The Flow

College Park, Md. (June 08, 2011) - A team of scientists has developed a way to coax tumor cells in the lab to grow into 3-D spheres. Their discovery takes advantage of an earlier technique of producing spherical cavities in a common polymer and promises more accurate tests of new cancer therapies.

As team leader Michael R. King, Ph.D., of Cornell University explains, "Sometimes engineering research tends to be a case of a hammer looking for a nail. We knew our previous discovery was new and it was cool. And now we know it's useful."

Three years ago, the team -- in collaboration with Lisa DeLouise, Ph.D., MPD, of Rochester, N.Y. -- perfected a low-cost, easy fabrication technique to make spherical cavities in PDMS (polydimethylsiloxane), a widely used silicon organic polymer. More recently, the Cornell team discovered that these cavities could be used as a scaffolding to grow numerous tumor spheroids, which could serve as realistic models for cancer cells. The Cornell team's work appears in the current issue of Biomicrofluidics, a publication of the American Institute of Physics.

The three-dimensional spheroids hold the potential to speed cancer drug discovery by providing a realistic and easily accessible substrate on which to test drugs. Their 3-D nature is an asset because in the body, tumor cells grow in 3-D--yet most laboratory studies of cancer have been done in 2-D, with a single layer of cancer cells grown on the bottom of a petri dish. Too often a promising 2-D drug candidate fails when it enters the 3-D stage of animal testing. The new 3-D tumor spheroids may help eliminate that problem. They also offer a realistic tumor oxygen environment that cues the blood vessel growth that nourishes tumors--an appealing target for anti-cancer drug design.

"Basically, any laboratory that works with cells could adopt our new spherical microcavity system to do their own 3-D experiments or drug screening on hundreds or even thousands of little tumor spheroids," said King.

The article, "Continuously perfused microbubble array for 3D tumor spheroid model" by Michael R. King, Sivaprakash Agastin, Ut-Binh T. Giang, Yue Geng, and Lisa A. DeLouise appears in the journal Biomicrofluidics.

I like it when articles ask me questions. right at the beginning, i usually throw out an answer and then reading the rest of the article is like a mystery novel... Let's see what kind of guesses we can come up with for this one.

A team of researchers from Hong Kong have just published their article, "Do droplets always move following the wettability gradient?" appearing today in Applied Physics Letters, the authors look at liquids on a superhydrophobic surface. To get an idea of how hydrophobic a superhydrophobe is, check out this picture of a drop of water on a lotus leaf. The standard definition is that the contact angles of a drop of water exceeds 150° and the roll-off angle is less than 10°. Interestingly enough, this is called the Lotus Effect and has some interesting properties.

The authors summarize:

[W]e systematically investigated droplet impacting dynamics on a nonuniform superhydrophobic surface with a wettability gradient. Different from previous reports that the droplet moves toward the direction of decreasing CA, interestingly, we found that the droplet can fashion strikingly different self-migration patterns (toward or against the wettability gradient) depending on the competition of the capillary pressure and the effective water hammer pressure. Our findings highlight the importance of controlling surface roughness (wettability) and impact condition in precise manipulation of droplet placement and trajectory in microfluidics, heat transfer, and water harvesting systems.

Congratulations! to the Small Matters winner:

Zach Gagnon, Johns Hopkins University

Thank you to all the entrants. Check back to the Biomicrofluidics homepage for announcements on next year's contest. Winners will be announced at the 2012 AMN-APLOC meeting in Dalian, China.

View the winning entry:

Biomicrofluidics is pleased to announce a video contest, Small Matters.  The contest is to highlight not only the exciting scientific merit of work conducted in the area of microfluidics and nanofluidics, but also the aesthetic and artistic qualities of the science.  Winning entries will demonstrate a novel scientific concept in an elegant presentation.  All finalists will be published in a special section of Biomicrofluidics and one grand prize winner will be chosen to receive an iPad.

The winners of Small Matters will be selected by an esteemed panel of scientists from the Editorial Advisory Board of Biomicrofluidics.  Winning entries will be announced at The Second Conference on Advances in Microfluidics and Nanofluidics in Singapore, January 2011 and will be on display for conference attendees to view.

The submission deadline to enter the contest is 1 December 2010 and must include a description of the scientific content presented in the video.  Text should be no greater than 1 printed page and videos should be no longer than 5 minutes.  For instructions on how to submit to the contest, please visit the contest instructions page.

Biomicrofluidics, a free to read, free to publish journal of the American Institute of Physics, hopes the community will find this contest valuable and will promote the exciting research being conducted in microfluidics and nanofludics.

WASHINGTON (ISNS) — Engineers and biologists at McMaster University in Hamilton, Ontario, have succeeded in coaxing tiny worms to move around a microchip using electric fields. This should help neurologists study the human nervous system.

The worms, called C. elegans, are one of the mainstays of neurological research. That’s because the worms, with only a few hundred neurons, have a simple nervous system. In the new McMaster experiment, the worms are coaxed into starting and stopping, pretty much on command.

"This technique provides us for the first time the ability to communicate with the worms and make them do a certain task" said Ravi Selvaganapathy, an engineer at McMaster. "For instance, we could expose the worm to a drug and quantitatively measure the speed of the worm and compare it to unexposed worms."

Previously worms could be made to move, but not in any reliable, repeatable way. Getting the worms to move in a definite way gives scientists a chance to be more precise in measuring the effect of various toxins or remedies.

C. elegans worms are used to study human illnesses because 60 percent of the genes in their cells have a human equivalent. They can suffer conditions similar to human diseases such as Parkinsonism and Huntington’s diseases. In the worms’ accelerated lifespan these diseases can play out in days rather than decades.

The ability to get the worms to respond to electric current solves the problem moving them to the right place at the right time, such as to receive a certain supply of nutrient. Some alternative methods of coaxing such as offering food or shining ultraviolet light on them can take too long to work.

The McMaster researchers, publishing their work in a recent issue of the journal Applied Physics Letters, hope to have the chance to observe up to a thousand worms at a time on a single platform, each moving in its own narrow channel. This will allow a quicker and more detailed look at reactions to a variety of drugs, chemicals, and nanoparticles. This will also help in studying the course of diseases such as obesity and hypertension.

Read the full article in Applied Physics Letters.
This story was written and published on the ISNS news site.
Applied Physics Letters is published by the American Institute of Physics, which also publishes Inside Science News Service.

For decades, the electrical properties of human blood have been of interest in a wide range of biomedical applications, such as in radiofrequency hyperthermia, body composition, electrocardiography, and the diagnosis and treatment of various physiological conditions.

In a recent article published in Biomicrofluidics, researchers at King Abdulaziz University in Saudi Arabia have published a study of the electrical and mechanical (viscosity) properties of blood and the effects of electrical conduction on its microstructure. The authors use many parameters in their research and conclusions, including the relaxation time of micro-cells, molecules, bacteria, protein, hormones, glucose, chemicals, vitamins, and antibodies, which all greatly influence the chemical and physical character of blood.

One of the tastiest things I can think of is Jell-O—and just in time to celebrate the Second Annual Jell-O Mold Competition, comes a bit of research from the ACS journal, Analytical Chemistry.

The article, "Using Inexpensive Jell-O Chips for Hands-On Microfluidics Education¹," presents an interesting model of microfluidic devices using, you guessed it, Jell-O.

The idea is to get anyone (probably mostly Jell-O enthusiasts) really excited about microfluidics. Getting students to design and build a microfluidic device could spark an immense interest in a technology that could one day be as commonplace as cellphones.

This figure at right shows the authors' scheme for "producing Jell-O chips using soft lithography," whose hopes are they certain key concepts—including photolithography, crosslinking density, photopolymerization, and rapid prototyping—will be easily conveyed to students of all levels. The article runs through a few different chip designs, including one that demonstrates pressure-driven flow, another that teaches principles of dimensionless numbers, and finally a "Jell-O chip" that can be used for teaching the fundamentals of pH sensing and parallelization,

This isn't explicitly mentioned, but I'm hoping the authors take into account how hungry the students are before proceeding with additional lessons... at the end of the day, there might not be enough Jell-O to go around.