METHOD FOR OPERATING AN ANALYZER, CARTRIDGE AND ANALYZER
20230191407 · 2023-06-22
Inventors
- Frank Schwemmer (Freiburg, DE)
- Oliver Strohmeier (Freiburg, DE)
- Mark Keller (Freiburg, DE)
- Thomas Van Oordt (Basel, CH)
Cpc classification
B01L2300/1805
PERFORMING OPERATIONS; TRANSPORTING
B01L2400/0677
PERFORMING OPERATIONS; TRANSPORTING
B01L3/5027
PERFORMING OPERATIONS; TRANSPORTING
B01L2200/16
PERFORMING OPERATIONS; TRANSPORTING
B01L2300/087
PERFORMING OPERATIONS; TRANSPORTING
B01L7/52
PERFORMING OPERATIONS; TRANSPORTING
International classification
Abstract
A method for operating an analysis device for carrying out an analysis process, more particularly by using a polymerase chain reaction, includes providing a cartridge having a microfluidic channel-and-chamber structure. At least one film bag containing a process liquid is disposed in a stick-pack chamber of the cartridge. In an opening step the stick-pack chamber or stick-pack chambers are heated to a temperature of 80 to 130 degrees Celsius, and in the opening step the cartridge rotates at a rotational speed of 20 to 80 Hz. A cartridge and an analyzer are also provided.
Claims
1. A method for operating an analyzer for carrying out an analysis process or an analysis process using a polymerase chain reaction, the method comprising the following steps: providing a cartridge having a microfluidic channel-and-chamber structure, and placing at least one film bag containing a process liquid in at least one stickpack chamber of the cartridge; in an opening step, heating the at least one stickpack chamber to a temperature of from 80 to 130 degrees Celsius; and in the opening step, rotating the cartridge at a speed of from 20 to 80 Hz.
2. The method according to claim 1, which further comprises using, as the film bag, a bag composed of a peel film having a heat-sealed separation seam.
3. The method according to claim 1, which further comprises subjecting the stickpack chamber to localized heating.
4. The method according to claim 1, which further comprises choosing a volume of the stickpack chamber and a liquid volume of the film bag so that the liquid volume of the film bag in a nondisplaced state is equal to or less than about a quarter of the volume of the stickpack chamber.
5. The method according to claim 4, which further comprises setting the volume of the stickpack chamber at about 1000 to 1500 microliters.
6. The method according to claim 1, which further comprises: locating the stickpack chamber radially outwardly of a rotation axis of the cartridge; using a radially outwardly connected channel to connect the stickpack chamber to a radially inwardly offset chamber; and lowering the speed of rotating the cartridge at a constant temperature in order to empty the stickpack chamber through the channel into the inwardly offset chamber.
7. The method according to claim 6, which further comprises lowering the speed of rotating the cartridge to about 5 to 20 Hz.
8. The method according to claim 6, which further comprises lowering the speed of rotating the cartridge to about 10 to 15 Hz.
9. A cartridge for an analyzer carrying out an analysis process or an analysis process using a polymerase chain reaction, the cartridge comprising: a microfluidic channel-and-chamber structure including at least one stickpack chamber; at least one film bag disposed in said at least one stickpack chamber and containing a process liquid; a planar, disk-shaped cartridge structure with a rotation axis; said at least one stickpack chamber disposed radially outwardly of said rotation axis; a chamber disposed downstream of said at least one stickpack chamber; and a radially outwardly connected channel forming a radially inwardly directed curve, said radially outwardly connected channel connecting said at least one stickpack chamber to said downstream chamber.
10. The cartridge according to claim 9, wherein said microfluidic channel-and-chamber structure is at least partially covered, and said at least one film bag is fixed in said at least one stickpack chamber.
11. An analyzer for carrying out an analysis process or an analysis process using a polymerase chain reaction, the analyzer comprising: an accommodation device for a cartridge; a rotary drive for rotation of the cartridge; a heating device for heat input into the cartridge; and a controller configured to carry out the method according to claim 1.
12. The analyzer according to claim 11, wherein said heating device is configured for localized heat input into the cartridge.
Description
BRIEF DESCRIPTION OF THE FIGURES
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DETAILED DESCRIPTION OF THE INVENTION
[0034] Referring now in detail to the figures of the drawings, in which parts corresponding to one another are always provided with the same reference signs, and first, particularly, to
[0035] In an optional variant (depicted herein), the disk 1 also has a (in this case: two-part, preferably self-adhesive) label 26 which is applied to the cover 14. The label 26 is configured in such a way that it allows read-out through the read-out windows 22 and 24. In an optional variant, the label 26 has transparent regions which cover the read-out windows 22 and 24. Conveniently, the transparent regions are not provided with adhesive—i.e., kept free of adhesive—so that fluorescence detection is not influenced by possibly luminescent adhesive.
[0036] Laterally molded in the cover 14 in a lateral wall 30 are recesses 28 which allow alignment and positioning of the disk 1 in an automatic feed of an analyzer.
[0037] The main body 2 has multiple (in this case: specifically two) through-holes 32 which are used for clear alignment and positioning of the disk 1 on a support plate (referred to hereinafter as a “rotary plate 34,” see
[0038] The rotary plate 34 of the analyzer is used for centrifugation, i.e., for rotation of the disk 1 about a rotation axis 40 (see
[0039] In an alternative exemplary embodiment, the heating elements 42 are formed by Peltier elements, which also allow active cooling.
[0040] Individual chambers, channels and further elements of the disk 1 will be described in greater detail below on the basis of the method sequence described below.
[0041] In order to carry out the analysis method, at least one disk 1, into which a swab 44 has been inserted through the inlet 10 as sample material carrier into a swab chamber 46 of the channel-and-chamber structure 4, the inlet 10 then being closed by using the cap 12, is inserted into the analyzer and positioned and placed on the rotary plate 34. If only one disk 1 is inserted, the analyzer is configured to automatically counterbalance the rotary plate 34 (in particular by arranging counterweights on the rotary plate 34). For fixation, the disk 1 is sucked onto the rotary plate 34 by using a vacuum pump. Sealing contours 48 encircling the heating elements 34 are used for this purpose. The disk 1 is in contact therewith and can therefore be regionally sucked onto the rotary plate 34. This conveniently allows close contact between the heating elements 42 and the regions of the disk 1 to be locally heated.
[0042] In an initial state (i.e., without already introduced sample or without swap 44), the disk 1 contains prestored liquid reagents in closed stickpacks 50 in a first stickpack chamber 52 and a second stickpack chamber 54. Furthermore, so-called primers are prestored in preamplification chambers 56. Further primers and so-called probes (also referred to as “gene probes,” usually in the form of polynucleotides or oligonucleotides) are prestored in multiple read-out chambers 58. The read-out chambers 58 are visible through the read-out window 24 of the cover 14. The primer pairs in the preamplification chambers 56 are—depending on the specific goal of the analysis method and/or of the specific procedure—identical or different. For example, the primers in the read-out chambers 58 are pairwise identical to the primers in the preamplification chambers 56 or, for example, provided for a “nested PCR,” as known in the prior art, and therefore different.
[0043] Prestored in a first, approximately round “lyochamber 60” and a second, likewise approximately round lyochamber 61 are lyophilisates containing, for example, enzymes, polymerase, dNTPs (deoxynucleoside triphosphates), salts and/or other prestored reagents (e.g., PCR additives, nuclease inhibitors, cofactors of the enzymes concerned, etc.). In the present exemplary embodiment, the swab chamber 46 contains a lysis and measures for process control, for example spores, fungi, phages or artificially produced targets. A lysis chamber 62 connected to the swab chamber 46 contains a lysis pellet and also a magnet and a grinding medium. The latter is, for example, glass particles and/or zirconia particles. The particles are optionally coated with EDTA or it has been added in order to prevent coagulation in blood as sample material. In order to bind inhibitors, activated carbon is optionally added. This means that, in such an optional case, activated carbon is likewise prestored.
[0044] After sampling—for example by using a blood capillary as an alternative to the swab 44 (in sterile form in the medical setting)—the sample carrier, i.e., the swab 44 in the present case, is thus inserted into the disk 1, specifically into the swab chamber 46, and the inlet 10 is closed with the cap 12 (cf.
[0045] After the disk 1 has been positioned and fixed on the rotary plate 34, the lysis of the sample material is started by magnets disposed in the analyzer being driven over the disk 1. As a result, a magnetic field variable relative to a reference system of the disk 1 is generated and the magnet disposed in the lysis chamber 62 is moved. Due to the movement of the magnet, the particles of the grinding medium that are present in the lysis chamber 62 are rubbed against one another, with the result that bacteria, fungi, viruses or other analytes are disrupted.
[0046] In an optional method step, this mechanical lysis is thermally assisted by heating the lysis chamber 62 by using the relevant locally assigned heating element 42.
[0047] Meanwhile, there is rotation of the rotary plate 34 and thus also of the disk 1, with the result that comparatively large sample particles are sedimented due to centrifugation. This not only increases tolerance of biochemical inhibition, but also reduces the risk of clogging of microfluidic channels of the channel-and-chamber structure 4.
[0048] Optionally, the sample can be already multiplied in this starting step by using a polymerase chain reaction (PCR) or an isothermal method (e.g., loop-mediated isothermal amplification or LAMP for short, or recombinase polymerase amplification or RPA for short). Also conceivable is a nonspecific amplification in this starting step by using so-called whole-genome amplification, based for example on PCR or MDA (multiple displacement amplification).
[0049] In general, the sample material is, however, first homogenized as a result of the movement of the magnet and the particles, optionally assisted by convection based on a temperature gradient occurring in the lysis chamber 62 due to the optional one-sided heating. If a biochemical reaction in the lysis chamber 62 should additionally be envisaged, the reaction conditions in the lysis chamber 62 are also simultaneously kept homogeneous as a result, i.e., in particular a stable temperature distribution is established and/or a high degree of mixing of materials is achieved. This is particularly relevant to samples of very low concentration or to difficult-to-lyse samples. Shearing of DNA or RNA that is likewise possible can assist later amplification, since secondary structures are reduced as a result. Due to the mechanical action of the moved magnet and the forces applied to the sample material as a result, what can be (randomly) cut (“sheared”) are namely DNA or RNA strands. The strength of the shearing can be controlled by the duration and intensity of the mechanical action (i.e., thus the “mechanical lysis”), for example the speed of movement of the magnet. However, care has to be taken that DNA and RNA are not excessively sheared, since amplification is otherwise no longer possible.
[0050] In addition, in a further method step, specifically a so-called “opening step,” the stickpack chambers 52 and 54 are heated locally to about 90° C. by using the relevant heating elements 42 and, afterwards (optionally also at the same time), the speed of the rotary plate is increased to over 30 Hz, in particular in the region of about 60 Hz. With this centrifugation at medium to high speed, the stickpacks 50 are opened within a comparatively short time of about 5 seconds due to the combination of heating and centrifugal force. Due to heating, what is thermally weakened is namely a tear seam or peel seam 67 of the stickpacks 50 formed from a so-called peel film. In
[0051] During rotation at least at 25 Hz, especially at more than 30 Hz, preferably about 60 Hz, described above, an overpressure p moreover also builds up inside the stickpack chamber 54 due to the heating of the stickpack chamber 54 (see
[0052] With subsequent reduction of the speed, the overpressure p in the stickpack chamber 54 leads to displacement of most of the liquid (preferably more than 90%) from the stickpack chamber 54 through the channel 68 to the lyochamber 61 (cf.
[0053] In accordance with the aforementioned, what also takes place is the opening of the stickpack 50 in the stickpack chamber 52 and the transfer of the liquid through the channel 68 from the stickpack chamber 52 into the swab chamber 46 and lysis chamber 62. With its radially outward edge, the lysis chamber 62 does lie approximately radially level with the stickpack chamber 52. But the channel 68 leading into the lysis chamber 62 (and into the swab chamber 46) initially runs from radially outside to radially inside in a curve, and so “direct” overflow of the liquid into the swab chamber 46 and lysis chamber 62 is prevented. The transfer of the liquid from the stickpack chamber 52 takes place before or during the above-described (mechanical) lysis in the lysis chamber 62 in order to be able to already utilize in this case the liquid of the stickpack 50 of the stickpack chamber 52.
[0054]
[0055] In a subsequent method step, the liquid (the “lysate”) is transported from the lysis chamber 62 into the subsequent lyochamber 60 (depicted in
[0056] The lyochamber 60 is connected to an overflow chamber 72 by using an overflow channel 70. During transport of the lysate from the lysis chamber 62 into the chamber 60, excess lysate flows through the overflow channel 70 into the overflow chamber 72. Connected to the overflow chamber 72 are control chambers 74 and 76, which are used to check for correct filling of the disk 1. Lysate flowing off into the overflow chamber 72 fills, from there, the control chambers 74 and the control chambers 76 (depicted schematically in
[0057] In a further method step, liquid is subsequently transferred from the lyochamber 60 into the preamplification chambers 56 through a transfer channel 78 by using a high speed of 40-60 Hz. Once the liquid level in the preamplification chambers 56 goes beyond a mouth of a respective outlet channel 80, there is compression of the trapped air volume in the (radially inwardly pointing) “head space” of the preamplification chambers 56 and in one downstream chamber 84 each, connected by an assigned channel 82 (see
[0058] Under high centrifugation at speeds of 40-80 Hz, what takes place in the subsequent method step is preamplification in the preamplification chambers 56. The overpressure in the preamplification chambers 56 and the chambers 84 is maintained during the preamplification due to the high centrifugation. Primers prestored in the preamplification chambers 56, for example spotted with trehalose, are first dissolved. If RNA is to be detected, reverse transcription can optionally first be carried out at a constant 35-70° C. for 30 seconds to 10 minutes or to 30 minutes in order to transcribe any RNA present into DNA. However, the preamplification by using PCR occurs by local and cyclic heating and cooling of the liquid in the preamplification chambers 56 between the ranges 50-75° C. and 80-100° C. The preamplification includes 5-30 preamplification cycles. Each cycle includes heating to 80-100° C. and subsequent cooling to 50-75° C.
[0059] The (preamplification) reaction inside the preamplification chambers 56 is assisted by a high degree of convection. It is caused by the one-sided heat input into the disk 1, specifically into the preamplification chambers 56 from the heat input side 8, and the simultaneously occurring rotation. The liquid in the preamplification chamber 56 is first heated at the heat input side 8 heated by using a heating element 42 and it thus forms a heated interface. At the same time, the density of the interface decreases relative to the rest of the liquid volume. The heated liquid of the interface rises in the artificial gravity field which is caused by the rotation of the disk 1 and which is oriented in the radial direction R, first “inwardly” against the radial direction R and then transversely to the radial direction R toward the top side 16. There, the liquid cools and falls “due to gravity” along the top side 16, outwardly in the radial direction R, and then back toward the heat input side 8. What thus occurs as a result of the heat input is convection and flow along the radial direction R. Furthermore, the Coriolis forces that likewise occur lead to the formation of a tangential (i.e., perpendicular to the radial direction R in the plane direction of the disk 1) flow component, which additionally supports the mixing of the liquid. Since the convection is caused by the artificial gravity field, it is increased by faster rotation of the disk 1. The convection that occurs at high speeds thus leads to particularly effective mixing of the reaction components inside the preamplification chambers 56, and this in turn allows efficient amplification conditions.
[0060] However, one side effect is that, in the case of very high heat output on the nonheated top side 16 of the disk 1, a high temperature gradient of, for example, 10° C. (or Kelvins) can form within the liquid volume of the preamplification chamber 56 of, for example, 10 Kelvins, which may be disadvantageous. Just the cover 14, which brings about air shielding, leads to a significant reduction in the temperature gradient to about 4-5 kelvins.
[0061] For further reduction of the heat output, the cover 14 has, in a further exemplary embodiment, a frame web 86 which annularly surrounds the preamplification chambers 56 and therefore further reduces the heat output due to convection on the top side 16 (see
[0062] In the event too of the occurrence in the preamplification chambers 56 of a reaction which requires an interaction, for example binding of molecules to a solid phase, for example to microarrays, or a reaction in which the concentration of the respective reaction partners is usually low and mutual contact of the respective reaction partners is therefore subject to a comparatively low probability, the high degree of convection (and therefore comparatively strong mixing) and the homogeneous temperature distribution can be advantageous.
[0063] After completion of the preamplification, the speed is reduced to about 5 to 20 Hz, specifically to about 10 Hz. As a result, the compressed air volume in the head space of the preamplification chambers 56 and in the chambers 84 can expand. This leads in turn to lowering of the liquid level inside the preamplification chambers 56, by liquid which is radially within the mouth of the outlet channels 80 being at least mostly displaced by the expanding air through the outlet channels 80 into a further chamber 88. This is made possible by the outlet channels 80 having a lower fluid resistance, specifically a larger channel cross section, than the transfer channel 78 leading into the preamplification chambers 56.
[0064] The disk 1 has vent channels 90 which, inter alia, are connected to the chamber 88 and allow internal venting of the disk 1 into other chambers. Therefore, air which would be compressed by liquid flowing into the chamber 88 can escape through the vent channels 90 in the direction of the lyochamber 60.
[0065] In a subsequent method step, the speed of the disk 1 (or the rotary plate 34) is adjusted, specifically increased, to a value range of 10-20 Hz, preferably to about 15 Hz. As a result, the liquid from the chamber 88 flows through a siphon 92 into a measurement chamber 94 which has radially outwardly three “measurement fingers” or chamber projections of differing volume. The measurement fingers are filled successively, and so the specified (measurement finger) volume leads to measurement of individual subvolumes (see
[0066] In the next method step (see
[0067] Now, present in the lyochamber 61 are a “main amplification buffer,” which was originally prestored in the stickpack 50 disposed in the stickpack chamber 54, a lyophilisate now dissolved in this liquid, which lyophilisate was prestored in the lyochamber 61, and the “preamplification product” contained in the liquid from the preamplification chambers 56, which preamplification product was supplied through the channel 96.
[0068] In a subsequent method step, the disk 1 is rotated under comparatively rapid changes of direction, each with a change rate of 5 to 40 Hz/s, preferably by about 30 Hz/s, between end values of −20 to 40 and +20 to 40 Hz. In this case, the signs indicate the different rotation directions. The components present in the lyochamber 61 are mixed due to the accelerations occurring with the changes of direction and to Euler and Coriolis forces generated as a result in the rotation system.
[0069] In parallel, the read-out chambers 58, measurement chambers 102 upstream thereof, and an overflow chamber 104 are heated by using the correspondingly assigned heating element 42. The air expanding as a result can escape into the chamber 100 through a compensation channel 106. The mixing operation is completed by ending the changes of direction and returning to a constant speed of about 20 Hz. Thereafter, the read-out chambers 58, the measurement chambers 102 and the overflow chamber 104 are cooled back down. As a result, a relative underpressure is formed in the relevant chambers 58, 102 and 104 and the fill level in a siphon channel 108 subsequently connected to the lyochamber 61 and in the compensation channel 104 connected to the chamber 100 rises depending on a ratio between centrifugal pressure and difference in air pressure. Once the liquid goes beyond the vertex 110 of the siphon channel 108, the entire liquid is driven out of the lyochamber 61 into the subsequent measurement chambers 102 (see
[0070] The liquid flows successively into the individual measurement chambers 102 and is measured as a result. Furthermore, the liquid in the measurement chambers 102 is initially retained by one centrifugal pneumatic value each in the form of one valve channel 114 each. Excess liquid flows off into the overflow chamber 104. The centrifugal pneumatic values are based on the fact that the liquid is retained in the respective valve channel 114 by the counter-pressure in the respectively subsequent read-out chamber 58 and cannot flow into the subsequent read-out chambers 58 at a speed in the medium speed range, specifically of about 15-25 Hz in this case.
[0071] In a subsequent method step, the speed is sufficiently increased, typically to over 40 Hz, for the (liquid) menisci in the respective valve channels 114 to become unstable due to the so-called “Rayleigh-Taylor instability” and for the liquid to therefore be at least mostly transferred into the corresponding read-out chamber 58 (see
[0072] In a further method step, what now take place in the read-out chambers 58 are the main amplifications. To this end, the primers and probes respectively prestored in the read-out chambers 58 are dissolved. The dissolution of the primers and probes and the subsequent amplification are assisted by a high degree of convection inside the read-out chambers 58, the cause of which is as described above for the preamplification chamber 56. The reaction is read after each cycle at about 60° C. in all read-out chambers 58 by using a fluorescence detector. It detects the fluorescence in different wavelengths. Readings are made through the read-out window 24 in the cover 14. The operation therefore corresponds to a so-called “real-time PCR.” In this case, what can take place in each of the twelve read-out chambers 58 is a multiplex reaction, for example 3-plex to 10-plex. A relevant rise in signal in the fluorescence detector indicates a detected target.
[0073] So that the optical evaluation by using the fluorescence detector is not influenced or is minimally influenced, the read-out chambers 58 have radially inwardly, beyond the region looked at by using the fluorescence detector, an indentation which is not depicted in greater detail and which is used “to collect” air bubbles and hold them back from the region looked at. An air bubble disposed in the indentation would have to be comparatively greatly deformed in order to enter the region looked at. Advantageously counteracting in this case is the bubble interface, especially influenced by the present surface tension conditions.
[0074] Further optionally, the read-out window 24 which covers the read-out chambers 58 and which is transparently closed in this case is also edged by a frame web (cf.
[0075] As an alternative to fluorescence detection, the evaluation can also be done by a so-called melt curve analysis, for example a “high-resolution melt curve analysis” or a “rapid melt curve analysis.” This would allow even much higher multiplexing. In an optional exemplary embodiment, what is carried out in the read-out chambers 58 is a “real-time PCR” based on so-called intercalating dyes (e.g., dyes known under the brand or the name “EvaGreen,” “SYBR Green,” “BoxTo”), the resultant PCR products being detected after amplification by melt curves. In this case, up to 20 PCR products can be detected and differentiated per chamber (20-plex).
[0076] The subject matter of the invention is not restricted to the above-described exemplary embodiments. Rather, further embodiments of the invention can be derived from the above description by a person skilled in the art. In particular, the individual features of the invention described on the basis of the various exemplary embodiments and their structural variants can also be combined with one another in another way.
[0077] The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention.
LIST OF REFERENCE SIGNS
[0078] 1 Disk [0079] 2 Main body [0080] 4 Channel-and-chamber structure [0081] 6 Sealing film [0082] 8 Heat input side [0083] 10 Inlet [0084] 12 Cap [0085] 14 Cover [0086] 16 Top side [0087] 18 Locking hook [0088] 20 Slot [0089] 22 Read-out window [0090] 24 Read-out window [0091] 26 Label [0092] 28 Recess [0093] 30 Lateral wall [0094] 32 Through-hole [0095] 34 Rotary plate [0096] 36 Rotation plane [0097] 38 Positioning pin [0098] 40 Rotation axis [0099] 42 Heating element [0100] 44 Swab [0101] 46 Swab chamber [0102] 48 Sealing contour [0103] 50 Stickpack [0104] 52 Stickpack chamber [0105] 54 Stickpack chamber [0106] 56 Preamplification chamber [0107] 58 Read-out chamber [0108] 60 Lyochamber [0109] 61 Lyochamber [0110] 62 Lysis chamber [0111] 64 Vent hole [0112] 66 Condensation trap [0113] 67 Peel seam [0114] 68 Channel [0115] 70 Overflow channel [0116] 72 Overflow chamber [0117] 74 Control chamber [0118] 76 Control chamber [0119] 78 Transfer channel [0120] 80 Outlet channel [0121] 82 Channel [0122] 84 Chamber [0123] 86 Frame web [0124] 88 Chamber [0125] 90 Vent channel [0126] 92 Siphon [0127] 94 Measurement chamber [0128] 96 Channel [0129] 98 Overflow [0130] 100 Chamber [0131] 102 Measurement chamber [0132] 104 Overflow chamber [0133] 106 Compensation channel [0134] 108 Siphon channel [0135] 110 Vertex [0136] 112 Vent channel [0137] 114 Valve chamber [0138] R Rotation direction [0139] p Overpressure [0140] h Height difference