Cross-linked poly(N-acetylethylenimine) as an isoelectric focusing matrix

Covalently cross-linked poly(2-oxazoline) materials for biomedical applications – from hydrogels to self-assembled and templated structures

We discuss covalently cross-linked poly(2-oxazoline)s including gels, nanogels and capsules on the basis of their synthetic origin in a biomedical context.

Poly(2-ethyl-2-oxazoline) as a sieving matrix for SDS-CE

The use of poly(2-ethyl-2-oxazoline) with a number-average molecular weight (of polymer) of 500,000 g/mol in a sieving matrix for SDS CE size separation of proteins is investigated using polymer solutions with concentrations between 6 and 12% w/v. Optimal separation efficiency is obtained using 10% w/v, with an average separation efficiency of 150,000 (12,000) theoretical plates observed for myoglobin (weight-average molecular weight=18 kDa) and 8,800,000 (2,400,000) theoretical plates for carbonic anhydrase (weight-average molecular weight=30 kDa) for 14 capillaries with an 80 cm effective length. Some adsorbed polymers were found to be effective in reducing EOF when applied to a clean capillary; however, a covalently attached polyacrylamide coating was found to be much less troublesome after initial wall treatment. Two different buffer systems, (i) 25 mM HEPES and (ii) 20 mM Tris with 40 or 60 mM tricene, were tried with 0.05 or 0.10% w/v SDS added. Tris-tricene gave generally better current stability than HEPES but with no observed improvement in separation efficiency. This polymer has all the desired characteristics for an SDS-CE sieving matrix using LIF detection, including hydrolytic stability, optical clarity, low viscosity, acceptable hydrophilicity, and commercial availability.

Determination of morphine by capillary electrophoresis immunoassay in thermally reversible hydrogel-modified buffer and laser-induced fluorescence detection

In this paper thermally reversible hydrogel used as a replaceable packed material for capillary electrophoresis was examined. A simple and rapid method of detecting morphine was developed, which demonstrated the potential of strong affinity antibodies as a selector for immunologically-based separations in serum by capillary electrophoresis. Polyclonal antibodies were linked to hydrogel and applied to the separation of free fluorescein isothiocyanate (FITC)-labeled antigen and bound FITC antigen. The separation was monitored with laser-induced fluorescence detection. Different separation conditions were studied. The results indicated that poly-N-isopropylacrylamide hydrogel (PNIPA) is a kind of steady, replaceable gel. The specific determination of morphine did not require a long incubation time and PNIPA hydrogel-modified antibodies can be stockpiled at 4 degrees C before assay. It can be used to determine morphine with good precision and a detection limit lower than 8.5 ng/ml. Details of the preparation of hydrogel cross-linked polyclonal antibody and of typical separations of bound and free antigen are presented.