Niti defended her Ph.D. proposal in Dec 2018. She has made a key discovery that some surfactants can self-assemble into long chains (called ‘wormlike micelles’) in polar solvents like glycerol. Niti has also designed food-grade dispersants for the cleanup of oil spills.
Kerry defended her Ph.D. in Chemistry in Aug 2018, after which she joined Gelest Inc. in Philadelphia. In her Ph.D. work, Kerry studied how to endow polymer capsules with ‘emergent‘ properties as a result of internal chemical reactions. Kerry won several departmental awards for her work and is a co-author on 3 publications.
The architecture of life is based on cells (microscale containers), which have organelles, i.e., smaller containers inside them. We are trying to mimic this by creating microscale capsules that have smaller capsules inside them. These multicompartment capsules (MCCs) can contain nanoparticles, enzymes, or bacteria in specific inner compartments (see paper in Chemical Science, 2017). We are collaborating with Prof. Bill Bentley (BioE) in this research.
Stopping blood loss from wounds is crucial during surgeries and on the battlefield. We got into this area when we discovered a ‘hemostatic’ polymer that is able to convert liquid blood into a gel (see above) by a self-assembly mechanism. The same polymer rapidly arrests bleeding from severe injuries in animal models. This technology won the Invention of the Year award at UMD in 2009, and since then has been patented and FDA-approved. Gel-e, Inc., a company run by a former student, is bringing this to the market.
1. S. Gharazi, B. C. Zarket, K. C. DeMella, S. R. Raghavan
This paper shows how to create a hydrogel that has many zones, each of which has different mechanical properties. The gel above has four zones, which stretch to different extents. The modulus of the stiffest zone is 100 times the modulus of the softest zone. Our approach could be used to build realistic mimics of the spinal discs present between our vertebrae, which have a soft core and a stiff shell.
Many molecules (‘gelators’) self-assemble into long fibers, which entangle to form molecular gels. Such gelation occurs in some organic solvents, but not in others. But is it possible to predict if gelation would occur beforehand? This paper provided a framework to predict molecular gelation using thermodynamic parameters of the various solvents. The same framework has now been used by many researchers.
Many materials in nature, including the onion, the egg, and tissues in our body have multiple concentric layers. To mimic this architecture, a simple synthesis technique is shown in this paper. In the resulting multilayered capsules, the composition and thickness of each layer can be varied. Such capsules could be used for the controlled delivery of drugs, cosmetic ingredients, or agrochemicals.
This paper showed for the first time how one could easily create a ‘photorheological fluid‘ in the lab, i.e., a fluid whose viscosity could be dramatically altered by shining light. The fluid contained molecules that self-assembled into long chains initially. Irradiation with UV light altered the geometry of the molecules, which made them re-assemble into tiny spheres. This caused a 10,000-fold drop in viscosity.