New Paper by Benjamin McDonald on Ion-Specific Interactions
Dr. Benjamin McDonald, who released one of the first papers as a member of the STEMJazz collective, has recently published a new paper titled “Ion-Specific Interactions Engender Dynamic and Tailorable Properties in Biomimetic Cationic Polyelectrolytes.”
Below is the abstract:
Biomaterials such as spider silk and mussel byssi are fabricated by the dynamic manipulation of intra- and intermolecular biopolymer interactions. Organisms modulate solution parameters, such as pH and ion co-solute concentration, to effect these processes. These biofabrication schemes provide a conceptual framework to develop new dynamic and responsive abiotic soft material systems. Towards these ends, the chemical diversity of readily available ionic compounds offers a broad palette to manipulate the physicochemical properties of polyelectrolytes via ion-specific interactions. In this study, we show for the first time that the ion-specific interactions of biomimetic polyelectrolytes engenders a variety of phase separation behaviors, creating dynamic thermal- and ion-responsive soft matter that exhibits a spectrum of physical properties, spanning viscous fluids to viscoelastic and viscoplastic solids. These ion-dependent characteristics are further rendered general by the merger of lysine and phenylalanine into a single, amphiphilic vinyl monomer. The unprecedented breadth, precision, and dynamicity in the reported ion-dependent phase behaviors thus introduce a broad array of opportunities for the future development of responsive soft matter; properties that are poised to drive developments in critical areas such as chemical sensing, soft robotics, and additive manufacturing.
Here is a bit from Dr. McDonald himself:
“The gist of the paper is that we were inspired by the ionic mechanisms that organisms like the mussel use to fabricate their structural materials. These occur by phase transitions of proteins dissolved in water, from homogeneous fluids, to phase separated fluids (coacervates or biomolecular condensates), to phase separated solids (gels). Cationic mussel proteins are programmed to respond to changes in salinity (seawater is NaCl), so we thought that the chemical identity of the dissolved salt should also matter quite a bit, which according to the basics of ionic interactions, it does! So we effectively added a new dimension to regulate the dynamic and equilibrium properties of protein-like cationic polymers, their assembly, structure, and physical properties. We also show that the polymers can dynamically change their equilibrium state as a function of salinity and/or temperature (they can contract or swell), properties that are also programmed by the chemical identity and concentration of the salt. We are working on using these to make actuators/materials for soft robotics.
We are also using this ion specific chemistry we’ve developed to control the assembly of nanomaterials decorated in these protein-like polymers, which should be a big splash coming in the next year. This first paper is a pretty big splash itself, as Angewandte is one of the top three chemistry journals and the first author is an undergraduate :D Hope this adds some context!”
Congratulations and thank you for your contribution, Benjamin!
