Biomedical subjects

Sara Ullsten

Publications and source records attributed to Sara Ullsten.

6 recordsLinked to original sources

PubMed2006

Urine profiling using capillary electrophoresis-mass spectrometry and multivariate data analysis.

This work presents the development of a general and fast method for metabolic profiling of urine, using capillary electrophoresis-electrospray ionisation mass spectrometry (CE-ESIMS) and multivariate data analysis (DA). Human urine samples collected before and after ingestion of paracetamol were analysed at acidic and basic CE conditions, using both positive and negative ESI-MS detection. Analysis of the entire resulting data set, with no prior knowledge of the target compounds, using pair-wise 'fuzzy' correlation and eigenvalue analysis enabled the samples to be discriminated between on the basis of blank urine and urine collected after drug intake. By generating two-dimensional loadings plots, it was also possible to identify the m/z values of the substances responsible for the differentiation between control and dosed samples.

Acetaminophen↗

PubMed2004

Quaternary ammonium substituted agarose as surface coating for capillary electrophoresis.

A novel positively charged polymer of quaternary ammonium substituted agarose (Q-agarose) has been synthesized and explored for use as a coating in capillary electrophoresis. The fast and simple coating procedure is based on a multi-site electrostatic interaction between the polycationic agarose polymer and the negatively charged fused-silica surface. By simply flushing fused-silica capillaries with hot polymer solution a positively charged, hydrophilic deactivation layer is achieved. The polymer surface provides an intermediate electroosmotic flow of reversed direction, over a range of pH 2-11, compared to unmodified fused-silica. The coating procedure was highly reproducible with an RSD of 4%, evaluated as the electroosmotic flow mobility for 30 capillaries prepared at 10 different occasions. The application of Q-agarose coated capillaries in separation science was investigated using a set of basic drugs and model proteins and peptides. Due to the intermediate electroosmotic flow generated, the resolution of basic drugs could be increased, compared to using bare fused-silica capillaries. Moreover, the coating enabled separation of proteins and peptides with efficiencies up to 300.000 plates m(-1).

Electrophoresis, Agar Gel↗

PubMed2004

A polyamine coating for enhanced capillary electrophoresis-electrospray ionization-mass spectrometry of proteins and peptides.

A procedure for enhanced capillary electrophoresis-electrospray ionization-mass spectrometry (CE-ESI-MS) of proteins is presented. The use of a newly presented capillary coating, PolyE-323, provided fast separations of typically a few minutes with high efficiency, good deactivation, and no bleeding into the mass spectrometer. Capillaries coated with PolyE-323 showed high stability over a range of pH 2-10, and tolerance towards methanol and acetonitrile, two modifiers commonly used in CE-ESI-MS. Due to the speed and simplicity of the coating procedure, the polymeric surface could, if necessary, easily be regenerated. This capability is especially valuable when working with samples of complex matrix, where a capillary surface cleaning step might be desired in order to eliminate possible memory effects. The potential of PolyE-323-coated capillaries in bioanalysis using CE-ESI-MS was demonstrated by analyzing peptides and proteins up to 66 kDa using time of flight (TOF)-MS. Due to the stable, anodal electroosmotic flow generated by the coating, the use of a sheathless ESI interface was enabled, demonstrated in peptide analysis with attomole sensitivity. The fast on-line CE-ESI-TOF system using PolyE-323-coated capillaries provided efficient separation and detection of a large number of peaks in a short time, exemplified by the analysis of a tryptic digest of bovine serum albumin (BSA). The capability of the developed capillary surface coating was demonstrated by the separation of human plasma and cerebrospinal fluid (CSF).

Acetonitriles↗

PubMed2004

Capillary electrophoresis off-line matrix-assisted laser desorption/ionisation mass spectrometry of intact and digested proteins using cationic-coated capillaries.

Capillary electrophoresis (CE) was coupled off-line with matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOFMS) for the analysis of proteins and peptides. CE fractions were collected directly on a matrix-coated MALDI target, using a sheath-flow interface. Protein adsorption during CE separations was prevented by coating the capillaries with the physically adsorbed, cationic polymer PolyE-323. The CE/MALDI-MS system was used for the analysis of model proteins and peptides at physiological pH as well as analysis of proteins in tear fluid. Moreover, tryptic on-target digestion of the collected protein fractions, with subsequent MALDI-MS and MS/MS peptide analysis, was demonstrated.

Electrophoresis, Capillary↗

PubMed2003

Novel polyamine coating providing non-covalent deactivation and reversed electroosmotic flow of fused-silica capillaries for capillary electrophoresis.

A new polycationic coating for use in capillary electrophoresis has been developed that enables chemical modification of fused-silica capillary surfaces for analysis of compounds like basic proteins. The cationic polyamine, containing short aliphatic blocks of combined 2 and 3-carbon length, was physically adsorbed onto the negatively charged fused-silica surface through ionic interaction by flushing the capillary with a polyamine solution, followed by a self-stabilization step. The polyamine coated capillaries generated an anodal electroosmotic flow that was independent of pH in the investigated range of pH 4-8. The capillary performance was demonstrated by fast separations of basic proteins with peak efficiencies in the range of 265,000-584,000 plates.

Adsorption↗

PubMed2002

Method for immobilization of liposomes in capillary electrophoresis by electrostatic interaction with derivatized agarose.

A novel procedure for immobilization of liposomes inside fused-silica capillaries is demonstrated. First, the inner wall of the capillaries was coated with a positively charged polymer, composed of derivatized agarose. Subsequently, negatively charged liposomes were immobilized by electrostatic interaction on the polymer coating. The developed liposome coated capillaries were used as a nanoseparation tool for studying interactions between small drug compounds and liposomes. Part of this work was presented at the 15th International Symposium on Microscale Separations and Analysis, HPCE 2002, Stockholm, Sweden, April 2002.

Electrophoresis, Agar Gel↗