Microtiter plate, system and method for processing samples

0001The invention concerns a microtiter plate for processing samples having a liquid component or a liquid and a solid component or a liquid and a gel component.

0002The invention further concerns a system for processing samples having a liquid component or a liquid and a solid component or a liquid and a gel component.

0003The invention further concerns a method for processing samples having a liquid component or a liquid and a solid component or a liquid and a gel component.

0004Microtiter plates are multi-well plates that are adapted for receiving samples to be processed at a plurality of wells. Each well defines a reaction site where a sample is usually mixed with one or more reagents in order to form a sample-reagent mixture which is the subject to analysis e.g. by means of a photometer or a fluorometer.

0005In recent developments in the field of processing large numbers of samples that have a liquid component or a liquid and a solid component or a liquid and a gel component there is a need for a device that makes possible to separate the liquid from the solid or gel component of each sample rapidly and at low cost. There is in particular a need for a device of this kind which is suitable for processing in the latter way individual samples of very low volume, e.g. lower than 30 microliter.

0006The aim of the invention is to provide a microtiter plate that is configured and dimensioned for performing the above-mentioned separations for a large number of samples rapidly and at low cost.

0007According to a first aspect of the invention the above aim of the invention is attained with a microtiter plate of the above mentioned kind comprising <ul id="ul0001" list-style="none" compact="compact"><li>a single piece body which is made by injection molding,</li><li>said body having an array of cavities and</li><li>each of said cavities having an upper end and a bottom end,</li><li>each of said cavities comprising a first chamber for receiving a sample to be processed, a second chamber and a passage which fluidically connects said first and second chambers with each other, said passage having a top opening,</li><li>a region in the lower part of said passage being adjacent to the bottom end of the cavity, said region being so configured and dimensioned that it allows passage of liquid from one of said chambers to the other, but does not allow passage of any solid or gel component the size of which is larger than a predetermined size.</li></ul>

0008According to a second aspect of the invention the above aim of the invention is attained with system for processing samples having a liquid component or a liquid and a solid component or a liquid and a gel component, said system comprising a microtiter plate according to the invention.

0009According to a third aspect of the invention the above aim of the invention is attained with a method for processing samples having a liquid component or a liquid and a solid component or a liquid and a gel component, said method comprising <ul id="ul0002" list-style="none" compact="compact"><li>(a) introducing a sample having a liquid component or a liquid and a solid component or a liquid and a gel component into a first chamber of a cavity of a microtiter plate according to the invention,</li><li>(b) centrifugating the microtiter plate for transferring liquid from said first chamber to said second chamber, the liquid component of said sample being thereby entirely removed from said first chamber leaving therein only the solid or gel component of the sample.</li></ul>

0010According to a fourth aspect of the invention the above aim of the invention is attained with a method for processing samples having a liquid component or a liquid and a solid component or a liquid and a gel component, said method comprising <ul id="ul0003" list-style="none" compact="compact"><li>(a) introducing a sample having a liquid component or a liquid and a solid component or a liquid and a gel component into a first chamber of a cavity of a microtiter plate according to the invention,</li><li>(b) fluidically connecting one end of a pipetting tip with a second chamber of a cavity of a microtiter plate (11) according to the invention,</li><li>(c) performing pipetting operations on said sample with said pipetting tip for either transferring liquid from said first chamber to said second chamber or for adding a liquid reagent to said sample contained in said first chamber.</li></ul>

0011Preferred embodiments are defined by subclaims attached to this specification.

0012The subject invention will now be described in terms of its preferred embodiments with reference to the accompanying drawings. These embodiments are set forth to aid the understanding of the invention, but are not to be construed as limiting. Fig. 1 shows a perspective view of a microtiter plate 11 according to the invention. Fig. 2 shows an enlarged view of part II of microtiter plate 11 in Fig. 1. Fig. 3 shows a partial cross-sectional view of microtiter plate 11 along plane III-III in Fig. 2. Fig. 4 shows the same view of microtiter plate 11 as Fig. 3a, but shows in addition a pipetting tip inserted in chamber 17. Fig. 5 shows a partial cross-sectional view of microtiter plate 11 along plane V-V in Fig. 2. Fig. 6 shows an enlarged cross-sectional view of a part of Fig. 3. Fig. 7 shows a partial cross-sectional view of microtiter plate 11 along plane VI-VI in Fig. 6. Fig. 8 shows a partial cross-sectional view of microtiter plate 11 along plane VII-VII in Fig. 6. Fig. 9 shows a top view of a portion of microtiter plate 11 in Fig. 1. <tables id="tabl0001" num="0001"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><thead valign="top"><row rowsep="1"><entry namest="col1" nameend="col2" align="left"><b>REFERENCE NUMBER LIST</b></entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">11</entry><entry namest="col2" nameend="col2" align="left">microtiter plate</entry></row><row><entry namest="col1" nameend="col1" align="left">12</entry><entry namest="col2" nameend="col2" align="left">single piece body</entry></row><row><entry namest="col1" nameend="col1" align="left">13</entry><entry namest="col2" nameend="col2" align="left">cavity</entry></row><row><entry namest="col1" nameend="col1" align="left">14</entry><entry namest="col2" nameend="col2" align="left">upper end of cavity 13</entry></row><row><entry namest="col1" nameend="col1" align="left">15</entry><entry namest="col2" nameend="col2" align="left">bottom end of cavity 13</entry></row><row><entry namest="col1" nameend="col1" align="left">16</entry><entry namest="col2" nameend="col2" align="left">first chamber of cavity 13</entry></row><row><entry namest="col1" nameend="col1" align="left">17</entry><entry namest="col2" nameend="col2" align="left">second chamber of cavity 13</entry></row><row><entry namest="col1" nameend="col1" align="left">18</entry><entry namest="col2" nameend="col2" align="left">passage</entry></row><row><entry namest="col1" nameend="col1" align="left">19</entry><entry namest="col2" nameend="col2" align="left">top opening of passage 18</entry></row><row><entry namest="col1" nameend="col1" align="left">20</entry><entry namest="col2" nameend="col2" /></row><row><entry namest="col1" nameend="col1" align="left">21</entry><entry namest="col2" nameend="col2" align="left">zone of passage 18</entry></row><row><entry namest="col1" nameend="col1" align="left">22</entry><entry namest="col2" nameend="col2" align="left">bottom of second chamber 17</entry></row><row><entry namest="col1" nameend="col1" align="left">23</entry><entry namest="col2" nameend="col2" align="left">bottom of first chamber 16</entry></row><row><entry namest="col1" nameend="col1" align="left">24</entry><entry namest="col2" nameend="col2" align="left">top side of microtiter plate 11</entry></row><row><entry namest="col1" nameend="col1" align="left">25</entry><entry namest="col2" nameend="col2" align="left">coating of bottom of passage 18</entry></row><row><entry namest="col1" nameend="col1" align="left">26</entry><entry namest="col2" nameend="col2" align="left">zone of minimum width of passage 18</entry></row><row><entry namest="col1" nameend="col1" align="left">27</entry><entry namest="col2" nameend="col2" align="left">circular line portion</entry></row><row><entry namest="col1" nameend="col1" align="left">28</entry><entry namest="col2" nameend="col2" align="left">circular line portion</entry></row><row><entry namest="col1" nameend="col1" align="left">29</entry><entry namest="col2" nameend="col2" align="left">bottom of passage 18</entry></row><row><entry namest="col1" nameend="col1" align="left">30</entry><entry namest="col2" nameend="col2" /></row><row><entry namest="col1" nameend="col1" align="left">31</entry><entry namest="col2" nameend="col2" align="left">curved line portion</entry></row><row><entry namest="col1" nameend="col1" align="left">32</entry><entry namest="col2" nameend="col2" align="left">curved line portion</entry></row><row><entry namest="col1" nameend="col1" align="left">33</entry><entry namest="col2" nameend="col2" align="left">pipetting tip</entry></row><row><entry namest="col1" nameend="col1" align="left">34</entry><entry namest="col2" nameend="col2" align="left">sealing means</entry></row><row><entry namest="col1" nameend="col1" align="left">35</entry><entry namest="col2" nameend="col2" align="left">side edge of microtiter plate 11</entry></row><row><entry namest="col1" nameend="col1" align="left">36</entry><entry namest="col2" nameend="col2" align="left">side edge of microtiter plate 11</entry></row><row><entry namest="col1" nameend="col1" align="left">37</entry><entry namest="col2" nameend="col2" align="left">solid element</entry></row><row><entry namest="col1" nameend="col1" align="left">38</entry><entry namest="col2" nameend="col2" /></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">39</entry><entry namest="col2" nameend="col2" /></row></tbody></tgroup></table></tables>

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS (outstanding)

EXAMPLE OF A MICROTITER PLATE FOR PROCESSING SAMPLES

0013Fig.1 shows a microtiter plate 11 according to the invention for processing samples having a liquid component or a liquid and a solid component or a liquid and a gel component.

0014Microtiter plate 11 comprises a single piece body 12 made by injection molding of a suitable plastic material, e.g. Polypropylene (PP), Cyclic Olefin Copolymer (COC), Acrylonitrile/Butadien/Styrene (ABS) or Polycarbonate (CC).

0015Body 12 has an array of cavities 13 and side edges 35, 36. The grid spacing is of e.g. 4.5 millimeter measured along each of edges 35, 36, i.e.in both X-direction and Y-direction shown by arrows in Figures 1 and 9.

0016As shown in particular by Figures 1 and 9, the cross-section of each of cavities 13 has a length axis which forms an angle <u>A</u> of about 45 degrees with a side edge 35, 36 of the microtiter plate 11. This spatial arrangement of cavities makes possible to form a relatively large number of such cavities in a microtiter plate of standard size. This plate has e.g. a length of 127.76 ± 0.25 millimeter and a width of 85.48 ± 0.25 millimeter.

0017In a preferred embodiment, single piece body 12 has standard outer dimensions of a microtiter plate and comprises 384 cavities 13. In another preferred embodiment, single piece body 12 has standard outer dimensions of a microtiter plate and comprises 1536 cavities 13.

0018As shown in particular by Figures 1, 2 and 9 each of cavities 13 has an inner surface the cross-section of which is a closed curve and the inner surface has no corner or sharp edge. In a preferred embodiment the closed curve has approximately the shape of two circular line portions 27, 28 connected with each other by curved line portions 31, 32.

0019As shown by Figures 2 to 9, each of cavities 13 has an upper end 14 and a bottom end 15 and each of cavities 13 comprises a first chamber 16 for receiving a sample to be processed, a second chamber 17 and a passage 18 which fluidically connects chambers 16 and 17 with each other. Passage 18 has a top opening 19. The total volume of a cavity 13 is e.g. about 30 microliter.

0020Chambers 16, 17 and passage 18 have side walls with an inclination angle of about 4 degrees.

0021In a preferred embodiment, chamber 16 is adapted for receiving a sample having a liquid component or a liquid and a solid component or a liquid and a gel component, whereas chamber 17 is adapted for receiving a pipetting tip 33 shown by Fig. 4.

0022In a preferred embodiment microtiter plate 11 further comprises sealing means 34, shown in Figure 4, which seal the contact surface of tip 33 with the microtiter plate 11 and second sealing means (not shown) which seal the top opening of passage 18.

0023As shown in particular by Figures 1, 2 and 9, passage 18 has a variable width in a direction extending from chamber 16 to chamber 17 and that width has a minimum at a zone 26 located between chambers 16 and 17.

0024A region 21 in the lower part of passage 18 is adjacent to the bottom end 15 of the cavity 13. Region 21 is so configured and dimensioned that it allows passage of liquid from one of chambers to the other, but does not allow passage of any solid or gel component the size of which is larger than a predetermined size.

0025In a preferred embodiment, region 21 of passage 18 is configured and dimensioned as a capillary passage adapted for supporting or facilitating flow of liquid from one of chambers 16, 17 to the other. This is for instance the case when the entire length of region 21 is a capillary adapted for receiving liquid and is thereby able to provide a fluidic connection between the bottom of chamber 16 and the bottom of chamber 17. The bottom of passage 18 (shown in Fig.7) has a radius R1, e.g. R1 = 0.3 millimeter. The radius R1 is preferably comprised e.g. in a range between 0.1 to 0.5 millimeter.

0026In another preferred embodiment, region 21 of passage 18 is configured and dimensioned as a capillary passage adapted for blocking through passage 18. This is the case when the narrowest point 26 of region 21 is so narrow that it prevents liquid flow through passage 18.

0027As shown by Figures 3 to 6, in a preferred embodiment the bottom 22 of chamber 17 lies at a lower level than the bottom 23 of first chamber 16 when the microtiter plate 11 is in horizontal position and the upper ends 14 of chambers are on the top side 24 of the microtiter plate 11. As shown by Fig. 6, the bottom of chamber 16 has an inclination of about 20 degrees with respect to the top side 24 of plate 11. As shown by Fig. 7, the deepest point of the bottom of chamber 17 has a depth H1, e.g. H1 = 5 millimeter. As shown by Fig. 8, chamber 16 has a depth H2, e.g. H2 = 4 millimeter.

0028In a preferred embodiment the inner surface of the bottom 29 of passage 18 which fluidically connects chambers 16 and 17 with each other has a shape that contributes to maximize the centrifugal force exerted on a sample contained in first chamber 16 when microtiter plate 11 is centrifuged by means of a centrifugation apparatus. Figure 6 shows such a shape of the bottom 29 of passage 18.

0029In a preferred embodiment of microtiter plate 11 at least a portion of the inner surface of the bottom of each of said cavities 13 is a hydrophilic or hydrophobic surface, or is a surface having a hydrophilic or hydrophobic coating. The purpose of these surface properties is to create flow conditions that are suitable for the intended use of the microtiter plate, e.g. when a preferred sense of flow is suitable for the desired liquid handling process.

0030In a preferred embodiment at least a portion of or the entire inner surface of the bottom 29 of passage 18 is a hydrophilic surface or is a surface having a hydrophilic coating 25 shown by Fig. 6. This feature facilitates the flow of liquid through passage 18 and thereby ensures that the entire volume of liquid in chamber 16 is transferable to chamber 17 by centrifugation of microtiter plate 11.

0031In a preferred embodiment at least a portion of or the entire inner surface of the bottom 23 of chamber 16 is a hydrophilic surface or is a surface having a hydrophilic coating (not shown). This feature facilitates the flow of liquid from chamber 16 to passage 18 and thereby ensures that the entire volume of liquid in chamber 16 is transferable to chamber 17 by centrifugation of microtiter plate 11.

0032In a preferred embodiment at least a portion of or the entire inner surface of the bottom 22 of chamber 17 is a hydrophobic surface or is a surface having a hydrophobic coating (not shown). This feature facilitates the flow of liquid from chamber 16 to passage 18 and thereby ensures that the entire volume of liquid in chamber 16 is transferable to chamber 17 by centrifugation of microtiter plate 11.

0033As shown by Figures 3 to 8, in a preferred embodiment each of cavities 13 tapers towards its bottom end 15, i.e. the cross-section of each cavity 13 diminishes towards the bottom thereof.

0034As shown by Figure 9, in a preferred embodiment a solid element 37, which is liquid permeable, is arranged in region 21 of passage 18.

0035Solid element 37 is e.g. a filter element having a porous structure that allows passage of particles having a size that is smaller than a predetermined size. Such a filter element is made e.g. of glass or of a plastic material. In a preferred embodiment, solid element 37 is a membrane that allows passage of particles having a size that is smaller than a predetermined size. Such membrane is made e.g. of a plastic material, paper, a gel or a microfiber.

0036In a preferred embodiment solid element 37 is a test element, e.g. a chromatographic test element. Test element 37 is e.g. a membrane or a strip similar to a chromatographic strip which in a first step is able to retain a sample material of a certain kind as a sample flows from chamber 16 to chamber 17 through passage 18 and in a subsequent step is able to release that sample material when said test element is brought in contact with a suitable reagent, the released sample and reagent mixture being then transferable to chamber 17 e.g. by centrifugation of plate 11.

0037In a preferred embodiment solid test element 37 or at least a portion thereof is a coating having hydrophilic properties or hydrophobic properties.

EXAMPLE 1 OF A SYSTEM FOR SAMPLE PROCESSING

0038According to the invention a first system for processing samples having a liquid component or a liquid and a solid component or a liquid and a gel component comprises a microtiter plate 11 of the kind described above with reference to Figures 1-8.

0039In a preferred embodiment this first system further comprises a centrifugation apparatus (not shown in the drawings) for centrifugating the microtiter plate 11.

EXAMPLE 2 OF A SYSTEM FOR SAMPLE PROCESSING

0040According to the invention a second system for processing samples having a liquid component or a liquid and a solid component or a liquid and a gel component comprises a microtiter plate 11 of the kind described above with reference to Figures 1-8.

0041In a preferred embodiment this second system further comprises a pipetting tip 33 (shown in Fig. 4) which is insertable into chamber 17 and which is connectable to a pipetting apparatus including overpressure or underpressure generating means

EXAMPLE 1 OF A METHOD FOR SAMPLE PROCESSING

0042According to the invention a first method for processing samples having a liquid component or a liquid and a solid component or a liquid and a gel component comprises <ul id="ul0004" list-style="none" compact="compact"><li>(a) introducing a sample having a liquid component or a liquid and a solid component or a liquid and a gel component into chamber 16 of a cavity 13 of a microtiter plate 11 of the above-described type,</li><li>(b) centrifugating the microtiter plate 11 for transferring liquid from chamber 16 to chamber 17, the liquid component of sample being thereby entirely removed from first chamber 16 leaving therein only the solid or gel component of the sample.</li></ul>

0043In a preferred embodiment, the above-mentioned transfer of liquid is effected exclusively by means of centrifugal force generated by centrifugation of the microtiter plate 11. The sample volume transferred from chamber 16 to chamber 17 by centrifugation is in the range of e.g. 0.05 to 2 microliter.

EXAMPLE 2 OF A METHOD FOR SAMPLE PROCESSING

0044According to the invention a second method for processing samples having a liquid component or a liquid and a solid component or a liquid and a gel component comprises <ul id="ul0005" list-style="none" compact="compact"><li>(a) introducing a sample having a liquid component or a liquid and a solid component or a liquid and a gel component into a first chamber 16 of a cavity 13 of a microtiter plate 11 of the above-described type,</li><li>(b) fluidically connecting one end of a pipetting tip 33 with a second chamber 17 of a cavity 13 of a microtiter plate 11 of the above-described type,</li><li>(c) connecting another end of pipetting tip 33 with a pipetting apparatus including underpressure generating means for aspirating and thereby removing the liquid component of said sample from said first chamber 16 and leaving therein only the solid or gel component of the sample.</li></ul>

EXAMPLE 3 OF A METHOD FOR SAMPLE PROCESSING

0045According to the invention a third method for processing samples having a liquid component or a liquid and a solid component or a liquid and a gel component comprises <ul id="ul0006" list-style="none" compact="compact"><li>(a) introducing a sample having a liquid component or a liquid and a solid component or a liquid and a gel component into a first chamber 16 of a cavity 13 of a microtiter plate 11 of the above-described type,</li><li>(b) fluidically connecting one end of a pipetting tip 33 with a second chamber 17 of a cavity 13 of a microtiter plate 11 of the above-described type,</li><li>(c) performing pipetting operations on said sample with pipetting tip 13 for either transferring liquid from first chamber 16 to second chamber 17 or for adding a liquid reagent to said sample contained in said first chamber 16.</li></ul>

EXAMPLE OF USE OF THE MICROTITER PLATE, SYSTEM AND METHOD ACCORDING TO THE INVENTION

0046In a preferred use of the microtiter plate, system and method according to the invention the gel component of the sample contains biomolecules to be analyzed.

0047Proper use of the microtiter plate according to the invention is subject to the condition that the volume of sample introduced into chamber 16 is smaller than a predetermined maximum value. When this condition is fulfilled only the liquid component of the sample passes through region 21 of passage when transferred from chamber 16 to chamber 17 and any solid or gel component of the sample remains in chamber 16. If the above mentioned condition is not fulfilled, some of the solid and/or gel components of the sample can pass from chamber 16 to chamber 17 through the upper part of passage 18 and the desired separation of the liquid from the solid and/or gel components of the sample is not or not completely achieved.