A method for dialysis of microsamples

A multi-sample microdialysis apparatus for proteins and nucleic acids

A multiposition microdialysis system suitable for simultaneous microsample applications (between 10 microL and 500 microL), has been developed. Each sample, contained in a specially designed microfuge dialysis tube (mDT), is dialysed independently from the other samples. Each mDT has its own membrane, and this feature allows the use of different membranes and dialysis times for different samples. The microdialysis apparatus is kept at constant temperature by an external thermostat, avoiding the use of a cold box. The dialysis release time for small ions, a parameter used for quantitation of microdialysis efficiency, decreases from 22.9 min (for a 200 microL sample) to 7 min (for a 50 microL sample). The sample is efficiently recovered by centrifugation. Quantitative recoveries (90%) of different proteins and DNA were achieved after microdialysis by mDT.

An inexpensive small volume equilibrium dialysis system for protein-ligand binding assays

A simple and inexpensive system for equilibrium dialysis-based binding assays has been developed employing 1.5-ml microtubes. The main advantages are small volume of test buffers, no time-consuming assembly of the test vials, and inexpensive test cells. A comparison of the results derived from this equilibrium dialysis system with those of polyethylenimine-filtration assay and those of a commercially available equilibrium dialysis test system (Diachema from Dianorm) shows good agreement.

A microtechnique for dialysis of small volume solutions with quantitative recoveries

An improved microtechnique designed for dialysis of solutions with volumes ranging from less than 10 microliter up to approximately 600 microliter is described. Samples, dispensed in Microfuge tubes, are dialyzed in situ across dialysis membrane secured over the tube opening by a perforated Microfuge tube cap. The retentate is efficiently recovered by centrifugation at 10,000g for 10 s. Fifty percent escape (E50) times of [14C]glycine from 25-microliter solutions of soybean trypsin inhibitor (0.1, 1.0, 4.0 mg/ml) in 0.2 M NaCl were approximately 19 min. The E50 times of 3H2O increased in a linear fashion from 2.7 min for 25-microliter samples to 75 min for 600-microliter samples of H2O (pH 7.0, 4 degrees C). The mean permeability coefficient (P) of the dialysis membrane to 3H2O during microdialysis, calculated as 3.0 X 10(-4) cm/s, was similar to membrane permeability coefficients reported for dialysis by conventional methods. Quantitative recoveries (greater than approximately 90%) of [14C]glycine-labeled type I collagen, [methyl-14C]antithrombin III, and [32P]DNA were achieved after microdialysis.

The development of a microimmunoadsorbent assay and a microdialysis method for the evaluation of immunoadsorbent efficiency and antibody quantitation

A microimmunoadsorbent assay which provides for the quantitative elution and recovery of active antibody from immunoaffinity columns has been developed. We have also designed a microdialysis chamber which permits the dialysis of sample volumes from 50 to 500 microliters and allows quantitative recovery of macromolecular compounds. These techniques permit the rapid evaluation of a large number of eluants and immunoadsorbents in a short period of time. The microimmunoadsorbent assay coupled with the microdialysis method has been used to evaluate the efficacy of different anti-isopentenyl adenosine immunoadsorbents under various elution conditions. In the present study the best eluants for immunoaffinity purification of anti-N6-(delta 2-isopentenyl)adenosine antibody contained 15% pyridine in a sodium phosphate buffer or 4 M imidazole-HCl at pH 10.0.

A novel technique for efficient multiple sample dialysis

Conventional methods for dialyzing numerous samples are either expensive or tedious and inefficient. These disadvantages were overcome through the construction and use of a Plexiglas dialysis sample holder (DSH). Large numbers of dialysis samples having 0.5 to 2.0-ml volumes may be attached to numbered positions on the DSH. Sample identification is greatly simplified and considerable savings in time and material are achieved. Furthermore, the risk of sample spill or mixing during filling or emptying of dialysis sacks, and the risk of leaks in dialysis tubing, are minimized.