posted on 2024-01-19, 15:34authored byWenhan Zhao, Jennifer S. Lin, Josefine Eilsø Nielsen, Kristian Sørensen, Anand Sunil Wadurkar, Jingjing Ji, Annelise E. Barron, Shikha Nangia, Matthew R. Libera
We have studied the complexation between cationic antimicrobials
and polyanionic microgels to create self-defensive surfaces that responsively
resist bacterial colonization. An essential property is the stable
sequestration of the loaded (complexed) antimicrobial within the microgel
under a physiological ionic strength. Here, we assess the complexation
strength between poly(acrylic acid) [PAA] microgels and a series of
cationic peptoids that display supramolecular structures ranging from
an oligomeric monomer to a tetramer. We follow changes in loaded microgel
diameter with increasing [Na+] as a measure of the counterion
doping level. Consistent with prior findings on colistin/PAA complexation,
we find that a monomeric peptoid is fully released at ionic strengths
well below physiological conditions, despite its +5 charge. In contrast,
progressively higher degrees of peptoid supramolecular structure display
progressively greater resistance to salting out, which we attribute
to the greater entropic stability associated with the complexation
of multimeric peptoid bundles.