Drying module

Details Drying module Drying module

2000-05-02

2001-05-08

Gravini, Stephen (Department: 3749)

Drying and gas or vapor contact with solids

Apparatus

With automatic control

C034S546000, C034S572000, C034S107000, C034S197000

Reexamination Certificate

active

06226892

ABSTRACT:

The invention relates to a dryer module for drying filter supports, as used in DNA preparation.
In modern DNA preparation procedures, the products of which are to be used in sequencing tasks, it is becoming clear, especially in the case of the more recent megasequencing projects (Human Genome Project), that automation of the labour-intensive manual steps is indispensable. Whereas previously so-called “ready-to-use kits” that simplified the working up of DNA sequences introduced by cloning were not available, today there are already a few commercially available aids in existence that are also suitable for automatically working through the corresponding protocols (such as, for example, the widespread Qiagen protocol) using robots.
The preparation protocol described by Qiagen comprises washing with ethanol-containing buffer the DNA adsorbed on filter elements of a filter support. Experiments have shown that traces of ethanol have a severely adverse effect on the result of the subsequent sequencing reactions. The participating enzymes are probably inhibited by ethanol. In this step, initially the larger amounts of ethanol are removed from the filters in known manner. When the protocol is carried out, for example, in an appropriate vacuum apparatus, the removal can be achieved by the vacuum being applied for longer than would be necessary for the purpose of removing the washing liquid. The air flow generated in the filter in that manner removes the larger amounts of ethanol from the filters, but the particular construction of the Qiagen filter supports causes contamination of the subsequent sequencing process if no special precautions are taken, since residues of ethanol remain on the walls between the outlet nozzles and the plastics housings on the underside of the filter support. Contamination by ethanol was also observed during the elution of the DNA from the filter material, the contamination occurring as follows: as the eluate is being sucked off into the eluate collectors, a drop forms on the outlet nozzle. Before that drop is drawn off it “migrates” upwards on the nozzles and comes into contact with the ethanol-containing liquid still to be found there. Mixing consequently occurs. The drop is then drawn off and falls into the eluate collector. The result is a general contamination of the eluate with ethanol to such an extent that the sequencing batch is “poisoned”.
The problem underlying the invention is therefore to provide an apparatus by which the remaining residual alcohol is removed from filter supports, as used, for example, in the Qiagen protocol.
This problem is solved by the features of claim
1
. The subsidiary claims relate to advantageous configurations of the invention.
The invention relates to a dryer module for drying filter supports in DNA preparation, wherein the dryer module has a receiving member for receiving the filter support, and at least one blower member, the blower member being arranged below the receiving member for receiving the filter support so that the filter support is blown on and dried from below.
Preferably, the dryer module according to the invention has at least one heating element for warming the air blown from below against the filter support.
Furthermore, an air shaft for guiding the drying air is arranged between the blower and the receiving member for the filter support, in which air shaft the heating elements are arranged.
Advantageously, the blower member is formed by a crossflow blower which is driven by an electric motor.
Furthermore, the upper end of the air shaft can be formed as a nozzle for channeling the lateral air flow.
Advantageously, the receiving member for the filter support is formed as a centring plate, the centring plate being arranged on foot members so that the centring plate, together with the foot members, forms a filter support stand.
Also, the dryer module can be arranged in an opening in a bench top. The dryer module can, however, also be operated as an individual piece of apparatus, either in an automated environment or as a stand-alone apparatus.
Advantageously, the step of removing the ethanol from the region between the outlet nozzle and the plastics housing of the filter support is not carried out manually but is automated. For that purpose, the dryer module blows warmed air (50° C. maximum) from below against the filter support and evaporates the ethanol. The filter dried in that way is introduced into a vacuum chamber again in order to be aerated once more for a certain time by the application of a vacuum. In that second step, remaining traces of ethanol are further removed. Finally, the filter treated in that way is again placed on the dryer module so as to ensure, by means of the heated air flow, that any possible traces of ethanol still present are finally evaporated off. Only then is the filter support, for example, reinserted into the pipetting robot in order for the eluant to be pipetted in for the purpose of releasing the DNA from the filters.


REFERENCES:
patent: 5451524 (1995-09-01), Coble et al.
patent: 5498394 (1996-03-01), Matschke
patent: 5572802 (1996-11-01), Alpenfels et al.
patent: 5704135 (1998-01-01), Riahi
patent: 5755039 (1998-05-01), Mae et al.
patent: 5970625 (1999-10-01), Scheufler et al.
patent: 6068874 (2000-05-01), Grocholski et al.

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