Publication details
Studies of proteins adsorption in polyethyleneimine coated capillaries in capillary zone electrophoresis
| Authors | |
|---|---|
| Year of publication | 2005 |
| Type | Article in Proceedings |
| Conference | 11th International Symposium on Separation Sciences ISSS 2005. Book of Abstracts. |
| MU Faculty or unit | |
| Citation | |
| Field | Analytic chemistry |
| Keywords | capillary coating; polyethyleneimine; electroosmotic flow; protein adsorption |
| Description | The magnitude and the direction of electroosmotic flow (EOF) has fundamental influence to separation in capillary zone electrophoresis. Adsorption of proteins on the negative charged silica surface of uncoated capillaries can lead to analyte loss and to irreproducibility of analyses. Therefore, in biomolecules analyses, the inner surface modification of fused-silica capillaries is recommended. One of the used coating is polyethyleneimine (PEI): as a polycationic polymer it creates positively charged covalent coating on the capillary inner wall and hence minimizes the adsorption of basic proteins at acidic pH and maintains the electroosmotic flow stable [1]. In this work, the properties of PEI coated capillaries with respect to different background electrolytes are described. The changes of inner surface of the capillary were followed by electroosmotic flow measurement [2]. Several buffers commonly used in electrophoretic separations of proteins (MES, acetate, borate) were tested, but the main interest was taken into carboxylic acids as a buffers (citrate, malate, malonate, tartrate and succinate). Interesting behaviour of EOF in PEI coated capillaries was observed: the direction (and the value) depend on pKa of the background electrolyte and at certain pH it can reversibly change from positive to negative. With this knowledge the influence of ionic strength and pH of background electrolyte on the separation of basic proteins was studied. As a model, the standard protein mixture of cytochrome C, ribonuclease A and lysozyme in concentration of 0.25 mg/ml was chosen. Finally, the experimental conditions for humanin analyses were optimized. |