Université de Fribourg

Against the rules: pressure induced transition from high to reduced order

Neuhaus, Frederik ; Mueller, Dennis ; Tanasescu, Radu ; Stefaniu, Cristina ; Zaffalon, Pierre-Léonard ; Balog, Sandor ; Ishikawa, Takashi ; Reiter, Renate ; Brezesinski, Gerald ; Zumbuehl, Andreas

In: Soft Matter, 2018, vol. 14, no. 19, p. 3978–3986

Envisioning the next generation of drug delivery nanocontainers requires more in- depth information on the fundamental physical forces at play in bilayer membranes. In order to achieve this, we combine chemical synthesis with physical–chemical analytical methods and probe the relationship between a molecular structure and its biophysical properties. With the aim of increasing the number of...

Université de Fribourg

Avoiding drying-artifacts in transmission electron microscopy: Characterizing the size and colloidal state of nanoparticles

Michen, Benjamin ; Geers, Christoph ; Vanhecke, Dimitri ; Endes, Carola ; Rothen-Rutishauser, Barbara ; Balog, Sandor ; Petri-Fink, Alke

In: Scientific Reports, 2015, vol. 5, p. 9793

Standard transmission electron microscopy nanoparticle sample preparation generally requires the complete removal of the suspending liquid. Drying often introduces artifacts, which can obscure the state of the dispersion prior to drying and preclude automated image analysis typically used to obtain number-weighted particle size distribution. Here we present a straightforward protocol for...

Université de Fribourg

Beyond global charge: role of amine bulkiness and protein fingerprint on nanoparticle–cell interaction

Burnand, David ; Milosevic, Ana ; Balog, Sandor ; Spuch-Calvar, Miguel ; Rothen-Rutishauser, Barbara ; Dengjel, Jörn ; Kinnear, Calum ; Moore, Thomas L. ; Petri-Fink, Alke

In: Small, 2018, vol. 14, no. 46, p. 1802088

Amino groups presented on the surface of nanoparticles are well‐known to be a predominant factor in the formation of the protein corona and subsequent cellular uptake. However, the molecular mechanism underpinning this relationship is poorly defined. This study investigates how amine type and density affect the protein corona and cellular association of gold nanoparticles with cells in...

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

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

Balog, Sandor ; Adolphe Merkle Institute, University of Fribourg, Switzerland ; Rodriguez-Lorenzo, Laura ; Monnier, Christophe A. ; Michen, Benjamin ; Obiols-Rabasa, Marc ; Casal-Dujat, Lucia ; Rothen-Rutishauser, Barbara ; Petri-Fink, Alke ; Schurtenberger, and 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 round...

Université de Fribourg

A guide to investigating colloidal nanoparticles by cryogenic transmission electron microscopy: pitfalls and benefits

Monnier, Christophe A. ; Thévenaz, David C. ; Balog, Sandor ; Fiore, Gina L. ; Vanhecke, Dimitri ; Rothen-Rutishauser, Barbara ; Petri-Fink, Alke

In: AIMS Biophysics, 2015, vol. 2, no. 3, p. 245–258

Synthetic colloidal nanoparticles are nowadays omnipresent. Nonetheless, adequately characterizing them and interpreting the data is challenging, as their surrounding environment, e.g. the medium they are dispersed in, is often an active contributor to their size, morphology and structural integrity. In this regard, cryo-transmission electron microscopy (cryo-TEM) is an ideal methodology. This...

Université de Fribourg

Heating behavior of magnetic iron oxide nanoparticles at clinically relevant concentration

Lemal, Philipp ; Balog, Sandor ; Geers, Christoph ; Taladriz-Blanco, Patricia ; Palumbo, Andrea ; M.Hirt, Ann ; Rothen-Rutishauser, Barbara ; Petri-Fink, Alke

In: Journal of Magnetism and Magnetic Materials, 2019, vol. 474, p. 637–642

Magnetic hyperthermia for cancer treatment has gained significant attention in recent years, due to its biocompatibility of applied nanoparticles and the possibility for spatially localized heating in deep tissues. Clinical treatments use nanoparticle concentrations of 112 mg Fe/mL, while the concentrations experimental studies have addressed are considerably smaller, usually between 0.1...

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

The influence of substituents on gelation and stacking order of oligoaramid – based supramolecular networks

Drechsler, Susanne ; Balog, Sandor ; Kilbinger, Andreas F. M. ; Casalini, Tommaso

In: Soft Matter, 2019, vol. 15, no. 36, p. 7250–7261

Self-assembly has proven to be a powerful tool for functional, smart materials such as hydrogels derived from low molecular weight compounds. However, the targeted design of functional gelators remains difficult. Here, we present a set of four Y-shaped aromatic amide tetramers with varying functionalities able to undergo different non- covalent interactions. These compounds were explored...

Université de Fribourg

In Vitro dosimetry of agglomerates

Hirsch, Vera ; Kinnear, Calum ; Rodriguez-Lorenzo, Laura ; Monnier, Christophe A. ; Rothen-Rutishauser, Barbara ; Balog, Sandor ; Petri-Fink, Alke

In: Nanoscale, 2014, p. -

Agglomeration of nanoparticles in biological fluids is a pervasive phenomenon that leads to difficulty in the interpretation of results from in vitro exposures, primarily due to the differing particokinetics of agglomerates to nanoparticles. Therefore, well-defined small agglomerates were designed that possessed different particokinetics profiles, and their cellular uptake was compared to a...