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Frantisek Foret

Publications and source records attributed to Frantisek Foret.

13 recordsLinked to original sources
PubMed2006

Aerodynamic mass spectrometry interfacing of microdevices without electrospray tips.

A new concept for electrospray coupling of microfluidic devices with mass spectrometry was developed. The sampling orifice of the time-of-flight mass spectrometer was modified with an external adapter assisting in formation and transport of the electrosprayed plume from the multichannel polycarbonate microdevice. The compact disk sized microdevice was designed with radial channels extending to the circumference of the disk. The electrospray exit ports were formed by the channel openings on the surface of the disk rim. No additional tips at the channel exits were used. Electrospray was initiated directly from the channel openings by applying high voltage between sample wells and the entrance of the external adapter. The formation of the spatially unstable droplet at the electrospray openings was eliminated by air suction provided by a pump connected to the external adapter. Compared with the air intake through the original mass spectrometer sampling orifice, more than an order of magnitude higher flow rate was achieved for efficient transport of the electrospray plume into the mass spectrometer. Additional experiments with electric potentials applied between the entrance sections of the external adapter and the mass spectrometer indicated that the air flow was the dominant transport mechanism. Basic properties of the system were tested using mathematical modeling and characterized using ESI/TOF-MS measurements of peptide and protein samples.

Journal Article↗
PubMed2006

On-line CE-MS using pressurized liquid junction nanoflow electrospray interface and surface-coated capillaries.

A simple and cost-effective laboratory-made liquid junction interface was used for coupling of CE with MS. In this device the capillary column and the spray tip were positioned in the electrode vessel containing appropriate spray liquid. The electrospray potential was applied on the electrode inside the liquid junction. A stable electrospray was produced at nanoliter per minute flow rates generated in the emitter tip without using an external pump. This arrangement provided high durability of the spray tip and independent optimization of the CE separation (use of coated capillaries) and ESI conditions. CE-MS analysis of mixtures of drugs, peptides, tryptic digests of proteins and biological fluids was optimized with respect to the effects of the distance between the separation capillary and electrospray tip and pressure applied on the liquid junction. The sensitivity of the system, in terms of the LOD (base peak monitoring) was below 10 ng/mL for the beta-blocker drugs and below 200 ng/mL for peptide analysis.

Adrenergic beta-Antagonists↗
PubMed2005

Characterization of a monolithic immobilized trypsin microreactor with on-line coupling to ESI-MS.

The preparation and characterization of a miniaturized trypsin reactor using on-line coupling with an ESI-TOF mass spectrometer are described. L-1-Tosylamido-2-phenylethyl chloromethyl ketone-trypsin was covalently immobilized on poly(glycidyl methacrylate-co-ethylene dimethacrylate) monolith prepared in a 75 microm ID fused silica capillary resulting in a bioreactor with high local concentration of the proteolytic enzyme. Covalent immobilization of trypsin on this support was performed using the epoxide functional groups in either a one- or a multistep reaction. For on-line protein digestion-MS analysis the bioreactor was coupled with the mass spectrometer using a liquid junction microelectrospray interface. The performance of the reactor was tested using an on-line flow through the system with flow rates of 50-300 nL/min. The resulting protein consumption was in the atto- to low femtomole range. Proteolytic activity was characterized in a wide range of conditions with respect to the flow rate, pH, and temperature. Complete protein digestion was achieved in less than 30 s at 25 degrees C with the sequence coverage of 80% (cytochrome c), which is comparable to 3 h digestion in solution at 37 degrees C. Besides the good performance at laboratory temperature, the immobilized trypsin in the bioreactor also performed well at lower pH compared to the standard in-solution protocols.

Capillary Action↗
PubMed2004

Ionic boundaries in biological capillary electrophoresis.

Ion migration in electrophoresis always leads to the formation of ionic boundaries. While some types of the ionic boundaries can be formed intentionally, e.g., to improve separation efficiency or sensitivity of the analysis, other, naturally formed boundaries, may cause unexpected effects during the electrophoretic experiment. Some of the boundaries often go unnoticed in practice; however, many effects of the ionic boundaries formed by the sample matrix and background electrolyte components are frequently observed in capillary electrophoresis (CE). The interpretation of these effects may not be trivial and different explanations of the same phenomena may be found in the literature. This critical article attempts to review some of the important effects of the ionic boundaries observed or utilized during the CE of biologically important samples.

Electrophoresis, Capillary↗
PubMed2004

Capillary electrophoresis and mass spectrometry for screening of metabolic disorders in newborns.

Clinical analyses always represent a challenge for the sensitivity and selectivity of the analytical techniques. Of the most critical are the techniques required for the quick determination of the disease state and application of the proper treatment in newborns. This short critical review overviews the present state of the art of the use of mass spectrometry and capillary electrophoresis for screening of metabolic disorders in newborns.

Electrophoresis, Capillary↗
PubMed2004

Immobilized microfluidic enzymatic reactors.

The use of enzymes for cleavage, synthesis or chemical modification represents one of the most common processes used in biochemical and molecular biology laboratories. The continuing progress in medical research, genomics, proteomics, and related emerging biotechnology fields leads to exponential growth of the applications of enzymes and the development of modified or new enzymes with specific activities. Concurrently, new technologies are being developed to improve reaction rates and specificity or perform the reaction in a specific environment. Besides large-scale industrial applications, where typically a large processing capacity is required, there are other, much lower-scale applications, benefiting form the new developments in enzymology. One such technology is microfluidics with the potential to revolutionize analytical instrumentation for the analyses of very small sample amounts, single cells or even subcellular assemblies. This article aims at reviewing the current status of the development of the immobilized microfluidic enzymatic reactors (IMERs) technology.

Animals↗
PubMed2003

Microdevice for separation and quantitative fraction collection.

A new microfluidic concept for quantitative whole-column fraction collection of electrophoretically separated zones was developed. The prototype device, fabricated on a polycarbonate disk by injection molding, integrated electrophoretic separation channels with fraction collection reservoirs distributed along the separation channel. The microdevice was designed in a CD-like format to use the centrifugal force for moving the liquid in the microchannels. A serpentine shape of the separation channel was selected to create segments for quantitative whole-column fraction collection. The operation was tested with visual monitoring of isotachophoretic separation and collection of cationic dyes.

DNA↗
PubMed2003

Application of high-resolution capillary array electrophoresis with automated fraction collection for GeneCalling trade mark analysis of the yeast genomic DNA.

Capillary array instrument was applied to transcript profiling of the yeast genomic DNA using GeneCalling trade mark chemistry. The instrument integrated a 12-capillary array for DNA separation with a replaceable sieving matrix, laser-induced fluorescence detection and an automated microfraction collector. The DNA fractions, exiting the separation capillaries, were continuously deposited in a 1536-well collection plate made of agarose gel. DNA fragments recovered from selected fractions were cloned and then sequenced. Over 80% of theoretically predicted fragments could be recovered in the collected fractions, cloned and sequenced with an average redundancy of threefold. Excellent correlation of the experimentally obtained sequences with the theoretically predicted gene fragments demonstrated the suitability of capillary array electrophoresis for micropreparative recovery of DNA fragments. This approach, useful especially for rapid DNA expression profiling of unknown genes for nonsequenced organisms, demonstrates the practical capability of the prototype multicapillary fraction collector.

Automation↗
PubMed2002

Design of a fraction collector for capillary array electrophoresis.

This paper describes a prototype instrument for high-throughput fraction collection with capillary array electrophoresis (CAE). The design of the system was based on a comprehensive collection approach, in which fractions from all capillaries were simultaneously collected in individual collection microwells in predefined time intervals. The location of the fractions in the microwells on the collection plate was determined by monitoring the individual zone velocities close to the end of each capillary. The collection microwell plate was fabricated from buffer-saturated agarose gel, which maintained permanent electrical contact with the separation capillaries during the collection process. Since the collection gel plate consisted of over 90% water, liquid evaporation from the collection wells was minimized. A 12-capillary array instrument was built with two-point detection using a side illumination scheme. The collection performance was demonstrated by reinjection of selected fractions of a double-stranded DNA (dsDNA) separation. The identity of collected DNA fragments was confirmed by PCR and sequencing.

DNA↗
PubMed2002

A miniaturized multichamber solution isoelectric focusing device for separation of protein digests.

A miniaturized multichamber device was constructed for solution isoelectric focusing (IEF) separation of complex peptide mixtures. The system, based on immobilized pH gels, consisted of 96 minichambers ( approximately 75 nuL each) arranged in eight rows. Neighboring chambers in a given row were separated by short glass tubes (4 mm inner diameter, 3 mm long), within which Immobiline gels of specific pH values were polymerized. During focusing, the device was sandwiched between two supporting blocks incorporating the reservoirs for anolyte and catholyte. In principle, multiple samples could be simultaneously fractionated, each separated into 12 fractions of various pI ranges. A variety of standard peptide mixtures and tryptic digests of proteins were separated by IEF using this device, and the fractions were characterized by mass spectrometry. For a codigested nine-protein mixture, both the total number of peptides identified and the average sequence coverage were similar to the results of ion-exchange chromatography (IEC), according to matrix assisted laser/desorption/ionization--time of flight (MALDI-TOF) data. The IEF separation provided concentrated and desalted fractions, suitable for an additional separation liquid chromatography, capillary electrophoresis (LC, CE) or mass spectrometry (MS) detection without additional sample cleanup. High loading capacity was achieved for the miniaturized multichamber IEF device. Importantly, a linear correlation was found between the experimentally determined and calculated pI values of peptides.

Acrylamides↗
PubMedDate not supplied

Microfabricated devices: A new sample introduction approach to mass spectrometry.

Instrument miniaturization is one way of addressing the issues of sensitivity, speed, throughput, and cost of analysis in DNA diagnostics, proteomics, and related biotechnology areas. Microfluidics is of special interest for handling very small sample amounts, with minimal concerns related to sample loss and cross-contamination, problems typical for standard fluidic manipulations. Furthermore, the small footprint of these microfabricated structures leads to instrument designs suitable for high-density, parallel sample processing, and high-throughput analyses. In addition to miniaturized systems designed with optical or electrochemical detection, microfluidic devices interfaced to mass spectrometry have also been demonstrated. Instruments for automated sample infusion analysis are now commercially available, and microdevices utilizing chromatographic or capillary electrophoresis separation techniques are under development. This review aims at documenting the technologies and applications of microfluidic mass spectrometry for the analysis of proteomic samples.

Biotechnology↗