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Jill Dill Pasteris

Professor
Ph.D., Yale University, 1980
A.B., Bryn Mawr College, 1974

Biomineralization and Applications of Raman Spectroscopy
and Mineralogy to Materials Science

Professor Jill Pasteris takes a traditional mineralogic-geologic approach to non-traditional materials. Her interdisciplinary research group consists of Dr. Brigitte Wopenka, chemist, and Dr. John Freeman, chemist-spectroscopist. Together they apply vibrational spectroscopy, laser scanning confocal microscopy, and more traditional geochemical analysis techniques to materials ranging from fluid inclusions in minerals and glasses to nanocrystalline precipitates and skeletal minerals in bacteria and humans. Below is a brief summary of Professor Pasteris' and her group's current projects in biomineralization, medical mineralogy, and environmental mineralogy.

Raman Spectroscopy as a Tool for the Geologist 

One of the primary research tools used by Professor Pasteris and her colleagues is the laser Raman microprobe. Among the petrologically and geochemically useful aspects of this analytical technique are its ability to identify and quantify chemical species (e.g., distinguishing carbonate from elemental carbon from carbon monoxide), to distinguish molecular and crystalline structure in allotropes and polymorphs (e.g., 8-fold vs. 6-fold rings of elemental sulfur, graphite vs. diamond, calcite vs. aragonite), and to determine degree of crystallinity of materials (e.g., silica glass vs. chert vs. quartz). The microprobe configuration of a Raman spectrometer allows for excellent spatial imaging and analysis of sample areas as small as 1 micrometer in diameter. For instance, within a 3-phase fluid inclusion 15 micrometers in diameter, one could identify anhydrite (as distinguished from the compositionally identical, except hydrated form, gypsum), determine the concentration of sulfate dissolved in the coexisting brine, and determine the molar proportions of methane and carbon dioxide in the coexisting gas phase. Professor Pasteris has collaborated with numerous researchers to apply Raman microprobe analysis both to natural samples (to better characterize them) and to experimental analogs (to better understand and track the controlling variables in geologic systems).

Medical Mineralogy, Environmental Mineralogy, and Biomineralization  

There are many "non-geological" areas of research that can benefit from a geologist's understanding of what a mineral is and how to analyze the properties of minerals. Each mineral represents the unique pairing of a composition and an ordered internal structure. An additional characteristic is the "degree of crystallinity" (e.g., compare quartz crystal to chert/flint to glass) of a material. Those three parameters of a material/mineral (composition, structure, crystallinity) define its physical and chemical properties. If any of those parameters is changed, the properties of the material are changed.

Geologists traditionally have measured the values of individual properties of natural geological materials and, less typically, of synthetic analogs. The same dependence of properties on attributes, however, also occurs in natural biological materials (and their synthetic analogs), e.g., bones and teeth, whose apatite can be thought of as a "biomineral." Over geologic time, organisms apparently have taken advantage of their ability to tweak the composition, structure, or crystallinity of biominerals in order to change their properties to better suit some biological function. Our own use of fluoridated toothpaste and drinking water is a modern example of how to tweak the properties of the biological apatite phase that comprises teeth.

Professor Pasteris and her group first became involved in this notion of biominerals (normal or pathologic materials precipitated by living organisms) when they were asked to use Raman spectroscopy to analyze minute particles in human tissue. They investigated precipitates associated with prosthetic devices implanted in the human body and particles in lung tissue. Since then, they have begun research on bone in collaboration with Professors Matthew Silva and Stavros Thomopoulos in the Department of Orthopaedic Surgery at the Washington University School of Medicine. Bone, like tooth, is a composite material that is dominated by extremely finely crystalline (grain sizes on the order of tens of nanometers) carbonated hydroxylapatite. The apatite grains are bound by ordered networks of collagen (protein) fibers. The mechanical properties of bone, including strength and susceptibility to fracture, are controlled in a complex and not well known way by the physical properties of the mineral grains, the collagen fibers, and the mineral-collagen interfaces.

Pasteris' initial joint project with Professor Silva, who is a mechanical engineer, involved Raman spectral comparisons within two sets of bones that had been removed from mice: 1) untreated bones from mice of different ages and 2) pairs of bones of the same age in which one member had been fluoridated in vitro (after removal from the animal) and the other left untreated. For the first set of bones, spectral analysis showed that the degree of crystallinity of the bone increased with age. The second set of bones showed two Raman spectral effects. The Raman peak position of the dominant phosphate band showed an upshift compatible with the replacement of the initial carbonated hydroxylapatite with a carbonated fluor-hydroxylapatite after only 12 hours of soaking in 2 molal NaF solution. The same Raman peak also became narrower due to fluoridation as a reflection of increasing degree of crystallinity of the bone's mineral component. Professor Silva's mechanical testing showed that the strength of the bone was degraded by fluoridation in a dose-dependent fashion. The results of this study are applicable to on-going questions about the possible effectiveness of fluoride treatments to decrease bone failure in osteoporotic patients. Joint research continues between Professor Silva's and Professor Pasteris' group on genetically altered mice that express the symptoms of diabetes.

Professor Pasteris' group recently completed a project on another biomineral, in this case within vesicles in sulfur-precipitating bacteria. This project was a collaboration with Drs. Kurt Buck and Shana Goffredi of the Monterey Bay Aquarium Research Institute (MBARI) in Moss Landing, California. Raman microprobe spectroscopy was done on filamentous, sulfur-oxidizing bacteria of the genera Thioploca and Beggiatoa. Raman analyses on individual 2-micrometer-diameter spherules within bacterial filaments on the order of 20-80 micrometers wide characterized the contents as elemental sulfur. The spectra also showed that the sulfur is bonded in the common, stable S8 ring configuration and is of an extremely fine-grained microcrystalline form. No additional (organo) sulfur compounds were detected spectroscopically in the vesicles. The present spectroscopic and optical data stand in contrast to reports and inferences of liquid-like elemental sulfur or homogeneous, complex sulfur compounds in other sulfur-oxidizing bacteria. The high reactivity and solubility observed in these vesicles is attributed to the extremely fine grain size of the solid elemental sulfur.

Thioploca, filamentous bacteria.  Optical microscopy shows cylindrical, equal-size cells, with vacuoles up to 80% of the volume of the cells.  Cells are densely populated with 1-2 micrometer spherules of elemental sulfur, which were analyzed by laser Raman microprobe spectroscopy.

Mineralogy on the Seafloor via in-situ Raman Spectroscopy

Professor Pasteris' group recently completed their part of a major collaborative project with MBARI geochemist-oceanographer, Dr. Peter Brewer. MBARI purchased for its ocean-floor research a fiber-optic-based, portable Raman spectrometer that Pasteris and colleagues had tested and specified with a vendor. MBARI's engineers built pressure-resistant housings to contain the spectrometer, the laser excitation source, and fiber-optically connected probe head through which a laser beam is focused onto a specified solid or liquid sample at depths up to 4 km on the sea floor. The instrument is routinely deployed by a state-of-the-art remotely operated vehicle (ROV) that currently is used in underwater research by the MBARI scientific and engineering teams. Pasteris' group was involved in testing the portable underwater Raman system and in helping to interpret spectral data retrieved from early experiments on the sea floor. One project of particular interest to Dr. Brewer's group is the investigation of clathrate hydrates on the sea floor, i.e., ice-like solids that encapsulate gas molecules (such as methane and carbon dioxide). Dr. Brewer's group earlier had used their ROV technology on several voyages to bring liquid carbon dioxide to several kilometers depth, release it, and monitor the formation of clathrate hydrate solid. Such experiments help scientists to evaluate the feasibility of stably incorporating unwanted greenhouse gases (such as carbon dioxide) into materials on the sea floor. The underwater analysis of these artificially produced clathrate hydrates was one of the first projects undertaken with the undersea Raman probe.

Geologic and Synthetic Analogs to Biomineralization

Natural halite from Searles Lake, California. The pink color is due to entrapment of single-celled algae Duniella, which contain beta-carotene.

Prof. Pasteris is the mineralogist on an interdisciplinary team of polymer chemists, spectroscopists, and materials scientists from 5 different universities, which is developing strategies for the synthesis and characterization of 1-, 2-, and 3-dimensional superstructures based on stabilized, ordered assemblies of nanoparticles. The polymer chemists have synthesized various compositions of cross-linked assemblages of copolymers into nano-scale, core-shell building blocks (nanoparticles). The ultimate goal is to create, from these organic-based particles, 3-D superstructures that will act as scaffolds or templates in the crystallization of inorganic compounds (“minerals”). Professor Pasteris’ group is particularly involved with geological and biomineral analogs (see photograph) as guides to the development of the proposed organic-inorganic composite materials. The group has used optical microscopy, laser scanning confocal microscopy, and Raman microprobe spectroscopy to characterize natural nanocomposites as well as the products of experiments in which NaCl and various crystallographic forms of CaCO3 were precipitated in the presence of polymer nanoparticles.

Environmental Remediation through Use of Bone Material

Raman spectroscopy shows very different degrees of atomic ordering in these examples of the lead phosphate mineral pyromorphite. The least atomically ordered pyromorphite is that precipitated directly onto the heated fish bone covered with carbonaceous char.
  

There is much concern about unsafe levels of heavy metals, such as lead and cadmium, dissolved in groundwater and soils. It has been known for many years that the addition of dissolved phosphate to lead-contaminated water will cause the precipitation of the highly insoluble lead-phosphate mineral pyromorphite. It is also known that addition of soluble phosphate (as in chemical fertilizer) to large natural land areas can cause run-off of phosphate into surface waters, which causes undesirable algal blooms. Thus, paleontologist-geochemist Dr. Judith Wright has promoted the use of fish bone as a less soluble source of phosphate to sequester lead from groundwater and soil. Professor Pasteris and Professor Daniel Giammar from the Department of Civil Engineering have teamed up to determine the mechanism(s) by which bone causes lead removal from contaminated water. The results are amazing – in laboratory experiments, lead concentrations drop from 10-4 M to 10-8 M in a matter of hours upon introduction of fish bone or synthetic hydroxyl apatite. Professor Pasteris and her group are doing Raman spectroscopy on the fish bones before and after reaction, as well as on all solid products of reaction (see spectra).

Professor Pasteris teaches undergraduate and graduate courses in Earth materials, mineralogy, and Earth resources. In the spring of 2001, she began offering a new course called "Environmental Mineralogy", which covers topics such as asbestos/fibrous minerals and their health effects, mineralogy of arsenic poisoning and remediation, clathrate hydrates as sources and sinks for greenhouse gases, environmental uses of clay minerals, and materials for the storage of nuclear wastes.

Among her other professional activities, Professor Pasteris is a recent, past member of the National Research Council's Board on Earth Sciences and Resources, as well as the Board's Executive Committee and its Committee on Earth Resources. She is an associate editor for the American Journal of Science and American Mineralogist. In her department, Professor Pasteris is the chairman of the Curriculum Committee and a member of the Curriculum Development Committee. Prof. Pasteris was also one of the 2003-2004 Distinguished Lecturers for the Mineralogical Society of America. She spoke at numerous geology departments in the U.S. and Europe on "Minerals: They Do a Body Good" and "Broadening Our View of Minerals: Importance of Geologic, Biologic, and Synthetic Minerals." In 2006, she is one of the touring speakers for the Society of Applied Spectroscopy.

Read about Professor Pasteris (Washington University Record, Sept. 28, 2001)

"With a grain of salt: What halite has to offer to discussions on the origin of life," Jill D.Pasteris, John J. Freeman, Brigitte Wopenka, Kai Qi, Qinggao Ma, and Karen L. Wooley. Astrobiology, 64, 625-643 (2006).

“A mineralogical perspective on the apatite in bone”, B. Wopenka and J.D. Pasteris. Materials Science and Engineering C. 25, 131-143 (2005).

“Lack of OH in nanocrystalline apatite as a function of degree of atomic order: Implications for bone and biomaterials,” J.D. Pasteris, B. Wopenka, J.J. Freeman, K. Rogers, E, Valsami-Jones, J.A.M. van der Houwen, and M.J. Silva. Biomaterials, 25, 229-238 (2004).

“Development of a laser Raman spectrometer for deep-ocean science,” P.G. Brewer, G. Malby, J.D. Pasteris, S.N. White, E.T. Peltzer, B. Wopenka, J. Freeman, and M.O. Brown. Deep Sea Research Part I: Oceanographic Research Papers, 51, 739-753 (2004).

“Spectroscopic successes and challenges: Raman spectroscopy at 3.6 km depth in the ocean”, J.D. Pasteris, B. Wopenka, J.J. Freeman, P.G. Brewer, S.N. White, E.T. Peltzer, G.E. Malby. Applied Spectroscopy, 58, 195A-208A (2004).

“Necessary, but not sufficient: Raman identification of disordered carbon as a signature of ancient life,” J.D. Pasteris and B. Wopenka. Astrobiology, 3, 727-738 (2003).

“Laser Raman spectroscopy used to study the ocean at 3600m depth,” P.G. Brewer, J. Pasteris, G. Malby, E. Peltzer, S. White, J. Freeman, B. Wopenka, M. Brown, D. Cline. EOS, 83, 469-470 (2002).

“Images of the Earth’s earliest fossils?” J.D. Pasteris and B. Wopenka. Nature, 420, 476-477 (2002).

“Understanding the mineralogical composition of ancient Greek pottery through Raman microprobe spectroscopy,” B. Wopenka, R. Popelka, J.D. Pasteris, and S. Rotroff. Applied Spectroscopy, 56, 1320-1328 (2002).

See also Department Publications

   314-935-5434    pasteris@levee.wustl.edu
   314-935-7361
Last revised:
18-Sep-2006 		 
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