Capillary device significantly improves manufacture of quality liposomes

May 21, 2014 by Michael E. Newman
Schematic of the NIST/University of Maryland 3D-microfluidic hydrodynamic focusing device for manufacturing vesicles known as liposomes. Phospholipids dissolved in alcohol flowing through the center capillary (red) mix with a water-based buffer solution added through the six surrounding tubes. Liposomes are created downstream from the convergence point. Credit: NIST

When the English author Sir Francis Bacon wrote "The world's a bubble" in 1629, it's a safe bet he wasn't thinking about microfluidics. However, for a research team led by scientists at the National Institute of Standards and Technology (NIST), Bacon's words could not be truer. Since 2004,their world has revolved around the development of increasingly sophisticated microfluidic devices to produce liquid-filled "bubbles" called liposomes for potential use as vehicles to deliver drugs directly to cancers and other diseased cells within the body.

Liposomes are spheres made of a double layer of phospholipids, the fat complexes that are the building blocks for animal cell membranes. They resemble simples cells with the "guts" removed. Widespread application of manufactured liposomes as artificial drug carriers has been hindered by a number of limiting factors such as inconsistency in size, structural instability and high production costs.

In a new article in the journal Lab on a Chip, the team from NIST and the University of Maryland (UM) describes a new approach for overcoming these obstacles. The group's novel system is made up of bundled capillary tubes, costs less than a $1 to make and requires no special fabrication technology or expertise, yet consistently yields large quantities of uniform and sturdy vesicles.

Previous NIST/UM microfluidic liposome-generating devices were two-dimensional designs incorporating tiny channels etched into a silicon wafer with the same techniques used for making integrated circuits. Phospholipid molecules dissolved in isopropyl alcohol were fed via a central inlet channel into a "mixer" channel and focused into a fluid jet by a water-based solution added through two side channels. The components blended together as they mixed at the interfaces of the flowing fluid streams, directing the phospholipid molecules to self-assemble into nanoscale vesicles of controlled size.

In the latest NIST/UM advance, the planar structure has been replaced by a three-dimensional microfluidic device. The new liposome generator consists of a 3-millimeter-diameter glass cylinder containing a bundle of seven tiny glass capillary tubes—each a millimeter across, or about the diameter of a pinhead—with one in the center and six surrounding it. A micro-sized plastic capillary (about 500 micrometers in diameter, or the length of an amoeba) is fed through the center tube and extended just beyond the end of the capillary bundle. All of the materials are commercially available at pennies per unit.

The water-based solution (known as PBS) flows through the outer six capillaries while the center channel carries the phospholipid dissolved in alcohol (in production, the PBS would carry a drug or other cargo for the vesicles). A standard glass pipette attached to the end of the improves mixing by concentrating the ratio of water to lipid/alcohol.

"With our 3D capillary device, we can increase production of high-quality threefold from what our 2D planar system can do in the same amount of time," says NIST research chemical engineer Wyatt Vreeland, one of the authors on the Lab on a Chip paper.

Explore further: Novel connector uses magnets for leak-free microfluidic devices

More information: R. Hood, D. DeVoe, J. Atencia, W. Vreeland and D. Omiatek. "A Facile Route to the Synthesis of Monodisperse Nanoscale Liposomes Using 3D Microfluidic Hydrodynamic Focusing in a Concentric Capillary Array." Lab on a Chip, May 2014. DOI: 10.1039/C4LC00334A

Related Stories

Researchers COMMAND a Better Class of Liposomes

April 28, 2010

(PhysOrg.com) -- Pop a bubble while washing the dishes and you're likely to release a few drops of water trapped when the soapy sphere formed. A few years ago, researchers at the National Institute of Standards and Technology ...

NIST's simple microfluidic devices now have valves

April 2, 2014

Researchers at the National Institute of Standards and Technology (NIST) have added yet another innovation—miniature valves—to their ever-growing collection of inexpensive, easy-to-manufacture and highly efficient microfluidic ...

Recommended for you

A marine creature's magic trick explained

September 2, 2015

Tiny ocean creatures known as sea sapphires perform a sort of magic trick as they swim: One second they appear in splendid iridescent shades of blue, purple or green, and the next they may turn invisible (at least the blue ...

Brazilian wasp venom kills cancer cells by opening them up

September 1, 2015

The social wasp Polybia paulista protects itself against predators by producing venom known to contain a powerful cancer-fighting ingredient. A Biophysical Journal study published September 1 reveals exactly how the venom's ...

Naturally-occurring protein enables slower-melting ice cream

August 31, 2015

(Phys.org)—Scientists have developed a slower-melting ice cream—consider the advantages the next time a hot summer day turns your child's cone with its dream-like mound of orange, vanilla and lemon swirls with chocolate ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.