Find answers to common questions about silver nanoparticle stability, crystallinity, surface chemistry, antimicrobial research, PVP-capped particles, and discontinued silver nanoplate products. For deeper technical information, explore our resources on silver nanoparticle physical properties and optical properties.
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Silver Nanoparticle Stability & Handling
Do silver nanoparticles oxidize?
Silver nanoparticles can undergo oxidation, sulfidation, dissolution, and other surface reactions depending on their environment. Exposure to oxygen, sulfur-containing species, halides, light, pH changes, and other solution components can alter the silver surface or particle morphology over time.
These effects depend on particle size, shape, surface chemistry, and formulation. Learn more in Silver Nanoparticle Physical Properties.
How can I tell if my silver nanoparticles have destabilized or degraded?
Well-dispersed small silver nanospheres typically appear yellow in solution and exhibit a distinct localized surface plasmon resonance in their UV-Visible spectrum. Monitoring this optical signature over time is a useful way to identify changes in the particle dispersion.
Aggregation commonly causes changes in color as well as spectral broadening, reduced intensity at the original plasmon peak, or increased extinction at longer wavelengths. Dissolution, oxidation, or changes in particle morphology can also alter the spectrum, so a spectral change does not necessarily indicate aggregation alone.
See Silver Nanoparticle Optical Properties for more information about using UV-Visible spectroscopy to monitor particle stability.
Are there special considerations for 10 nm PVP-capped silver nanoparticles?
Yes. Small PVP-capped silver nanoparticles can have different long-term stability considerations than larger silver particles. See Stability & Shelf Life of Small PVP Silver Nanoparticles for detailed guidance.
Silver Nanoparticle Structure & Surface Chemistry
Are silver nanospheres amorphous or crystalline?
nanoComposix silver nanospheres are considered polycrystalline. Individual particles contain multiple crystalline domains rather than a completely amorphous silver structure.
These domains can sometimes be observed in TEM images as lines, regions of different contrast, or other internal features within a particle. The presence of multiple crystal domains also allows the overall nanoparticle to maintain a near-spherical morphology even though the underlying silver is crystalline.
Do you offer “bare” or uncapped silver nanoparticles?
Colloidal silver nanoparticles require some form of surface stabilization to remain dispersed. Without a stabilizing surface, attractive particle-particle interactions can lead to rapid and irreversible aggregation.
nanoComposix offers citrate-capped silver nanoparticles when a relatively accessible surface is desired. Citrate provides electrostatic stabilization and can be displaced under appropriate conditions, making citrate-capped particles useful as a starting point for ligand exchange, passive adsorption, or other surface-modification strategies.
Nanoparticles can be stabilized through electrostatic repulsion, in which charged surfaces help prevent particles from approaching one another, or steric stabilization, in which a polymer or other larger surface ligand physically limits close particle-particle contact. Some formulations use a combination of these mechanisms.
Learn more about Citrate Surface Chemistry and Silver Nanoparticle Surface Chemistry.
Applications & Product Availability
Do silver nanoparticles have antimicrobial properties?
Silver nanoparticles are widely studied for antimicrobial activity, which is influenced in part by the release of biologically active silver ions. Particle size, surface chemistry, dissolution behavior, concentration, exposure conditions, and the biological system can all affect the observed response.
Published research includes antibacterial, antiviral, wound-care, coating, and antimicrobial-material applications. Results are specific to the nanoparticle formulation and experimental conditions evaluated and should not be generalized across all silver nanoparticles.
See Antimicrobial Silver Nanoparticles for research examples and particle-selection considerations, and Silver Nanoparticle Safety for additional safety context.
I used to order silver nanoplates from nanoComposix. Are they still available?
Silver nanoplates and silica-shelled silver nanoplates with peak resonances at 660 nm, 800 nm, 980 nm, and 1064 nm have been discontinued as standard catalog products.
Contact us about potential remaining inventory or discuss a new nanoplate configuration through Custom Nanoparticle Development. For technical information about nanoplate resonance, surface chemistry, stability, and applications, see Silver Nanoplates.
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Talk with our technical team about particle size, surface chemistry, stability, formulation, characterization, or custom development.
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