Javier Rosa is a on a mission. As an undergraduate at Rutgers University double-majoring in computer science and mathematics, he hopes to one day pursue an advanced degree in computer science with a focus on computational biology or bioinformatics and work to fight cancer.
Many college students studying at top-tier research universities have similarly ambitious goals, but two factors make Javier's academic journey particularly remarkable. For one thing, his passion for fighting cancer is personal--he was diagnosed with testicular cancer last year. Secondly, he is one of the few students from a minority background studying computer science at a tier-one research institution.
According to Richard A. Tapia, professor at Rice University, many minority students enrolled in undergraduate computer science programs at these institutions feel isolated and unsupported. As a result, he says, many leave the field to pursue a different major. "Students migrate to more welcoming degree programs," Tapia says, "where they feel they have support and a high probability of success."
Tapia and colleagues at nearly a dozen universities have teamed up with private industry and other groups to provide that support and prevent what he calls the "loss of the precious few" minority students majoring in computer science. He serves as director of the Empowering Leadership (EL) Alliance, an organization supported by funding from the National Science Foundation to provide these students with a community of support as they pursue their degrees.
"At the nation's top institutions, there are many choices inside and outside the university environment that offer vibrant opportunities and a welcoming environment," Tapia says. "We aim to provide both within the computing disciplines."
The EL Alliance's work could not come at a more crucial time. Despite the importance of information technology to the U.S. economy and society, the number of students from all backgrounds pursuing doctorates in computer science has actually declined in recent years. The statistics are even more dire for students from minority backgrounds. Such students are under-represented as undergraduates, and at the graduate level only 3 percent of doctorate students in computer science are African-American, Native American or Hispanic. Given that minority populations are the fastest growing segments of the U.S. population, this trend will continue unless efforts are made to reverse it.
One of the tools the EL Alliance uses is bringing these students together so they can meet and support each other. This past October, hundreds of students from around the country, many from the EL Alliance, came to Orlando for the Richard Tapia Celebration of Diversity in Computing conference where they interacted with national leaders in computing from the academic and business sectors. The Alliance has also established an online mentoring group that connects undergraduate and graduate students with national leaders in the computing fields who can offer their experience and advice as students make their way through their academic careers. The Alliance has also created a group on Facebook for its members to connect with each other.
These are just a few of the activities that Alliance members have in mind as they enter their second year. The partnership itself is comprised of universities, including Rice University; Boston University; University of California, Berkeley; University of Colorado, Boulder; University of Texas, Austin; University of IllinoisArizona State University, Auburn University, Carnegie Mellon University, Cornell University, Duke University, Harvey Mudd College, Portland State University, Princeton University, Purdue University, University of Maryland, and the University of Wisconsin, Madison. Several national laboratories and research centers such as Lawrence Berkeley National Laboratory, National Center for Women in IT, National Center for Atmospheric Research, Renaissance Computing Institute, Sandia National Laboratories are also involved, along with several professional societies such the American Association for the Advancement of Science, the Association for Computing Machinery, the Computing Research Association and corporations such as AMD Corporation, HP, IBM, Intel Corporation, Microsoft Corporation and Texas Instruments.
Rosa attended the Tapia Celebration and said it helped him visualize his own participation in academic conferences, something he plans to do in the near future. "I really enjoyed the exposure to other people who were promoting their ideas and experiences," Rosa says, "as well as the opportunity to meet with so many role models and fellow students."
Source: Dana Cruikshank
National Science Foundation
вторник, 7 июня 2011 г.
понедельник, 6 июня 2011 г.
Mathematicians' Study Of How The Lily Blooms Has Implications For Sensor Development And Other Applications In Materials Science
The "lily white" has inspired centuries' worth of rich poetry and art, but when it comes to the science of how and why those delicately curved petals burst from the bud, surprisingly little is known.
Now, however, mathematics has revealed that differential growth and ruffling at the edges of each petal - not in the midrib, as commonly suggested - provide the driving force behind the lily's bloom.
The research, conducted at Harvard's School of Engineering and Applied Sciences (SEAS), contradicts earlier theories regarding growth within the flower bud. The petals, in fact, behave like leaves.
Published online this week in the journal Proceedings of the National Academy of Sciences, the findings characterize the blooming process using mathematical theory, observation, and experiment.
"That differences in planar growth strains can lead to shape changes has been known for some time," says principal investigator L. Mahadevan, the Lola England de Valpine Professor of Applied Mathematics at SEAS. "But showing that it is at work and dominant in lily blooming is new, as our measurements and simple theory show."
"What is most surprising is that a subject that is so rich in metaphor - the blooming of a flower - had been studied so little from a quantitative perspective."
Mahadevan collaborated with Haiyi Liang, formerly a postdoctoral fellow at SEAS and now a professor at the University of Science and Technology of China in Hefei.
Together, they studied the asiatic lily Lilium casablanca, the bud of which comprises three inner petals wrapped in three outer sepals.
A stiff midrib runs along the center of each petal and sepal, protecting the structure of the developing flower bud. The edges of the sepals also rest in grooves along the midribs of the petals, forming a locking mechanism that holds the bud closed until the growth inside reaches a critical point.
It was previously suggested that growth in the midribs might provide enough internal stress for the petals to burst out of their casing. Another plausible theory held that if the internal (adaxial) face of each petal and sepal grew faster than the external (abaxial) face, the flower would eventually be forced to bend outward. In some plants, these mechanisms do drive the blooming process.
Liang and Mahadevan's new research shows that in the lily, however, midrib growth and differential adaxial/abaxial growth play only minor roles. Rapid growth and wrinkling at the periphery of the petals actually create the stress within the bud that forces it to burst open.
The researchers used observation and experimentation to measure growth in various parts of the petals and to determine which types of growth are necessary for blooming. They then characterized the process mathematically in order to quantify, synthesize, and generalize their observations beyond the specific instance.
Source:
Caroline Perry
Harvard University
Now, however, mathematics has revealed that differential growth and ruffling at the edges of each petal - not in the midrib, as commonly suggested - provide the driving force behind the lily's bloom.
The research, conducted at Harvard's School of Engineering and Applied Sciences (SEAS), contradicts earlier theories regarding growth within the flower bud. The petals, in fact, behave like leaves.
Published online this week in the journal Proceedings of the National Academy of Sciences, the findings characterize the blooming process using mathematical theory, observation, and experiment.
"That differences in planar growth strains can lead to shape changes has been known for some time," says principal investigator L. Mahadevan, the Lola England de Valpine Professor of Applied Mathematics at SEAS. "But showing that it is at work and dominant in lily blooming is new, as our measurements and simple theory show."
"What is most surprising is that a subject that is so rich in metaphor - the blooming of a flower - had been studied so little from a quantitative perspective."
Mahadevan collaborated with Haiyi Liang, formerly a postdoctoral fellow at SEAS and now a professor at the University of Science and Technology of China in Hefei.
Together, they studied the asiatic lily Lilium casablanca, the bud of which comprises three inner petals wrapped in three outer sepals.
A stiff midrib runs along the center of each petal and sepal, protecting the structure of the developing flower bud. The edges of the sepals also rest in grooves along the midribs of the petals, forming a locking mechanism that holds the bud closed until the growth inside reaches a critical point.
It was previously suggested that growth in the midribs might provide enough internal stress for the petals to burst out of their casing. Another plausible theory held that if the internal (adaxial) face of each petal and sepal grew faster than the external (abaxial) face, the flower would eventually be forced to bend outward. In some plants, these mechanisms do drive the blooming process.
Liang and Mahadevan's new research shows that in the lily, however, midrib growth and differential adaxial/abaxial growth play only minor roles. Rapid growth and wrinkling at the periphery of the petals actually create the stress within the bud that forces it to burst open.
The researchers used observation and experimentation to measure growth in various parts of the petals and to determine which types of growth are necessary for blooming. They then characterized the process mathematically in order to quantify, synthesize, and generalize their observations beyond the specific instance.
Source:
Caroline Perry
Harvard University
воскресенье, 5 июня 2011 г.
Hepatic Diseases Treated With Stem Cells From Umbilical Cord
Scientists of the University of Granada, in collaboration with the University of Leon, have confirmed that stem cells from human umbilical cord blood can be an appropriate therapy for the treatment of hepatic diseases such as hepatitis, and therefore mean an effective alternative to bone marrow. According to a scientific paper which will be shortly published in the renowned journal Cell Transplantation, human umbilical cord blood cells (HUCBCs) can be useful for hepatic regenerative medicine, as they can nest in the liver after carrying out a human-to-rat xenotransplant.
This work, carried out by Ana I. ГЃlvarez-Mercado, MarГa J. SГЎez-Lara, MarГa V. GarcГa-Mediavilla, Sonia SГЎnchez-Campos, Francisco AbadГa, MarГa Cabello-Donayre, ГЃngel Gil, Javier GonzГЎlez-Gallego and Luis Fontana, did research into the regenerative potential of HUCBCs cells using a xenotransplant model from human to rat in which HUCBCs were injected through the hepatic portal vein of rats with hepatitis caused by D-galactosamine.
Success in rats
The scientists explain that the cell transplant carried out in rats caused an improvement both in the histological damage and in the hepatic function, as proved by the enzymatic activities of alanine transaminase, alkaline phosphatase, gama-glutamyl-transpherase and lactate dehydrogenase, as well as the concentrations of total and direct bilirubin. The present treatment for terminal hepatic failure consists of a liver transplant. However this method is limited due to the lack of donor organs. In addition, there is not at present a specific treatment for the fibrosis caused by many hepatic diseases. The development of such alternatives is therefore an essential objective for present research to improve suffering in many patients.
Note: video in es.youtube/watch?v=uEzdKwym3CI
Source: Dr. Luis Fontana Gallego
Universidad de Granada
This work, carried out by Ana I. ГЃlvarez-Mercado, MarГa J. SГЎez-Lara, MarГa V. GarcГa-Mediavilla, Sonia SГЎnchez-Campos, Francisco AbadГa, MarГa Cabello-Donayre, ГЃngel Gil, Javier GonzГЎlez-Gallego and Luis Fontana, did research into the regenerative potential of HUCBCs cells using a xenotransplant model from human to rat in which HUCBCs were injected through the hepatic portal vein of rats with hepatitis caused by D-galactosamine.
Success in rats
The scientists explain that the cell transplant carried out in rats caused an improvement both in the histological damage and in the hepatic function, as proved by the enzymatic activities of alanine transaminase, alkaline phosphatase, gama-glutamyl-transpherase and lactate dehydrogenase, as well as the concentrations of total and direct bilirubin. The present treatment for terminal hepatic failure consists of a liver transplant. However this method is limited due to the lack of donor organs. In addition, there is not at present a specific treatment for the fibrosis caused by many hepatic diseases. The development of such alternatives is therefore an essential objective for present research to improve suffering in many patients.
Note: video in es.youtube/watch?v=uEzdKwym3CI
Source: Dr. Luis Fontana Gallego
Universidad de Granada
суббота, 4 июня 2011 г.
The Art Of Dividing
A basic requirement for growth and life of a multicellular organism is the ability of its cells to divide. Chromosomes in the cells duplicate and are then distributed among the daughter cells. This distribution is organized by a protein complex made up of several hundred different proteins, called the centrosome. In cancer cells, the centrosome often assumes an unnatural shape or is present in uncontrolled numbers. The reasons for this were previously largely unknown. Scientists at the Max Planck Institute for Molecular Genetics in Berlin, together with colleagues at the German Cancer Research Center in Heidelberg and at the Leibniz Institute for Age Research Fritz Lipmann Institute in Jena have investigated the functions of the different centrosomal components. The researchers led by Bodo Lange now present their results in the renowned EMBO Journal, detailing the centrosome's components and their functions. Their work extends our knowledge of regulation of cell division and opens the door to new investigations into cancer development. [MГјller et al., EMBO J, 03.09.2010, doi:10.1038/emboj.2010.210]
As part of their research, the scientists examined centrosomes of the fruit fly Drosophila as well as those from human cells. "The fruit fly is a terrific system for investigating the centrosome, because the basic mechanisms of cell division are very similar between fly and human", Bodo Lange, the research group leader, explains. The group isolated centrosomes from the eggs of fruit flies and, using mass spectrometry methods, identified more than 250 different proteins making up this complex. These components were then subjected to targeted inactivation through RNA interference (RNAi), to discover their role in the structure of the centrosome and in chromosome distribution. The scientists were able to determine the protein functions quantitatively through use of state-of-the-art automatic and robotic microscopes. They found a whole series of proteins responsible for the separation of chromosomes, number of centrosomes and their structure. As these characteristics are often disrupted in cancer cells, the researchers believe their findings will have a significant impact on the understanding of cell division and the development of cancerous diseases.
The work of these scientists has brought new insight into the abnormalities seen in cancer cells. "Based on our findings, we hope to be able to unravel regulatory networks in the future, which will help to target and interfere with the division of cancer cells."
Sources: Max Planck Institute for Molecular Genetics, AlphaGalileo Foundation.
As part of their research, the scientists examined centrosomes of the fruit fly Drosophila as well as those from human cells. "The fruit fly is a terrific system for investigating the centrosome, because the basic mechanisms of cell division are very similar between fly and human", Bodo Lange, the research group leader, explains. The group isolated centrosomes from the eggs of fruit flies and, using mass spectrometry methods, identified more than 250 different proteins making up this complex. These components were then subjected to targeted inactivation through RNA interference (RNAi), to discover their role in the structure of the centrosome and in chromosome distribution. The scientists were able to determine the protein functions quantitatively through use of state-of-the-art automatic and robotic microscopes. They found a whole series of proteins responsible for the separation of chromosomes, number of centrosomes and their structure. As these characteristics are often disrupted in cancer cells, the researchers believe their findings will have a significant impact on the understanding of cell division and the development of cancerous diseases.
The work of these scientists has brought new insight into the abnormalities seen in cancer cells. "Based on our findings, we hope to be able to unravel regulatory networks in the future, which will help to target and interfere with the division of cancer cells."
Sources: Max Planck Institute for Molecular Genetics, AlphaGalileo Foundation.
пятница, 3 июня 2011 г.
Discovery Of New Prostate Cancer Marker In Urine
Howard Hughes Medical Institute researchers have identified a new biological marker present in the urine of patients with prostate cancer that indicates whether the cancer is progressing and spreading.
In experiments reported in the February 12, 2009, issue of the journal Nature, the scientists identified 10 metabolites that become more abundant in prostate cells as cancer progresses. Their studies showed that one of these chemicals, sarcosine, helps prostate cancer cells invade surrounding tissue.
HHMI investigator Arul Chinnaiyan and colleagues at the University of Michigan showed that as prostate cancer develops and progresses, sarcosine levels increase in both tumor cells and urine samples, suggesting that measurements of the metabolite could aid in non-invasively diagnosing the disease. Researchers might also be able to inhibit prostate cancer's spread by designing drugs that manipulate the sarcosine pathway.
The study is the first to analyze the levels of more than 1,000 different metabolites in human tumors. Scientists know that cells undergo complex changes as cancer develops and progresses to metastatic disease. Chinnaiyan's lab, which has extensively analyzed how genes and proteins in prostate cancer cells reflect these changes, thought that profiling cells' metabolites would offer an even more "holistic picture of the molecular alterations that occur," he said.
"This allows us to have more of a systems perspective of cancer development," he noted. "We are also looking at gene and protein markers, for therapeutic consideration, biomarker consideration, and just understanding the biology. We are not sure yet how it's going to sort out, so we're being non-discriminatory with what types of technologies we use."
In the experiments reported in Nature, the scientists used mass spectrometry, a technique that identifies chemicals based on the size and electrical charge of their components, to compare the levels of 1,126 metabolites in healthy prostate tissue, clinically localized prostate cancer, and metastatic prostate cancer. Sixty metabolites were present in tumor cells, but not in benign tissue. Of these, there were about 10 molecules whose levels increased dramatically during cancer progression. "This is proof-of-principle that we can identify metabolites, or panels of metabolites, that might be correlated with aggressive prostate cancer versus slower-growing prostate cancer," Chinnaiyan said.
Having demonstrated that "metabolomic" profiles change in predictable ways as cancer progresses, the group began more focused analyses. "We began to mine the data to look for metabolites that might serve as biomarkers or as therapeutic targets," Chinnaiyan explained. They chose to focus on sarcosine because it was elevated in clinically localized disease and very highly elevated in metastatic cancer.
They confirmed these dramatic increases in a new set of tissue samples, and also found that there was more sarcosine in the urine of patients with prostate cancer than in healthy individuals.
The team went on to test how sarcosine affected the behavior of cancer cells grown in the laboratory. Adding the chemical to prostate cells or manipulating cells' biochemical pathways so they produced more sarcosine on their own caused benign prostate cells to become cancerous and invasive. Conversely, shutting down sarcosine production in cancer cells blocked invasion.
"This really told us that sarcosine is involved biologically in some of the processes of a cancer cell," Chinnaiyan said. The results suggest that drugs that alter sarcosine metabolism might be useful in treating prostate cancer, but Chinnaiyan cautions that these Petri-dish findings still need further validation in animal models.
An important next step, he says, will be to do similar experiments on the other nine potential biomarkers they identified in this study. For reliable diagnosis of aggressive disease, he said, "we need to have panels, not just rely on a single metabolite."
Source: Jennifer Michalowski
Howard Hughes Medical Institute
In experiments reported in the February 12, 2009, issue of the journal Nature, the scientists identified 10 metabolites that become more abundant in prostate cells as cancer progresses. Their studies showed that one of these chemicals, sarcosine, helps prostate cancer cells invade surrounding tissue.
HHMI investigator Arul Chinnaiyan and colleagues at the University of Michigan showed that as prostate cancer develops and progresses, sarcosine levels increase in both tumor cells and urine samples, suggesting that measurements of the metabolite could aid in non-invasively diagnosing the disease. Researchers might also be able to inhibit prostate cancer's spread by designing drugs that manipulate the sarcosine pathway.
The study is the first to analyze the levels of more than 1,000 different metabolites in human tumors. Scientists know that cells undergo complex changes as cancer develops and progresses to metastatic disease. Chinnaiyan's lab, which has extensively analyzed how genes and proteins in prostate cancer cells reflect these changes, thought that profiling cells' metabolites would offer an even more "holistic picture of the molecular alterations that occur," he said.
"This allows us to have more of a systems perspective of cancer development," he noted. "We are also looking at gene and protein markers, for therapeutic consideration, biomarker consideration, and just understanding the biology. We are not sure yet how it's going to sort out, so we're being non-discriminatory with what types of technologies we use."
In the experiments reported in Nature, the scientists used mass spectrometry, a technique that identifies chemicals based on the size and electrical charge of their components, to compare the levels of 1,126 metabolites in healthy prostate tissue, clinically localized prostate cancer, and metastatic prostate cancer. Sixty metabolites were present in tumor cells, but not in benign tissue. Of these, there were about 10 molecules whose levels increased dramatically during cancer progression. "This is proof-of-principle that we can identify metabolites, or panels of metabolites, that might be correlated with aggressive prostate cancer versus slower-growing prostate cancer," Chinnaiyan said.
Having demonstrated that "metabolomic" profiles change in predictable ways as cancer progresses, the group began more focused analyses. "We began to mine the data to look for metabolites that might serve as biomarkers or as therapeutic targets," Chinnaiyan explained. They chose to focus on sarcosine because it was elevated in clinically localized disease and very highly elevated in metastatic cancer.
They confirmed these dramatic increases in a new set of tissue samples, and also found that there was more sarcosine in the urine of patients with prostate cancer than in healthy individuals.
The team went on to test how sarcosine affected the behavior of cancer cells grown in the laboratory. Adding the chemical to prostate cells or manipulating cells' biochemical pathways so they produced more sarcosine on their own caused benign prostate cells to become cancerous and invasive. Conversely, shutting down sarcosine production in cancer cells blocked invasion.
"This really told us that sarcosine is involved biologically in some of the processes of a cancer cell," Chinnaiyan said. The results suggest that drugs that alter sarcosine metabolism might be useful in treating prostate cancer, but Chinnaiyan cautions that these Petri-dish findings still need further validation in animal models.
An important next step, he says, will be to do similar experiments on the other nine potential biomarkers they identified in this study. For reliable diagnosis of aggressive disease, he said, "we need to have panels, not just rely on a single metabolite."
Source: Jennifer Michalowski
Howard Hughes Medical Institute
четверг, 2 июня 2011 г.
New e-Science Service Could Accelerate Cancer Research
The University of Manchester and the European Molecular Biology Laboratory's European Bioinformatics Institute (EMBL-EBI) have launched a major new e-science resource for biologists which could accelerate research into treatments for H1N1 flu and cancer.
Biocatalogue, a centralised registry of curated life science Web Services, is being officially launched today (Wednesday 1 July) at the 17th Annual International Conference on Intelligent Systems for Molecular Biology and the 8th European Conference on Computational Biology conference (ISMB-ECCB 2009) in Stockholm.
This type of systematic access has the potential to significantly accelerate the work of researchers in the medical, agronomical and pharmaceutical fields. The service allows researchers to discover, annotate, register and use biological web-based services.
Biocatalogue already has around 1,000 biological Web Services and more and more will be registered and annotated by services providers, curators and users on a daily basis.
Services are monitored by automated mechanisms and by the user community for their availability and reliability. A simple traffic light system displays the current status of a Web Service.
In addition to providing the means to programmatically access life science tools and databases over the Internet, the facility acts as a place where researchers can contact and meet the experts and maintainers of these services.
Web services have gained a momentum as a means for packaging existing data and computational resources in a form that is amenable for use and composition by third party applications.
The life science community is among the first adopters of Web Services. Taverna, a workflow workbench that is popular within the life science community and which was jointly developed by computer scientists at The University of Manchester provides access to over 3,500 Web Services that can be composed by scientists for constructing and enacting their in silico experiments.
But one of the main issues that hinders the wide adoption and use of Web Services is the difficulty in locating those that perform the analysis the scientist is interested in.
With Biocatalogue, Web Services are annotated by expert curators, service providers and by the wider Community using tags, rating, comments and ontologies. Automated mining and monitoring tools are also used.
The project has been led by Prof Carole Goble at The University of Manchester and Rodrigo Lopez at EMBL EBI.
Other contributors include Khalid Belhajjame, Franck Tanoh, Jiten Bhagat, Katy Wolstencroft and Robert Stevens from The University of Manchester and Eric Nzuobontane, Hamish McWilliam and Thomas Laurent from EMBL EBI.
The project is been funded by the Biotechnology and Biological Sciences Research Council (BBSRC).
Source: Manchester University
Biocatalogue, a centralised registry of curated life science Web Services, is being officially launched today (Wednesday 1 July) at the 17th Annual International Conference on Intelligent Systems for Molecular Biology and the 8th European Conference on Computational Biology conference (ISMB-ECCB 2009) in Stockholm.
This type of systematic access has the potential to significantly accelerate the work of researchers in the medical, agronomical and pharmaceutical fields. The service allows researchers to discover, annotate, register and use biological web-based services.
Biocatalogue already has around 1,000 biological Web Services and more and more will be registered and annotated by services providers, curators and users on a daily basis.
Services are monitored by automated mechanisms and by the user community for their availability and reliability. A simple traffic light system displays the current status of a Web Service.
In addition to providing the means to programmatically access life science tools and databases over the Internet, the facility acts as a place where researchers can contact and meet the experts and maintainers of these services.
Web services have gained a momentum as a means for packaging existing data and computational resources in a form that is amenable for use and composition by third party applications.
The life science community is among the first adopters of Web Services. Taverna, a workflow workbench that is popular within the life science community and which was jointly developed by computer scientists at The University of Manchester provides access to over 3,500 Web Services that can be composed by scientists for constructing and enacting their in silico experiments.
But one of the main issues that hinders the wide adoption and use of Web Services is the difficulty in locating those that perform the analysis the scientist is interested in.
With Biocatalogue, Web Services are annotated by expert curators, service providers and by the wider Community using tags, rating, comments and ontologies. Automated mining and monitoring tools are also used.
The project has been led by Prof Carole Goble at The University of Manchester and Rodrigo Lopez at EMBL EBI.
Other contributors include Khalid Belhajjame, Franck Tanoh, Jiten Bhagat, Katy Wolstencroft and Robert Stevens from The University of Manchester and Eric Nzuobontane, Hamish McWilliam and Thomas Laurent from EMBL EBI.
The project is been funded by the Biotechnology and Biological Sciences Research Council (BBSRC).
Source: Manchester University
среда, 1 июня 2011 г.
New Nanochemistry Technique Encases Single Molecules In Microdroplets
Inventing a useful new tool for creating chemical reactions between single molecules, scientists at the National Institute of Standards and Technology (NIST) have employed microfluidics - the manipulation of fluids at the microscopic scale - to make microdroplets that contain single molecules of interest. By combining this new microfluidic "droplet-on-demand" method with "optical tweezers" that could merge multiple droplets and cause their molecular contents to react, the research may ultimately lead to a compact, integrated setup for obtaining single-molecule information on the structure and function of important organic materials, such as proteins, enzymes, and DNA.
With the aid of NIST's Center for Nanoscale Science and Technology, physicists Carlos LГіpez-Mariscal and Kristian Helmerson created a tiny microfluidic device with a channel through which water can flow. Squeezed into a narrow stream by a mixture of oils whose viscosity, or resistance to flow, exerts pressure on it, the water then enters a narrow constriction. The water's abrupt pressure drop - accompanied by a dash of detergent - breaks its surface tension, splitting it into small droplets. (This same effect occurs when a thin stream of water falling from a faucet breaks up into small drops.)
The droplet sizes are highly uniform and can be tuned by adjusting the width of the constriction. With this technique, the researchers made droplets about a micrometer in diameter - or half an attoliter (half a billionth of a billionth of a liter) in volume.
In the microfluidic channel, the water is laced with desired molecules of just the right concentration, so that resulting droplets each pick up on average just one molecule of interest. Inside each droplet, the individual molecules of interest slosh around freely in the relatively roomy sphere, along with the water molecules that make up the bulk of every droplet.
By using laser beams, the researchers can move two or more single-molecule-containing droplets, cause them to coalesce, and observe the reactions through optical methods. For their initial reactions, the researchers are mixing fluorescent molecules that emit different colors, but in the future, they envision more interesting chemical reactions, such as those between an infectious agent and an antibody, or a chromosome and a drug. The researchers can shape a laser beam into any desired pattern and thereby trap not only single drops, but arrays of them, opening up new possibilities for single-molecule spectroscopy.
* C. LГіpez-Mariscal and K. Helmerson. Optical trapping of hydrosomes. Proc. SPIE, Vol. 7400, 740026 (2009).
Source:
Ben Stein
National Institute of Standards and Technology (NIST)
With the aid of NIST's Center for Nanoscale Science and Technology, physicists Carlos LГіpez-Mariscal and Kristian Helmerson created a tiny microfluidic device with a channel through which water can flow. Squeezed into a narrow stream by a mixture of oils whose viscosity, or resistance to flow, exerts pressure on it, the water then enters a narrow constriction. The water's abrupt pressure drop - accompanied by a dash of detergent - breaks its surface tension, splitting it into small droplets. (This same effect occurs when a thin stream of water falling from a faucet breaks up into small drops.)
The droplet sizes are highly uniform and can be tuned by adjusting the width of the constriction. With this technique, the researchers made droplets about a micrometer in diameter - or half an attoliter (half a billionth of a billionth of a liter) in volume.
In the microfluidic channel, the water is laced with desired molecules of just the right concentration, so that resulting droplets each pick up on average just one molecule of interest. Inside each droplet, the individual molecules of interest slosh around freely in the relatively roomy sphere, along with the water molecules that make up the bulk of every droplet.
By using laser beams, the researchers can move two or more single-molecule-containing droplets, cause them to coalesce, and observe the reactions through optical methods. For their initial reactions, the researchers are mixing fluorescent molecules that emit different colors, but in the future, they envision more interesting chemical reactions, such as those between an infectious agent and an antibody, or a chromosome and a drug. The researchers can shape a laser beam into any desired pattern and thereby trap not only single drops, but arrays of them, opening up new possibilities for single-molecule spectroscopy.
* C. LГіpez-Mariscal and K. Helmerson. Optical trapping of hydrosomes. Proc. SPIE, Vol. 7400, 740026 (2009).
Source:
Ben Stein
National Institute of Standards and Technology (NIST)
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