01 | SECURE
Undesired effects of silver nanoparticles (NPs) are mainly mediated by residual FREE IONS. HighQuant silver NPs eliminate adverse effects by a controlled and low level of FREE IONS.
02 | SENSITIVE
Distinct strong Localized Surface Plasmon Resonance (LSPR) effect enables orders of magnitude improvement of the detection limit.
03 | REPRODUCIBLE
Controlled and low level of residual FREE IONS, significantly improving the reliability of the experimental results and the reproducibility of their respective application.
Figure 1 shows a Transmission Electron Microscopy (TEM) image of silver nano-spheres. Due to the quantum size and their Localized Plasmon Surface Resonance (LSPR) eﬀect, noble metal nanoparticles have optical and electromagnetic properties that are significantly different from those of bulk materials. They show an enhanced electrical and thermal conductivity, surface-enhanced Raman scattering (SERS), chemical stability, catalytic activity and nonlinear optical behavior as the result. These properties make them of value in microelectronics, medical imaging and diagnostics at the cellular and molecular level. Photonic devices including photovoltaics, which take advantage of the enhanced optical properties of these nanomaterials benefit from silver NPs. HighQuant Silver NPs also provide protection against microorganisms. That qualifies them highly valuable in a diverse range of consumer products, including plastics, detergents, food, fibers and textiles as well as for antimicrobial coatings, keyboards, wound dressings, and medical devices.
HighQuant monodisperse silver NPs of high concentration, free from agglomeration, and with a controlled low level of free Ag-ions. They are ready to unfold their full potential in your research, development, and use in industrial scale in your demanding applications. Batches of manufactured HighQuant NPs are precisely characterized using UV/VIS spectrometry to ensure consistent materials in every shipment. Absorbance data are regularly validated using transmission electron microscopy (TEM) images, dynamic light scattering (particle size analysis) and/or Zeta potential measurements.
Figure 1: Transmission electron microscopy (TEM) images of HighQuant PRO silver NPs with diameters of 10 nm.
Figure 2: Localized Surface Plasmon Resonance (LSPR): free electrons in the metal NP are driven into oscillation due to a strong coupling with a specific wavelength of incident light.
HighQuant NP´s Optical Properties – Distinct strong Localized Surface Plasmon Resonance (LSPR)
In contrast to dyes and pigments, optical properties of silver NPs mainly depend on their sizes and geometries.
LSPR effect is most pronounced for metallic nanoparticles < 30 nm in diameter, due to their superior surface/volume ratio, compared to larger NPs. Therefore, PHORNANO focuses on high concentrated, high-LSPR NPs of ≤10 and 20 nm in diameter.
The strong light-matter interaction of the silver NPs occurs because the conduction electrons on the metal surface undergo a collective oscillation when excited by light at specific wavelengths (Figure 2). This oscillation results in unusually strong scattering and absorption properties. That allows silver NPs to show effective absorbance (scattering & absorption) cross sections several times larger than their physical cross section.
For most applications, HighQuant NPs guarantee high absorption intensity also for longer wavelengths, as their absorption maximum is stronger than those of larger NPs, which present their weaker peak absorption at longer wavelengths. By selecting the size of spherical silver NPs, their LSPR peak absorbance wavelength can be tuned from < 400 nm to >500 nm and influences the appearance of the sample under visible light (Figure 3).
Control of the presence of unwanted residual free ions
Their extended stability is a consequence of the well-controlled low concentration of free ions. Free ions are a sign of imperfection, building blocks not properly utilized to build the NPs once the manufacturing process has been terminated prematurely or the reactance were not in perfect equilibrium for the desired product.
Spectroscopy has been proven to be the proper tool for characterizing the content of ions. The peak absorption of the ions is different to the LSPR absorption of the NPs. Silver ions show their characteristic absorption between 200 and 300 nm, while the silver NPs show their LSPR absorption peak around 400 nm. 4n has chosen to characterize its NPs beginning from this UV wavelength range to demonstrate both, the non-desired and well controlled smaller absorption peak of the remaining free ions as well as the strong LSPR related absorption peak of the NPs. Most of the literature omits the presence of free ions and only shows the absorbance spectrum around the LSPR-absorption related peak (Figure 4).
Figure 3: Cuvettes containing silver nano-spheres of diameters ranging from 10 nm to 80 nm including HighQuant PRO and HighQuant 20 NPs
Figure 4: Absorbance (scattering + absorption) spectra of HighQuant silver NPs. The peak at around 400 nm represents the LSPR peak of HighQuant 20 sNPs of 20 nm in diameter, while the peak between 200 and 250 nm represents the well-controlled low level of free ions in the NP-suspension. The extension of the spectrum down to 200 nm from usually 300 nm is a proof of quality for all HighQuant NPs.
Physicochemical assessment techniques
Qualitative and quantitative physicochemical characterization of silver NPs provides:
of the manufactured nanoparticles.
HighQuant Silver NP´s Surface Chemistry
When nanoparticles are in solution, molecules associate with the NP surface to establish a double layer of charge that stabilizes the particles and prevents aggregation. PHORNANO offers its HighQuant silver NPs suspended in aqueous medium. A citrate-based agent was selected as a stabilizer, because the weakly bound capping agent provides long term stability and is readily displaced by various other molecules including thiols, amines, polymers, antibodies, and proteins.
HighQuant Silver NP´s Applications
HighQuant Silver nanoparticles are being used in a large variety of technologies and incorporated into consumer products that take advantage of their desirable optical, electronical, thermal and antimicrobial properties.
- Diagnostic Applications: HighQuant Silver NPs are used in bio-imaging, biosensors and as biological tags for quantitative detection.
- Antimicrobial Applications: HighQuant Silver NPs are incorporated in apparel, footwear, paints, wound dressings, appliances, cosmetics, and plastics for their antibacterial and antifungal properties.
- Conductive Applications: HighQuant Silver NPs are used in conductive inks and integrated into composites to enhance thermal and electrical properties.
- Optical Applications: HighQuant Silver NPs are used to efficiently harvest light and for enhanced optical spectroscopies including metal-enhanced fluorescence (MEF) and Surface-Enhanced Raman Scattering (SERS)
Table 1: Applications:
yellow = more significant,
blue = less significant.
TPEF: Fluorescence microscopy
PA: Photo acoustics
FLIM: Fluorescence lifetime imaging
SERS: Surface enhanced Raman spectroscoy
HighQuant nanoparticles focus on the most important characteristics offered by metallic nanoparticles:
SECURE / Undesired effects of silver nanoparticles (NPs) are mainly mediated by residual FREE IONS. HighQuant silver NPs eliminate adverse effects by a controlled and low level of FREE IONS.
SENSITIVE / Distinct strong Localized Surface Plasmon Resonance (LSPR) effect enables orders of magnitude improvement of the detection limit.
REPRODUCIBLE / Controlled and low level of residual FREE IONS, significantly improving the reliability of the experimental results and the reproducibility of their respective application.
PHORNANO offers HighQuant silver NPs in aqueous suspension with a citrate-stabilized surface as shown in Table 2.
Distinct strong Localized Surface Plasmon Resonance (LSPR) effect;
Undesired effects of silver nanoparticles (NPs) are mainly mediated by residual FREE IONS. HighQuant silver NPs eliminate adverse effects by a controlled and low level of FREE IONS.Undesired effects of silver nanoparticles (NPs) are mainly mediated by residual FREE IONS. HighQuant silver NPs eliminate adverse effects by a controlled and low level of FREE IONS.