WO1992010293A1

WO1992010293A1 - Dispenser

Info

Publication number: WO1992010293A1
Application number: PCT/GB1991/002161
Authority: WO
Inventors: Grenville Arthur Robinson; John Worthington Attridge
Original assignee: Applied Research Systems Ars Holding N.V.
Priority date: 1990-12-06
Filing date: 1991-12-05
Publication date: 1992-06-25
Also published as: GB9026536D0; AU9017491A

Abstract

A method for delivering controlled amounts of reagent, which involves the use of a device comprising a nozzle through which the reagent is able to flow and a reservoir for the reagent, the reservoir being connected to a nozzle, with a ball valve between the nozzle and reservoir to accurately regulate the flow of reagent. Such a method allows the accurate and reproducible delivery of reagents such as biochemical reagents.

Description

DISPENSER

The present invention relates to a method of delivering controlled amounts of a reagent, the method being of particular use in the field of immunoassay. Conventional automated techniques of immunoassay require that at least some of the reagents used in the assay be present in the immunoassay apparatus in a soluble, releasable form. Such reagents may be applied in a solution the solvent of which readily evaporates once the solution has been applied. Before the assay can proceed, the reagents must be delivered to an appropriate site in the immunoassay apparatus.

If the assay is to be accurate then it is important that the amount of reagent delivered to the reagent site in the immunoassay apparatus is accurately controlled. Conventionally, devices such as micropippettes are used in manual or automated systems to deliver microlitre or smaller volumes of reagent to the reagent site. The delivery of microlitre or smaller volumes of reagent is termed "microdosing". Such conventional microdosing techniques, however, have several disadvantages. They do not give a sufficient degree of control over the volume of reagent delivered and this leads to a lack of precision and sensitivity in the assay which is subsequently conducted. Furthermore, this lack of control results in more time being expended in attempting to deliver equal volumes, thus slowing the process. There is also a consequential lack of reproducibility in assays since it is very difficult to ensure that equal volumes of reagents are being used in comparable assays. Moreover, conventional micropippette delivery devices can be expensive.

Conventional microdosing techniques are far from ideal. There is therefore a need for an improved method of microdosing reagents which shows a high degree of accuracy of delivery, an increased rate of delivery, and an increased reproducibility of delivery. We have now developed a method which substantially meets this need. Viewed from one aspect, therefore, the present invention provides a method of delivering controlled amounts of reagent, said method comprising delivering said reagent from a device comprising a nozzle through which said reagent is able to flow and a reservoir for said reagent, said reservoir being connected to or integral with said nozzle, with flow regulating means in the form of a ball valve between said nozzle and said reservoir, said means being operable in use to regulate the flow of said reagent from said reservoir to said nozzle.

Viewed from a further aspect, the present invention provides a biochemical reagent delivery unit capable of delivering controlled amounts of said reagent, said unit comprising a reservoir containing a biochemical reagent (by "biochemical reagent" is meant a reagent suitable for use in biochemical applications such as immunoassays) , said reservoir being connected to a nozzle through which said reagent is able to flow, there being provided flow regulating means between said nozzle and said reservoir, said means being operable in use to regulate the flow of said reagent from said reservoir to said nozzle.

In use, the reagent of interest is placed into the reservoir. The reagent is then dispensed through the nozzle by causing the flow regulating valve to open. The amount of reagent dispensed will be determined by the diameter of the nozzle, the period for which the valve is open, and the volume of the reservoir. These are parameters which can be very accurately controlled and so the volume of reagent dispensed will be both accurate and reproducible. This will lead to an increase in speed of delivery of reagent to several reaction sites.

It is particularly advantageous to use a conventional drawing pen (such as of the type manufactured by Rotring) as a dispensing device for use in the method of the present invention. Thus, according to a further aspect of the present invention, there is provided the use of a drawing pen as a delivery system for a biochemical reagent. Such drawing pens comprise a cylindrical barrel (as nozzle) down which a fine wire passes. At the "non- writing" end of the barrel rests a ball-valve which is in contact with the fine wire; the liquid to be dispensed (normally ink, but in the present invention the reagent of interest) is contained within a cylinder, conveniently plastic, above the ball valve. The fine wire will protrude slightly from the "writing" end of the barrel.

On pressing the protruding wire against a surface, the wire pushes against the ball valve thus causing it to be displaced. The reagent is thus allowed to pass from the reservoir into the barrel (nozzle) and out onto the reagent site.

The preferred method of application of the reagent to the reagent site is to momentarily press the nozzle end (and fine wire) against the desired reagent site, thus leaving a spot of reagent on the reagent site. By repeatedly doing this a pattern of spots may be formed and so the total amount of reagent delivered to the reagent site may be accurately controlled. The amount of reagent delivered per spot, at constant valve opening time, may be controlled by using nozzles (barrels) of different diameters. Barrels of greater diameter will dispense a greater volume of reagent per spot than those of smaller diameter, all other parameters being equal. In automated systems it is particularly advantageous to prepare a particular pattern of dots on a computer using an appropriate graphics package (such graphics packages being commonly available) and then, with the delivery unit, e.g. an ordinary drawing pen of the Rotring type, connected to an automatic plotting device, reproduce the pattern of dots at a reagent site under computer control. This gives a great improvement in the reproducibility and speed of the process.

The reagent delivery unit, e.g. a drawing pen, may be calibrated by taking a unit which produces a known line width and, using a reagent of known concentration, drawing on a solid surface lines of reagent of specific dimensions. The resultant "printed" reagent is then assayed for biochemical activity.

The method of the present invention is useful in situations where specific, small amounts of a biochemical reagent have to be dosed onto a surface, for example in the production of biosensors. In particular, the method may be used to dispense reagents used in immunoassay, such as labelled or unlabelled antigens, and is particularly useful for immunosensors and especially FCFD immunosensors, for example of the type described in EP-A-171 148.

Therefore, according to another aspect of the present invention there is provided a biosensor carrying at least one reagent which has been applied thereto by a method according to the present invention.

Thus, the present invention allows the simple use of commonly available items such as drawing pens, which are manufactured to high tolerances, for dispensing accurately measured amounts of reagents. As well as the above-mentioned advantages, this leads to a cost saving. A specific embodiment of the invention will now be described with reference to the accompanying drawings in which:

Fig. l is a schematic representation of an embodiment of the delivery unit of the present invention; and

Fig. 2 is a schematic representation of the operation of the delivery unit of the present invention.

Referring to Fig. 1, the dispenser 1 comprises a body which forms a reservoir 2 which contains the liquid reagent 7. There is present a nozzle 3, the entrance to which is blocked by a ball valve 4 resting on the sides, 5,6 of the nozzle 3. Downward pressure of the reagent 7 in the reservoir 2 maintains the ball valve 4 against the sides 5,6 of the nozzle 3. A thin wire member 8 passes down the centre of the nozzle 3 and is in contact with the ball valve 4 and, in its normal position, one end thereof extends beyond the end of nozzle 3.

Referring now to Fig. 2(a), when not in use the ball valve 4 is in its closed position, thus preventing passage of the reagent 7 into the nozzle 3. When the nozzle 3 is pressed against an external surface 9 (see

Fig. 2b) the wire member 8 is pushed up against the ball valve 4, thus pushing the ball valve 4 away from its closed position and allowing the egress of reagent 7 into the nozzle. On taking the dispenser away from the surface 9 (see Fig. 2c) the ball valve 4 returns to its original position thus stopping the egress of reagent 7 and leaving a small volume of reagent 10 on the surface 9.

Claims

1. A method of delivering controlled amounts of reagent, said method comprising delivering said reagent from a device comprising a nozzle through which said reagent is able to flow and a reservoir for said reagent, said reservoir being connected to or integral with said nozzle, with flow regulating means in the form of a ball valve between said nozzle and said reservoir, said means being operable in use to regulate the flow of said reagent from said reservoir to said nozzle.

2. A method as claimed in claim 1 wherein said device is a drawing pen.

3. A method as claimed in claim 1 or claim 2 wherein said reagent is a biochemical reagent.

4. A method as claimed in claim 3 wherein said biochemical reagent is a labelled or an unlabelled antigen.

5. A biochemical reagent delivery unit capable of delivering controlled amounts of said reagent, said unit comprising a reservoir containing a biochemical reagent, said reservoir being connected to a nozzle through which said reagent is able to flow, there being provided flow regulating means between said nozzle and said reservoir, said means being operable in use to regulate the flow of said reagent from said reservoir to said nozzle.

6. A biosensor carrying at least one reagent which has been applied thereto by a method as claimed in any one of claims 1 to 4.

7. A biosensor as claimed in claim 6 being an immunosensor.

8. A biosensor as claimed in claim 6 being an FCFD immunosensor.

9. The use of a drawing pen as a delivery system for a biochemical reagent.