Cosmetics and Pharmaceuticals

Use Cases

Are lipid-based Janus particles stable

enough for pharmaceutical and cosmetic applications ?

Reference: Benrabah, L., Kemel, K., Twarog, C., Huang, N., Solgadi, A., Laugel, C., & Faivre, V. (2020). Lipid-based Janus nanoparticles for pharmaceutical and cosmetic applications: Kinetics and mechanisms of destabilization with time and temperature. Colloids and Surfaces B: Biointerfaces, 195, 111242.

The aim of this paper is to investigate the time and thermal stability of innovative multicompartmental Janus nanoparticles (JNP). An important step consisted in characterizing the interfacial properties of two oily excipients used in the preparation of JNP: Labrafil M 2125 CS and M1944 CS. Using an automatic drop tensiometer (TRACKER™  by TECLIS), the authors showed that surface tension increases with temperature. This behavior has been attributed to PEG esters contained in the oil phase for which an increase of hydrophobicity is observed with increasing temperature. Further investigations allowed to identify a two-regimen destabilization mechanism for the Janus nanoparticles: a slight size increase by Ostwald ripening and then a rapid coalescence. Additional work must be done to improve the most stable formulation, diluted L2125, to reach a stability of 6 months at 40 °C which is a standard in the pharmaceutical and cosmetic fields.

 

TECLIS product: TRACKER™  automatic drop tensiometer

Key words: Janus nanoparticles, stability, Ostwald ripening, Coalescence, oil/water interface, surface tension

How do microgels behave at an oil-water interface and how do they respond to compression?

Scaling-up to emulsions

Reference: Adsorption of microgels at an oil–water interface: correlation between packing and 2D elasticity. F. Pinaud; K. Geisel; P. Massé; B. Catargi, L. Isa; W. Richtering; V. Ravaine; V. Schmitt; Soft Matter, 2014, 10, 6963. DOI: 10.1039/c4sm00562g.

Probing oil-water interfaces laden with microgels evidences that these soft particles adsorb quasi irreversibly and that their structure adopts different packing states when the interface is compressed. Moreover, experiments with a drop tensiometer (TRACKER™ ) shows that microgels adopt spontaneously a compressed morphology at an oil-water interface. The surface elasticity deduced from these measurements exhibits a maximum corresponding to the flattened conformation.

 

Finally, the same spontaneous adsorption coverage is observed in emulsions, thus proving the usefulness of microgels in controlling the structure and the stability of emulsions.

 

TECLIS product: TRACKER™  automatic drop tensiometer

Key words: microgels, oil-water interface, surface dilational rheology, Langmuir trough, drop tensiometer , emulsions