The Department of Chemistry at the University of Michigan has a rich tradition of excellence in the field of Analytical Chemistry. Hobart H. Willard made this department his home from 1903 to 1951, and ushered in the era of instrumental analysis in modern analytical chemistry. Philip J. Elving, a renowned electroanalytical chemist, maintained Michigan’s stature in the field during the period of 1952–1984, with pioneering research and influential editorial work. Thanks to the solid foundation that Willard and Elving provided, the graduate analytical chemistry program at Michigan continues to flourish in the 21st century. Particular areas of expertise are:
- Chemical and Biosensors
- In Vivo Measurements
- Mass Spectrometry
Examples of research projects in these areas are highlighted below.
Faculty associated with this research cluster
Chemical and Biosensors
The ability to monitor concentrations of key chemicals/biochemical species in complex environmental or physiological matrices via electrochemical or optical transducers requires the design of chemically selective coatings or interfaces. Our analytical program has active research efforts on a number of fronts relative to modern chemical sensor technology. These include the development of microarray sensors for gas phase monitoring based on resistance changes of surface modified gold nanoparticles and conducting polymer films, use of metal ion-ligand complexes in polymeric films to create anion and gas sensors, design of nanoparticle optical sensors for intracellular measurements, and the use of surface immobilized biocatalysts to prepare a new generation of biosensors.
Figure 1. Fluorescent indicator-dye embedded PEBBLE nanoparticle sensor for in vitro > and in vivo monitoring of intracellular and extracellular oxygen
Charged interfaces are at the heart of many chemical sensing modalities and energy conversion/ storage technologies. The University of Michigan Chemistry Department has a long tradition in the development and application of electroanalytical methods such as voltammetry, chronoamperometry, potentiometry, and AC impedance for studying the fundamental and practical aspects of charged interfaces. Coupled with complementary spectroscopic and scanning probe analyses, electroanalytical techniques provide detailed kinetic and thermodynamic information on interfacial processes. Current work is directed towards studying and controlling electrochemical sensor architectures, the corrosion stability of chemically modified semiconductor photoelectrodes in aqueous solutions, the efficacy of implantable biosensors, and the activity of fuel-forming electrochemical systems.
Figure 1. Substrate-Overlayer SERS analysis of semiconductor surface chemistry in operando
In Vivo Measurements
An exciting frontier in chemical measurement science is in vivo measurement of molecules in living systems. At the University of Michigan, we have several groups who are investigating different aspects of this field with a variety of techniques. Topics include developing more biocompatible implantable sensors for chronic measurements, sampling and rapid separation methods to monitor brain chemistry in living subjects, designing nanoscopic sensors for monitoring the chemical environment in living cells, tracking single molecules in living bacteria cells, and inventing new spectroscopic tools for non-invasive investigation of bone and soft tissues.
Figure 1. Raman spectroscopic analysis of mammalian musculoskeletal tissue integrity.
Figure 2. Depiction of implantable sensor catheter in an artery. Reprinted with permission from M. Frost and M. E. Meyerhoff, “In Vivo Chemical Sensors: Tackling Biocompatibility,” Anal. Chem., 78,7370-7377, 2006. Copyright 2006 American Chemical Society.
Researchers at The University of Michigan are developing state-of-the-art mass spectrometry technologies including cutting-edge ionization techniques, ultra high-performance mass analyzers, novel chemical probes, and millisecond time-scale separations. We engage broadly in basic research involving mass spectrometry, ranging from the development of new tandem Mass Spectrometry (MS) techniques, to the design of new chemical cross-linking reagents, to optimizing new approaches for gas-phase ion mobility separations. The study of complex biological molecules and systems are significant focus areas at UM, and our faculty scientists are world-leaders in the use of mass spectrometry to tackle long-standing challenges in proteomics, metabolomics, peptidomics, glycomics, neurobiology, cell signaling, and structural biology. Currently, our mass spectrometry faculty members are interested in a wide range of disease-associated research, including the discovery of new therapies and diagnostics for diabetes, cancer, and neurodegenerative disorders.
Figure 1. Ion mobility-mass spectrometry separation of multiprotein complexes.
Use of microfabrication techniques to create fluidic networks for performing chemical analysis promises to revolutionize chemical instrumentation. The University of Michigan has a large concentration of microfluidics researchers investigating all aspects of this exciting new field including fabrication methods, properties of microfluidics, and developing new chemical instrumentation. Students can participate in this research as well as the Microfluidics in Biomedical Sciences Training Program which offers numerous training, course, and seminar opportunities within a community of engineering, physics, biomedical, and chemistry researchers.
Figure 1. Capillary-PDMS Microfluidic Chip
Chemical separations remain a core tool in the arsenal of analytical chemists involved in anything from biological research to pharmaceutical industry to environmental analysis. The continued evolution of separation methods such as chromatography and electrophoresis is driven by the need for analysis of complex mixtures on smaller scale in shorter times. At Michigan, we have research aimed at developing new instrumentation, methods, and applications of electrophoresis and chromatography. A particular emphasis is on miniaturizing separation methods so that analysis can be performed on extremely small samples, i.e., “lab-on-a-chip” systems. Studies to increase the speed of separation analysis to sub-second levels for rapid, high-throughput analysis and interfacing separations to a variety of spectroscopic detectors are ongoing. Applications to a variety of topics including metabolomics, proteomics, glycomics, neuroscience, and pharmaceuticals are being explored.
Figure 1. Pocket-sized, wireless two dimensional micro gas chromatograph
Modern spectroscopies provide powerful tools for studying and manipulating chemical reactions, for investigating molecular materials, and for probing nano-scale systems. Research at the University of Michigan ranges from the study of atmospheric reactions, where physical conditions cover extreme ranges of pressure and temperature, to the use of the worlds smallest light source for optical and spectral imaging on the nanometer scale. Spectroscopic methods of characterization are used in the study of non-crystalline materials including photo-conducting polymers, inorganic-organic composites, molecular aggregates and nanoparticulates.
Spectroscopic data are finger prints of molecules and their environment. At the University of Michigan, advanced techniques including Raman spectroscopy/imaging, super-resolution optical microscopy, sum frequency generation spectroscopy/imaging, four-wave mixing spectroscopy, and coherent anti-Stokes Raman spectroscopy (CARS) imaging are used to investigate a variety of chemical, biochemical, and biophysical problems. Raman spectroscopy and imaging are applied to examine orientations of single molecules on surfaces to the composition of large musculoskeletal tissue. Metal nanoparticles are used to increase the resolution of super-resolution optical microscopy for bio-imaging applications. Various nonlinear spectroscopic tools are used to investigate mechanisms of membrane protein and peptide functions, biocompatibility of polymeric materials, marine biofouling, and polymer adhesion. Multi-dimensional NMR techniques are developed to investigate the role of non soluble and non-crystalline amyloid peptides that play important roles in aging-related diseases, the toxicity of antimicrobial peptides in cell membranes, polymorphism of pharmaceutical drugs, and the microstructures of bone and synthetic nanocomposites.