IES85039Y1 - A well plate for holding a sample during analysis and a method for analysing a sample - Google Patents

Abstract

ABSTRACT The present invention relates to a well plate for holding a sample during analysis thereof, and in particular, though not limited to a well plate for holding a liquid sample such as bodily fluid during analysis thereof. The invention also relates to a method for analysing a sample, and in particular, though not limited to a sample of bodily fluid.

Description

A well plate for holding a sample during analysis and a method for analysing a sample” The present invention relates to a well plate for holding a sample during analysis thereof, and in particular, though not limited to a well plate for holding a liquid sample such as bodily fluid during analysis thereof. The invention also relates to a method for analysing a sample, and in particular, though not limited to a sample of bodily fluid.

Well plates for holding samples, and in particular, liquid samples, such as bodily fluids, for example, blood, blood plasma, urine and other such bodily fluids during analysis in analytical apparatus are known. Typically, such well plates comprise a plate having a plurality of wells located therein in which the samples to be analysed are placed, typically, by pipetting into the wells from a vial containing the sample.

Such well plates may comprise an elongated strip plate which may be of flexible, semi-rigid or rigid material having a plurality of wells located therein arranged in a single column extending longitudinally along the strip plate. Alternatively, the well plate may comprise a plate having the wells arranged in a matrix formed by a plurality of rows and columns of the wells. Typically, the well plate is adapted for use in a particular analytical apparatus in which the samples are to be analysed.

The wells may be of a type which are adapted for optical analysis whereby light is directed at or through the sample in the well, and the spectrum of the reflected or transmitted light is analysed in order to determine a characteristic of the sample, for example, a characteristic which would indicate the state of health of a subject from whom the sample of bodily fluid was obtained.

Alternatively, the wells may be of the type which are adapted for carrying out a mechanical analysis of a sample. Such mechanical analyses, in general, are carried out by determining the viscosity of the sample. Many mechanical methods are used in analytical apparatus for determining sample viscosity. A particularly common method is based on determining the speed at which a ball travels through the liquid.

Typically, the ball is of steel or another suitable magnetically sensitive material, and is energised to move through the sample by applying a magnetic field externally of the well. The viscosity is determined by comparing the speed with which the ball moves through the sample with the strength of the energising magnetic field.

Such known well plates are adequate for carrying out optical and mechanical analysis where the accuracy of the sample size which is placed in the well is not critical. However, where the sample size is critical, such well plates are unsuitable.

This is as a result of the fact that, in general, the sample is transferred to a well in the well plate by pipetting from a vial containing the sample. Such vials typically are closed by a stopper of a rubber or rubber type plastics material. Pipetting of the sample from the vial to the well is carried out by piercing the stopper of the vial with a pointed cannula which is then inserted through the stopper into the vial, and a volume of the sample is withdrawn into the cannula. However, due to the fact that the vial is closed by the stopper during pipetting of the sample, the pressure within the vial may vary above or below atmospheric pressure as a result of temperature, and indeed, the mere insertion of the stopper in the vial when closing the vial may be sufficient to increase the pressure within the vial above atmospheric pressure.

Accordingly, variation in pressure within the container from which the sample is being pipetted will result in a variation of the sample size withdrawn from the vial by pipetting. This is unsatisfactory where the sample size is critical.

Another problem with well plates known heretofore is that in general, the wells are unsuitable for mixing a sample with a reagent.

There is therefore a need for a well plate for holding a sample of material during analysis which addresses at least some of the problems of known well plates, and there is also a need for a method for analysing a sample using a well plate.

The present invention is directed towards providing such a well plate and a method.

According to the invention there is provided a well plate for holding a sample during analysis thereof, the well plate comprising a plate, at least one analysis well located in the plate for holding the sample during analysis, and at least one holding well located in the plate for receiving the sample prior to transfer to thelanalysis well.

Preferably, each holding well is located adjacent at least one of the analysis wells.

In one embodiment of the invention each holding well defines a hollow interior region extending downwardly from an upwardly facing open mouth for accommodating the sample into the hollow interior region. Preferably, the hollow interior region defined by each holding well terminates in a downwardly tapering portion.

In another embodiment of the invention the downwardly tapering portion of the hollow interior region defined by each holding well is of frustoconical shape.

Alternatively, the downwardly tapering portion of the hollow interior region defined by each holding well is of conical shape.

In another embodiment of the invention a portion of the hollow interior region intermediate the open mouth and the downwardly tapering portion of each holding well is of cylindrical shape.

Preferably, each holding well extends downwardly from the plate. Advantageously, each holding well is located between two adjacent analysis wells.

In one embodiment of the invention at least one of the analysis wells is a first well adapted for holding a sample during an optical analysis thereof. Preferably, each first well defines a hollow interior region extending downwardly from an open mouth for accommodating the sample into the hollow interior region. Advantageously, the hollow interior region defined by each first well terminates in a sample accommodating portion for holding the sample during analysis thereof comprising a planar base and an upwardly extending side wall. Ideally, the planar base of each first well is of rectangular shape.

In one embodiment of the invention the sample accommodating portion of each first well comprises a pair of spaced apart side walls extending upwardly from the base thereof, joined by a pair of spaced apart end walls extending upwardly from the base.

Preferably, the side walls of the sample accommodating portion of each first well extend parallel to each other. and the end walls of the sample accommodating portion of each first well extend parallel to each other. Advantageously, the hollow interior region defined by each first well tapers downwardly from the open mouth thereof to the sample accommodating portion. Ideally, the tapering portion of the hollow interior region of each first well is of rectangular transverse cross—section.

In one embodiment of the invention the tapering portion of the hollow interior region of each first well is formed by a pair of spaced apart side walls diverging upwardly from each other from the sample accommodating portion, joined by a pair of spaced apart end walls diverging upwardly from each other from the sample accommodating portion.

Preferably, each first well extends downwardly from the plate. in another embodiment of the invention at least one of the analysis wells is a second well adapted for holding the sample during a mechanical analysis thereof.

Preferably, each second well defines a hollow interior region extending downwardly from an open mouth for accommodating the sample into the hollow interior region.

Advantageously, the hollow interior region defined by each second well terminates in a sample accommodating portion for holding the sample during analysis thereof.

Ideally, the hollow interior region defined by each second well tapers downwardly from the open mouth thereof to the sample accommodating portion.

In one embodiment of the invention the sample accommodating portion of each second well is adapted for carrying out a viscosity analysis of the sample.

In another embodiment of the invention the sample accommodating portion of each second well is adapted for accommodating a ball of magnetically sensitive material therein and for facilitating movement of the ball therein in response to an applied magnetic field. Preferably, the sample accommodating portion of each second well comprises a base of circular shape and a side wall extending around and upwardly from the base. Advantageously, the sample accommodating portion of each second well defines an annular channel for guiding the ball around the base of the sample holding portion. Ideally, the annular channel of the sample accommodating portion of each second well is defined between the side wall of the sample accommodating portion and a projection extending upwardly from the base spaced apart from the side wall. Preferably, the projection extending upwardly from the base of the sample accommodating portion of each second well tapers upwardly from the base.

Advantageously, the projection extending upwardly from the base of the sample accommodating portion of each second well is of conical shape.

Preferably, each second well extends downwardly from the plate.

In one embodiment of the invention a plurality of holding wells are provided, the holding wells being arranged in spaced apart columns, each column comprising a plurality of holding wells. Preferably, the columns of the holding wells extend parallel to each other. Advantageously, the holding wells of the respective columns are aligned to form a plurality of parallel rows thereof.

In another embodiment of the invention a plurality of analysis wells are provided, the analysis wells being located in a plurality of spaced apart columns, each column comprising a plurality of analysis wells, and the columns of holding wells and analysis wells being arranged alternately on the plate. Preferably, the analysis wells are aligned in the respective columns thereof to form a plurality of rows of the analysis wells. Advantageously, the analysis wells in each column thereof are alternately arranged as first wells and second wells. Ideally, the analysis wells of each row of analysis wells are of one of the first well type and the second well type.

In one embodiment of the invention each holding well and each analysis well is adapted for holding a liquid sample.

Additionally, the invention provides a method for analysing a sample, the method comprising transferring the sample into a holding well of a well plate, transferring a measured quantity of the sample from the holding well to an analysis well of the well plate, and analysing the sample in the analysis well.

Preferably, the sample is mixed with a reagent in the holding well prior to being transferred to the analysis well. Advantageously, two accurately measured samples are transferred from the holding well to respective ones of first and second wells of the analysis wells. Ideally, the sample in the first well is analysed by an optical analysis method, and the sample in the second well is analysed by a mechanical analysis method. in one embodiment of the invention the sample is a liquid sample.

In another embodiment of the invention the sample is a sample of bodily fluid.

The well plate according to the invention has many advantages. The well plate according to the invention facilitates pipetting of samples of relatively accurate sample size into the analysis wells, and additionally, facilitates mixing of samples with a reagent or other substance. Furthermore, the well plate according to the invention facilitates the provision of a sample of relatively accurate sample size which in turn can be mixed with a reagent or other substance.

By virtue of the fact that the well plate comprises holding wells, samples of relatively inaccurate size may be pipetted into the holding wells, and then subsequently pipetted from the holding well to an appropriate one of the first or second analysis well, or both by relatively accurate pipetting. Accurate pipetting of samples from the holding well to the analysis well or wells is achieved by virtue of the fact that the sample from the holding well is sampled at atmospheric pressure. The provision of each holding well with a hollow interior region which terminates in a downwardly tapering portion facilitates pipetting of samples therefrom due to the fact that the liquid level in the holding well for a sample of given size is higher than would be the case it the holding well terminated in a relatively flat or planar base.

A further advantage of the invention is achieved where it is desired to mix a sample with a reagent, in that the sample may be mixed in one of the holding wells with the reagent prior to being transferred to an appropriate one of the first and second analysis wells or both. Additionally, if it is desired to mix a sample of relatively accurate size with a reagent, an accurate sample may be pipetted from one holding well to another, and the accurate sample may then be mixed with the reagent in the holding well into which it has been transferred, before a sample of the mixed sample and reagent is pipetted into an appropriate one of the first and second analysis wells or into both a first and a second analysis well.

The invention will be more clearly understood from the following description of a preferred embodiment thereof, which is given by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a top plan view of a portion of a well plate according to the invention, Fig. 2 is a transverse cross-sectional end elevational view of the well plate of Fig. 1 on the line ll-ll of Fig. 1.

Referring to the drawings, there is illustrated a well plate according to the invention, indicated generally by the reference numeral 1, for holding a sample, for example, a sample of bodily fluid, such as blood, blood plasma, urine and the like during analysis thereof in an analytical apparatus (not shown). The analytical apparatus does not form part of the invention, and will not be described, however, such analytical apparatus will be well known to those skilled in the art. The analytical apparatus may be of the type which is suitable for carrying out an optical analysis or a mechanical analysis of the sample, or, and more typically, it may be of the type which carries out both an optical and a mechanical analysis of the apparatus. In this embodiment of the invention the well plate 1 is suitable for use in a range of analytical apparatus sold under the trade name AMAX DESTINY by Trinity Biotech PLC of Ireland.

The well plate 1 comprises a plate 2, which in this embodiment of the invention is of a semi-rigid plastics material. A plurality of analysis wells, in this embodiment of the invention first wells 3 and second wells 4 for holding samples during analysis thereof extend downwardly from the plate 2, and are arranged in a plurality of columns 5 and rows 6 as will be described below. The first wells 3 are adapted for facilitating the carrying out an optical analysis on a sample placed therein, while the second wells 4 are adapted for facilitating the carrying out a mechanical analysis on a sample placed therein, as will be described below. A plurality of holding wells 8 for holding samples prior to being transferred to an appropriate one or ones of the first and second wells also extend downwardly from the plate 2. The holding wells 8 are also arranged in columns 9 which are alternately located with the columns 5 of the first and second wells 3 and 4. The holding wells 8 are also arranged within the rows 6 of the first and second wells 3 and 4. Typically, a sample is pipetted from a vial or other such container into an appropriate one of the holding wells 8, and then an accurate sample of the sample in the holding well 8 is accurately pipetted from the holding well 8 into one or more of the first and second wells 3 and 4, so that the samples pipetted into the first and second wells 3 and 4 are of accurate size.

Additionally, if desired, the sample may be mixed with a reagent in the holding well 8, or a more accurate sample size may be pipetted from the holding well into another one of the holding wells 8, and the reagent could then be mixed with the accurate sample in the holding well 8 prior to a sample of the mixed sample and reagent being transferred into the first and/or second wells 3 and 4.

Each holding well 8 comprises an upper cylindrical side wall 10 which extends downwardly from the plate 2 and terminates in a lower conical side wall 12, which in turn terminates in a lower apex 14. The cylindrical side wall 10 and the conical side |\) LII wall 12 together define a hollow interior region 15 for holding the sample, and the cylindrical side wall 10 defines an upwardly facing open mouth 16 for accommodating the sample into the hollow interior region 15. The conical side wall 12 results in the hollow interior region 15 terminating in a downwardly tapering lower portion 17 which results in the level of the sample in the hollow interior region 15 and in the tapering portion 17 being maintained at a higher level than would otherwise be the case if the hollow interior region terminated in a flat base, and the tapering portion 17 also facilitates more even distribution of constituents being mixed in the holding wells 8.

Each first well 3 comprises a planar base 19 of rectangular shape and a pair of spaced apart side walls 20 extending upwardly from the base 19 and joined by a pair of spaced apart end walls 21, which also extend upwardly from the base 19. The base 19, the side walls 20 and the end walls 21 of each first well 3 define a hollow interior region 23, and the side and end walls 20 and 21 terminate in the plate 2 and define an open mouth 25 for accommodating a sample into the hollow interior region 23. Lower portions 27 of the side walls 20 extend upwardly from the base 19 parallel to each other, and lower portions 28 of the end walls 21 also extend upwardly from the base 19 parallel to each other. The side and end walls 20 and 21 are polished for facilitating the optical analysis of the samples in the first wells 3. Upper portions 29 of the side walls 20 extend upwardly from the lower portions 20 thereof to the plate 2, and diverge upwardly from each other. Upper portions 30 of the end walls 21 extend upwardly from the lower portions 28 thereof to the plate 2, and diverge upwardly from each other.

Each second well 4 comprises a base 33 of circular shape and a lower cylindrical side wall 34 extending upwardly from and around the base 33. A pair of spaced apart upper side walls 35 extends upwardly from the lower cylindrical side wall 34 and terminate in the plate 2. A pair of spaced apart end walls 36 extend upwardly from the lower cylindrical side wall 34 to the plate 2 and join the upper side walls 35.

The side walls 35 diverge upwardly from each other as do the end walls 36. The base 33 and the lower side wall 34 and upper side and end walls 35 and 36 define a hollow interior region 37 for receiving the sample to be analysed, and the upper side and end walls 35 and 36 define an open mouth 38 for accommodating the sample into the hollow interior region 37. A projection 39 of conical shape terminating in an upper apex 40 extends upwardly from the centre of the base 33 of each second well 4, and defines with the cylindrical side wall 34 an annular channel 41 for accommodating and guiding a ball 42 through a circular annular path around the base 33 within the sample for facilitating a determination of the viscosity of the sample. The ball 42 is illustrated in the channel 41 in one of the second wells 4 illustrated in Fig. 2, and is propelled along the annular path 41 by an externally applied magnetic field which is applied by the analytical apparatus in which the well plate 1 is placed for carrying out the analysis of the sample. The ball 42 does not form part of the invention. The lower side wall 34, the upper side wall 35 and the upper end wall 36 are polished for facilitating optical analysis of the sample in the second wells 4, if desired.

The first and second wells 3 and 4 are alternately located along each column 5 of first and second wells 3 and 4. Each row 6 comprises only first and second wells 3 and 4 of the same type. For example, the first of the rows 6a comprise second wells 4 only, while the second row 6b comprises first wells 3 only, and the third row 6c comprises second wells 4 only, and so on. However, each row 6 of first wells 3 and second wells 4 also comprises holding wells 8, which are located alternately with the corresponding ones of the first wells 3 and the second wells 4.

A downwardly extending reinforcing lip 64 extends downwardly and around the plate 2 for strengthening the plate 2. A plurality of spaced apart webs 45 extend downwardly from the plate 2 between the holding wells 8 and the first wells 3, and between the holding wells 8 and the second wells 4. ln this embodiment of the invention the well plate is of injection moulded plastics material, and the first and second wells 3 and 4 and the holding wells 8 are integrally injection moulded with the plate 2. in use, the well plate 1 is inserted in an analytical apparatus, and a first pipetting mechanism also associated with the analytical apparatus sequentially pipettes samples to be analysed from vials containing the samples which are also located in the apparatus into the holding wells 8. Where it is desired to subject a sample to both optical and mechanical analysis, two samples are accurately sequentially pipetted from the appropriate holding well 8 by a second pipetting mechanism, also associated with the analytical apparatus to adjacent ones of the first and second wells 3 and 4, although in certain cases the sample may be transferred from the holding well 8 to one or each of the first and second wells 3 and 4 by the first pipetting mechanism. The samples in the first and second wells 3 and 4 are then subjected to optical and mechanical analysis in the analytical apparatus. If the samples are blood or blood plasma samples, the samples may be analysed for determining a characteristic of the sample, in order to, for example, make a diagnosis of a condition of a subject.

Where it is desired to carry out only one of an optical and mechanical analysis, a relatively accurate sample is pipetted from the holding well 8 into an appropriate one of the first and second wells 3 and 4, or two relatively accurate samples may be pipetted from the holding well 8 into two adjacent ones of the first and second wells 3 and 4.

Should it be desired to mix the sample with a reagent, the sample pipetted into the holding well 8 is mixed in the holding well 8 with the reagent, and one or more relatively accurate samples of the mixed sample and reagent are pipetted from the holding well 8 to one or more of the first and/or second wells 3 and 4 as desired.

The samples in the first well 3 and/or the second well 4 are then subjected to the appropriate one of optical and mechanical analysis.

Should it be desired to mix a relatively accurate sample with a reagent, a relatively accurate sample is pipetted from the holding well 8, into which the sample has been pipetted by the first pipetting mechanism, into another holding well 8 by the second pipetting mechanism, and the relatively accurate sample is mixed in the holding well with the reagent and subsequently transferred to one or more of the first and second wells 3 and 4.

The actual analysis which is carried out by the analytical apparatus will depend on the samples and the characteristics of the samples which are to be detected or monitored, and will also depend on the material sampled.

While the well plate has been described as comprising analysis wells which are suitable for both optical and mechanical analysis, in certain cases, it is envisaged that the analysis wells may be all of one type, for example, may all be suitable for only one of optical or mechanical analysis. It will also be appreciated that while the first and second wells and the holding wells have been described as being located on the plate of the well plate in rows and columns, in certain cases, it is envisaged that the plate of the well plate may be provided as a single elongated strip which would comprise a plurality of the wells arranged in a single column extending longitudinally along the strip plate. In which case, it is envisaged that the holding wells and the analysis wells would be alternately arranged along the column, and where the well plate comprised both first and second wells, the first and second analysis wells would be arranged so that the first and second analysis wells would be alternately arranged with the holding wells.

While the well plate has been described as being of a plastics material and formed by injection moulding, the well plate may be of any other suitable material, and may be formed by any other suitable process.

While the samples have been described as being transferred by pipetting, any other suitable means of transferring the samples may be used.

While the side and end walls of the second wells have been described as being polished, while this is advantageous, in that it permits the second wells to be used for both mechanical and optical analysis, it is not essential. It is also envisaged in certain cases that the base of the second wells may also be polished for facilitating optical analysis.

While the side and end walls of the first wells have been described as being polished, in certain cases, it is envisaged that only the side walls would be polished, or only the end walls would be polished. It is also envisaged in certain cases that only a part of the side and/or end walls would be polished, and it is also envisaged that in certain cases the base ofthe first wells may be polished.

While the well plate has been described as being suitable for a particular range of analytical apparatus, it will be readily apparent to those skilled in the art that the well plate may be used in any other analytical apparatus, and may be readily adapted for use in other analytical apparatus if required.

Claims (5)

Claims

1. A well plate comprising a plate, at least one first analysis well located in the plate adapted to hold a sample during an optical analysis thereof, at least one second analysis well located in the plate adapted to hold a sample and to accommodate a ball of magnetically responsive material therein with the ball being moveable in the sample in response to an applied magnetic field for carrying out a mechanical analysis of the sample, and at least one holding well located in the plate adapted to receive a sample prior to transfer to one of the at least one first analysis well and the at least one second analysis well.

2. A well plate as claimed in Claim 1 in which the at least one second analysis well defines a hollow interior region extending downwardly from an open mouth for accommodating the sample into the hollow interior region and terminating in a sample accommodating portion for holding the sample during analysis thereof, the sample accommodating portion defining an annular channel for guiding the ball through the sample in the sample accommodating portion.

3. A well plate as claimed in Claim 2 in which the at least one second analysis well terminates in a base of circular shape, and a lower cylindrical side wall extends around and upwardly from the base to define the sample accommodating portion thereof, the annular channel of the sample accommodating portion being defined between the cylindrical side wall of the sample accommodating portion and a projection extending upwardly from the base into the sample accommodating portion spaced apart from the side wall.

4. A well plate for holding a sample during analysis thereof. the well plate being substantially as described herein with reference to and as illustrated in the accompanying drawings.

5. A method for analysing a liquid sample using the well plate as claimed in any preceding claim, the method comprising transferring the sample into one of the holding wells of the well plate and transferring two accurately measured samples from the holding well to each of one of the first analysis wells and one of the second analysis wells.