AmericanChemicalSociety.com

A key feature of many biological structures is that they frequently display hierarchical organization on length-scales ranging from the nanometer to the macroscopic level.  Such organization provides the foundation for many of the material properties, including for example the remarkable mechanical properties of bone, the dazzling optical effects of butterfly wings, the self-cleaning ability of the lotus leaf, and the dry adhesion in gecko foot hairs.  More fascinating is that the fabrication of structured materials follows a bottom-up approach based on the assembly of suitable organic components under ambient growth conditions. Taking a cue from Nature, the “Synthesis of Bio-inspired Hierarchical Soft and Hybrid Materials” symposium, co-organized by Professor Shu Yang from University of Pennsylvania, Professor Fiona Meldrum from University of Bristol, United Kingdom, Professor Nicholas A. Kotov from University of Michigan, and Professor Christopher Li from Drexel University, at MRS meeting, San Francisco, CA, April 13-17, 2009, provided a forum to highlight the latest advances of using soft materials in the way that Nature has been using for millions of years. A total of 112 papers (85 oral presentations and 27 posters) were presented in this exciting 4.5-day symposium, with focuses on the strategies of design and synthesis of soft and hybrid materials with multi-scale structures.

A total of 20 internationally renowned speakers presented their latest research findings in the field at the MRS meeting, including Kellar Autumn (Lewis and Clark College), Ali Dhinojwala (Univ. Akron), Dennis Discher (Univ. Pennsylvania), Paula Hammond (female, Massachusetts Inst. of Technology), Craig Hawker ((Univ. of California-Santa Barbara), Scott Hollister (Univ. Michigan), Hiroaki Imai (Keio Univ., Japan), Jacob Israelachvili (UCSB), Xinqiao Jia (female, Univ. Delaware), Nils Kröger (Georgia Tech.), Chris Ober (Cornell University), Andrew Parker (Oxford Univ.), Darrin Pochan (Univ. Delaware), Virgil Percec (Univ. Pennsylvania), Mehmet Sarikaya (Univ. Washington), Matt Tirrell (Univ. of California-Santa Barbara), Gerard Wong (Univ. of Illinois, Urbana-Champaign), Shuhong Yu (Univ. Science and Technology of China, China) etc.

To summarize a few of the technical presentations, Prof. Gerard Wong (Univ. of Illinois, Urbana-Champaign) discussed the study of interactions and self-assembly between lipid vesicles and a prototypical family of synthetic phenylene ethynylene antimicrobial oligomers with tunable activity profiles. Prof. Virgil Percec (Univ. Pennsylvania) elaborated new synthetic methods and architectural concepts for the creation of complex molecular, macromolecular, and supramolecular synthetic systems to mimic and extend biological functions. Using a wide range of experimental techniques, such as ultra-high resolution synchrotron x-ray scattering and spectroscopy and x-ray and electron microscopy, Prof. Xinqiao Jia (Univ. Delaware), a recent awardee of NSF/CAREER grant in the Biomaterials program, presented her latest findings in developing strong, yet soft and flexible biomaterials that can be used to engineer damaged tissues, particularly the vocal folds. In order to harness the potential of nanomaterials and their hierarchical architectures for various technological applications, the patterning of the biomolecules and polymers into 2D or 3D structures is crucial. Prof. Chris Ober (Cornell University) discussed various patterning techniques developed in his group, including self-assembly of block copolymers, liquid crystals, 2-photon lithography, and the convergence of bottom-up and top-down approaches for directed assembly. Prof. Kellar Autumn (Lewis and Clark College) discussed biomechanics and evolution of animal locomotion, specifically the hierarchical organization of pillar structures in gecko foot hairs. Along these lines, Prof. Ali Dhinojwala (Univ. Akron) discussed their recent development of a synthetic gecko tape from micropatterned carbon nanotube arrays on a flexible polymer substrate, which offers peeling and adhesive properties better than the natural gecko foot.

On the international speaker side, Prof. Shu-Hong Yu (School of Chemistry & Materials, University of Science and Technology of China) presented his talk on the combination of polymer additives with a suitable mineralization media or an interface to access various inorganic superstructures with complexity and specialty. He also discussed the optical, electronic, magnetic, and catalytic properties of these materials and their applications in nanodevices and biotechnology. Prof. Hiroaki Imai (Keio Univ., Japan) discussed self-organized crystal growth of hierarchically structured inorganic crystals in cooperation with polymeric species. Through control of the diffusion of ionic species and an exquisite association of the crystals and polymers, this group has shown hierarchical superstructures of various types of inorganic crystals, such as helices, films, cones, hollow horns and wires consisting of bridged nanocrystals. The ability to engineer organized inorganic crystals with predictable size, shape, and morphology is an important aspect in designing advanced materials. Prof. Andrew Parker (Green College, Oxford Univ.) focused on the study of diversity and evolution of structural color in animals and plants, and discussed the application of the engineering mechanism discovered in nature to design novel optical devices.

Overall, the symposium successfully provided a platform for scientist as well as students to discuss the most recent advanced in Synthesis of Bio-inspired Hierarchical Soft and Hybrid Materials. The symposium was extremely successful. This grant was used to partially support 5 invited speakers travel to San Francisco and present their work.  This funding support from PRF is greatly appreciated.