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Silver AND Nanoparticles

Rongrong Qin, Yongchun Liu, Fei Tao, Chen Li, Wenfei Cao, Peng Yang
The welding and sintering of nanomaterials is usually achieved at high temperatures and high pressures. Here, it is found that merging of metal nanoparticles occurs under ambient conditions in an aqueous solution via protein bonding. It is discovered that the silver nanoparticles from the in situ reduction of silver ammonium ions by glucose undergo confined nucleation and growth and are bound by ultrathin amyloid-like β-sheet stacking of lysozyme. This merging of silver nanoparticles creates a freestanding large-area (e...
December 9, 2018: Advanced Materials
Jasmine Singh, William Moore, Farjana Fattah, Xingya Jiang, Jie Zheng, Pamela Kurian, Muhammad S Beg, Saad A Khan
BACKGROUND: Silver nanoparticles (AgNP) show efficacy in cancer cell lines. We present the first in-human outcome of AgNP in a cancer patient. METHODS: Homemade AgNP solution is manufactured using online instructions by a 78-year old male. He started consuming AgNP while on hospice after he developed nasal cavity squamous cell cancer metastatic to liver and lung. RESULTS: Electron microscopy of AgNP solution revealed bimodal nanoparticle size distribution: 3 and 12 nm...
December 11, 2018: Head & Neck
Jovana Zvicer, Vesna Miskovic-Stankovic, Bojana Obradovic
In this work, functional characterization of biomaterials concerning potential application as articular cartilage implants was performed by using a biomimetic bioreactor with dynamic compression in the physiological regime (10 % strain, 0.84 Hz frequency, 1 h on/1 h off). Specifically, two alginate types with low (LG) and high (HG) guluronic/mannuronic residue ratios with electrochemically synthesized silver nanoparticles (AgNPs) were evaluated. HG Ag/alginate hydrogels were clearly indicated as potential candidates due to better initial mechanical properties as compared to LG hydrogels (dynamic compression modulus of ~60 vs...
December 10, 2018: Journal of Biomedical Materials Research. Part A
Wenwen Li, Changyue Sun, Songlin Yu, Zhihua Pu, Penghao Zhang, Kexin Xu, Zhenqiang Song, Dachao Li
This paper proposes a novel fiber attenuated total reflection (ATR) sensor with silver nanoparticles (AgNPs) on the flattened structure based on mid-infrared spectroscopy for detecting low concentration of glucose with high precision. The flattened structure was designed to add the effective optical path length to improve the sensitivity. AgNPs were then deposited on the surface of the flattened area of the fiber via chemical silver mirror reaction for further improving the sensitivity by enhancing the infrared absorption...
November 23, 2018: Biomedical Microdevices
Kamalesh Chaudhari, Tripti Ahuja, Vasanthanarayan Murugesan, Vidhya Subramanian, Mohd Azhardin Ganayee, Thomas Thundat, Thalappil Pradeep
We report simultaneous plasmonic scattering and Raman spectroscopic observations of single citrate capped silver nanoparticles (AgNPs) which exhibit surface enhanced Raman scattering (SERS) upon meeting specific conditions induced by laser (532 nm) exposure. We show that nanoparticles which are not initially SERS active become SERS active by laser-induced reshaping/reorientation. A set-up developed for these observations enabled in situ high speed time-lapse characterization using plasmonic and Raman spectroscopies in conjunction with dark-field microscopy (DFM)...
December 11, 2018: Nanoscale
Hongzhi Lu, Chunwei Yu, Shuai Quan, Shoufang Xu
Based on the inner filter effect and charge transfer dual response mechanism, a dual response ratiometric fluorescent probe (D-RFP) with two reversible signal changes for sensing H2O2 and glucose was developed. The D-RFP was proposed by embedding glycine-derived carbon dots (CDs) (λem = 400 nm) into silica nanoparticles and covalently linking CdTe quantum dots (QDs) (λem = 600 nm) onto the surface of silica nanoparticles. When silver nanoparticles (Ag NPs) were mixed with D-RFP, the fluorescence intensity of CDs can be quenched by Ag NPs via the inner filter effect...
December 11, 2018: Analyst
Piaopiao Chen, Shixin Yan, Erica Sawyer, Binwu Ying, Xiawei Wei, Zhengzhi Wu, Jia Geng
Ascorbic acid (AA) and alkaline phosphatase (ALP) serve as an important coenzyme and enzyme in multiple biological metabolism reactions, respectively, and abnormal levels of these substrates have been associated with several diseases. Herein, a new and simple fluorescence strategy has been developed for AA and ALP sensing by exploiting CdTe quantum dots (QDs) as an effective signal indicator. This method is mainly based on the selective fluorescence-quenching reaction between Ag+ and CdTe QDs, as opposed to silver nanoparticles (Ag NPs); Ag+ can be reduced to Ag NPs by AA...
December 10, 2018: Analyst
Gwénaëlle Lamri, Artur Movsesyan, Edite Figueiras, Jana B Nieder, Jean Aubard, Pierre-Michel Adam, Christophe Couteau, Nordin Felidj, Anne-Laure Baudrion
The control of quantum dot (QD) photoluminescence (PL) is a challenge for many applications. It is well known that plasmonic resonances can enhance this PL. In this work, we couple QDs with silver nanoparticles and immerse the system in a photochromic organic material. As these molecules are optical switches going from a transparent to a colored isomer by absorbing UV light, we observe on one hand a Förster Resonant Energy Transfer (FRET) between the QD emission and the absorbing isomer and on the other hand a plasmonic PL enhancement...
December 10, 2018: Nanoscale
Domna Iordanidou, Tryfon Zarganes-Tzitzikas, Constantinos G Neochoritis, Alexander Dömling, Ioannis N Lykakis
The catalytic efficacy of silver nanoparticles was investigated toward the chemoselective reduction of nitro-tetrazole or amino acid-substituted derivatives into the corresponding amines in high isolated yields. This highly efficient protocol was thereafter applied toward the multicomponent reaction synthesis of heterocyclic dihydroquinoxalin-2-ones with high isolated yields. The reaction proceeds with low catalyst loading (0.8-1.4 mol %) and under mild catalytic conditions, a very good functional-group tolerance, and high yields and can be easily scaled up to more than 1 mmol of product...
November 30, 2018: ACS Omega
Sandhya Gopalakrishnan, Sabu Thomas, Nandakumar Kalazikkal
No abstract text is available yet for this article.
October 2018: Journal of Indian Prosthodontic Society
(no author information available yet)
OBJECTIVES: The aim of this study was to establish and evaluate the mortality rate, hatching rate and observe the presence of sublethal changes in zebrafish embryos after exposure to silver ions and nanoparticles. METHODS: Tests were conducted on newly fertilized zebrafish embryos, according to the modified OECD guideline 236, using a semistatic method and 96 hour incubation time. Silver nitrate and two different silver nanoparticles, stabilized with 0.01% solution of maltose and gelatine in the first case, and stabilized with polyvinylpyrrolidone, in the latter, were tested...
October 10, 2018: Neuro Endocrinology Letters
Indushekhar Persaud, Jonathan H Shannahan, Achyut J Raghavendra, Nasser B Alsaleh, Ramakrishna Podila, Jared M Brown
Prior research has demonstrated cells exposed to silver nanoparticles (AgNPs) undergo endoplasmic reticulum (ER) stress leading to cellular apoptosis and toxicity, however, the fundamental mechanism underlying AgNP-induced ER stress is unknown. We hypothesize the biophysical interactions between AgNPs and adsorbed proteins lead to misfolded proteins to elicit an ER stress response. Our investigation examined rat aortic endothelial cells (RAEC) exposed to 20 or 100 nm AgNPs with or without a biocorona (BC) consisting of bovine serum albumin (BSA), high density lipoprotein (HDL) or fetal bovine serum (FBS) to form a complex BC...
December 4, 2018: Ecotoxicology and Environmental Safety
Luoxiao Ran, Yini Zou, Junwen Cheng, Fei Lu
In recent years, silver nanoparticles have widely been used in antibacterial dressings to solve antibiotic resistance problems. However, traditional methods for reducing silver nanoparticles are usually toxic. To overcome this problem, Sanghuangporus sanghuang polysaccharides (FSHPs) were used as a green reducing agent to prepare silver nanoparticles (AgNPs) with a size of 3-35 nm. The FSHPs‑silver nanoparticles (FSHPs-Ag) composite with chitosan solution were then freeze-dried to obtain a porous sponge dressing of chitosan-FSHPs-Ag (CS-FSHPs-Ag)...
December 5, 2018: International Journal of Biological Macromolecules
Subrata Sardar, Sanhita Maity, Sampa Pal, Hasan Parvej, Shahnaz Begum, Ramkrishna Dalui, Nayim Sepay, Umesh Chandra Halder
Silver nanoparticles (SNPs) have been increasingly used in medicines and biomaterials as a drug carriers and diagnostic or therapeutic material due to their smaller size, large surface area and cell penetration ability. Here we report the preparation of SNPs of diameter 10 ± 3 nm by using silver nitrate and sodium borohydride and the interaction of synthesized SNPs with our model protein β-lactoglobulin (β-lg) in 10 mM phosphate buffer at pH 7.5 after thermal exposure at 75 °C. Heat exposed β-lg forms amyloidal fibrillar aggregates whereas this protein aggregates adopt rod-like shape instead of fibrillar structure in presence of SNP under the same conditions...
December 6, 2018: International Journal of Biological Macromolecules
Hércules Bezerra Dias, Maria Inês Basso Bernardi, Taís Maria Bauab, Antônio Carlos Hernandes, Alessandra Nara de Souza Rastelli
OBJECTIVE: The aim of this study was to evaluate the antibacterial activity of a composite resin modified by TiO2 and TiO2 /Ag nanoparticles and their influence over different properties. METHODS: TiO2 and TiO2 /Ag NPs were synthesized by polymeric precursor and microwave-assisted hydrothermal methods and then, characterized by different techniques. Direct contact test was performed using Filtek™ Z350XT blended with 0.5; 1 and 2% (wt.) of NPs against Streptococcus mutans to determine the best concentration to the other tests...
December 7, 2018: Dental Materials: Official Publication of the Academy of Dental Materials
Pu Wang, Bo Zhang, Hui Zhang, Yiliang He, Choon Nam Ong, Jun Yang
With increasing emission of silver nanoparticles (AgNPs) into the environment, it is important to understand the effects of ambient concentration of AgNPs. The biological effects of AgNPs on Scenedesmus obliquus, a ubiquitous freshwater microalgae, was evaluated. AgNPs exerted a minor inhibitory effect at low doses. Non-targeted metabolomic studies were conducted to understand and analyze the effect of AgNPs on algal cells from a molecular perspective. During the 48 hr of exposure to AgNPs, 30 metabolites were identified, of which nine had significant changes compared to the control group...
February 2019: Journal of Environmental Sciences (China)
Nickolas Rigopoulos, Eleni Thomou, Αntonios Kouloumpis, Eleni Rafaela Lamprou, Varvara Petropoulea, Dimitrios Gournis, Efthymios Poulios, Haralampos C Karantonis, Efstathios Giaouris
In this study, silver nanoparticles (AgNPs) were synthesized using Banana Peel Extract (BPE), and characterized using UV- Vis absorbance spectroscopy, X-Ray Powder Diffraction (XRD), Atomic Force Microscopy (AFM), and Fourier Transform Infrared Spectroscopy (FTIR). UV - Vis absorbance spectroscopy showed the characteristic plasmon resonance of AgNPs at 433 nm. Nanoparticle size (between 5 and 9 nm) was measured using AFM, whereas their crystallinity was shown by XRD. FTIR identified the ligands that surround the nanoparticle surface...
December 9, 2018: Current Pharmaceutical Biotechnology
Ahmed M Abdellah, Mahmoud A Sliem, Mona Bakr, Rehab M Amin
AIM: There is an urgent need to develop alternative antimicrobial agents and, one of which is via the use of nanotechnology. Green synthetic routes are recently being replaced for nanoparticles preparation. Methods results: Silver-curcumin nanoconjugates (Ag-CurNCs) were prepared in an eco-friendly method. The prepared nanomaterials were characterized and the photostability was studied under the influence of UV irradiation. Results showed that, the conjugation between curcumin and silver in the nanoform improve the photostability of curcumin...
December 11, 2018: Future Medicinal Chemistry
Molly R Kogan, Nicole E Pollok, Richard M Crooks
Here we report on the seemingly simple process of galvanic exchange (GE) between electrogenerated AuCl4 - and silver nanoparticles (AgNPs). The results were obtained in the specific context of using AgNPs as labels for bioassays in paper fluidic devices. Results obtained from a combined electrochemistry and microscopy study indicate that the GE process results in recovery of only ∼5% of the total equivalents of Ag present in the system. This low value is a consequence of two factors. First, after an initial fraction of each AgNP undergoes GE, a Au shell forms around the remaining AgNP core preventing further exchange...
December 11, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Nicolas Macia, Roger Bresoli-Obach, Santi Nonell, Belinda J M Heyne
Plasmonic nanoparticles can strongly interact with adjacent photosensitizer molecules, resulting in significant alteration of their singlet oxygen (1O2) production. In this work, we report the next generation of metal-enhanced 1O2 nanoplatforms exploiting the lightning rod effect, or plasmon hot spots, in anisotropic (non-spherical) metal nanoparticles. We describe the synthesis of Rose Bengal decorated silica-coated silver nanocubes (Ag@SiO2-RB NCs) with silica shell thicknesses ranging from 5 to 50 nm based on an optimized protocol yielding highly homogeneous Ag NCs...
December 9, 2018: Journal of the American Chemical Society
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