Université de Fribourg

Characterization of the shape anisotropy of superparamagnetic iron oxide nanoparticles during thermal decomposition

Vanhecke, Dimitri ; Crippa, Federica ; Lattuada, Marco ; Balog, Sandor ; Rothen-Rutishauser, Barbara ; Petri-Fink, Alke

In: Materials, 2020, vol. 13, no. 9, p. 2018

Magnetosomes are near-perfect intracellular magnetite nanocrystals found in magnetotactic bacteria. Their synthetic imitation, known as superparamagnetic iron oxide nanoparticles (SPIONs), have found applications in a variety of (nano)medicinal fields such as magnetic resonance imaging contrast agents, multimodal imaging and drug carriers. In order to perform these functions in medicine,...

Université de Fribourg

Mimicking the chemistry of natural eumelanin synthesis: the ke sequence in polypeptides and in proteins allows for a specific control of nanosized functional polydopamine formation

Bergtold, Camille ; Hauser, Daniel ; Alain Chaumont ; El Yakhlifi, Salima ; Mateescu, Mihaela ; Meyer, Florent ; Metz-Boutigue, Marie-Hélène ; Benoît Frisch ; Schaaf, Pierre ; Ihiawakrim, Dris ; Ersen, Ovidiu ; Monnier, Christophe A. ; Petri-Fink, Alke ; Rothen-Rutishauser, Barbara ; Ball, Vincent

In: Biomacromolecules, 2018, vol. 19, no. 9, p. 3693–3704

The oxidation of dopamine and of other catecholamines leads to the formation of conformal films on the surface of all known materials and to the formation of a precipitate in solution. In some cases, it has been shown that the addition of additives in the dopamine solution, like certain surfactants or polymers, polyelectrolytes, and certain proteins, allows to get polydopamine nanoparticles...

Université de Fribourg

Taylor dispersion of inorganic nanoparticles and comparison to dynamic light scattering and transmission electron microscopy

A.Urban, Dominic ; M.Milosevic, Ana ; Bossert, David ; Crippa, Federica ; L.Moore, Thomas ; Geers, Christoph ; Balog, Sandor ; Rothen-Rutishauser, Barbara ; Petri-Fink, Alke

In: Colloid and Interface Science Communications, 2018, vol. 22, p. 29–33

Taylor dispersion analysis (TDA) is an analytical method that has so far mainly been utilized to determine the diffusion coefficient of small molecules, and proteins. Due to increasing interest in nanoscience, some research has been done on the applicability of TDA towards characterizing nanoparticles. This work aims to expand this knowledge and give insight into the range for which TDA can...

Université de Fribourg

Hypothesis test of the photon count distribution for dust discrimination in dynamic light scattering

Bossert, David ; Crippa, Federica ; Petri-Fink, Alke ; Balog, Sandor

In: Analytical Chemistry, 2018, vol. 90, no. 6, p. 3656–3660

Users of dynamic light scattering (DLS) are challenged when a sample of nanoparticles (NPs) contains dust. This is a frequently inevitable scenario and a major problem that critically affects the reproducibility and accuracy of DLS measurements. Current methods approach this problem via photon correlation spectroscopy, but remedy exists only for a few special cases. We introduce here a...

Université de Fribourg

A new angle on dynamic depolarized light scattering: number-averaged size distribution of nanoparticles in focus

Geers, Christoph ; Rodriguez-Lorenzo, Laura ; Urban, Dominic Andreas ; Kinnear, Calum ; Petri-Fink, Alke ; Balog, Sandor

In: Nanoscale, 2016, vol. 8, no. 34, p. 15813–15821

Size polydispersity is a common phenomenon that strongly influences the physicochemical properties of nanoparticles (NPs). We present an analytical approach that is universally applicable to characterizing optically anisotropic round NPs and determines directly the number-averaged size distribution and polydispersity via depolarized dynamic light scattering (DDLS). To demonstrate, we use...

Université de Fribourg

Dynamic depolarized light scattering of small round plasmonic nanoparticles: When imperfection is only perfect

Balog, Sandor ; Rodriguez-Lorenzo, Laura ; Monnier, Christophe A. ; Michen, Benjamin ; Obiols-Rabasa, Marc ; Casal-Dujat, Lucia ; Rothen-Rutishauser, Barbara ; Petri-Fink, Alke ; Schurtenberger, Peter

In: The Journal of Physical Chemistry C, 2014, vol. 118, no. 31, p. 17968–17974

Although small round gold nanoparticles (Au NPs) possess only a small degree of shape anisotropy, they support localized surface plasmon resonances and exhibit intrinsic optical anisotropy. These inherent features promote depolarized light scattering, whose temporal fluctuations carry information about rotational Brownian dynamics, and thus can be used to describe the size distribution of...