Influence of Oxygen on the Optical Properties of Silver Nanoparticles

Rentería-Tapia, Víctor; García-Macedo, Jorge A.

doi:10.1166/jnn.2008.18423

Cited by 12 publications

(6 citation statements)

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“…The sample collected from the bulk hydrogel surface after oxygen exposure also exhibited reduced antimicrobial action (Table S1 in the Supporting Information). Such size-dependent antimicrobial activity of silver nanoparticles was also observed by many other workers. − …”

Section: Resultssupporting

confidence: 82%

“…This hydrogel showed shifting in surface plasmon resonance (SPR) of pure silver (∼430 nm) to ∼500 nm. In the presence of oxygen, this red shift in the hydrogel is due to the oxidation on the surface of silver nanoparticles to silver oxide yield in an oxygen atmosphere. − In the presence of tea extract, a peak was noted in the range of approximately 280 nm, which is a characteristic of natural phenolic. , A similar kind of phenomenon was also observed in an earlier report …”

Section: Resultssupporting

confidence: 66%

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Hierarchical Assembly of Nanodimensional Silver–Silver Oxide Physical Gels Controlling Nosocomial Infections

et al. 2020

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Microbial infections originating from medical care facilities are raising serious concerns across the globe. Therefore, nanotechnology-derived nanostructures have been investigated and explored due to their promising characteristics. In view of this, silver-based antimicrobial hydrogels as an alternative to antibiotic-based creams could play a crucial role in combating such infections. Toward this goal, we report a simple method for the synthesis and assembly of silver nanoparticles in a biopolymer physical gel derived from Abroma augusta plant in imparting antimicrobial properties against nosocomial pathogens. Synthesized silver nanoparticles (diameter, 30 ± 10 nm) were uniformly distributed inside the hydrogel. Such synthesized hydrogel assembly of silver nanoparticles dispersed in the biopolymer matrix exhibited hemocompatibility and antimicrobial and antibiofilm characteristics against nosocomial pathogens. The developed hydrogel as a surface coating offers reduced hardness and modulus value, thereby minimizing the brittleness tendency of the gel in the dried state. Hence, we believe that the hierarchical assembly of our hydrogel owing to its functional activity, host toxicity, and stability could possibly be used as an antimicrobial ointment for bacterial infection control.

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Section: Resultssupporting

confidence: 82%

Section: Resultssupporting

confidence: 66%

Hierarchical Assembly of Nanodimensional Silver–Silver Oxide Physical Gels Controlling Nosocomial Infections

et al. 2020

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“…EDX measurements were performed during the TEM observations with a probe diameter of 30 nm (the smallest one providing a measurable signal) in order to identify the film content. On the other hand, the oxidation of silver nanoparticles was frequently observed with heat treatments at increasing temperature. ,− This oxidation is all the easier as the nanoparticles are small. , As in the studies of refs − , the formed thin shells are not clearly distinguishable on the TEM pictures because they are too small to be crystallized and because they are all the more difficult to observe as the nanoparticles are buried in the silica matrix. In our experiments, the silver oxidation is likely to result from a local heating around the nanoparticles occurring after exposures to laser doses greater than about 100 J/cm 2 at 244 nm wavelength.…”

Section: Discussionmentioning

confidence: 97%

“…On the other hand, the oxidation of silver nanoparticles was frequently observed with heat treatments at increasing temperature. 5,[36][37][38][39][40] This oxidation is all the easier as the nanoparticles are small. 36,37 As in the studies of refs 36-38, the formed thin shells are not clearly distinguishable on the TEM pictures because they are too small to be crystallized and because they are all the more difficult to observe as the nanoparticles are buried in the silica matrix.…”

Section: Nanoparticle Growth In Mesostructured Hybrid Silica Filmsmentioning

confidence: 99%

Growth Mechanisms and Kinetics of Photoinduced Silver Nanoparticles in Mesostructured Hybrid Silica Films under UV and Visible Illumination

et al. 2010

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The growth of silver nanoparticles in mesostructured hybrid silica films under laser illumination is investigated by optical absorption spectroscopy and transmission electron microscopy. At low laser doses in the UV range, a blue-shift of the plasmon resonance is observed for increasing particle size. This size dependence is interpreted on the basis of the Mie theory assuming a two-layer core-shell model resulting from the localization of the nanoparticles in the block copolymer part of the film. At higher laser doses, the observed red-shift of the resonance wavelength and decrease of the absorbance level at resonance are attributed to the formation of a high refractive index shell around the nanoparticles that thickens slowly with the dose. The growth kinetics of silver nanoparticles is also studied for different illumination wavelengths in the UV and visible ranges. Surprisingly, the nanoparticles also grow under visible illumination. This is partly attributed to the release of electrons by the degrading copolymer under illumination. The decrease of the photoreduction process rate with the incident wavelength increase has been evaluated quantitatively. We propose an autocatalytic model that fits well with the experimental data and suggest that the absorption of some incident wavelengths by the generated small silver clusters boosts their own growth.

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“…11 However, as silver is more reactive than gold, SPR active silver nanoparticles will develop a thin oxide layer and the SPR absorption will be dampened and red shifted. 12 SPR is a phenomenon that occurs at the surface of particles and is therefore sensitive to the dielectric constant of both the surrounding medium and the metal itself, as well as the shape and size of the particle. The intensity and wavelength of SPR absorptions are dependent on the surrounding medium as it affects both the incident light on the metal particle and the light reflected by the metal particle.…”

Section: Surface Plasmon Resonancementioning

confidence: 99%

Synthesis and Characterisation of Core-shell Gold Nanoparticles

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<p>Technology developed at Victoria University of Wellington by Professor James H. Johnston and Dr Kerstin Lucas allows for the colouring of high quality wool fibres using spherical gold nanoparticles. Gold nanoparticles have interesting colours and optical properties due to surface plasmon resonance effects and, using this technology, a boutique range of colours can be imparted onto wool fibres. The colour of gold nanoparticles is determined by their size and shape, hence the colour range achievable using spherical nanoparticles is limited to those obtained by changing the particle diameter and degree of aggregation of these particles. This limitation can be overcome by using gold nanoparticles of different shapes in conjunction with other materials. This research details the synthesis and characterisation of gold nanoshells on spherical silica cores and their use for the colouring of wool. Silica cores were used in this research as they are reasonably chemically inert and so serve as a stable substrate for the gold shells. Silica spheres are also easily prepared in a manner that allows control over the final particle diameter. Several syntheses of these core-shell particles have been previously devised however they are not suitable for commercial use. Such syntheses involve many time-consuming steps, high temperatures or light-sensitive reagents. Synthetic methods set out in this research involve a novel in-situ seeding of gold nanoparticles for the growth of the shells eliminating the step of growing gold nanoparticles ex-situ commonly involved in other synthetic schemes. The need for light-sensitive reducing agents is eliminated by the use of other reductants such as sodium borohydride and hydroxylamine. All steps of the synthetic schemes are carried out at less than 100 °C. Several methods of synthesising core-shell particles are outlined in this research, which achieved varying degrees of success. Many syntheses investigated successfully produced core-shell particles but also left many silica spheres without the desired gold shell coating. This was not a problem for the proposed application of colouring wool. As silica is easily dispersed in water and does not have the same affinity to bind to wool as gold does, the silica spheres without gold shells simply wash off after colouring. This allowed the core-shell particles synthesised in this research to be successfully used to colour wool fibres and achieve a shade of purple not previously obtained using the earlier methodologies.</p>

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Influence of Oxygen on the Optical Properties of Silver Nanoparticles

Cited by 12 publications

References 0 publications

Hierarchical Assembly of Nanodimensional Silver–Silver Oxide Physical Gels Controlling Nosocomial Infections

Hierarchical Assembly of Nanodimensional Silver–Silver Oxide Physical Gels Controlling Nosocomial Infections

Growth Mechanisms and Kinetics of Photoinduced Silver Nanoparticles in Mesostructured Hybrid Silica Films under UV and Visible Illumination

Synthesis and Characterisation of Core-shell Gold Nanoparticles

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