Ultrasensitive Detection of Methylene Blue Using an Electrochemically Synthesized SERS Sensor Based on Gold and Silver Nanoparticles: Roles of Composition and Purity on Sensing Performance and Reliability

Author(s):  
Mai Quan Doan ◽  
Nguyen Ha Anh ◽  
Nguyen Xuan Quang ◽  
Ngo Xuan Dinh ◽  
Doan Quang Tri ◽  
...  
2020 ◽  
Vol 128 (9) ◽  
pp. 1380
Author(s):  
А.П. Русинов ◽  
М.Г. Кучеренко

By continuous-pump Z-scanning, the nonlinear light absorption of aqueous and alcohol solutions of methylene blue was studied. It was shown that the mechanisms of optical nonlinearity of these solutions vary depending on the dye concentration and type of solvent. The dependence of the amplitude of nonlinear absorption of dye molecules on the concentration and sign of the surface charge of gold and silver nanoparticles in solution is revealed. Mathematical models of optical nonlinearity for concentrated and diluted solutions of dye molecules are considered; in the latter case, the influence of plasmon nanoparticles on the nonlinear optical characteristics of methylene blue solutions is taken into account


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Diego Alberto Lomelí-Rosales ◽  
Adalberto Zamudio-Ojeda ◽  
Sara Angélica Cortes-Llamas ◽  
Gilberto Velázquez-Juárez

AbstractNowadays, there are several approaches reported to accomplish the green synthesis of metal nanoparticles by using bacterial and fungi supernatants or by-products generated by these microorganisms. Therefore, agars as solely reductive regents have started to be used in order to obtain metal nanoparticles. This paper shows the results of the synthesis of gold and silver nanoparticles with different morphology, mainly triangular and truncated triangular, using Eosin Methylene Blue (EMB) agar as reducing agent. To control the reaction process, the necessary activation energy for the reducer was provided by three different techniques: microwave radiation, using a domestic microwave oven, ultraviolet radiation, and heating on a conventional plate. The evolution of the reduction process and stability of the samples was performed by ultraviolet visible spectroscopy. Morphology was carefully analyzed using high-resolution transmission electron microscopy (HRTEM) and Transmission electron microscopy (TEM). A one step synthesis for gold and silver nanoparticles was optimized with an eco-friendly and economic process.


2021 ◽  
Vol 6 (22) ◽  
pp. 5474-5487
Author(s):  
Nishanthi Ezhumalai ◽  
Manivannan Nanthagopal ◽  
Shanmugam Chandirasekar ◽  
Manikandan Elumalai ◽  
Mathivanan Narayanasamy ◽  
...  

2021 ◽  
Vol 9 (6) ◽  
pp. 678
Author(s):  
Kaliyamoorthy Kalidasan ◽  
Nabikhan Asmathunisha ◽  
Venugopal Gomathi ◽  
Laurent Dufossé ◽  
Kandasamy Kathiresan

This work deals with the identification of a predominant thraustochytrid strain, the optimization of culture conditions, the synthesis of nanoparticles, and the evaluation of antioxidant and antimicrobial activities in biomass extracts and nanoparticles. Thraustochytrium kinnei was identified as a predominant strain from decomposing mangrove leaves, and its culture conditions were optimized for maximum biomass production of 13.53 g·L−1, with total lipids of 41.33% and DHA of 39.16% of total fatty acids. Furthermore, the strain was shown to synthesize gold and silver nanoparticles in the size ranges of 10–85 nm and 5–90 nm, respectively. Silver nanoparticles exhibited higher total antioxidant and DPPH activities than gold nanoparticles and methanol extract of the strain. The silver nanoparticles showed higher antimicrobial activity than gold nanoparticles and petroleum ether extract of the strain. Thus, Thraustochytrium kinnei is proven to be promising for synthesis of silver nanoparticles with high antioxidant and antimicrobial activity.


Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4585
Author(s):  
Nicole Jara ◽  
Nataly S. Milán ◽  
Ashiqur Rahman ◽  
Lynda Mouheb ◽  
Daria C. Boffito ◽  
...  

Nanomaterials have supported important technological advances due to their unique properties and their applicability in various fields, such as biomedicine, catalysis, environment, energy, and electronics. This has triggered a tremendous increase in their demand. In turn, materials scientists have sought facile methods to produce nanomaterials of desired features, i.e., morphology, composition, colloidal stability, and surface chemistry, as these determine the targeted application. The advent of photoprocesses has enabled the easy, fast, scalable, and cost- and energy-effective production of metallic nanoparticles of controlled properties without the use of harmful reagents or sophisticated equipment. Herein, we overview the synthesis of gold and silver nanoparticles via photochemical routes. We extensively discuss the effect of varying the experimental parameters, such as the pH, exposure time, and source of irradiation, the use or not of reductants and surfactants, reagents’ nature and concentration, on the outcomes of these noble nanoparticles, namely, their size, shape, and colloidal stability. The hypothetical mechanisms that govern these green processes are discussed whenever available. Finally, we mention their applications and insights for future developments.


2021 ◽  
Author(s):  
Xiangrong Huang ◽  
Na Wu ◽  
Wenxiu Liu ◽  
Yazhuo Shang ◽  
Honglai Liu ◽  
...  

In this work, a novel redox hydrogel was proposed for ultrasensitive label-free electrochemical detection of carcinoembryonic antigen (CEA). The redox hydrogel composed by cellulose nanocrystalline (CNC), methylene blue (MB), multi-walled...


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