ChemSemBlog

The speaker of Chemistry Seminar held in March 4, 2010 was Joseph Heinzelmann, who has 6 years of experience at Dendrictic Nanotechnologies (DNT). As a product manager, he has worked for business and development of Priostar and PAMAM dendrimers at his company. So, during his seminar he emphasized the importance of marketing and business in chemical industry. The chemical industry has shown rapid growth, and the U.S. chemical output is $400 billion a year.

In addition, through his presentation, I could learn more about dendrimers. DNT produces two product lines of dendrimers, Priostar and PAMAM, and both dendrimers have endless possibility. Dendrimers are highly branched polymer molecules consisting of core molecules, branch structures usually until fifth generation, and surface groups of several kinds of ions. The surface of dendrimers can be modified, and void space between generation structures is capable of carrying molecues like drugs or imaging agents. Therefore dendrimers can cover a very wide range of application area including druge delivery, siRNA and DNA transfection vectors, surface modifier for conjugating antibodies, peptides, or dyes, and so on.

In spite of these a lot of advantages, in fact, dendrimers are not yet used in therapeutics as drug carriers for treatment of cancer. There are several significant problems that need to be solved. At first, researchers face manufacturing problem, and the safety of dendrimer is required to be studied before dendrimers are used to cure cancer. In addition, drug delivery takes a long time and a lot of money.

To my non-science friends, I would say that dendrimer is a highly branched spheroid or globular molecules that have a lot of applications in life sciences research, industrial, and pharmaceutical areas.

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The guest speaker of the chemistry seminar held on January 28 was Basar Bilgicer, who is an assistant professor in the Department of Chemical & Biomolecular Engineering at University of Notre Dame. During the presentation, he focused on antibodies, such as IgG, and their aggregations to form multivalent molecules in biological systems and friendly explained about them. I think his seminar really helped students get a deeper understanding of antibody aggregation.

I was very interested in the pathway to make cyclic dimers and trimers from monomers. Bivalent hapten makes it possible to generate several forms of aggregations such as trimer, tetramer, and other polymers. Moreover, depending on the concentration of the ligands that bind to the tips of antibody, more complex form can be produced. For example, a synthetic trivalent hapten, which is monocyclic, aggregates IgG into bicyclic trimers. Through his presentation, I also learned about the thermodynamics and kinetics of multivalent molecules of antibodies, based on the basic dynamic principles. For example, the bicyclic trimer is kinetically and thermodynamically more stable than monomeric aggregates of this IgG.

On the other hand, I have a question about the aggregation of other antibodies rather than IgG antibody that he focused on for his research and about the potential application of antibody aggregates in future biotechnology.

I would say to my ‘non-science’ friends or family that the study of antibody is very important for design of diagnostic molecules for therapy of diseases, and Dr. Bilgicer has worked in multivalent interactions of antibody aggregation in biological systems.

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Our guest speaker for the chemistry seminar held on November 12 was Jeffrey Turk, who is currently an assistant professor of chemistry at Alma College. His research includes medicinal or drug-related chemistry and fragrance chemistry. The topic of his presentation was mainly Sandalwood aroma compounds. During the presentation, Dr. Turk did a great job at setting up the background and foundation about olfactory system and presenting his research project about fragrance molecules of Sandalwood, so that I could overall understand and easily follow what he talked about.

Most of all, because I had a chance to smell some compounds he brought, I was so excited. Interestingly some samples had very good odors, but others didn’t. In addition, one thing I was interested in was that the molecules which were stereoisomers each had different odors depending on their S or R configuration.

Also, I learned a lot about fragrance molecules from his talk. He said that odor molecules, less than 300g/mol, are generally detectable and volatile. To be detected, at first, the molecules should bind to olfactory receptors, such as G protein coupled receptor (GPCR). Surprisingly more than 400 genes are coded for different olfactory receptors.

I also learned that the fragrance molecules of Sandalwood for his research were synthesized via Allene-Claisen rearrangement. One of the significant goals of his research was to produce these aromatic compounds with atom-efficient reaction to reduce wastes. In the fragrance industry his research works were very important because he could synthesize fragrance molecules which were nature identical or similar with much less cost.

For my non-science friend, I would say that organic chemistry plays an important role in fragrance industry to synthesize compounds that smell good.

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Our guest speaker for the chemistry seminar held on November 5 was Jyllian Kemsley, who is currently an associate editor of Chemical & Engineering News (C&EN). This seminar was special because we had a communication with the speaker via online, which was performed as a new form of presentation at Andrews University, and it was done very successfully.

Through the seminar, I learned a lot about science writing. She said that many science writers were recommended to have broad chemistry intelligence. In fact, she had B.A. degree in Chemistry at Amherst College and Ph.D. in bio-inorganic chemistry at Stanford University. Nevertheless, she is still making an effort to keep learning. In addition to science backgrounds, the talent for writing clearly and accurately is needed to be a good writer as well.

Another thing I learned from the seminar was that science writers are working in many more fields than I have thought. With science knowledge and writing skill, they are performing their job not only in science-focused media and publications but also at many different organizations, such as research institutes, government agencies, many companies, and hospital.

On the other hand, she said that science writers often face some difficulties, one of which was that they sometimes have to take care of an unfamiliar field. So, I was wondering during the seminar how she deals with this challenge in more specific way.

I think the seminar was very interesting for me because I could learn a lot from her. Actually, when I try to express my thoughts and opinion in written words, I sometimes have a difficulty. However, I realized that widely reading of scientific papers or local and national newspapers could help me establish a good writing skill. Also I would say to my ‘non-science’ friend or family that science writer can be a great job for one who is interested in writing with science knowledge.

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This week’s presentation speaker was Hisashi Yamamoto, a professor of chemistry at the University of Chicago. He has made an extremely noticeable achievement in acid catalysis in organic synthesis. Because it was a great opportunity to meet a world-famous organic chemist, I was very excited about his seminar.

First of all, I learned the importance of a cascade approach for organic synthesis. One of the significant topics he spoke about during the presentation was the cascade reaction of an organic compound that needs a lot of steps to be synthesized. If chemists reduce many reaction steps and synthesize the molecule in very few steps, their findings can lead to a great change. To save steps means that they can make the compound efficiently by saving materials and times. In addition, I learned about the “super Brønsted acid.” He mentioned the Mukaiyama aldol reaction, and in order to improve this reaction, he made super acid catalysts. In spite of a small amount of Brønsted acid, the super acid catalyst functions very well  in the synthesis of complex organic molecules.

Another thing I found out was that he successfully made “super silyl” group. Super silyl is so reactive and selective that it provides sufficient reactivity of silyl enol ether and is used as a protecting group in several organic reactions.

One of the questions I had during the seminar was about “chiral” Lewis acid, what chiral Lewis acid catalyst is, and how it works differently when compared to achiral acid catalyst.

I think the seminar was very interesting for me because I could learn a lot from him in terms of acid catalyzed synthetic reactions including Lewis acids and Brønsted acids. Also I would say to my ‘non-science’ friend or family that Professor Yamamoto has developed acid catalysts to improve ease and economy during organic synthesis.

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This week’s talk was on Rate and rate-determining processes in natural weathering of rock-forming minerals linking microscopy and the major-element geochemistry of natural waters by Michael Velbel.

Our guest speaker for this week’s presentation was Michael Velbel, who is a professor of Geological Sciences at Michigan State University. I think the presentation was good and easy to follow, and he was very enthusiastic to tell students about his research.

I was very interested in Velbel’s presentation because the topic of the presentation regarding geological science is a completely new field for me. I learned that mineralogy–studying formation, distribution, and utilization of mineral groups — is closely related to chemistry.

Velbel usually works at Coweeta watershed to study silicate minerals which are the largest and most important component of rock-forming minerals and to examine weathering rates of primary silicate minerals. I also learned about some names of silicate minerals like Feldspar, Micas, Garnets, and so on.

The most interesting thing that I learned during his presentation is that the reaction of Na-Feldsper weathering that occurs in nature is different from the reaction equation that is described in the textbook.

On the other hand, I had a question about what kind of other factors such as temperature in groundwater environments can also influence the weathering rate of rock-forming minerals.

For a non-science friend, I would say that Geological science, the study of the solid and liquid matter that constitutes the Earth, helps us understand phenomena on Earth and its systems from microscopic to global scales, specifically, studying minerals and their reactions within natural waters.

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This Thursday, Wendell Griffith, an assistant professor of Chemistry at the University of Toledo, made a presentation about mass spectrometry (MS) and hemoglobin. His presentation was very interesting because during biochemistry class I recently learned about proteins, specifically hemoglobin.  So this presentation increased my understanding of hemoglobin and hemoglobin-binding proteins.

In addition to the subject about hemoglobin and hemoglobin-binding proteins, I learned a lot of information about mass spectrometry as well as his recent research project. He said he usually uses mass spectrometry as an alternative analytical tool rather than NMR and X-Ray crystallography.  MS provides mass information based on m/z ratio by vaporizing analytes, ionizing them, and generating charged molecules or molecule fragments. Especially, an electrospray ionization mass spectrometry (ESI-MS) gives wonderful protein images such as structural information of proteins and their macromolecular interactions. It was very interesting that a denatured protein has a larger range of charge distribution in ESI-MS than a normal protein.

Another thing that I would like to learn more about is the hemoglobin assembly/dissociation pathway. Hemoglobin consists of two alpha and two beta globins and four hemo. Beta globin chins are very flexible for the efficient accommodation to alpha chains. When hemoglobins are made, a form of an alpha globin combining with hemo and a beta globin without binding hemo works as an important intermediate in the hemoglobin assembly/dissociation pathway.  On the other hand, there is a new concept that I couldn’t understand very well. I wondered what haptoglobin is and why haptoglobin-hemoglobin binding protein is important.

For my ‘non-science’ friend this presentation was about mass spectrometry, which is a great analytical technique generally used for determination of the composition of organic compounds, but it can also give us a deeper understanding of protein structure and function.

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The Evolution of Synthesis: 11-O-Debenzoyltashironin by Silas Cook

Our chemistry seminar speaker this week was Silas Cook, who is an assistant Professor of Chemistry Department at Indiana University.

Through his seminar, I now have new knowledge of Synthetic Organic Chemistry., which the speaker said is divided into total synthesis and methodology.  Dr. Cook’s research purpose is to discover new strategies in total synthesis, catalysis and study the molecular pharmacology of the compounds made.

I learned about the importance of synthetic organic chemistry, especially in the area of pharmaceutical research.  I also understand better that there are many useful natural compounds to treat disorders, but they are often very complex and expensive to synthesize.

So Dr. Cook is devoted to developing new methods to make natural compounds. For example, he found the synthetic ‘tools’ needed to synthesize 11-O-Debenzoyltashironin from phenols and allenes.

On the other hand, I am wondering how 11-O-Debenzoyltashironin can be applied to the invention of medicines that allow real patients to get healthier.

Also I would like to know more about the speaker’s most recent research area that he is working on.

In generally, I was interested in his presentation very much because I was overwhelmed  by his enthusiasm for his research, and I also got involved in his presentation by giving responses to his questions.

In addition, although I understood the mechanisms involved in the synthesis of 11-O-Debenzoyshironin, I learned a lot about how many researchers, including Dr. Cook,  invests so much time, knowledge, and passion to achieve a successful synthesis. I was surprised that he spent five years and  used more than twenty three steps to get his desired product.

To my friend lacking scientific information, I’d like to introduce Synthetic Organic Chemistry, a field of study to synthesize needed molecules, demonstrate the limitation of current methods and develop new methods.

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Name: Seonui Kang

Increasing the ability of contrast agents for MRI using lanthanide chemistry by Matthew Allen

Mathew Allen, the first guest speaker of Chemistry/Biochemistry Seminar for this semester, is an assistant professor of Chemistry at Wayne State University. He looks very young and is an enthusiastic researcher who is working on research projects spanning different scientific fields including inorganic chemistry, organic synthesis, analytical chemistry, and biology. The topic of his presentation was lanthanide based MRI (Magnetic Resonance Imaging) contrast agents.

I learned more about lanthanides, which includes fourteen elements from lanthanum to lutetium. Lanthanides have unique photophysical characters and their distinctive properties, such as, oxidation and fluorescence, are determined by f-orbitals. Another thing that I learned more about from Allen’s seminar is that the ability of contrast agents, a chemical substance that shows the contrast between two tissues for MRI, can be enhanced by using lanthanide chemistry.  Allen’s research project uses Gd(Ⅲ) and Eu(Ⅱ) as the lanthanide. His unique approach involves synthesis of dendrimer – lanthanide systems and selective break down of the dendrimer.  I would like to know more about proton relaxation involved in MRI imaging and its contrast agent.

In generally, I was interested in his presentation because I could feel his intensity to introduce his very recent research to us. Although I did not understand all the things he said, I did learn a lot from Allen’s talk about MRI and its contrast agents. Simply put, MRI is a very powerful technique used to look inside the body and develop three-dimensional images.  Allen’s research involves using lanthanide – dendrimer contrast agents to enhance this powerful technique.

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