INDIANAPOLIS, Sept. 9, 2013 — Electronic sutures that monitor surgical incisions for healing and infection. Electronic films that cling to the heart like shrink wrap, monitoring and regulating the heartbeat and alerting the patient and cardiologist when medical attention is needed. Flexible plastic electronic appliques that stick to the skin like temporary tattoos and monitor hydration in athletes.
Those and other futuristic advances that marry electronics with the human body in ways that could enhance human health and performance are on the agenda here today at a symposium during the 246th National Meeting & Exposition of the American Chemical Society (ACS), the world's largest scientific society.
Presentations in the symposium, entitled "Nanoscale and Nanomaterials: Enhanced Motion," are among almost 7,000 scheduled for the meeting, which continues through Thursday in the Indiana Convention Center and downtown hotels.
Materials for a new generation of electronic devices that promise to revolutionize health care in the world of tomorrow are part of a presentation by John A. Rogers, Ph.D., of the Departments of Materials Science, Engineering, and Chemistry, University of Illinois at Urbana-Champaign and editorial advisory board member for ACS Nano.
Other presenters include
- Paul S. Weiss, Ph.D., Departments of Chemistry & Biochemistry and Materials Science & Engineering, California NanoSystems Institute, University of California, Los Angeles, and editor-in-chief of the journal ACS Nano.
- Paula T. Hammond, Ph.D., Department of Chemical Engineering and the Koch Institute of Integrative Cancer Research, Massachusetts Institute of Technology and associate editor of ACS Nano.
- Dawn Bonnell, Ph.D., Department of Materials Science, The University of Pennsylvania and editorial advisory board member for ACS Nano.
- Henry Hess, Ph.D., Department of Biomedical Engineering, Columbia University and editorial advisory board member for Nano Letters.
Abstracts of their talks appear below.
A press conference on this topic will be held Monday, Sept. 9, at 10:30 a.m. in the ACS Press Center, Room 211 in the Indiana Convention Center. Reporters can attend in person or access live audio and video of the event and ask questions at http://www.ustream.tv/channel/acslive.
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Abstracts
Motion and dynamics across scales
Paul S. Weiss, psw@cnsi.ucla.edu, Departments of Chemistry & Biochemistry and Materials Science & Engineering, California NanoSystems Institute, Los Angeles, CA 90095, United States
Nature has extraordinarily efficient means to convert chemical to mechanical energy and motion. No synthetic or hybrid systems come close to such efficiencies at any scale. Through design of precisely assembled synthetic systems and close coupling to theory and simulation, we hope to elucidate the roles of key nanoscale features that enable high efficiency. To date, most systems studied interfere when functional molecules and assemblies are put in proximity. These results point to the need for greater control in spacing and interactions at the chemical and assembly scales. First examples of cooperative function have been demonstrated in simple synthetic systems and will be discussed. Understanding the differences between our intuition, which is based on the macroscopic world, and the rules of nanoscale motion will be critical to further advances.
Tuning surfaces for cellular function, motion and uptake using nanolayer assemblies
Paula T. Hammond, hammond@mit.edu, Department of Chemical Engineering and the Koch Institute of Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, United States
Electrostatic layer-by-layer (LBL) process, is a simple and elegant method of creating designer biomaterials systems that can "shed" their layers to release drugs in a controlled and systematic fashion. It is possible to use these systems to engage cells in vitro and in vivo, and manipulate cellular behavior for biomaterials and biomedical applications. We demonstrate the ability to modulate drug release over periods of several weeks to months in sequence through the use of nanomaterials as separating barrier layers between multilayers loaded with different delivery agents. Such nanolayered systems can be used to induce the migration of cells to materials surfaces, enhance their adhesion these surfaces, and promote proliferation or differentiation of cells to create new tissue. Furthermore, we have recently developed systems that allow direct release of siRNA to tissues, including challenging biological environments such as open wounds. In these cases, siRNA is released in a highly sustained fashion to tissue over several days, leading to significant and consistent knockdown in localized areas. Applications of multilayer thin films for bone tissue engineering and implant coatings as well as wound healing will be discussed. On the other hand, it is possible to design nanoparticles that consist of several nanolayers wrapped around a core materials system. The resulting polyelectrolyte nanolayer assemblies can "surf" the bloodstream without being taken up by the monocyte-phagoctytic system, enabling their accumulation in tumors, where siRNA, molecular inhibitors and chemotherapy drugs can be released together or in controlled sequence. These siRNA nanoparticles in motion can be thought of as carriers with specific addresses: they have been designed to induce cells to take them up in the tumor site based on environmental triggers or molecular targeting. Finally, in this context, a new approach to the design of siRNA nanoparticles based on the generation of poly-siRNA generated with rolling circle transcription will be discussed. This approach enables the use of RNA nanotechnology to generate siRNA that self-assembles with itself or other components to create pre-formed nanoparticle systems.
Plasmon induced hot electrons in molecular electronics
Dawn Bonnell, bonnell@lrsm.upenn.edu, Department of Materials Science, The University of Pennsylvania, Philadelphia, PA 19104, United States
Plasmonic nanostructures can induce a number of interesting responses in devices. Here we show that hot electrons can be extracted from plasmonic particles and directed into a molecular electronic device. Such interactions have been invoked in water splitting reactions, but the mechanism remains controversial. To isolate plasmon induced hot electron generation from alternative and sometimes simultaneous mechanisms of plasmon-exciton interactions we designed a family of hybrid nanostructure devices consisting of Au nanoparticles and optoelectronically functional porphyin molecules that enable precise control of electronic and optical properties. Temperature and wavelength dependent transport measurements are analyzed in the context of optical absorption spectra of the molecules, the Au particle arrays and the devices. Enhanced photocurrent associated with exciton generation in the molecule is distinguished from enhancements due to plasmon interactions. Mechanisms of plasmon induced current are examined and it is found that hot electron generation can be distinguished from other possibilities.
Active transport for biosensing
Henry Hess, hh2374@columbia.edu, Department of Biomedical Engineering, Columbia University, New York City, NY 10027, United States
Biological nanomotors, such as the motor protein kinesin, can be employed in hybrid nanodevices for applications including actuation, computation, and sensing. In particular, significant progress has been made by us and others in constructing nanoscale transporters.
The focus of this presentation is the general lessons which can be derived from utilizing nanoscale transporters powered by biomolecular motors for the purpose of analyte sensing. These nanoscale transporters, often referred to as molecular shuttles, can be functionalized with specific linkers which enables the capture of a wide range of analytes (Figure 1). The capability to actively transport these captured analytes can then be applied to generate an observable signal or to aggregate analytes at a detection site.
Our analytical models of the aggregation kinetics of analytes captured by nanoscale transporters can be transferred to other classes of nanomotors, such as microrockets or active transport on surface gradients. Using these analytical models, Monte Carlo simulations of transporter movement, and Brownian Dynamics simulations, we investigate the interplay between diffusive and directed motion, the competition between analyte transport by diffusion and by nanoscale transporters, and the importance of transporter metrics such as its ability to maintain a defined direction of movement.
The dynamics of these active transport processes is further enriched by force-dependent binding and unbinding events between the molecular building blocks in these nanosystems, and the stochastic nature of nanoscale assembly processes.
Materials for devices that can wrap the soft, dynamic tissues of the body
John A. Rogers, jrogers@illinois.edu, Departments of Materials Science, Engineering, and Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States
Materials, mechanics designs and manufacturing systems are now available for electronic systems that achieve effective elastic moduli and bending stiffnesses matched to the surfaces of major organs of the body, including the skin, the heart and the brain. Laminating such devices onto these tissues leads to conformal contact, and adequate adhesion based on van der Waals interactions alone, in a manner that can accommodate natural motions, without mechanical constraint. In this talk, we highlight key aspects of this type of technology, with an emphasis on the materials, the soft lithographic manufacturing methods and several examples of clinically relevant modes of use.