Silicon dioxide covered Au and Ag nanoparticles for shell-isolated nanoparticle enhanced spectroscopies in the near-infrared

RSC Advances ◽  
2015 ◽  
Vol 5 (73) ◽  
pp. 59373-59378 ◽  
Author(s):  
Tatiana B. V. Neves ◽  
Sandra M. Landi ◽  
Lídia A. Sena ◽  
Bráulio S. Archanjo ◽  
Gustavo F. S. Andrade

SHINERS and SHINEF from Ag@SiO2and Au@SiO2excited in the near-infrared are presented, with high enhancement factors, together to TEM/EDX evidences of silica coverage over Au and Au nanoparticles.

Pharmaceutics ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 52
Author(s):  
Atanu Naskar ◽  
Sohee Lee ◽  
Kwang-sun Kim

Antibiotic therapy is the gold standard for bacterial infections treatment. However, the rapid increase in multidrug-resistant (MDR) bacterial infections and its recent use for secondary bacterial infections in many COVID-19 patients has considerably weakened its treatment efficacy. These shortcomings motivated researchers to develop new antibacterial materials, such as nanoparticle-based antibacterial platform with the ability to increase the chances of killing MDR strains and prevent their drug resistance. Herein, we report a new black phosphorus (BP)-based non-damaging near-infrared light-responsive platform conjugated with ZnO and Au nanoparticles as a synergistic antibacterial agent against Staphylococcus aureus species. First, BP nanosheets containing Au nanoparticles were assembled in situ with the ZnO nanoparticles prepared by a low-temperature solution synthesis method. Subsequently, the antibacterial activities of the resulting Au–ZnO–BP nanocomposite against the non-resistant, methicillin-resistant, and erythromycin-resistant S. aureus species were determined, after its photothermal efficacy was assessed. The synthesized nanocomposite exhibited excellent anti-S. aureus activity and good photothermal characteristics. The non-resistant S. aureus species did not produce drug-resistant bacteria after the treatment of multiple consecutive passages under the pressure of the proposed nanoantibiotic, but rapidly developed resistance to erythromycin. This work clearly demonstrates the excellent photothermal antibacterial properties of Au–ZnO–BP nanocomposite against the MDR S. aureus species.


2018 ◽  
Author(s):  
Roberts Lozins ◽  
Dzintars Ozoliņš

AbstractIn this study, yeast, Gram positive and Gram negative bacteria were attached to silicon dioxide microparticles or silica in order to measure their absorbance, also known as physical absorption of light, changes using spectrophotometry. The goal of the study was to determine if spectrophotometry is an effective way to distinguish microorganisms and if microorganisms have an affinity for silicon dioxide since it is a suitable material for the production of prostheses. The experiment was done by examining the light absorption properties of yeast, Gram positive and Gram negative bacteria in a spectrophotometer with and without silicon dioxide microparticles. During the experiment there have been several promising results. First of all, the spectrophotometers presented graphs of yeast were noticeably different from the graphs of both Gram positive and Gram negative bacteria. Secondly, the absorption of light in both Gram positive and Gram negative bacteria at near infrared (700-1500 nm) wavelengths increased when silicon dioxide microparticles were added to the suspension, unlike yeast. When silicon dioxide microparticles were added to yeast, the absorption of light decreased during the whole wavelength interval of the spectrophotometer measurement. The results indicate that spectrophotometry could be used to distinguish yeast from bacteria and possibly bacteria from each other. The results also suggest that silicon dioxide should not be used in the production of prostheses since it could be a favourable material for the development of biofilms.


Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 527
Author(s):  
Luukas Kuusela ◽  
Alexander Veber ◽  
Nadia G. Boetti ◽  
Laeticia Petit

The impact of the progressive addition of ZnO up to 5 mol% on the thermal, structural, and optical properties of Er3+-doped phosphate glasses within the system NaPO3-NaF-ZnO-Ag2O is discussed. The glass network was found to depolymerize upon the addition of ZnO. This promotes a slight increase in the intensity of the emission at 1.5 µm as well as enhances the silver ions clustering ability under the heat treating. The Ag-nanoparticles formed after moderate heat-treatment can further enhance the emission at 1.5 µm, whereas an excessive amount of the clusters leads to the opposite effect. The addition of ZnO helps to slightly increase the glass ability of the system. The crystallization behavior study revealed that surface crystallization is observed for all the glasses. It is found that even a small ZnO addition changes the crystalline phases formed after devitrification. Moreover, the addition of ZnO decreases the crystallization tendency of the glass.


RSC Advances ◽  
2017 ◽  
Vol 7 (13) ◽  
pp. 7469-7475 ◽  
Author(s):  
Ryeri Lee ◽  
Yogeenth Kumaresan ◽  
Sei Young Yoon ◽  
Soong Ho Um ◽  
Il Keun Kwon ◽  
...  

In this study, we designed core/shell nanostructures (CSNs) of silicon dioxide (SiO2)/titanium dioxide (TiO2), which were decorated with gold (Au) nanoparticles (NPs), to activate the visible light-driven photocatalytic reaction.


Nanomaterials ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 622 ◽  
Author(s):  
Álvaro Martínez ◽  
Yanchao Lyu ◽  
Fabrizio Mancin ◽  
Paolo Scrimin

The challenge to obtain plasmonic nanosystems absorbing light in the near infrared is always open because of the interest that such systems pose in applications such as nanotherapy or nanodiagnostics. Here we describe the synthesis in an aqueous solution devoid of any surfactant of Au-nanowires of controlled length and reasonably narrow dimensional distribution starting from Au-nanoparticles by taking advantage of the properties of glucosamine phosphate under aerobic conditions and substoichiometric nanoparticle passivation. Oxygen is required to enable the process where glucosamine phosphate is oxidized to glucosaminic acid phosphate and H2O2 is produced. The process leading to the nanosystems comprises nanoparticles growth, their aggregation into necklace-like aggregates, and final fusion into nanowires. The fusion requires the consumption of H2O2. The nanowires can be passivated with an organic thiol, lyophilized, and resuspended in water without losing their dimensional and optical properties. The position of the broad surface plasmon band of the nanowires can be tuned from 630 to >1350 nm.


2014 ◽  
Vol 2 (23) ◽  
pp. 3667-3673 ◽  
Author(s):  
Xiaosheng Ye ◽  
Hui Shi ◽  
Xiaoxiao He ◽  
Kemin Wang ◽  
Duo Li ◽  
...  

A shape-controllable and spectrum-adjustable synthesis strategy is proposed to develop Au@Ag/Au nanoparticles with intense NIR-absorption, efficacious thermotherapy and low dark-cytotoxicity.


2011 ◽  
Vol 1351 ◽  
Author(s):  
Zhixun Luo ◽  
Boon H. Loo ◽  
Jiannian Yao

ABSTRACTColloidal Au/Ag nanoparticles can be controllably assembled on anodic aluminum oxide (AAO) surfaces; monolayer coating on the membrane on AAO with smaller pores, or a nano-net arrangement along the edges of AAO with larger pores. The supported Au and Ag nanoparticles on the AAO membranes are closely packed and exhibited localized surface plasmon resonance (LSPR). Thus AAO membrane coated with Au or Ag nanoparticles is a highly surface-enhanced Raman scattering (SERS) active substrate. High quality SERS spectra were obtained using fullerene molecules C60 & C70 as the probe molecules and the filtered Au nanoparticles as the substrate. Furthermore, new SERS systems were obtained from Au nanoparticles assembled into the pores of AAO-supported fullerene nano-tubes, and the C60/C70 nano-tube arrays loaded with Au nanoparticles. The new SERS systems made use of the contributions from AAO, the LSPR of the Au nanoparticles, and a uniform assembly of the probe molecules in the nanostructures. These approaches have also been applied to small organic molecule systems using Ag nanoparticles.


Sign in / Sign up

Export Citation Format

Share Document