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Université de Fribourg

Liposome‐containing mechanoresponsive hydrogels

Stalder, Etienne ; Zumbuehl, Andreas

In: Macromolecular Materials and Engineering, 2017, p. -

The direct injection of a drug into a joint can relieve osteoarthritic pain for a short period of time. The problem is that the drug will not stay at the allocated location. Therefore, a proof-of-concept in situ is designed forming hydrogel containing liposomes that are covalently linked to the hydrogel network. When the liposomes are filled with a cargo, the formed hydrogel is thus loaded...

Université de Fribourg

Vesicle origami and the influence of cholesterol on lipid packing

Tanasescu, Radu ; Lanz, Martin A. ; Mueller, Dennis ; Tassler, Stephanie ; Ishikawa, Takashi ; Brezesinski, Renate Reiter∥⊥, Gerald ; Zumbuehl, Andreas

In: Langmuir, 2016, vol. 32, no. 19, p. 4896–4903

The artificial phospholipid Pad-PC-Pad was analyzed in 2D (monolayers at the air/water interface) and 3D (aqueous lipid dispersions) systems. In the gel phase, the two leaflets of a Pad-PC-Pad bilayer interdigitate completely, and the hydrophobic bilayer region has a thickness comparable to the length of a single phospholipid acyl chain. This leads to a stiff membrane with no spontaneous...

Université de Fribourg

Surprising lack of liposome-induced complement activation by artificial 1,3-diamidophospholipids in vitro

Bugna, Simon ; Buscema, Marzia ; Matviykiv, Sofiya ; Urbanics, Rudolf ; Weinberger, Andreas ; Meszaros, Tamas ; Szebeni, Janos ; Zumbuehl, Andreas ; Saxer, Till ; Müller, Bert

In: Nanomedicine: Nanotechnology, Biology and Medicine, 2016, vol. 12, no. 3, p. 845–849

Cardio-vascular diseases are the main cause of death, emphasizing the need to improve patient treatment and survival. One therapeutic approach is a liposome-based drug carrier system specifically targeting constricted arteries. The recently discovered mechano-sensitive liposomes use hemodynamic shear-stress differences between healthy and constricted blood vessels as trigger for drug release....

Université de Fribourg

Phase behavior of selected artificial lipids

Zumbuehl, Andreas ; Dobner, Bodo ; Brezesinski, Gerald

In: Current Opinion in Colloid & Interface Science, 2014, vol. 19, no. 1, p. 17–24

The flexibility of biomembranes is based on the physical-chemical properties of their main components - glycerophospholipids. The structure of these modular amphiphilic molecules can be modified through organic synthesis making it possible to study specific physical-chemical effects in detail. In particular, the roles of the hydrophobic tails of the phospholipids and their...

Université de Fribourg

Rigid urea and self-healing thiourea ethanolamine monolayers

Stefaniu, Cristina ; Zaffalon, Pierre-Léonard ; Verolet, Alessio Carmine ∥, Quentin ; Fernandez, Samuel ; Wesolowski, Tomasz A. ; Brezesinski, Gerald ; Zumbuehl, Andreas

In: Langmuir, 2015, vol. 31, no. 4, p. 1296–1302

A series of long-tail alkyl ethanolamine analogs containing amide-, urea-, and thiourea moieties was synthesized and the behavior of the corresponding monolayers was assessed on the Langmuir–Pockels trough combined with grazing incidence X-ray diffraction experiments and complemented by computer simulations. All compounds form stable monolayers at the soft air/water interface. The phase...

Université de Fribourg

Bilayer Properties of 1,3-Diamidophospholipids

Weinberger, Andreas ; Tanasescu, Radu ; Stefaniu, Cristina ; Fedotenko, lllya A. ; Favarger, France ; Ishikawa, Takashi ; Brezesinski, Gerald ; Marques, Carlos M. ; Zumbuehl, Andreas

In: Langmuir, 2015, vol. 31, no. 6, p. 1879–1884

A series of 1,3-diamido phosphocholines was synthesized, and their potential to form stable bilayers was investigated. Large and giant unilamellar vesicles produced from these new lipids form a wide variety of faceted liposomes. Factors such as cooling rates and the careful choice of the liposome preparation method influence the formation of facets. Interdigitation was hypothesized as a main...

Université de Fribourg

Exit-strategies – smart ways to release phospholipid vesicle cargo

Mellal, Denia ; Zumbuehl, Andreas

In: Journal of Materials Chemistry B, 2014, vol. 2, no. 3, p. 247–252

This highlight describes recent trends in fundamental phospholipid research towards possible future drug delivery technology. In particular it focuses on synthetic phospholipids and their vesicular constructs and describes selected “smart” ways to release cargo from liposomes. Various chemical and physical release triggers are discussed such as temperature changes, application of ultrasound,...

Université de Fribourg

Phosphate Test 2.0

Stalder, Etienne ; Zumbuehl, Andreas

In: CHIMIA International Journal for Chemistry, 2013, vol. 67, no. 11, p. 819–821

The accurate measurement of the phosphate content of a liposomal suspension is important when working with differential scanning calorimetry. Standard phosphate tests date back several decades and require extended hands-on time. Here, we present a rapid version of a phosphate test taking advantage of microwave-assisted chemical digestion and multiwell plate reading technology allowing for the...

Université de Fribourg

Monolayer properties of 1,3-diamidophospholipids

Fedotenko, lllya A. ; Stefaniu, Cristina ; Brezesinski, Gerald ; Zumbuehl, Andreas

In: Langmuir, 2013, vol. 29, no. 30, p. 9428–9435

While nature provides an endless variety of phospholipids presenting hydrolyzable ester linkages for the 1,2-positioned hydrocarbon tails, we designed and synthesized 1,3-diamidophospholipids which contain stable fatty acid amides. These new phospholipids form faceted unilamellar vesicles with mechanosensitive properties. Aiming to understand the mechanism responsible for this behavior at a...

Université de Fribourg

Study of surfactant alcohols with various chemical moieties at the hydrophilic–hydrophobic interface

Zaffalon, Pierre-Léonard ; D'Anna, Vincenza ; Hagemann, Hans ; Zumbuehl, Andreas

In: RSC Advances, 2013, vol. 3, no. 20, p. 7237–7244

The melting behavior, the solubility, and the influence of hydrogen bonds were analyzed for a series of single- and double-tailed surfactant alcohols. Various effects such as the presence of free amides or the intermolecular spacing were found to be important factors for increasing or decreasing the melting temperature of a surfactant. Furthermore, we present a model for the packing of...