A systematic comparison of different techniques to determine the zeta potential of silica nanoparticles in biological medium

Sikora, Aneta; Bartczak, Dorota; Geißler, Daniel; Kestens, Vikram; Roebben, Gert; Ramaye, Yannic; Varga, Zoltán; Pálmai, Marcell; Shard, Alexander G.; Goenaga‐Infante, Heidi; Minelli, Caterina

doi:10.1039/c5ay02014j

Cited by 69 publications

(49 citation statements)

References 18 publications

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“…This behavior can be correlated with the deprotonation of carboxyl groups with increasing pH, which results in higher concentration of negatively charged surface groups and therefore more negative values of zeta potential. In charged colloids, as N-CDs, it is generally assumed that zeta potential higher than |30 mV| indicates good stability against aggregation because of electrostatic repulsion between particles [42,43]. This is consistent with our experimental macroscopic observations of N-CDs dispersions at different pH values.…”

Section: Colloidal Properties Of N-cds Aqueous Dispersionssupporting

confidence: 91%

On the Colloidal Stability of Nitrogen-Rich Carbon Nanodots Aqueous Dispersions

Fiuza

Gomide

Campos

et al. 2019

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The present survey reports on the colloidal stability of aqueous dispersions of nitrogen-rich carbon nanodots (N-CDs). The N-CDs were synthesized by thermally induced decomposition of organic precursors and present an inner core constituted of a β - C 3 N 4 crystalline structure surrounded by a surface shell containing a variety of polar functional groups. N-CDs size and structure were checked by combined analysis of XRD (X-ray Diffraction) and TEM (Transmission Electron Microscopy) measurements. FTIR (Fourier-Transform Infrared Spectroscopy) experiments revealed the presence of carboxyl and amide groups on N-CDs surface. Towards a better understanding of the relation between colloidal stability and surface charge development, zetametry experiments were applied in N-CDs dispersions at different pHs and constant ionic strength. The increase of the absolute values of zeta potential with the alkalinization of the dispersion medium is consistent with the deprotonation of carboxyl groups on N-CDs surface, which agrees with the macroscopic visual observations of long-term colloidal stability at pH 12. The saturation value of N-CDs surface charge density was evaluated by means of potentiometric-conductometric titrations. The difference between carboxyl-related surface charge and the one determined by zeta potential measurements point to the presence of oxidized nitrogen functionalities onto the N-CDs surface in addition to carboxyl groups. These novel results shed light on the electrostatic repulsion mechanism that allows for the remarkable colloidal stability of N-CDs dispersions.

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Section: Colloidal Properties Of N-cds Aqueous Dispersionssupporting

confidence: 91%

On the Colloidal Stability of Nitrogen-Rich Carbon Nanodots Aqueous Dispersions

Fiuza

Gomide

Campos

et al. 2019

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“…The observed IEP for the ASP-synthesized γ-Fe 2 O 3 is significantly lower than that reported for the maghemite nanoparticles synthesized by co-precipitation (pH IEP = 6.6 [20]). Generally, the particles with a ζ-potential higher than +30 mV or lower than −30 mV are considered to be electrostatically stable in colloids; at lower ζ-potential values, the particles are prone to agglomeration [21,22]. Note that the ζ-potential of non-stabilized ASP-synthesized γ-Fe 2 O 3 nanoparticles is below these threshold values in acidic medium.…”

Section: Resultsmentioning

confidence: 99%

Humic acid-stabilized superparamagnetic maghemite nanoparticles: surface charge and embryotoxicity evaluation

Goldt¹,

Polyakov²,

Sorkina³

et al. 2019

Nanosystems: Phys. Chem. Math.

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Superparamagnetic iron oxide γ-Fe 2 O 3 (maghemite) nanoparticles (SPION) encapsulated into water-soluble microspheres of rock salt were synthesized via a new aerosol spray pyrolysis procedure. Humic acids (HA) were employed to stabilize the aqueous suspensions of γ-Fe 2 O 3 nanoparticles released upon dissolution of the NaCl matrix. The effect of HA on the surface charge of maghemite-based colloids was studied in pH range of 3 -10. Humic polyanions compensate positive charges on a hydrated γ-Fe 2 O 3 surface resulting in strongly negative ζ-potential (< −40 mV) of colloid even in acidic environment. In neutral and alkaline environment, ζ-potential of maghemite-based colloid drops below −55 mV; thus, HA should effectively stabilize the nanoparticle colloid over the whole pH range studied. Meanwhile, bare maghemite SPION at pH 3 -6 have ζ-potential in the +20 mV to −20 mV range (isoelectric point at pH 4.35), which is insufficient for electrostatic stabilization of the suspensions. The absence of embryotoxicity of HA-stabilized nanoparticles was demonstrated.

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“…EB-NS have a similar zeta potential (-22 mV) as spherical silica nanoparticles, which highlights that they can be dispersed and applied in aqueous solutions ( fig. S5) 40 .…”

Section: Fig 1: Exfoliation Of Egyptian Blue (Eb) Into Egyptian Bluementioning

confidence: 99%

Exfoliated near infrared fluorescent CaCuSi₄O₁₀ nanosheets with ultra-high photostability and brightness for biological imaging

Selvaggio

Preiß

Chizhik

et al. 2019

Preprint

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Imaging of complex (biological) samples in the near infrared (nIR) range of the spectrum is beneficial due to reduced light scattering, absorption, phototoxicity and autofluorescence.However, there are only few near infrared fluorescent materials known and suitable for biomedical applications. Here, we exfoliate the layered pigment CaCuSi4O10 (known as Egyptian Blue, EB) via facile tip sonication into nanosheets (EB-NS) with ultra-high nIR fluorescence stability and brightness. The size of EB-NS can be tailored by tip sonication to diameters < 20 nm and heights down to 1 nm. EB-NS fluoresce at 910 nm and the total fluorescence intensity scales with the number of Cu 2+ ions that serve as luminescent centers. Furthermore, EB-NS display no bleaching and ultra-high brightness compared to other nIR fluorophores. The versatility of EB-NS is demonstrated by in vivo single-particle tracking and microrheology measurements in developing Drosophila embryos. Additionally, we show that EB-NS can be uptaken by plants and remotely detected in a low cost stand-off detection setup despite strong plant background fluorescence. In summary, EB-NS are a highly versatile, bright, photostable and biocompatible nIR fluorescent material that has the potential for a wide range of bioimaging applications both in animal and plant systems.

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A systematic comparison of different techniques to determine the zeta potential of silica nanoparticles in biological medium

Cited by 69 publications

References 18 publications

On the Colloidal Stability of Nitrogen-Rich Carbon Nanodots Aqueous Dispersions

On the Colloidal Stability of Nitrogen-Rich Carbon Nanodots Aqueous Dispersions

Humic acid-stabilized superparamagnetic maghemite nanoparticles: surface charge and embryotoxicity evaluation

Exfoliated near infrared fluorescent CaCuSi₄O₁₀ nanosheets with ultra-high photostability and brightness for biological imaging

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A systematic comparison of different techniques to determine the zeta potential of silica nanoparticles in biological medium

Cited by 69 publications

References 18 publications

On the Colloidal Stability of Nitrogen-Rich Carbon Nanodots Aqueous Dispersions

On the Colloidal Stability of Nitrogen-Rich Carbon Nanodots Aqueous Dispersions

Humic acid-stabilized superparamagnetic maghemite nanoparticles: surface charge and embryotoxicity evaluation

Exfoliated near infrared fluorescent CaCuSi4O10 nanosheets with ultra-high photostability and brightness for biological imaging

Contact Info

Product

Resources

About

Exfoliated near infrared fluorescent CaCuSi₄O₁₀ nanosheets with ultra-high photostability and brightness for biological imaging