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Designer gradients speed surface science experiments
June 09, 2006Researchers from the National Institute of Standards and Technology (NIST) have demonstrated an elegantly simple technique for synthesizing a wide variety of complex surfaces that vary in a controlled fashion across a test strip. The new technique is so flexible that it can be applied to surface science experiments ranging from developing better paints to exploring the bonding of proteins to cell membranes.
So-called "gradient composition surfaces"—their chemical composition changes gradually across the surface—have been shown to be powerful research tools for rapid, high-throughput testing of complicated surface properties, but they can be tricky to build. The new NIST technique described in a recent paper in Advanced Materials* coats a silicon wafer with a brush-like copolymer surface, varying the relative concentration of two components, or monomers, of the polymer along the length of the substrate. The dense polymer brush provides a controlled interaction surface at the top while effectively masking the underlying substrate.
The heart of the NIST technique is a combined microfluidic mixer and reaction chamber. The two components are injected into the mixer with gradually changing flow rates and mix thoroughly before filling a thin reaction chamber holding the silicon wafer substrate. Once the solution leaves the mixing region, the narrow dimensions of the reaction chamber inhibit further mixing, so the varying composition ratios through the chamber remain stable while the solution polymerizes on the substrate.
Because it keeps the fluid mixture concentrations stable for long periods, the new technique is unique in its ability to accommodate a wide variety of materials, potentially producing test surfaces for studying surface phenomena ranging from nanoscale interactions of biomolecules—critical for improving the performance of tissue-engineered medical products or for identifying the fundamental mechanisms key to cell/surface adhesion—to the performance of new products like paints or adhesives. The specific polymer used in these proof-of-concept experiments, for example, is typical of a temperature- or acidity-sensitive polymer that might be used in a drug delivery system.
National Institute of Standards and Technology (NIST)
Because it keeps the fluid mixture concentrations stable for long periods, the new technique is unique in its ability to accommodate a wide variety of materials, potentially producing test surfaces for studying surface phenomena ranging from nanoscale interactions of biomolecules—critical for improving the performance of tissue-engineered medical products or for identifying the fundamental mechanisms key to cell/surface adhesion—to the performance of new products like paints or adhesives. The specific polymer used in these proof-of-concept experiments, for example, is typical of a temperature- or acidity-sensitive polymer that might be used in a drug delivery system.
National Institute of Standards and Technology (NIST)
Surface Current Events and Surface News RSSNewly identified cells make fat
To understand where fat comes from, you have to start with a skinny mouse. By using such a creature, and observing the growth of fat after injections of different kinds of immature cells, scientists at the Howard Hughes Medical Institute and Rockefeller University have discovered an important fat precursor cell that may in time explain how changes in the numbers of fat cells might increase and lead to obesity.
Nanodiamond drug device could transform cancer treatment
A Northwestern University research team has developed a promising nanomaterial-based biomedical device that could be used to deliver chemotherapy drugs locally to sites where cancerous tumors have been surgically removed.
New robotic repair system will fix ailing satellites
Researchers at Queen's University are developing a new robotic system to service more than 8,000 satellites now orbiting the Earth, beyond the flight range of ground-based repair operations.
Shift in bald eagle diet linked to sea otter decline
A newly published study has found that the decline of sea otters along Alaska's Aleutian Islands has forced a change in the diet of a terrestrial predator - the bald eagle. The study demonstrates the extraordinary complexity of marine ecosystems and how far-ranging the impacts can be when there is a population shift in a keystone species like the sea otter.
So-called 'sandfish' could help materials handling and process technology specialists
It moves as quickly in sand as a fish moves through water, which is why this lizard, a species of skink (Scincus scincus) that grows to about 15 cm long and lives in the deserts of North Africa and the Near East, is commonly known by the name "sandfish."
Arctic sea ice annual freeze-up underway
After reaching the second-lowest extent ever recorded last month, sea ice in the Arctic has begun to refreeze in the face of autumn temperatures, closing both the Northern Sea Route and the direct route through the Northwest Passage.
Disease diagnosis in just 15 minutes
Testing for diseases such as cancer and multiple sclerosis could soon be as simple as using a pregnancy testing kit.
Genes influence effectiveness of weight-loss drug
Obese patients with a specific genetic make-up lose more weight when taking the weight loss drug sibutramine and undergoing behavioral therapy compared to those without this genetic make-up, reports a new study in Gastroenterology, the official journal of the American Gastroenterological Association (AGA) Institute.
Case Western Reserve University project ties soil conservation and river management together
Sediment in rivers comes from erosion of the landscape as well as the erosion and collapse of the banks themselves. Just how much each source contributes to a river - and how it affects the flow and path of that river - is the subject of research by Peter Whiting, professor of geological sciences at Case Western Reserve University.
Case Western Reserve University researchers track Chernobyl fallout
When a reactor in the Chernobyl nuclear power plant exploded in 1986 in what was then the Soviet republic of Ukraine, radioactive elements were released in the air and dispersed over the Soviet Union, Europe and even eastern portions of North America.
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