A Stretchy Polymer with self-healing abilities revolutionizes artificial muscle implants

This new advancement in science may help many people who need artificial muscles. Artificial muscles used today do not have a self-healing capability. In today’s world, if the material used receives any damage it has to be replaced.  Imagine the next generation of materials, that can heal themselves when damaged.

A revolutionary breakthrough towards this has been created by Professor Zhenan Bao and her team of researchers at Stanford. The polymer material is known as an elastomer due to its stretchiness. When punctured the elastomer self-heals at room temperature. And when put in an electric field it expands and contracts, like real muscle. 

The machine used by Bao could only stretch the elastomer to a limit of 45 inches. This extremely stretchy polymer was found to stretch more than 100 inches after researchers simply pulled the polymer like taffy.  In addition to its ability to stretch the material heals at room temperature and up to (-20 C).  This phenomenal material can be damaged and left to age for days but will still heal.

The stretchiness and resilience of the elastomer are due to the molecular structure resembling the crosslinking of a fishnet. Metal ions in the material bind to two or more ligands. According to Bao, if there is a stress on one part of the structure, the metal ions are still attached to other sites so the elastomer keeps its form. When the stress is released the metal ions simply reconnect with the closest ligand. This material could lead to medical implants that will last years without need of being replaced.  Further applications include robotics and prosthetics. Their research may save lives and help generations of people to come.

The work was accomplished by Professor Zhenan Bao, Cheng-Hui Li, Jing-Lin Zuo, Lihua Jin, Yang Sun, Peng Zheng, Yi Cao, Christian Linder and Xiao-Zeng You.

 Written by: Angelica Ramirez

Sources

Bao, Z. (2016). A highly stretchable autonomous self-healing elastomer. Nature Chemistry.

CSUCI Attends ACS San Diego

Several undergraduate research groups from CSUCI presented their research this year at the 251^st ACS meeting in San Diego. Research projects conducted at the school focus on a variety of topics ranging from environmental chemistry, organic synthesis, analytical studies, materials science and instrumentation.

The American Chemical Society national meetings are the largest scientific conferences in the world. Besides serving as a platform to present their own scientific work, attending the meetings represents a chance for students to develop their professional network. Many young students make connections at ACS meetings that launch their scientific careers into industry or graduate school.

CSUCI research students and advisors.

From left to right: Chemistry Dean Simone Aloisio, Courtney Mayhew and Timothy Goodman
presenting a project measuring the levels of mercury in rice.

From left to right: Simone Aloisio, Samantha Freitag and Kylan Malloy. Research

concerned with measuring mercury  levels in commercial cigarettes was also credited to

Melissa J Soriano, not pictured.

From left to right: Cameron McLaughlin, Angel Torres, Aisling Williams and
Professor Brittnee Veldman, advisor. Research on self-assembling nanocomposite materials.

New Phase of Carbon is Harder Than Diamond, Ferromagnetic

While attempting to develop a new method to produce synthetic diamond, scientists at North Carolina State University have discovered an entirely new phase of carbon called “Q-carbon”. This new material was found to possess fascinating physical and chemical properties some of which resolve long-standing scientific mysteries. It is harder than diamond, magnetic at room temperature, stable at ambient conditions and is electrically conductive. Further, its production doesn’t require extreme temperature and pressure and it can easily be converted into conventional diamond.

Phase diagram of carbon. Conventional methods to produce
diamond push graphite into diamond by increasing temperature
and pressure. The dotted green line shows the interface between
supercooled liquid carbon and diamond, which can be crossed
at ambient pressure.
Source: http://dx.doi.org/10.1063/1.4936595 

Diamond is an extremely useful material due to its physical characteristics. Its hardness and clarity lend it to use in a wide variety of industrial applications such as in abrasives and optics while its thermal and electrical traits are useful in technological hardware. However, the scarcity of diamond of appropriate quality in nature forces scientists to look for ways to mass produce it. The conventional approach requires extremely high temperatures and pressures along with chemical catalysts. This is extremely energy-intensive, costly and inefficient.

Researchers Jagdish Narayana and Anagh Bhaumik at North Carolina State were hoping to find a more straightforward synthetic pathway to diamond by utilizing a strange quirk of physics called ‘supercooling’. Most people are familiar with supercooling as it applies to water. A common demonstration involves placing a bottle of very pure water in the freezer and taking it out after around two and a half hours. It appears liquid, but upon hitting it against a surface, it suddenly crystallizes and forms fluffy ice. 

This is a slightly different process from the one used for making Q-carbon, though. While the water demonstration starts in the liquid form, becomes supercooled liquid and then returns to its normal freezing point to crystallize into ice, the scientists at NCSU melted solid carbon with a laser tuned to a highly specific energy. The laser excites the atoms electrically rather than thermally, and so their crystal structure falls apart at a much lower temperature than it conventionally would. This liquid carbon was then cooled extremely rapidly, a process known as ‘quenching’ (hence the “Q” in Q-carbon). This locked the carbon atoms in their unusual physical arrangement. The rapid cooling doesn’t allow the atoms any time to form an organized crystal, and thus Q-carbon was born.

(left) Q-carbon formed by quenching supercooled liquid carbon, (right) a thread
of Q-carbon (white) ending at a crystal of conventional diamond.
Source: http://dx.doi.org/10.1063/1.4936595 

 Subsequent characterization experiments revealed its surprising physical properties. Its magnetic qualities solve an old mystery regarding carbon’s potential as a candidate for ferromagnetism. Scientists had theoretically predicted it, but it had never been experimentally verified until now. It is also suggested that because the physical conditions necessary to produce it exist at the centers of many of our solar system’s planets, it could potentially be responsible for their magnetic fields.

The potential applications for this new material are as yet largely unknown. In any case, its ability to transform into conventional diamond through a second laser pulse is bound to be useful as it circumvents the problems of current energy-intensive production methods. Further studies will certainly need to be done before we can be sure that Q-carbon has practical use, but if verified, the discovery could prove revolutionary for technology and industry. 

Written by: Aisling M Williams

References

Narayan, J.; Bhaumik, A. Novel Phase of Carbon, Ferromagnetism, and Conversion into Diamond. J. Appl. Phys. Journal of Applied Physics. Dec 2015, 118, 215303.

mrsciguy. "Supercooled Water". Online Video Clip. Youtube. 11 Feb 2016. Web. https://youtu.be/DpiUZI_3o8s

CSUCI Science Research Represented at SCCUR 2015

Simone Aloisio, PhD (right) with student researchers presenting his
project studying mercury levels in cigarettes.

Five chemistry research projects were represented by CSUCI students this year at SCCUR.

The Southern California Conference for Undergraduate Research is an interdisciplinary research conference showcasing the best undergraduate research currently underway across California. The event includes research from a wide variety of academic fields ranging from political science and gender studies to ecology and physics. 

Hosted on November 21^st at Harvey Mudd College, the conference attracted student representatives from across the state. Among those in attendance were CSUCI science researchers representing five projects carried out under the supervision of advisors Simone Aloisio (pictured above), Ahmed Awad and Brittnee Veldman.

The event ran from 8 AM to 5 PM and opened with a keynote address by Nadia Abuelezam, a Harvey Mudd alumni and Harvard graduate. Her talk entitled Understanding the Global HIV/AIDS Epidemic with (Sexy) Mathematical Models interspersed discussion of the technical details of her research with the story of how she came to be involved with it, along with pieces of advice she learned along the way.

A variety of student-led research presentations followed, along with three independent poster sessions where rows of posters summarizing research projects were showcased in the college’s Activity Center. Representatives from each group stood by their posters to explain the details and answer the questions of attendees.  

The conference is a first for many of the students in attendance, serving as valuable practice before they move on to present at larger national events. Students gain insight into a wide variety of research projects along with experience in public speaking and networking.

The interdisciplinary focus of the conference also provides a unique opportunity for students to communicate across fields of study.  

“A lot of Chemistry researchers were interested in our poster,” said Angel Torres, whose research focuses on materials chemistry, “but I feel like I got the most out of explaining the research to non-science majors. They asked questions I wasn’t expecting which forced me to think about our project differently. The process of trying to verbalize science concepts without using jargon actually helped me understand them more clearly myself.”


Written by: Aisling Williams

Students Seriously Injured in High School Chemistry Demonstration

A commonly-performed chemistry demonstration at W. T. Woodson High left five students and a teacher injured on Friday morning after the experiment started an out-of-control fire. All of the students’ injuries were serious enough to warrant hospitalization, with two of the five being transported by helicopter. One student is in critical condition.

The experiment in question, commonly referred to as “the rainbow experiment”, is meant to show how the color of fire depends on the compound undergoing combustion. Similar experiments are virtually ubiquitous in high school level chemistry classes, with one even making an appearance in the TV show Breaking Bad.

The exact cause of the accident is not known with certainty. However, students present at the time of the accident describe the teacher “adding more alcohol straight from the bottle” in an attempt to keep the reaction going after the flame had begun to die down. Shortly thereafter, the students near the front of the room were suddenly engulfed in flames. One student describes it not as an explosion, but more of a “sideways fireball”.

 Of the 31 students and 2 teachers present, 5 students and one teacher were injured.

Following the accident, the school was evacuated. The fire was still burning by the time firefighters arrived and had damaged 50% of the room, but fortunately it was subdued before it spread further.

This is not the first time the rainbow fire experiment has caused accidents. According to the American Chemical Society, the demonstration should not be performed indoors. "These demonstrations present an unacceptable risk of flash fires and deflagrations that can cause serious injuries to students and teachers," the ACS said.

An extremely similar incident occurred in 2004. Once the colored flame began to die down, the teacher attempted to add more fuel before the small fire had completely gone out. That accident left a 15-year-old student with burns to 40% of her body. The student in question describes her experience in the video below.

The effort required to avoid this sort of accident is minuscule, and yet it continues to occur year after year. This serves to demonstrate the unfortunate reality that safety measures are often neglected at every level of chemistry. When accidents are uncommon it is very easy for even professionals to become complacent. Although it is vital to remain vigilant at every level, it may be especially true for those teaching younger students. Demonstrations at the elementary and high school levels are for more than sharing the beauty of chemistry. They are also an opportunity to lead by example, and to instill in students a healthy respect for the dangers involved.

Written by: Aisling Williams

Sources.

Jackman, T., Shapiro, T. R., and Brown, E. (2015) Six injured in chemistry classroom fire at Woodson High School in Fairfax. Washington Post. The Washington Post.

(2015) Chemistry Experiment Sparked Explosion in Va. High School. NBC4 Washington.

Gilligan, Vince. "Breaking Bad - Pilot." Chemistry Class. HBO. N.d. YouTube. Web. 30 Oct. 2015

Matt Ackland (mattacklandfox5). Twitter.

USCSB. "After the Rainbow." YouTube. USCSB, 10 Dec. 2013. Web. 30 Oct. 2015.

Steroids in Dust from Cattle Feed Lots Significant Pollution Source

The steroid growth hormones given to cattle on factory farm operations have long been of interest to environmental scientists. Because these drugs pose the most serious risk to aquatic life, past studies have focused mainly on their transport to bodies of water via surface runoff. However, a recent study confirms the viability of a vector no one had ever considered before – dust.

Researcher Brett Blackwell setting up monitoring equipment.
Credit: Jerod Foster

Cattle given drugs such as steroids do not break them down completely. The compounds are excreted in their manure, which can then dry and be pulverized into airbourne dust.

Researcher Philip N. Smith, an ecotoxicologist at Texas Tech, first considered the possibility when he was out duck hunting downwing from a cattle feed yard. The dust in the air was so thick that it coated his teeth, and he began to wonder what was in it.  He and colleages at the Environmental Protection Agency set up sampling equiptment at five feed yards in Texas and Oklahoma, which remained collecting samples and taking measurements for two years. 

After analysis was complete, they determined that the most abundant hormone was the estrogen 17α-estradiol, which appeared on 94% of filters with a mean concentration of 21-ng/g particulate matter.

The biggest risk posed by such airbourne contaminants is to aquatic life. The particles were large enough that people are unlikely to inhale them, as they would not travel very far. Only those people working on feedlots or living very nearby would be exposed to appreciable quantities, but the health impacts of such exposures are not well-understood.

The largest feed yard in the study was found to emit 63 mg of 17α-estradiol per day in dust alone. This amount is comparable to what might be transported each day in runoff, making dust a significant source of potential environmental harm.

By: Aisling Williams

Source

Lockwood, Deirdre. “Cattle Feed Yard Dust Can Transport Steroids Into Environment.” Chemical & Engineering News: (2015) n. pag. 7 July. Web. 25 July 2015.

Comet Lander Philae comes Back to Life

The European Space Agency’s comet lander Philae has successfully delivered a long-anticipated data stream to Earth after several nerve-wracking months of silence.

The dishwasher-sized lander, dispatched from the Rosetta spacecraft which now orbits comet 67P/Churyumov-Gerasimenko, landed rather roughly on the surface back in 2014.Unfortunately, the machine unexpectedly settled in a shadowy crater and ran out of power after 60 hours without sunlight to charge its solar cells.

Because the comet has been moving nearer to the sun, the lander may have been able to harness the increased solar energy and recharge itself. The earthbound scientists at European Space Operations Centre in Darmstadt, Germany, held their breath and powered up the lander’s listening capabilities on March 12^th.

A real-scale representation of the comet's size
compared to the city of Los Angeles.

On June 14^th Philae’s message finally arrived, indicating that it is in fact receiving power.

Rosetta is the first man-made object to orbit a comet, and Philae the first to land on one. The mission promises to be rich with discoveries that will lend insight into many unanswered questions about the natural world. Comets and other such deep-space objects represent goldmines of information about the early universe and the physical history of the solar system, and by extension the Earth and her human inhabitants.

One such mystery that the mission hopes to investigate is the relative abundance of left-handed chemical isomers in the biological world. Many molecules come in mirror-image “versions” of one another. Despite being composed of the same atoms, and those atoms being connected in identical ways, they are physical reflections of each other and possess unique physical and chemical properties. For reasons poorly-understood, biological systems overwhelmingly favor the left- versions of molecules.

One theory proposed in 1983 posits that spiraling radiation generated during supernovae is responsible. The polarization of the radiation emitted during the collapse of primordial stars may have twisted those first molecules into left-handed orientations, resulting in a dominance that we still see today. If the preference for left- chirality is found to extend outside the Earth biosphere, a cosmic origin would be the most reasonable explanation.

The lander possesses an array of cutting-edge scientific instruments, including UV, visible and infrared spectrometers, remote imaging systems, and radar.

One of the first images received by the lander revealed what appeared to be
"sand dunes". The scale of this image is massive; the length of a human
being would be represented as a single pixel.

The mission has already uncovered an abundance of information about the comet. Although it is massive enough to have a gravitational field, the rock is only about ¼ to 1/8 the volume of the object that wiped out the dinosaurs. Its gravity, although strong enough to hold onto the Rosetta orbiter, is incredibly weak. The escape velocity of the comet is about 1/300,000^th of Earth’s. In

simpler terms, if a person standing on its surface jumped with the amount of force needed to reach one centimeter from the ground on Earth, they would escape its gravity and float off into space, never to return. If you stepped off of a chair on this comet, it would take you a whole 1.3 minutes to eventually fall to the ground.

As it moves nearer the sun, the comet will heat up and begin expelling dust and gas. This stream of detritus, when comets such as Philae’s swing near enough to the sun, can become ionized by solar wind and produce the luminous glowing tail which is visible from Earth. These mysterious streaks of light have been objects of wonder since the dawn of human kind, and now through the culmination of our thousands of years of scientific inquiry, we will for the first time finally have the chance to reach across the vast gulf of the cosmos and touch one. 


Written by Aisling Williams

Sources

Claudia. "The Sound of Touchdown." Web log post. ESA Blog. European Space Agency, 20 Nov. 2014. Web. 16 June 2015.

Doherty, Paul. “Rosetta Mission|Spring 2015 Update.” Online video. Youtube. Exploratorium, 15 May 2015. Web. Jun. 27 2015.

Wilson, Elizabeth K. “Comet Lander Philae Wakes Up.” Chemical & Engineering News: (2015) n. pag. 15 June 2015. Web. 17 June 2015.

CI's Student ACS Chapter Receives National Recognition

CSUCI students received national recognition this year at the ACS meeting in Denver. 

The American Chemical Society national meeting is one of the largest scientific conferences of the year, representing over 10,000 topics ranging from astronomy to zoology. 

Members of the Free Radicals with
Phil Hampton Ph.D, the faculty advisor for the group

The CSUCI student chapter of the ACS, called the Free Radicals, received an award in acknowledgement of their involvement in science outreach programs, such as the annual Science Carnival, as well as their high student participation.

Undergraduate involvement in research and in the scientific community is a high priority for faculty at CSUCI. In order for students to get a feel for how scientists work in the real world, it is imperative for them to get a first-hand experience. Trips to meetings such as these are one of many ways that this is accomplished.

The meeting mostly focuses on the original research of those scientists in attendance. Presented on posters, in slideshows and in presentations, attendees not only learn about the most cutting-edge research ongoing today, but are given a chance to network with those conducting it. 

Oscar Santillan, an undergraduate involved in research focused on electrochemical materials, was one of the eight CI students in attendance. “The topics I followed were chemistry of materials and electrochemistry. In particular, the overlap of the two was of the greatest interest to me. They not only covered topics I find deeply intriguing, but also did so with concision and clarity.”

Corie Hill and Amber Kramer, seniors at CI, presented their research on mercury concentrations in seafood.  

“It was an incredibly valuable experience,” said Corie, “being able to engage with chemistry from around the world, hear cutting edge chemistry lectures and meeting other students who are at my level as well.”

“I took away how diverse and vast the field of chemistry is. There are so many institutions that come together in the name of chemistry: Industry, government and academia and everything in-between. ... It’s incredible to see the level of detail put into the event.”

Besides serving as a window into the details of ongoing research, the ACS meeting serves to broaden the scientific horizons of those in attendance. Students may discover areas of study that they otherwise would never have known about, and perhaps most importantly, meet and talk to the people involved in those areas. Ultimately, science is a social undertaking, and events such as these facilitate the meeting of minds and ideas, which fosters the birth of insight so crucial to any scientific discipline.

Written by Aisling Williams

Liquor Serves as a Good Substitute for HPLC Solvent

A recent study looking into alternative solvents for HPLCs has discovered a rather surprising candidate -  liquor store spirits.

As far as chemical analytical tools go, HPLCs are among the most useful and widely utilized. Enabling chemists to separate mixtures, identify their components and determine their relative abundance, high-pressure liquid chromatographs are indispensable in labs around the world.

Unfortunately, these machines have their drawbacks. They require vast quantities of expensive solvents to run, which must be disposed of as hazardous waste. In 2009, the price of the most commonly-used solvent, acetonitrile, skyrocketed. Chemists seeking reprieve then turned to HPLC-grade ethanol.  Unfortunately, this too can cost as much as $120 per liter.

The machines are becoming more universally accessible due to improvements in technology and manufacturing. Naturally, the next step should be making the eluents more accessible as well. The researchers at Merck Research Laboratories combined various liquors with store-bought ammonia and white vinegar. 

Other than grain alcohol, the drinks tested included rum, vodka, cachaça, and aguardiente. The eluent was then used to separate a mixture of five compounds—uracil, caffeine, 1-phenylethanol, butylparaben, and anthracene—in a conventional HPLC instrument.

The low-cost mixtures performed surprisingly well. Grain alcohol performed about as well as HPLC-grade ethanol in some cases. While lower-proof spirits tended to produce poorer separation, the results were reasonable, especially with more polar analytes. 

Source

Cooney, Catherine M. "Liquor-Store Spirits Provide Green Alternative To HPLC Solvents "Chemical & Engineering News (2015): n. pag. 17 April 2015. Web. 28 April 2015. 

New Type of Chemical Bond Discovered

In 1989, researchers investigating the properties of exotic atoms discovered something entirely unexpected. Under certain circumstances, the rate of a reaction paradoxically sped up as temperature was decreased. This peculiar behavior was found to occur between Muonium, an exotic form of hydrogen made up of an antimuon and an electron, and bromine. Muonium’s behavior with other elements, such as chlorine and fluorine, were more well-behaved; the reaction rate sped up as temperature increased, exactly as expected. Bromine, however, represented a bizarre exception.

In order to explain this mystery, scientists proposed a model where the lighter atom formed a new sort of structure where it was flanked by two heavier atoms, a structure that would be held together not by normal forces but by a new sort of ‘vibrational’ bond.

Credit: Flemming et. al.

"In this scenario, the lightweight muonium atom would move rapidly between two heavy bromine atoms, 'like a Ping Pong ball bouncing between two bowling balls,' Fleming says. The oscillating atom would briefly hold the two bromine atoms together and reduce the overall energy, and therefore speed, of the reaction.”

Due to the exceedingly short lifespan of muonium, it was impossible at the time to investigate this idea in very much depth. But with recent technological developments, it finally became possible to answer this question with certainty. The researchers took the question to nuclear accelerator at Rutherford Appleton Laboratory in England. 

There, they watched the microscopic interplay unfold, and confirmed the new type of chemical bond. It is hypothesized that this exotic new bond may take place between a variety of ultra-light and heavy atoms. Although this new interaction is exceedingly brief, their discovery represents an important development in our understanding of atomic-scale physics and the chemical world.

Sources

Nordrum, Amy. "Chemists Confirm the Existence of New Type of Bond." Scientific American Feb 2015. Web.

New Research Rewrites Understanding of Explosive Alkali Metals

Despite being a staple demonstration in many introductory chemistry classes, the classic explanation for the explosive reaction between alkali metals and water has long been incorrect.

Many middle and high school students are familiar with the demonstration. Almost immediately following contact with water, alkali metals such as sodium and potassium produce a brilliant and highly energetic explosive pop. Instructors the world over would often confidently follow by explaining that the  reaction produces hydrogen gas, whose subsequent ignition is responsible for the theatrics.

However, recent research published in Nature Chemistry shows that things are not actually so simple. Although the hydrogen gas may indeed eventually ignite, the initial rapid explosion is caused by something almost entirely unrelated.

In retrospect, it seems obvious that there was something wrong with the orthodox explanation. In order for a reaction to produce an explosion, the reactants would have to mix very effectively in order to react rapidly and release energy suddenly. This is why flour mills are so susceptible to explosive outbreaks of fire; a build-up of finely ground flammable particles suspended in the oxygen-rich air allows any spark to consume an enormous amount of fuel virtually instantaneously.

Alkali metals, on the other hand, are solids. The water can only come into contact with the outer surface, which should result in a brief layer of products preventing it from reaching deeper layers right away. Water isn’t immediately in contact with every metal atom, so at the very least the reaction should proceed more slowly than it does.

In order to investigate this further, researcher Pavel Jungwirth and others set out to scrutinize the reaction with the use of high-speed cameras. Because pure alkali metals tend to accumulate an oxidized layer on their outer surfaces, causing them to be less reactive in water, he used an alloy of sodium and potassium that is liquid at room temperature.

The images captured by the cameras were very telling. The reaction begins less than a millisecond after the droplet contacts the water. At 0.4 milliseconds, spike-like tendrils of metal shoot outward, much too quickly to have been produced by heat. Most interestingly, this spiked droplet develops a never-before-seen aura of dark bluish purple color in the surrounding solution between 0.3 and 0.5 seconds (see supplemental video). This blue color turned out to be the key to understanding what was really going on.

The origin of this mysterious color was confirmed when Jungwirth’s colleage Frank Uhlig recreated the reaction in a quantum-mechanical simulation. This digital analysis revealed that atoms at the surface of the cluster were each stripped of an electron within just a few picoseconds. The electrons then rapidly shoot away from one another and become solvated in the surrounding solution. Free electrons in solution, as many chemists know, appear blue to the naked eye. The loss of these electrons leaves the atoms positively charged, resulting in an incredibly strong repulsive force blowing the cluster apart.

This research represents a feature of science that keeps so many people fascinated by it. Although it may seem like the basics are well-understood, surprises like this frequently come from the most unexpected of places. Scientific knowledge is highly dynamic and constantly evolving, as nature proves time and time again that the richness and complexity of reality rivals the limits of human imagination.

Written by: Aisling Williams

Source

Mason, Philip E., Frank Uhlig, Vaclav Vanek, Tillmann Buttersack, Sigurd Bauerecker, and Pavel Jungwirth. "Coulomb Explosion during the Early Stages of the Reaction of Alkali Metals with Water." Nature.com. Nature Publishing Group, 26 Jan. 2015. Web. 8 Feb. 2015.

Targeting Cancer Cells with Self-Assembling Molecular Cages

Taking inspiration from nature, chemists have developed a new method to destroy bone cancer cells that utilizes artificial extracellular matrices.

Because extracellular matrices provide support and structure to the cells making up many organs and tissues, their artificial production has been very appealing to tissue engineers. Scientists searching for a method to produce them in the lab have mainly focused on self-assembling peptides.

Cancer cells before (left) and after (right) 7 hours of exposure to self-assembling
carbohydrate molecules.

Credit: J. Am. Chem. Soc.

In order to exploit one of the common features of bone cancer cells, Bing Xu of Brandeis University designed such a peptide with one important modification; it is only capable of self-assembly upon removal of a phosphate group. Once it’s gone, the molecules have a hydrophobic and a hydrophilic end, allowing them to aggregate into films like the lipids that form membranes in the body.

This property made them perfect for targeted destruction of certain types of cancer cells, which produce alkaline phosphatase, an enzyme that removes phosphate, in far greater quantities than healthy cells do.

Another researcher, Rein V. Ulijn of the City University of New York’s Hunter College, took it a step further. Because carbohydrates can produce such a rich diversity of structures, he endeavored to use them in a similar way. 

To create a carbohydrate molecule that would self-aggregate, he attached a hydrophilic glucosamine to a hydrophobic aromatic. Then he added a phosphate group that would interfere with the molecules’ mutual attraction to its peers, thereby postponing the formation of a film until the group was cleaved off, hopefully, near a phosphatase-rich cancer cell.

Subsequent tests investigating the effectiveness of the substance against cancer cells yielded optimistic results. The chemical killed 95% of cultured bone cancer cells, while only 15% of healthy control cells perished after 7 hours of exposure. 

Written by: Aisling Williams

Source

Berg, Erika G. "Self-Assembling Carbohydrates Trap Cancer Cells In A Cage." Chemical & Engineering News (2015): n. pag. 20 Jan. 2015. Web. 27 Jan. 2015.

Crystal Nucleation More Nuanced Than Once Thought

The formation of crystals is paramount to the production of an enormous variety of products we use every day. From things as simple as sugar or salt to revolutionary technology involving crystalline metals and silicon, the understanding of the processes of crystal growth has been a staple of scientific progress. However, recent research indicates that nucleation – the process initiating the growth of a crystal – may be much more complex than previously imagined.

The classical model of crystal growth breaks the process down into two major steps. First, ions or molecules come together into a tiny crystalline seed, on whose structure the properties of the emerging crystal will depend. From that point, other solvated ions fall into place, thereby expanding the lattice and growing the crystal. As the crystal grows, the bulk free energy of the mass decreases; yet at the same time, the solid-liquid interface expands, increasing free energy. Nucleation is officially defined as the point at which the crystal reaches the critical size threshold beyond which the energy benefit of growth exceeds the cost.

However, this model is proving to be inadequate in the face of mounting evidence. There seem to be a variety of different mechanisms from which a crystal structure can emerge. For instance, research done in 2002 at MIT involved inducing crystallization in glycine using laser pulses. By altering the polarization of the incident laser, the group produced a variety of different crystal polymorphs. 

According to MIT Chemical Engineering professor Allan S. Myerson, such a phenomenon indicated that the laser must have been acting on some pre-existing structure that was somewhere in between an ordered crystal and completely solvated molecules.

A more recent study in 2014 visually examined the microscopic behavior of calcium carbonate as it formed crystals. Calcium carbonate represented an interesting substance for such a study due to its tendency to form a wide variety of crystal polymorphs, including calcite, aragonite, and vaterite. While material often appeared to nucleate into any of the three directly, sometimes the molecules would aggregate into unstructured blobs which then transformed into aragonite or vaterite. 

This sort of behavior may be important beyond the formation of the initial crystal ‘seedling’, as it is possible for actual crystal growth to depend on the formation of such viscous blobs. Perhaps individual ions or molecules are incapable of adding to the growing crystal in isolation, and need to first form groups to proceed.

The behavior of real systems appears to be extremely diverse. In the words of James J. De Yoreo, who lead the calcium carbonate study, “Think up any mechanism or pathway you want, and there will probably be some system that behaves that way.”

Written by: Aisling M Williams

Sources

Kemsley, Jyllian. "Illuminating Crystal Nucleation." Chemical & Engineering News93.2 (2015): 28-29. CEN RSS. Chemical & Engineering News, 12 Jan. 2015. Web. 13 Jan. 2015.

6th Annual Science Carnival

On November 1^st, the 6^th annual CSUCI-hosted Science Carnival proved once more to be a roaring success.

Being entirely volunteer-run, the carnival remains free to attend and continues to attract guests of all ages. Students between Kindergarten and 8^th grade, many with siblings and parents in tow, flocked to Thurgood-Marshall elementary school to participate in the festivities.

From Biology and Chemistry to Paleontology and Physics, the carnival provided over 70 dazzling science demonstrations and activities to fascinate and inspire a younger generation.

Students admire a demonstration of UV fluorescent chemicals.

Fire isn't always yellow! This volunteer shows a crowd how the color of a flame
can actually depend on what compound is undergoing combustion.

The high-frequency electromagnetism associated with the plasma filaments in a
plasma lamp can induce a nearby fluorescent lightbulb to light up!

This ball python was one of many animals present at the science carnival.

Angular momentum is a physical phenomenon so rarely encountered that even
adults found this demonstration strange and fascinating.

This ping pong ball cannon made it clear
just how powerful air pressure can be.

This apparatus pumps air in and out of a pair of real lungs!

Many guests were surprised by the rich topography
of the microsocopic world.

Live crabs, starfish and many other marine creatures
made this booth particularly popular.

Unprecedented Control Over Organic Synthesis Using Modified Enzymes

Drawing inspiration from the world of biology, researchers have developed a novel approach to solving a long-standing problem in organic synthesis – regioselectivity.

The vast majority of drugs contain nitrogen, driving chemists to search for more efficient and selective methods to form new C-N bonds in substrate hydrocarbons. However, one of the most stubborn obstacles in the way of creating the desired compound is regioselectivity – the preference of a reaction to make or break bonds at particular sites of the substrate molecule over others.

This troublesome habit of nature often makes it very cumbersome to come up with a reaction mechanism that produces a desired molecular structure, at least with anything like a reasonable yield. The traditional approach would be to focus on the substrate molecule, modifying it in such a way as to make some particular carbon more likely to be that which forms the bond. Sometimes this means coming up with weird, exotic molecules that may be expensive or otherwise difficult to obtain.

Rather than manipulating the substrate, it would be much more desirable to have selectivity be determined by the catalyst. This way a chemist could produce different products from the same starting material simply by modifying the catalyst of the reaction.

Regioselectivity is determined by the enzyme catalyst.

Researchers at California Institute of Technology have come up with a way to accomplish just that. By engineering a natural biological enzyme, the team created two artificial variants which steer nitrogen atom transfer of a particular reaction in complementary directions. One enzyme favors ring-closing amination at the α-position of an alkyl substituent on a benzene sulfonyl azide. The other enzyme favors amination at the β-position. Simply by changing the catalyst, they have been able to switch the reaction to favor one product over the other by over 95%.

Synthetic biology may still seem like it belongs in the realm of science fiction to many, but the degree to which these enzymes have controlled the outcome of the reaction is difficult to ignore.

Considering the trouble these types of reactions have given scientists in the past, it may be reasonable to expect these new methods to gain favor in the future. The modification of enzymes for use in organic synthesis, according to the researchers, represents a promising platform for solving long-standing selectivity problems.

Source

Hyster, Todd K., Christopher C. Farwell, Andrew R. Buller, John A. McIntosh, and Frances H. Arnold. "Enzyme-Controlled Nitrogen-Atom Transfer Enables Regiodivergent C–H Amination." Journal of the American Chemical Society. N.p., 5 Nov. 2014. Web. 09 Nov. 2014, 136 (44), pp 15505–15508