Introduction scienova Xpress Dialyzer

The sample preparation of macromolecules is an often-required procedure in daily laboratory routine. Dialysis is a gentle method for molecule separation and is used in many protein biochemical laboratories for purification of protein samples. The classical method, the dialysis tube, is often used. However, this turns out to be disadvantageous for small sample volumes, high sample numbers and safe handling and thus increases process times and costs. But especially in routine analytics, screening experiments or experiments with many parallels, personnel costs and process times are significant cost factors.

The dialysis cartridges from scienova combine the advantages of laboratory dialysis with the requirements of modern laboratory work. The dialysis cartridges were developed by scientists from the University Hospital of Jena and their main focus was on the following properties:

• High dialysis speeds
• Easy and safe handling
• Low sample losses and high reproducibility of the results
• High scalability of sample number from 1 to 96
• Suitable for standard microplate patterns
• Suitability for automated pipetting systems

The Xpress Dialyzers have a unique, patented geometry that provides an optimum volume-to-surface ratio with short diffusion paths. This ensures short dialysis times. The vertically arranged dialysis membrane reduces membrane clogging to a minimum. This means that sample components are not settled on the membrane, sample losses are prevented and there is no negative effect on the dialysis speed.

To reduce handling and process times, the dialyzers are delivered “ready-to-use”. This means that they can be used directly and do not have to be pre-incubated. In individual cases pre-incubation can be useful, e.g. if interference occurs in very sensitive assays after dialysis. A simple protocol is available for these cases on our website.

On the upper side there are openings for filling or emptying the inner compartment, which usually contains the sample to be dialyzed. The openings are designed so that standard pipette tips can be used reliably (see Figure 1).

The use of standard laboratory pipettes enables safe sample filling and sampling as well as low volume losses. Right from the start, care was taken to ensure that these openings were located in the grid of the known microtiter plates (i.e. 8 x 12 samples) with a total of 96 different test cavities.

One cartridge consists of 8 individual segments and can be placed in a 96-deep well plate. A set of 12 cartridges is offered in a complete kit (see figure 2). The focus was on the suitability of automatic pipetting systems (liquid handling devices). Not only the design of the dialysis cartridges is advantageous, but also the arrangement of the dialysis vials.

Figure 1: Xpress Dialyzer segment in a micro tube / openings for filling or emptying the sample

Figure 2: Xpress Dialyzer cartridges in 96-Deep well plate

The dialysis cartridges, known as Xpress Dialyzers, are available in five different versions with different sample volumes. The Micro Dialyzers take up a sample up to 100 µl and two variants up to 300 µl sample inside, while the Mini Dialyzers can be loaded with up to 1000 µl sample. A new variant has recently become available, the Xpress Dialysis Reactor (XDR) with a volume of 19 ml.

This means that smallest volumes of 10 µl can be processed with the Micro Dialyzer MD100. The large selection of cut offs between 2 and 140 kDa ensure a wide range of applications. The dialysis membranes consist mainly of regenerated cellulose, a proven material which is characterized by minimal interaction with most samples.

The Micro Dialyzers from scienova show that sample dialysis is reliable and possible with low process costs:

• Fast and easy handling
• Ready-to-use
• Short dialysis times
• Up to 96 parallel samples
• Usage of multichannel pipettes
• Suitable for use in automatic pipetting systems

The wide range of applications will be explained by some examples in separate articles.