This is just a quick post describing some new work that is now available online.  First up, we have Development of Self-Assembling Mixed Protein Micelles with Temperature-Modulated Avidities that is online at Advanced Healthcare Materials. This is another collaborative effort between my group and Tom Barker’s, with his former student Allyson Soon being the lead author. In this work, Allyson developed block copolymer micelles composed of elastin-like polypeptides with fibrinogen-binding peptides (GPRP) tethered to the outer micelle surface. By switching the micelle structure (and hence the GPRP binding availability) she was able to thermally switch micelle-fibrinogen binding. We supported this very nice work with some light scattering studies (Mike Smith) and some AFM (Emily Herman). Allyson is currently a postdoc at UCLA with Tatiana Segura and seems to be doing quite well. Since I am also at UCLA right now on sabbatical, and have been infiltrating the Segura group meetings, Allyson has unfortunately not rid herself of me yet – I am still bugging her…

The second new paper is Plastic Deformation, Wrinkling, and Recovery in Microgel Multilayers, which is online at Polymer Chemistry (RSC). Jeff Gaulding and Mark Spears teamed up on this work, which was invited as part of a special issue on Self-Healing Polymers. This is an extension of our previous work on microgel-based, LbL-fabricated, thin films that can be damaged by deformation, but then re-heal upon immersion in water. Perhaps the two key results from this work involved the use of AFM to image the films during deformation and damage, and the use of humid environments to induce slow healing. The AFM studies conclusively show that the damage induced during linear stress is plastic deformation or stretching of the film, with wrinkling occurring after release of the stress. Before these studies, it was not at all clear whether the damage patterns observed were wrinkles or cracks, making determination of the damage and healing pathways difficult. Secondly, we did not have a clear sense of what drove healing. Whereas hydration was important, it was not known whether surface tension or film swelling was driving healing. By precisely controlling the humidity around the film, we were able to show that film swelling is sufficient to induce healing, suggesting that the polymer mobility in the film during swelling is sufficient to restore the film to a state approximating the as-prepared structure.

If you have the time and interest, go check out both papers, and feel free to provide any feedback you feel is warranted.