In nanoscale science and engineering research one seeks novel and robust ways for the manipulation of biological or synthetic matter with at least one of the dimensions smaller than typically 100 nm. Examples include synthesis of novel materials via molecular self-assembly and fabrication of devices by nanolithography. Technological impact of such research ranges from medicine and sustainable production of chemicals/fuels to THz information processing and renewable energy harvesting. At Syracuse University, BMCE faculty research in this area focuses on the synthesis and characterization of nanostructured materials for biomedical, optoelectronic, catalytic and renewable energy harvesting applications, developing computational and experimental approaches to explore the mechanisms of molecular self-assembly and investigations of the environmental impacts of nanotechnology. Specific examples of current research projects are:
Scanning electron microscope (SEM) images of nanoscale patterns generated by pulsed laser melting of a 4 nm thick Co film deposited on a glass substrate via e-beam evaporation. The patterns result from hydrodynamic instabilities in the molten metal film. A variety of metals can be patterned by using this technique. Such nanostructured interfaces have unique optical and magnetic properties which can be tuned by their size, shape and length scale (collaboration with Dr. Kalyanaraman, University of Tennessee, Knoxville).
For further details, see:
- Trice, C. Favazza, D.G. Thomas, H.G. Garcia, R. Kalyanaraman, R. Sureshkumar, A novel self-organization mechanism in ultrathin liquid films: theory and experiment, Phys. Rev. Lett., 101, 017802 (2008)
Environmental Impact of Nano ZnO
ZnO NPs (20 nm diameter) in presence of bacterial cells: in aqueous solution (C) where the nanoparticles agglomerate and do not impact the cell wall appreciably and after electrospray (D) where the individual NPs attack the cell. The latter scenario would correspond to aerosol mode of exposure (collaboration with Dr. Yinjie Tang, Washington University in Saint Louis).
ZnO nanoparticles (NPs) are widely used as pigments, semiconductors, sunscreens, and food additives. To determine the potential eco-toxicity of ZnO NPs, researchers have investigated their toxicological properties, fate, and transport in the environment. Injurious effects of ZnO NPs upon a variety of organisms in aquatic environments have recently been reported. Several studies indicated that the dissolved Zn2+ from ZnO NPs in the aquatic environment causes these eco-toxicities. Other studies have shown that metal NPs may be more toxic than either their ionic forms or their parent compounds. NPs tend to aggregate in aquatic environments to form micrometer-sized particles, and this state of dispersion reduces the influences of particle size, particle shape, and surface charge on the NPs’ eco-toxicity: see figure below. Further, many microorganisms such as Shewanella oneidensis MR-1 and Escherichia coli secrete extracellular polymeric substrates (EPS) which can inhibit the binding of NPs onto the cell. The focus is the study is to understand the effect of different modes of exposure (aqueous medium, aerosol) on the eco-toxicity of NPs.
For more details, see:
- Wu, Y. Wang, Y. Lee, A. Horst, Z. Wang, D. Chen, R. Sureshkumar & Y. Tang, Comparative Eco-toxicities of Nano-ZnO Particles under Aquatic and Aerosol Exposure Modes, Environmental Science and Technology
Concerns of nanotoxicity caused by nanoparticle-cell interactions are becoming increasingly important as the applications of nanoparticles continue to grow. There is significant interest in correlating the properties of nanoparticles such as size, shape, surface charge, and chemical functionality to their toxicity to biological systems. A recent study by Nangia and Sureshkumar showed that simple shape and charge modifications of chemically functionalized gold nanoparticles can cause tremendous change in their uptake by the cell. Using high-performance molecular dynamics simulations, interactions of charged nanoparticles of six distinct shapes (cone, cube, rod, rice, pyramid, and sphere) were performed with a model cell membrane. The results indicated that depending on nanoparticle shape and surface functionalization charge, the translocation rates can span over 60 orders of magnitude.
Figure: The translocation of nanoparticles is highly shape-dependent with rice-shaped particle that penetrates on microsecond time-scale, versus other shapes like sphere, pyramid, cone, rod, and cube that occur on much longer scales.