Efforts are under way to develop a nanofluidic size-exclusion chromatograph (SEC), which would be a compact, robust, lightweight instrument for separating molecules of interest according to their sizes and measuring their relative abundances in small samples. About as large as a deck of playing cards, the nanofluidic SEC would serve, in effect, as a "laboratory on a chip" that would perform the functions of a much larger, conventional, bench-top SEC and ancillary equipment, while consuming much less power and much smaller quantities of reagent and sample materials. Its compactness and low power demand would render it attractive for field applications in which, typically,it would be used to identify and quantitate a broad range of polar and nonpolar organic compounds in soil, ice, and water samples.
Size-exclusion chromatography is a special case of high-performance liquid chromatography. In a conventional SEC, a sample plug is driven by pressure along a column packed with silica or polymer beads that contain uniform nanopores. The interstices between, and the pores in, the beads collectively constitute a size- exclusion network. Molecules follow different paths through the size-exclusion network, such that characteristic elution times can be related to sizes of mole- cules:basically, smaller molecules reach the downstream end of the column after the larger ones do because the smaller ones enter minor pores and stay there for a while, whereas the larger ones do not enter the pores. The volume accessible to molecules gradually diminishes as their size increases. All molecules bigger than a pore size elute together. For most substances, the elution times and sizes of molecules can be correlated directly with molecular weights.
Hence, by measuring the flux of molecules arriving at the downstream end as a function of time, one can obtain a liquid mass spectrum for the molecules present in a sample over a broad range of molecular weights. The developmental nanofluidic SEC is based on the same size-separation principle as that of a conventional SEC. However, instead of a packed macroscopic column containing porous beads, the nanofluidic SEC would contain a size-exclusion network in a miniature column in the form of a microscopic channel containing nanometer-scale features (see figure). More specifically,the nanometer-scale features in the channel would be sized, shaped, and positioned to define a matrix of micron-width subchannels topped with a gap of varying thickness of the order of tens of nanometers. The miniature column would be fabricated by established techniques now used to produce integrated circuits (ICs)and microelectromechanical systems (MEMS). One or more device(s)to detect molecules could be integrated onto the column chip at the downstream end. These devices could be based, for example, on electrochemical (in particular, amperometric) and laser-induced-fluorescence detection techniques.
This work was done by Sabrina Feldman, Danielle Svehla, Frank Grunthaner, Jason Feldman, and P. Shakkottai of Caltech for NASA's Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free on-line at www.techbriefs.com/tsp under the Physical Sciences category.
In accordance with Public Law 96-517, the contractor has elected to retain title to this invention.Inquiries concerning rights for its commercial use should be addressed to:
Intellectual Assets Office
JPL Mail Stop 202-233
4800 Oak Grove Drive
Pasadena,CA 91109-8099
(818)354-2240
E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
Refer to NPO-30499 ,volume and number of this NASA Tech Briefs issue, and the page number.
This Brief includes a Technical Support Package (TSP).
(NANO) Nanofluidic Size-Exclusion Chromatograph
(reference NPO-30499) is currently available for download from the TSP library.
Don't have an account?
Overview
The document outlines the development of a Nanofluidic Size Exclusion Chromatograph (SEC) by researchers at NASA's Jet Propulsion Laboratory (JPL), including Sabrina Feldman, Frank Grunthaner, and others. This innovative device aims to enhance the analysis of molecular samples by utilizing a miniature, low-power separation technique based on size-exclusion principles.
Traditional size exclusion chromatography (SEC) relies on packed columns with silica or polymer beads to separate molecules by size. In contrast, the proposed nanofluidic SEC employs a microchannel with nanometer-scale features, fabricated using established techniques from integrated circuits (ICs) and microelectromechanical systems (MEMS). This design allows for a more compact instrument, approximately the size of a deck of cards, which is significantly smaller than conventional benchtop SEC systems.
The nanofluidic SEC is expected to provide high performance in separating molecules with a broad range of molecular weights, typically from 1,000 to 1,000,000 Daltons. The device will feature a matrix of micron-width channels with gaps in the tens of nanometers, analogous to the nanopores in traditional SEC. This configuration allows for adjustable separation matrices tailored for specific molecules, enhancing the versatility of the instrument.
One of the key motivations for developing this technology is the need for portable, low-power instruments capable of detecting microbial life and organic compounds in extraterrestrial environments. The nanofluidic SEC is designed to operate in situ, providing detailed geochemical and biological analyses of samples from other planetary bodies. The expected mass of the complete instrument, including detection systems, is around 500 grams, with a power requirement of 1-2 watts.
Detection methods integrated into the device may include electrochemical amperometric detection and laser-induced fluorescence detection, allowing for a wide range of applications in both scientific research and potential field missions. The document emphasizes the significance of this technology in advancing our capabilities to explore and analyze unknown chemical building blocks in various environments, particularly in the search for life beyond Earth.
Overall, the nanofluidic SEC represents a significant advancement in analytical chemistry, promising to deliver robust, efficient, and portable solutions for molecular analysis in challenging conditions.
