed solvent was used to exfoliate the nanoflakes from the bulk powder. Then the Pt/MoS<sub>2</sub> composites were prepared by reducing Pt NPs from chloroplatinic acid hexahydrate using a novel reduction technique using sulfide salt. The successful reduction and composite preparation were confirmed using various material characterization tools like Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Raman spectroscopy and UV-visible spectroscopy (UV-Vis)...
January 15, 2018: Nanotechnology
Rubul Mout, Vincent M Rotello
In this protocol, we describe a method for direct cytosolic protein delivery that avoids endosomal entrapment of the delivered proteins. We achieved this by tagging the desired protein with an oligo glutamic acid tag (E-tag), and subsequently using carrier gold nanoparticles to deliver these E-tagged proteins. When E-tagged proteins and nanoparticles were mixed, they formed nanoassemblies, which got fused to cell membrane upon incubation and directly released the E-tagged protein into cell cytosol. We used this method to deliver a wide variety of proteins with different sizes, charges, and functions in various cell lines (Mout et al...
December 20, 2017: Bio-protocol
Kai-Xuan Xu, Mei-Hong Guo, Yu-Ping Huang, Xiao-Dong Li, Jian-Jun Sun
A highly sensitive and rapid method of in-situ surface-enhanced Raman spectroscopy (SERS) combining with electrochemical preconcentration (EP) in detecting malachite green (MG) in aquaculture water was established. Ag nanoparticles (AgNPs) were synthesized and spread onto the surface of gold electrodes after centrifuging to produce SERS-active substrates. After optimizing the pH values, preconcentration potentials and times, in-situ EP-SERS detection was carried out. A sensitive and rapid analysis of the low-concentration MG was accomplished within 200s and the limit of detection was 2...
April 1, 2018: Talanta
Shuo Li, Qiong Wu, Pinyi Ma, Yue Zhang, Daqian Song, Xinghua Wang, Ying Sun
A novel surface plasmon resonance (SPR) biosensor based on hollow gold nanospheres (HGNPs) and an improved sandwich assay was developed to detect rabbit IgG. The electromagnetic coupling between the HGNPs and Au film, and the notable plasmonic fields spread over the inner and outer surfaces of HGNPs, led to the considerable amplification of the SPR signal. Polydopamine-Ag@Fe3O4/reduced graphene oxide (PDA-Ag@Fe3O4/rGO) was introduced to bind detection antibody (Ab2) to form the improved sandwich structure. Ag nanoparticles were excited to produce SPR and their hot electrons were doped on graphene thin films, which amplified the response of biomolecules...
April 1, 2018: Talanta
Min Ma, Taotao Zhe, Yiyue Ma, Zonghan Wang, Qiang Chen, Jianlong Wang
Novel nanocomposite has tailorable properties and ordered 3D architecture similar to the structure of materials prepared by electrodeposition which is convenient and efficient but the reproducibility is limited because of the uncontrollable preparation process, was scientifically synthetized in controllable way and used for non-enzymatic glucose sensor for the first time. Flower-like α-Ni(OH)2 with high specific surface areas and good anion transport ability benefited from its distinctive stacking faults and turbostratic disorder structure was synthesized through facile one-step hydrothermal method...
April 1, 2018: Talanta
Smruti R Sahoo, Ramacharyulu Vrk P, Shyue-Chu Ke
Quantitative X-ray photoelectron spectroscopic (XPS) analysis combined with spectral modeling of photoelectrons can be valuable while investigating the surface chemistry of nanoparticles (NPs) with different morphologies. Herein, with the use of NIST Simulation of Electron Spectra for Surface Analysis (SESSA), a comparative analysis of experimental and simulated photoelectron peak intensities in gold nanoparticles (AuNPs) of different morphologies is presented. Three sets of supported AuNPs with different morphologies were selected from a series of as synthesized Au-TiO2 catalyst samples...
January 15, 2018: Analytical Chemistry
Artem Danilov, Gleb Tselikov, Fan Wu, Vasyl G Kravets, Igor Ozerov, Frederic Bedu, Alexander N Grigorenko, Andrei V Kabashin
When excited over a periodic metamaterial lattice of gold nanoparticles (~ 100nm), localized plasmon resonances (LPR) can be coupled by a diffraction wave propagating along the array plane, which leads to a drastic narrowing of plasmon resonance lineshapes (down to a few nm full-width-at-half-maximum) and the generation of singularities of phase of reflected light. These phenomena look very promising for the improvement of performance of plasmonic biosensors, but conditions of implementation of such diffractively coupled plasmonic resonances, also referred to as plasmonic surface lattice resonances (PSLR), are not always compatible with biosensing arrangement implying the placement of the nanoparticles between a glass substrate and a sample medium (air, water)...
December 9, 2017: Biosensors & Bioelectronics
Tesfaye Tolessa, Zhi-Qiang Tan, Jing-Fu Liu
Antimony (Sb) is a toxic element which causes different health problems including cardiac problems and lung cancer in humans, and its levels in surface water can be noticeably increased to 100 μg/L typically in the proximity of anthropogenic sources. Thus, besides instrumental techniques, it is of great significance to develop a simple, sensitive and selective analytical method for direct analysis of Sb(III) at trace level without the need of any expensive and/or complicated instrumentations and sample preparation processes...
April 3, 2018: Analytica Chimica Acta
Songsong Tang, Yuan Gu, Huiting Lu, Haifeng Dong, Kai Zhang, Wenhao Dai, Xiangdan Meng, Fan Yang, Xueji Zhang
Herein, a highly-sensitive microRNA (miRNA) detection strategy was developed by combining bio-bar-code assay (BBA) with catalytic hairpin assembly (CHA). In the proposed system, two nanoprobes of magnetic nanoparticles functionalized with DNA probes (MNPs-DNA) and gold nanoparticles with numerous barcode DNA (AuNPs-DNA) were designed. In the presence of target miRNA, the MNP-DNA and AuNP-DNA hybridized with target miRNA to form a "sandwich" structure. After "sandwich" structures were separated from the solution by the magnetic field and dehybridized by high temperature, the barcode DNA sequences were released by dissolving AuNPs...
April 3, 2018: Analytica Chimica Acta
Navid Zanganeh, Vamshi Krishna Guda, Hossein Toghiani, Jason M Keith
A novel gold-copper based silica encapsulated mixed metal oxide (MMO) core-shell catalyst - with sub 5-nm MMO particles - was successfully synthesized via a reverse micelle process. The SiO2 encapsulated MMO catalyst was reduced under hydrogen flow to produce Au-Cu@SiO2 catalyst. XRD and XPS characterization confirmed the presence of Au-Cu nanocomposites in the catalyst while TEM characterization revealed the core-shell structure of the catalyst with the presence of sub 5-nm Au-Cu nanoparticle cores inside SiO2 shells...
January 12, 2018: ACS Applied Materials & Interfaces
So Jung Park, Seyong Kim, Daeseong Yong, Youngson Choe, Joona Bang, Jaeup U Kim
We systematically examined the polymer-mediated interparticle interactions between polymer-grafted nanoparticles (NPs) within chemically identical homopolymer matrices through experimental and computational efforts. In experiments, we prepared thermally stable gold NPs grafted with polystyrene (PS) or poly(methyl methacrylate) (PMMA), and they were mixed with corresponding homopolymers. The nanocomposites are well dispersed when the molecular weight ratio of free to grafted polymers, α, is small. For α above 10, NPs are partially aggregated or clumped within the polymer matrix...
January 12, 2018: Soft Matter
Yubiao Niu, Philomena Schlexer, Bela Sebok, Ib Chorkendorff, Gianfranco Pacchioni, Richard E Palmer
Au nanoparticles represent the most remarkable example of a size effect in heterogeneous catalysis. However, a major issue hindering the use of Au nanoparticles in technological applications is their rapid sintering. We explore the potential of stabilizing Au nanoclusters on SiO2 by alloying them with a reactive metal, Ti. Mass-selected Au/Ti clusters (400 000 amu) and Au2057 clusters (405 229 amu) were produced with a magnetron sputtering, gas condensation cluster beam source in conjunction with a lateral time-of-flight mass filter, deposited onto a silica support and characterised by XPS and LEIS...
January 12, 2018: Nanoscale
Akihisa Miayagawa, Makoto Harada, Tetsuo Okada
We present a novel analytical principle in which an analyte (according to its concentration) induces a change in the density of a microparticle, which is measured as a vertical coordinate in a coupled acoustic-gravitational (CAG) field. The density change is caused by the binding of gold nanoparticles (AuNPs) on a polystyrene (PS) microparticle through avidin-biotin association. The density of a 10-m PS particle increases by 2 % when 500 100-nm AuNPs are bound to the PS. The CAG can detect this density change as a 5-10-m shift of the levitation coordinate of the PS...
January 12, 2018: Analytical Chemistry
Amna Bashir, Sudhanshu Shukla, Jia Haur Lew, Shashwat Shukla, Annalisa Bruno, Disha Gupta, Tom Baikie, Rahul Patidar, Zareen Akhter, Anish Priyadarshi, Nripan Mathews, Subodh G Mhaisalkar
Carbon based perovskite solar cells (PSCs) are fabricated through easily scalable screen printing techniques, using abundant and cheap carbon to replace the hole transport material (HTM) and the gold electrode further reduces costs, and carbon acts as a moisture repellent that helps in maintaining the stability of the underlying perovskite active layer. An inorganic interlayer of spinel cobaltite oxides (Co3O4) can greatly enhance the carbon based PSC performance by suppressing charge recombination and extracting holes efficiently...
January 12, 2018: Nanoscale
Yuzhi Shi, Sha Xiong, Lip Ket Chin, Jingbo Zhang, Wee Ser, Jiuhui Wu, Tianning Chen, Zhenchuan Yang, Yilong Hao, Bo Liedberg, Peng Huat Yap, Din Ping Tsai, Cheng-Wei Qiu, Ai Qun Liu
The past two decades have witnessed the revolutionary development of optical trapping of nanoparticles, most of which deal with trapping stiffness larger than 10-8 N/m. In this conventional regime, however, it remains a formidable challenge to sort out sub-50-nm nanoparticles with single-nanometer precision, isolating us from a rich flatland with advanced applications of micromanipulation. With an insightfully established roadmap of damping, the synchronization between optical force and flow drag force can be coordinated to attempt the loosely overdamped realm (stiffness, 10-10 to 10-8 N/m), which has been challenging...
January 2018: Science Advances
Puneet Tyagi, Jose Luis Santos
With the advent of technology, newer forms of drugs, such as proteins, DNA, and RNA, have entered mainstream product development. However, systemic delivery of macromolecules is limited by rapid blood clearance, poor stability in vivo, and inadequate uptake by cells. Nanoparticle (NP)-based delivery systems have emerged as suitable carriers for overcoming such pharmacokinetic limitations of macromolecule delivery. Nanocarriers, such as liposomes, provide protection for sensitive drug materials and also enhance the circulation half-life of=therapeutics...
January 8, 2018: Drug Discovery Today
Yun-Wen Chen, Shu-Chen Hsieh, Yi-Chin Yang, Shan-Hui Hsu, Mei-Lang Kung, Pei-Ying Lin, Hsien-Hsu Hsieh, Ching-Hao Lin, Cheng-Ming Tang, Huey-Shan Hung
Vascularization of engineered tissues remains one of the key problems. Here, we described a novel approach to promote vascularization of engineered tissues using fibronectin (FN) incorporated gold nanoparticles (AuNP) coated onto catheters with mesenchymal stem cells (MSCs) for tissue engineering. We found that the FN-AuNP composite with 43.5 ppm of AuNP exhibited better biomechanical properties and thermal stability than pure FN. FN-AuNP composites promoted MSC proliferation and increased the biocompatibility...
January 8, 2018: Nanomedicine: Nanotechnology, Biology, and Medicine
Reşat Apak, Sema Demirci Çekiç, Ayşem Üzer, Saliha Esin Çelik, Mustafa Bener, Burcu Bekdeşer, Ziya Can, Şener Sağlam, Ayşe Nur Önem, Erol Erçağ
Since an unbalanced excess of reactive oxygen/nitrogen species (ROS/RNS) causes various diseases, determination of antioxidants that can counter oxidative stress is important in food and biological analyses. Optical/electrochemical nanosensors have attracted attention in antioxidant activity (AOA) assessment because of their increased sensitivity and selectivity. Optical sensors offer advantages such as low cost, flexibility, remote control, speed, miniaturization and on-site/in situ analysis. Electrochemical sensors using noble metal nanoparticles on modified electrodes better catalyze bioelectrochemical reactions...
January 11, 2018: Sensors
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