Yarger Scientific

Tattoos are currently used as body art. My group wishes to add functionally to tattoos and make 'Smart Tattoos'. These would be tattoos that could be used as sensors, electronics, energy storage, CO2 fixation, etc. The first project my research group is undertaking is making a Tattoo that changes its optical properties in a reversible way based on the level of glucose surrounding the tattoo 'ink'. Hence, we would have a glucose sensor for diabetics.

This is a very primary research project and I will include more details as we start developing the tattoo chemistry and 'smart inks'.

While the mechanical properties of spider silk have been extensively studied1, still little is known about the molecular structure and dynamics of this primarily amorphous biopolymer. The proposed research will elucidate the molecular structure and dynamics in a number of important and varying spider silk fibers. Emphasis will be placed on the amorphous fraction of these materials (typically > 75% amorphous), where there is little current molecular information. While a large part of the work will focus on NMR characterization, we are a very diverse research group and have expertise in several techniques for the elucidation of structure in disordered materials. Hence, we will also use our expertise in amorphous materials x-ray and neutrons diffraction, vibrational spectroscopy of amorphous materials, Brillouin spectroscopy, and thermal analysis of glasses to more completely characterize the properties and physical behavior of silk fibers. Furthermore, besides determination of the protein structure that comprises silk, it is also very important to expound the role of water as (i) a solvent, (ii) a plastizer and (iii) as a intercalated molecule which is always present in silk. Again, the characterization tools discussed above will play a vital role in elucidating the role of water in spider silk. For example, we have already embarked on a project to determine the molecular underpinnings for supercontraction in major ampullate Nephila clavipes spider silk, while the minor ampullate silk from the same spider does not supercontract. Figure 1 shows an SEM image of major and minor ampullate spider silk fibers. Our preliminary NMR findings are discussed in a recently accepted paper in Biomacromolecules2 and reveal a complex interplay of structural and dynamics changes induced by hydration of the amorphous region of silk fibers.
This proposal outlines a schedule of research work based largely on nuclear magnetic resonance (NMR), neutron, x-ray, DSC, Raman and Brillouin scattering techniques, which we believe will make possible a major extension of our knowledge of the molecular structure and dynamics in the disordered region in spider silk fibers. The objectives are as follows:



    The objective of the proposed research is to synthesize ligand-capped metal and inorganic oxide NPs (NPs) and to develop NMR methods to characterize the capping chemistry and nanoparticle structure. The broader impact of the proposed research will come in several forms, including (i) elucidating the structure of an important class of nanomaterials and providing general characterization techniques for the nano-materials research communities, (ii) training the next generation of materials chemists and NMR spectroscopists, and (iii) develop educational outreach in the area of nano-chemistry to local high school teachers and classrooms. A list of specific aims that Profs Holland and Yarger hope to achieve in the proposed research is given below:

      The primary intellectual merit of the proposed project is focused on uncovering fundamental chemistries both structural and dynamic at the NP-ligand interface using a suite of NMR spectroscopy techniques from both the solids and liquid state NMR sciences. It is our hopes that this will lead to a broader impact in nanoscience by providing generalized NMR techniques and analysis for the characterization of ligand-capped NPs.



      While the transition from supercooled liquid to glass has been extensively studied (“the glass transition”), transitions within the amorphous state have just recently started to gain attention.3,4 The proposed research will develop new understandings in the structural and dynamic changes involved in condensed phase liquid-liquid and amorphous-amorphous polymorphism (polyamorphism), and initiate research into new polyamorphic systems. For example, evidence of polyamorphism in amorphous germanium has been presented by several research groups over the past few years.5-12 In figure 1, transmission electron microscopy (TEM) results from our group clearly demonstrate experimental evidence for polyamorphism in amorphous germanium brought to ambient conditions. This material has been synthesized at 8 GPa and 900oC, but quenched to room pressure and temperature conditions for TEM observation. Hence, we have used a polyamorphic transition as a path to a new high-density glass at ambient condition.13 It is this type of recent discovery and characterization we propose to continue in this research proposal.
      Exposure to many forms of spectroscopic characterization tools, multi-institutional collaborations, and education outreach will provide a unique experience base for students and should benefit the surrounding educational and industrial institutions. This proposal outlines a schedule of research work based largely on characterization of amorphous-amorphous phase transitions (and polyamorphism) in a number of molecular and network materials, which we believe will make possible a major extension of our knowledge of the phase behavior of liquids and amorphous solids. The objectives are as follows:

        After some 6 years of exploration of the concept of medium temperature range fuel cells based on the application protic ionic liquids as the proton-carrying electrolyte, characterized by some breakthrough conceptual developments but without breakthrough practical applications, we seek support for some fundamental studies of the protic ionic liquids themselves. We need to understand better the state of the proton in the PILs. To this end we propose to invoke the powerful techniques of nuclear magnetic resonance in some of its less frequently applied but powerful strategies, frequency dependent electric field relaxation techniques, and proton-selective IR studies. These will be applied to PILs chosen using the proton energy level diagram developed in our earlier studies, so as to allow study of liquids of different ionicities at several different levels of acidity. We believe this distinction, and the possibility of studying these properties independently, has not been made before. Of particular interest is the behavior of proton carrying entities at the superacid level of proton activity, which is so far a novel and unexplored area. It leads us to unexpected types of proton-conducting polymers, for instance those in which the weakly basic nitrogens in the P-N backbone of phosphonitrile polymers can be the protonated species. An applications-oriented component of the program will involve the evaluation of polymers of this character, plasticized by ionic liquids if necessary, in fuel cell systems.

        Amorphous drugs have enhanced solubility and faster dissolution rates compared to their crystalline analogues due to the increased surface wetting of the randomized structure. Here we define the term amorphous to mean that the material does not exhibit Bragg peaks that result from the diffraction of x-rays by a repeating, long range periodic atomic or molecular structure in a material. The provisional patent ‘Containerless processing of amorphous and nanophase organic materials’ was filed by Argonne National Laboratory legal department in January 2011. Over the next year we plan to capitalize on this work and test the containerless processing on a range of different types of drugs. Three of the most important questions we wish to answer are (1) can we amorphize drugs with a strong tendency to crystallize using the two methods developed ? (2) for how long do the drugs we make remain amorphous ? and (3) can we use the x-ray structural data measured during the amorphization process to understand and predict stability ? To answer these questions we will investigate the effects of laser heating on enhancing vitrification and the mixing of polymer blends (stabilizers) to enhance the amorphization process from solutions. The use and regular availability of hard (100 KeV) x-rays at the APS is essential to this proposal, as the pair distribution function technique covers a wide momentum transfer range, providing high real space resolution of the structure of amorphous and nanocrystalline materials. We will also continue to measure the evolution of the amorphization from solution in-situ using a single axis acoustic levitator integrated on the 11-ID-C beamline. To date the experimental analysis has been qualitative in nature, the to push the project forward a full quantitative structural analysis is now required on selected systems. In collaboration with Argonne National Labs, our group at ASU plans to use NMR spectroscopy to characterize the molecular structure of amorphous pharmaceuticals.

        Also, we are looking into pressure induced amorphization as an alternative means to make amorphous drugs.