Electrochemistry of Biosystems
Linking Glucose Oxidation to Luminol-based Electrochemiluminescence using bipolar Electrochemistry
Asymmetric Modification of TiO2 Nanofibers with Gold by Electric-Field-Assisted Photochemistry
Stimuli-responsive microgels for electrochemiluminescence amplification

A. Perro, L. Giraud, N. Coudon, S. Shanmugathasan, B. Goudeau, J.-P. Douliez and V. Ravaine

Journal of Colloid and Interface Science 2019 548, 275-283.

Coacervation is a phase separation process involving two aqueous phases, one solute-phase and one solute-poor phase. It is frequently observed among oppositely-charged polyelectrolyte systems. In this study, we focus on self-coacervation involving a single polymer chain and investigate its potential for encapsulation applications. Negatively charged polyacrylic acid polymer chains were partially cationized using diamine and carbodiimide chemistry affording ampholytes, named PAA-DA, with tunable charge ratio. When dispersed in water, at pH 7, PAA-DA was soluble but a phase separation occurs when decreasing pH close to the isoelectric point. Coacervation is found only for a given amine-to-acid ratio otherwise precipitation is observed. Increasing the pH above 4 yielded progressive destruction of the coacervates droplets via the formation of vacuoles within droplets and subsequent full homogeneous redispersion of PAA-DA in water. However, addition of calcium allowed increasing the coacervate droplet stability upon increasing the pH to 7 as the divalent ion induced gelation within droplets. Moreover, the coacervate droplets present the ability to spontaneously sequestrate a broad panel of entities, from small molecules to macromolecules or colloids, with different charges, size and hydrophobicity. Thanks to the reversible character of the coacervates, triggered-release could be easily achieved, either by varying the pH or by removing calcium ions in the case of calcium-stabilized coacervates. Self-coacervation presents the advantage of pathway-independent preparation, offering a real output interest in pharmacy, water treatment, food science or diagnostics.

JCIS 3

 

Thumbnail J. Kalecki, M. Cieplak, M. Dąbrowski, W. Lisowski, A. Kuhn,  P. Sindhu Sharma ACS Sensors (2019) in press, doi.org/10.1021/acssensors.9b01878 Homogenous nanostructuration of molecularly imprinted...
Thumbnail S. Assavapanumat,  M. Ketkaew,  A. Kuhn, C.Wattanakit J. Am.Chem.Soc. 141 (2019) 18870(Front Cover) see also CNRS press release The enantioselective synthesis of chiral compounds is of crucial...
Thumbnail C. Wattanakit, A. Kuhn Chemistry-A European Journal (2020) 26, 2993-3003 The concept of encoding molecular information in bulk metals has been proposed over the past decade. The structure of various types of...