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Nano Chemistry at the University of Michigan focuses on the unique properties of nanometer-scale materials and bio-molecules. These research endeavors have implications for basic chemistry as well as applications in medicine and energy. A few examples of Nano Chemistry at UM include:
Protein Nanoassembly and Neurodegenerative Disease
The aggregation of proteins is normally tightly controlled, and misfolded proteins are generally removed by the proteosome before aggregation of the misfolded protein can occur. For reasons not clearly understood, in some individuals this degradation process breaks down and misfolded proteins accumulate as time progresses. Out of the many proteins within the human genome, a small but growing number have been found to form the long, highly ordered nanostructures that comprise amyloid deposits (A). A high percentage of these proteins have been linked as causative factors in common and incurable disorders including Alzheimer’s, type II diabetes and Parkinson’s. We are currently using a variety of biophysical techniques, including solution and solid-state NMR spectroscopy, to understand the nanoassembly of amyloid proteins and investigate compounds able to suppress amyloid fibril formation and toxicity. A major focus of our work is to understand the interaction of these protein nano-structures with biological membranes, using solid and solution state NMR to characterize the structure of these and other nanostructures (such as dendritic polymers) (B) and the interactions of these nanostructures with the cell membrane that leads to toxicity (C). (Acc. Chem. Res. 45, 454 and JACS 132, 8087).
Optical Properties of Noble Metal Nanoparticles
pon resonance excitation of a noble metal nanoparticle (NP) much smaller than the incident wavelength, collective oscillations of the free electrons establish a strongly localized local surface plasmon mode, producing an enhanced field in the particle vicinity. Plasmonic metal NPs plasmon modes are central to many important optical effects, from surface-enhanced Raman spectroscopy (SERS) to photovoltaic concentrators, and in the Biteen Lab, we are particularly concerned with the effect of plasmon-enhanced fluorescence.
We have demonstrated enhanced emission from quantum dots, organic dyes, and fluorescent proteins, have used the enhancement effect to map the local field, and have begun to extend this work to membrane proteins in live cells. We are interested in exploring the fundamental optical properties of the nanoparticles as well as using this enhancement to improve the resolution of single-molecule fluorescence imaging.
Mutifunctional Nanoparticle Platform for Imaging and Treatment of Cancer and Heart Disease
Multifunctional, biomedical nanoparticles have been developed and applied for in-vivo MRI (magnetic resonance imaging) enhancement and photodynamic therapy (PDT) of a rat implanted human brain tumor (9L glioma). The nano-particles have a polyacrylamide (PAA) core containing Photofrin as photosensitizer, iron oxide as MRI contrast agent and F3 peptide as molecular targeting group for the recognition of the tumor neovasculature. The tumor targeting and PDT efficacy of the nanoparticles were monitored by MRI after the intravenous injection of the nanoparticles. The MRI enhancement was observed and extended over 22 hours post injection for targeted nanoparticles. A single iv injection of a targeted therapeutic nanoparticle dose, coupled with a single 5 min PDT treatment, leads not only to an increase in the rat survival rate but accomplishes complete tumor remission.
Assembling Enzyme Cascades on DNA Nano-Pegboards for Efficient Energy Production.
Impact: The cellular activities of all organisms are governed by a variety of biochemical pathways, each of which is composed of an intricate network of discrete nanostructures. These pathways mediate important functions such as cellular respiration, homeostasis, signal transduction and gene expression. In cellular environments, these macromolecular systems have often evolved to spontaneously self-assemble into highly organized spatial structures, where the function of the pathway is critically dependent on the relative position and orientation of the participating molecules. For example, many multi-enzyme complexes catalyze biochemical reactions with extremely high efficiency and specificity by spatially organizing the pathway components to facilitate substrate diffusion between enzymes. Synthetic and therefore reconfigurable analogs of such efficient enzyme cascades are yet to be designed.
Objective: To translate biochemical enzyme cascades to non-cellular environments where they can be exploited to produce energy through methanol oxidation or photosynthesis.
Approach: Through a large Multidisciplinary University Research initiative (MURI) between the UM, Arizona State University, Harvard University, and MIT () we are on our way to utilizing DNA origami pegboards to arrange protein enzymes into any desired assembly architecture for efficient energy production, then performing quality control by imaging these nanoassemblies and their turnover at the single molecule level.
Bottom-Up Nanomaterial Synthesis.
The Bartlett group develops solution-based methods to synthesize oxide nanoparticles from molecular precursors (the bottom-up approach). One example is using hydrothermal synthesis to generate materials used in high-power lithium-ion batteries. Aqueous reactions carried out at higher temperature and pressure allow us to solubilize metal oxides. This reaction scheme generates a crystalline product composed of 30 – 100 nm particles as the reaction vessel returns to ambient conditions. Li-ion test cells composed of LiMn2O4 spinel nanoparticles cycle reversibly even at fast rates.
- Analytical Chemistry
- Chemical Biology
- Inorganic Chemistry
- Materials Chemistry
- Organic Chemistry
- Physical Chemistry
- Research Themes
- Bioanalytical Chemistry
- Bioinorganic Chemistry
- Bioorganic Chemistry
- Biophysical Chemistry
- Computational and Theoretical
- Energy Science
- Environmental Chemistry
- Nano Chemistry
- Optics and Imaging
- Organometallic Chemistry
- RNA BioChemistry
- Sensor Science
- Surface Chemistry
- Sustainable Chemistry
- Ultrafast Dynamics