Quantitative ligand immobilization using alginate hydrogel formed in a capillary: application for online affinity concentration.

To simplify a quantitative immobilization procedure of ligands with maintaining their activities, we developed an automated preparation method using an alginate hydrogel partially formed in a capillary. After a sodium alginate solution containing a ligand was injected into the capillary, a background solution containing Ca(2+) was then introduced into the sodium alginate solution zone by applying an appropriate voltage for the hydrogelation, resulting in encapsulation of the ligand by the formed alginate hydrogel. According to the estimated binding capacity for biotin by the encapsulated avidin, the injected avidin was immobilized quantitatively by the formed hydrogel with keeping its affinity.

Hydrophilic interaction electrokinetic chromatography using bio-based nanofillers.

Hydrophilic interaction (HI)-based separation like HILIC is effective for analyzing hydrophilic biological samples such as carbohydrates, peptides, and metabolites. To overcome the drawbacks of conventional HILIC such as large consumption of organic solvents and easy deterioration of the separation column, we developed HI electrokinetic chromatography (EKC) by employing bio-based nanomaterials as the hydrophilic pseudostationary phase. By mechanical/chemical treatments, cellulose, chitin, and chitosan were processed to 10-nm wide nanofibers/nanowhiskers (NFs/NWs), which are longer/shorter than 1000/200 nm, respectively.

Toward 10,000-fold sensitivity improvement of oligosaccharides in capillary electrophoresis using large-volume sample stacking with an electroosmotic flow pump combined with field-amplified sample injection.

A combination of two online sample concentration techniques, large-volume sample stacking with an electroosmotic flow pump (LVSEP) and field-amplified sample injection (FASI), was investigated in CE to achieve highly sensitive oligosaccharide analysis. In CE with LVSEP-FASI, analytes injected throughout the capillary were concentrated on the basis of LVSEP, followed by an electrokinetic introduction of concentrated analytes from the inlet vial by the FASI mechanism. After switching the inlet vial solution from the sample to running buffer, the concentrated analytes were then separated by CZE.