title: Size exclusion chromatography of microliter volumes for on-line use in low-pressure microfluidic systems.
abstract: We have developed a new cartridge format for on-line size exclusion processing in low-pressure, portable microfluidic devices. The described system allows size exclusion chromatography of microliter volumes (termed muL-SEC) to be performed with ready integration in complex protocols for continuous-flow sample processing and analysis. The refillable cartridge format was employed for the preparation of Bacillus subtilus spores lysed in the presence of a strong reducing agent. While the reducing agent is known to interfere with subsequent fluorescent labeling of the solubilized proteins, the described continuous-flow size exclusion processing allowed complete isolation of interferences from a 10-muL sample in 70 s. Following efficient labeling, the protein sample was injected and separated on-chip using gel electrophoresis. To increase the resolution, speed, and sample capacity of buffer exchange under low-pressure operation (40 psi), parameters such as the size exclusion resin, load volumes, flow rates, buffer composition, and cartridge geometry were optimized and are presented here. The muL-SEC analysis is compatible with automated sample preparation for microfluidic systems and has resulted in significantly increased analysis speed and throughput over benchtop methods. The presented technique has the potential to improve capabilities such as buffer exchange, size fractionation, and high-abundance protein removal-steps that are frequently required prior to on-chip, point-of-care, and mass spectrometric analyses.
authors.affiliation: Sandia National Laboratories, 7011 East Avenue, Building 929, MS 9291, Livermore, California 94551, USA. gschiri@sandia.gov
authors.forename: G
authors.initials: G
authors.lastname: Chirica
authors.forename: J
authors.initials: J
authors.lastname: Lachmann
authors.forename: J
authors.initials: J
authors.lastname: Chan
mesh_terms: D001412:Bacillus subtilis / Q000737:chemistry; D002850:Chromatography, Gel / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation* / Q000379:methods; D010316:Particle Size; D011312:Pressure; D011506:Proteins / Q000032:analysis; D012680:Sensitivity and Specificity; D013997:Time Factors
chemical_list: D011506:Proteins