Optical and structural changes of silver nanoparticles during photochromic transformation

2006 ◽  
Vol 88 (1) ◽  
pp. 011923 ◽  
Author(s):  
C. Dahmen ◽  
A. N. Sprafke ◽  
H. Dieker ◽  
M. Wuttig ◽  
G. von Plessen
2013 ◽  
Vol 7 (3) ◽  
pp. 271-275 ◽  
Author(s):  
Vinita Ernest ◽  
M. Joyce Nirmala ◽  
S. Gajalakshmi ◽  
Amitava Mukherjee ◽  
N. Chandrasekaran

2020 ◽  
Vol 21 (4) ◽  
pp. 1510 ◽  
Author(s):  
Md. Amdadul Huq

Silver nanoparticles (AgNPs) have shown great promise in biomedical applications. The exact mechanism and mode of action of AgNPs regarding antimicrobial activity are still not well known. Moreover, synthesis of nanoparticles by physical and chemical methods is expensive and not ecofriendly. This study highlights the green, rapid, facile, cost-effective and ecofriendly synthesis of AgNPs using Pseudoduganella eburnea MAHUQ-39 and also investigates their antibacterial mechanisms. The transmission electron microscopy (TEM) image revealed a spherical shape of the AgNPs. The size of the synthesized AgNPs was 8 to 24 nm. The elemental mapping and selected area electron diffraction (SAED) and X-ray diffraction (XRD) patterns revealed the crystalline structure of AgNPs. Fourier-transform infrared spectroscopy (FTIR) analysis identified the functional groups that are involved in the reduction of silver ion to AgNPs. The green synthesized AgNPs exhibited strong antimicrobial activity against multidrug-resistant pathogenic microbes. Minimal inhibitory concentrations (MICs) of Staphylococcus aureus and Pseudomonas aeruginosa were 100 μg/mL and 6.25 μg/mL, respectively, and the minimum bactericidal concentrations (MBCs) of S. aureus and P. aeruginosa were 200 μg/mL and 50 μg/mL, respectively. Our data demonstrated that synthesized AgNPs created structural changes of cells and destroyed the membrane integrity of strains S. aureus and P. aeruginosa. Therefore, AgNPs synthesized by strain MAHUQ-39 can be used as a powerful antimicrobial agent for various therapeutic applications.


2012 ◽  
Vol 537 ◽  
pp. 65-68 ◽  
Author(s):  
Tetsu Yonezawa ◽  
Shigeo Arai ◽  
Hironori Takeuchi ◽  
Takeo Kamino ◽  
Kotaro Kuroda

2018 ◽  
Vol 69 (7) ◽  
pp. 1774-1778
Author(s):  
Irina Gradinaru ◽  
Leonard Ignat ◽  
Florica Doroftei ◽  
Maurusa Elena Ignat ◽  
Magda Ecaterina Antohe

The purpose of this study was to test the structural improving that may be acquired by adding hydroxyapatite microparticles bearing or not silver nanoparticles to three different commercial products commonly used in dental practice. The practical part of this study consisted in the preparation of a common protocol of nine samples resulting from the creation of cavities and their filling similarly to the solving of different clinical situations of carious processes, extracted teeth belonging to both the anterior and the posterior area, with different architectures of the loss of dental substance. Before use, both HA and HA/AgNP have been subjected to calcination in an oven at 6000C for three hours in order to eliminate the residual organic matter. The structural changes have been studied on three types of composites known in the medical practice under the tradenames of Ceram X Duo, Swiss Tec and Herculite XRV Ultra. The structural changes materialized at the level of dentinal component are clearly visible in the SEM images recorded for each starting commercial material. Thus, the addition of HA with high polydispersity (within the range of tens of nanometers and several microns) was effective on lowering the surface rugosity and apparent macro-porosity, while enhancing the phase mixing and component cohesion, but only in the case of Ceram X Duo and Swiss Tec materials. For Herculite XRV Ultra these effects seems to be limited or even reversed, phenomenon that could be explained by the fact that this material already contains nano-fillers, and their concentration tends to saturation.


2019 ◽  
Vol 7 (13) ◽  
pp. 11088-11100 ◽  
Author(s):  
Manoj Kumar Banjare ◽  
Kamalakanta Behera ◽  
Ramesh Kumar Banjare ◽  
Reshma Sahu ◽  
Srishti Sharma ◽  
...  

2021 ◽  
Vol 11 (6) ◽  
pp. 15068-15074

This work aimed to study the interaction of silver nanoparticles (AgNP) and lipases with models of biological membranes based on natural phospholipid and cholesterol. The crude phosphatidylcholine from egg yolk (PCe1) and synthetic cholesterol (Chol) were obtained from Sigma-Aldrich. Porcine pancreatic lipase (PPL) was obtained by purification from the hog pancreas. AgNP dispersion was prepared by the well-known citrate method. Measurement of surface tension (ST) was carried out using a BPA-1P device. The equilibrium surface tension (eST) was obtained by calculating the ST-time isotherms using the ADSA program. The particle sizes were determined by the dynamic light scattering method. An addition of AgNPs led to a pronounced decrease in both ST and eST (whereas almost no changes occurred by lipase addition), and AgNPs destructed the large lipid particles. The average lipid particle diameter values changed drastically, whereas the effective particle diameter values were almost the same by lipase addition. Thus, the interactions of AgNPs or lipase with the mixture of natural phospholipid and cholesterol have had entirely different features. These effects are interesting for modeling the interactions of inorganic and organic compounds with biological membranes.


2018 ◽  
Vol 20 (33) ◽  
pp. 21498-21505
Author(s):  
Prompong Pienpinijtham ◽  
Sanpon Vantasin ◽  
Oraporn Wong-u-ra ◽  
Yasutaka Kitahama ◽  
Sanong Ekgasit ◽  
...  

Local structural changes of graphene oxide (GO) in silver/graphene oxide (AGO) nanocomposites were successfully investigated using tip-enhanced Raman scattering (TERS).


2019 ◽  
Vol 70 (2) ◽  
pp. 591-595
Author(s):  
Anca Vitalariu ◽  
Monica Tatarciuc ◽  
Odette Luca ◽  
Catalina Holban Cioloca ◽  
Bogdan Bulancea ◽  
...  

Acrylic resins are frequently used in dentistry for the removable partial or complete denture but, epidemiological studies report that approximately 70% of removable denture wearers suffer from denture stomatitis. Silver nanoparticles (AgNps) incorporation aims to avoid or at least to decrease the microbial colonization over dental materials, but their influence on the mechanical features is still not very well known. A total of 100 heat curing and 100 of self-curing acrylic resin samples were made, and divided into three groups for both resins (ten for each), according to the concentration of AgNPs solution (5%, 10%, and 20% vol.) incorporated into the monomer. One control group without AgNPs for each resin was prepared, as well. The dimensions of the used AgNPs, were 20, 40 and 60 nm. The structural changes were analyzed with Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The thermal behavior was evaluated through Differential Scanning Calorimetry (DSC). The results demonstrated that AgNPs incorporation doesn�t induce significant structural and thermal changes in dental resins.


Nanomaterials ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 2031
Author(s):  
Rita La Spina ◽  
Dora Mehn ◽  
Francesco Fumagalli ◽  
Margaret Holland ◽  
Fabiano Reniero ◽  
...  

Silver nanoparticles (AgNPs) may be synthesized by many different methods, with those based on the thermal reduction of silver salts by citric acid or citric acid/tannic acid being amongst the most commonly used. These methods, although widely used and technically simple, can produce particles in which the size, polydispersivity and morphology can vary greatly. In this work nearly mono-dispersed spherical AgNPs have been synthesized via a one-step reduction method by using sodium citrate and varying quantities of Tannic Acid (TA), which was thermally conditioned prior to use in the growth process. It was found that the final size can be further tailored by controlling the amount of TA and the thermal conditioning of the TA at 60 °C at different time points, which changes the size and polydispersivity of AgNPs. To better understand the origin of this effect, optical spectroscopic analysis and 1H NMR of the TA following mild thermal conditioning of the solution have been done. Comparison of thermally conditioned TA and TA exposed to basic pH shows that similar chemical modifications occur and consequently produce similar effects on growth when used in the synthesis of AgNPs. It is proposed that thermal preconditioning of the TA introduces either chemical or structural changes, which decrease the final particle size under a given total silver content.


2002 ◽  
Vol 106 (12) ◽  
pp. 3041-3045 ◽  
Author(s):  
Kei Murakoshi ◽  
Hiroyuki Tanaka ◽  
Yoshitaka Sawai ◽  
Yoshihiro Nakato

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