This application claims priority to Italian Application Number TO2012A000320, filed Apr. 12, 2012, incorporated by reference in its entirety.
The present disclosure relates to a device and a method for preparing biologic samples to render the prepared sample suitable for use in subsequent processes of analysis, particularly in lab-on-chip devices.
An example of preparation of a sample consists of extracting and subsequently purifying biological material for use in subsequent analysis. Preparation of the biologic sample, including extraction of DNA and subsequent purification, also referred to as “sample preparation”, is the starting point of numerous processes of DNA analysis, such as RT-PCR, electrophoresis, genotyping, etc.
Currently, sample preparation can be performed using suitable kits available on the market, which are operated manually performing a particular procedure.
In a first step, referred to as “pretreatment”, the selected biologic sample, from which the DNA is to be extracted, for example whole blood, is subjected to a cell lysis comprising dissolving the cell by disrupting the cell membrane. Lysis is carried out, e.g., by arranging the biologic sample in a hypotonic solution. After lysis, using suitable enzymes such as proteinase K, digestion of the contaminating proteins is performed.
The second step, referred to as “DNA binding”, consists of the separation and recovery of the nucleic acid from the solution containing the lysed cell material. One of the most recent methods consists in the use of a matrix of silica gel in presence of chaotropic salts that adsorbs and binds the DNA.
In the third step, referred to as “washing”, the gel matrix is washed using a suitable solution such as, for example, buffer and/or ethanol, in order to eliminate interfering residue, such as proteins and lipids.
In the fourth step, referred to as “elution”, the silica-gel matrix, binding the DNA, is eluted using an aqueous solution with low saline concentration. By virtue of this treatment, the DNA previously captured on the surface of the gel matrix is removed and made available in a solution within the test tube. The prepared sample is ready for use in the downstream application, for example RT-PCR.
In order to carry out RT-PCR, the prepared sample is subsequently collected with a pipette and transferred into the wells provided in a silicon chip accommodated on a disposable cartridge. Next, this cartridge is inserted in a thermal cycler with a fluorescence detector for carrying out DNA analysis.
All of the previously described steps regarding preparation of the sample and loading of the prepared sample into the wells in a silicon chip are performed manually using the devices provided with the kit (test tubes, pipettes, buffers, etc.). The sequence of the various steps involves handling a large number of devices and transferring liquids in the transition from one step to the next of the method.
Because of the large number of manoeuvres and devices involved and the precision required in the manual manipulations, the method is particularly slow, cumbersome in its implementation, and exposed to accidental errors of execution and to contamination by the surrounding environment. Thereby it is, as a whole, far from robust and reliable in relation to the quality of the end result.
The method described above is moreover far from effective in terms of economic yield, requiring the use of large amounts of costly reagents. Finally, it can be carried out only by highly specialized staff, limiting use thereof to just the hospital and/or laboratory environment.
The disclosure provides a device and a relevant method for preparing and for loading a sample containing biological material into wells within a silicon chip, suitable for subsequent use in an analysis. The device and the associated method for preparing a sample containing biological material has to be simple to implement, enable a high rapidity in preparation of the sample and thus short analysis times, have reduced costs, provide robustness in terms of quality of the end result, and finally be usable by staff that are not necessarily highly qualified. The step of loading the sample into the wells must be integratable with the device. In other words, the sample preparation and loading device should be modular, designed to integratingly fit into a lab-on-chip device such that sample transfer steps are eliminated once the device is loaded for the first time.
According to the present disclosure, a device, an apparatus, and a method for preparing a sample containing biological material are provided.
For a better understanding of the disclosure and the advantages thereof, some non-limiting embodiments are described hereinafter, with reference to the attached drawings, wherein:
For example, the body 1 can have a parallelepipedal shape, with dimensions of about 5×4×3 cm3, so as to have an overall volume not greater than 60 cm3.
The cartridge 2 comprises a support 17, for example of plastic material of the type used in the production of printed circuits, and a chip 16, for example of silicon, arranged in a cavity of the support 17 and provided with a plurality of wells 33, each of which may contain, for example, various primers and/or probes for parallel and/or multiplex analysis of the sample. The body 1 is made, for example, of partially or completely transparent plastic material, such as transparent polycarbonate manufactured using moulding and forging techniques. The body 1 and the cartridge 2 are fixed together by means of lateral clips 29.
The body 1 comprises fluid advancing means, here comprising two suction units, including a first piston housing 14, accommodating a first piston 13, and a second piston housing 12, accommodating a second piston 19. The first and second pistons 13 and 19 and the respective housings 14 and 12 are conformed so as to enable the first and second pistons 13, 19 to fluid-tightly slide within the housings 14 and 12, respectively.
The body 1 further comprises a first and a second syringe chambers 7, 8, each forming a fluid inlet, open towards the outside on a top surface 80 of the body 1, but sealed (prior to use) by an adhesive and perforatable outer closing layer 9, for example of aluminium, plasticized on the part in contact with the top surface 80. The bottom wall of the first and second chambers 7, 8 is defined by a diaphragm 30, for example having two plastic layers and an intermediate sealing and perforatable aluminium layer.
The body 1 further comprises a filtering compartment 6 arranged underneath the diaphragm 30 and accommodating a filtering matrix 5 (shown as black dots) in the presence of adsorption agents, for example silica gel in presence of chaotropic salts. In the embodiment shown, the top surface of the filtering compartment 6 is formed by the diaphragm 30. In use, the filtering compartment 6 is fluidically connected to the syringe chambers 7, 8 by tearing or perforating the diaphragm 30, as described in greater detail hereinafter.
According to an embodiment, the filtering compartment 6, for example, having a parallelepiped shape, accommodates a partial diaphragm 15, which extends transversely from the side walls of the filtering compartment, substantially parallel to the bottom base of the body 1, and occupies only partially a cross-section of the filtering compartment 6 that is parallel to the bottom base of the body 1, thus forming a connection opening 42. The partial diaphragm 15 divides the volume of the filtering compartment 6 into a conveying duct 40, which extends above the partial diaphragm 15, and a matrix compartment 41, which extends underneath the partial diaphragm 15 and accommodates the filtering matrix 5.
The conveying duct 40 and the matrix compartment 41 are fluidically connected to each other through the connection opening 42. The filtering compartment 6 further comprises an outlet opening 6a, arranged on the bottom base of the filtering compartment 6 and opening towards a fluidic circuit comprising a first, a second and a third communication ducts 3, 4, 11, as described in greater detail hereinafter.
In the embodiment shown in
The second communication duct 4 (forming, together with the first communication duct 3, a discharge circuit and, together with the third communication duct 11, a loading circuit) extends downwards from the outlet opening 6a as far as an inlet port 51 of a hydraulic T connector 50. The latter further has a first and a second outlet port 52, 53.
The first communication duct 3 extends from the first outlet port 52 of the hydraulic T connector 50 in a substantially horizontal direction and opens onto a discharge chamber 20, through an inlet hole 20b arranged on a side wall thereof. As represented in the embodiment of
The first communication duct 3 arranged between the T connector 50 and the inlet hole 20b has a first hydraulic valve 27 intended for regulating the passage of the fluids from the first communication duct 3 to the discharge chamber 20.
The third communication duct 11 extends from the second outlet port 53 of the hydraulic T connector 50 in a substantially horizontal direction (opposite communication duct 3) and opens onto a suction chamber 10, through a further inlet hole 10d arranged on a side wall thereof and in the proximity of its own bottom base. As represented in the embodiment of
A further partial diaphragm 10c extends within the suction chamber 10 from the side wall of the suction chamber 10 where the further inlet hole 10d is located and above it. The further partial diaphragm 10c extends in a substantially horizontal direction with respect to the bottom base of the suction chamber and terminates in proximity of the wall of the suction chamber 10 opposite to the starting one, without connecting thereto and thus forming a suction opening 10b. In this way, the further partial diaphragm 10c divides the suction chamber 10 into two further volumes: an air chamber 10e, which develops above the partial diaphragm 10c, and a preparation-conveying chamber 10f, which develops underneath the partial diaphragm 10c. The air chamber 10e and the preparation-conveying chamber 10f are fluidically connected together through the opening 10b.
The third communication duct 11 is further provided with a second hydraulic valve 28, arranged between the suction chamber 10 and the T connector 50, and designed for adjustment of the passage of the fluids from the third communication duct 11 to the plurality of nozzles 18.
The device 1000 further comprises a first ringnut 26 for micrometric movements applied to the first piston 13 and a second ringnut 25 for micrometric movements applied to the second piston 19. The first ringnut 26 and the second ringnut 25 are conformed to enable a fine sliding adjustment of the first piston 13 within the first housing 14 and of the second piston 19 within the second housing 12, respectively.
With reference to
With reference to
Next, the sample injection step 102 of
During the sample injection step 102, the first hydraulic valve 27 is open, and the second hydraulic valve 28 is closed.
Simultaneously or subsequently, the first piston 13 is displaced towards the outside of the body 1, for example using the first ringnut 26. The fluid-tight movement of the first piston 13 within the respective housing 14 creates a negative pressure in the discharge chamber 20, which, by virtue of opening of the first hydraulic valve 27, propagates as far as the filtering compartment 6 fluidically connected thereto, forcing flow of the pre-treated sample 21a into the conveying duct 40, towards the filtering matrix 5; thereby minimizing contamination. It is also possible to perform these steps using positive pressure and changing the relative positions of the pistons.
Next (adsorption step 103 of
After the pre-treated sample 21a has traversed the filtering matrix 5 and, consequently, is without the part of DNA and of interfering materials adsorbed by the filtering matrix 5, it exits the filtering compartment 6 through the outlet opening 6a, traverses the second communication duct 4 and, through the T connector 50, passes into the first communication duct 3, finally flowing into the discharge chamber 20. The second valve 28, being closed, prevents the pre-treated sample 21a from accidentally reaching the nozzles 18. At the end of this step, the pre-treated sample 21a, except for the part adsorbed on the filtering matrix 5, is inside the discharge chamber 20.
In the subsequent washing liquid injection step 104 of
Simultaneously or subsequently, the first piston 13 is further displaced towards the outside (top) of the body 1, for example using the first ringnut 26. The movement of the first piston 13 creates a further negative pressure in the discharge chamber 20, which, due to the first hydraulic valve 27 that is open, propagates as far as the filtering compartment 6 fluidically connected thereto, forcing the flow of the washing liquid 31a in the conveying duct 40 towards the filtering matrix 5.
Next (washing step 105 of
After traversing the filtering matrix 5, the washing liquid 31a, enriched with the interfering substances removed from the surface of the filtering matrix 5, exits the filtering compartment 6 through the outlet opening 6a, traverses the second communication duct 4, and, through the T connector 50, passes into the first communication duct 3, finally flowing into the discharge chamber 20. It should be noted that the second hydraulic valve 28, being closed, prevents the washing liquid 31a from accidentally reaching the nozzles 18. At the end of this step, all of the washing liquid 31a is contained within the discharge chamber 20.
Next (valve-switching step 107 of
Afterwards (eluent liquid injection step 108 of
Simultaneously or subsequently, a second piston 19 is displaced towards the outside of the body 1, for example using the second ringnut 25. The movement of the second piston 19 creates a negative pressure in the suction chamber 10, which, by virtue of the second hydraulic valve 28 being open, propagates as far as the filtering compartment 6 fluidically connected thereto, forcing the flow of the eluent liquid 61a towards the filtering matrix 5.
Then (elution step 109 of
Next (well loading step 110 of
It should be noted that the off condition of the first hydraulic valve 27 prevents the prepared sample 70 from accidentally reaching the discharge chamber 20. In this way, the prepared sample 70 is available within the plurality of wells 33.
Finally (sealing step 111), the clips 29 are removed, the cartridge 2 is detached from the body 1, and a liquid sealant, for example mineral oil, is poured on the wells 33 to obtain sealing of the prepared sample within the wells 33. The cartridge, with the prepared sample 70 contained therein, can thus be introduced in a thermal cycler (not shown) for performing the RT-PCR analysis, in a per se known manner not described in detail.
The body 200 comprises a first and a second inlet wells 201, 202, each forming a fluid inlet. The first and second inlet wells 201 and 202 are open outwards on the top surface 270 of the body 200 and are coated or covered prior to use with an outer closing layer (not shown).
A first delivery hole 201a is arranged on the lateral (side) surface of the first inlet well 201, and a first delivery duct 203 extends therefrom in a horizontal direction and is connected to a first inlet port 205a of a first hydraulic T connector 205. A second delivery hole 202 is arranged on the lateral surface of the second inlet well 202, and a second delivery duct 204 extends therefrom in a horizontal direction and is connected to a second inlet port 205b of the first hydraulic T connector 205.
A third delivery duct 206 extends in a horizontal direction from an outlet port 205c of the first hydraulic T connector 205 and is connected to a third delivery hole 207a arranged on the lateral surface of a filtering compartment 207, to the inside whereof the filtering matrix 5 is fixed. The filtering compartment 207 is further provided with an outlet hole 207b, for example arranged opposite to the inlet hole 207a, and a first communication duct 209 extends therefrom in a horizontal direction and is connected to an inlet of a second hydraulic T connector 210.
A discharge duct 211 extends in a horizontal direction from the second hydraulic T connector 210 and opens onto a discharge chamber 212, through an inlet hole 212a arranged on the lateral surface thereof. The discharge chamber 212 is further provided on its own lateral surface with a first suction hole 212b; a first intake duct 213 extends therefrom in a horizontal direction and terminates on a first inlet hole 213a available on the lateral surface of the body 200. Outside the body 200, a first pumping unit 214 is connected to the first inlet hole 213a via connectors 221.
Moreover the second hydraulic valve 27 is arranged on the discharge duct 211 for adjusting the passage of the fluids from the discharge duct 211 to the discharge chamber 212.
A preparation duct 215 extends in a horizontal direction from the second hydraulic T connector 210 and has a preparation outlet, here formed by a plurality of injection ducts 218, fluidically connected to the preparation duct 215. The injection ducts 218 extend in a horizontal direction, parallel to each other, and end within a chip-housing chamber 217 designed to house the chip 16. The chip 16 is fixed to the bottom of the chip-housing chamber 217, for example, by gluing or by friction fit. The injection ducts 218 are configured to terminate or have openings (not shown) facing the wells 33.
The chip housing chamber 217 has, on its own lateral surface, a second suction hole 217a; a second intake duct 219 extends therefrom and ends on a second inlet hole 219a, which is available on the lateral surface of the body 200 and connects the second intake duct 219 with the outside of the body 200. A second pumping unit 220 is connected to the second inlet hole 219a via connectors 221. In this embodiment, the first and second pumping units 214, 220 form fluid moving means.
The first hydraulic valve 28 is here arranged on the preparation duct 215, between the injection ducts 218 and the second T connector 210.
The method for preparing a sample containing biological material using the device 2000 of
After loading the prepared sample, it is possible also in this case to seal the wells 33 with e.g., oil to prevent evaporation during thermal cycling. In this case, a further inlet well (not shown) may be arranged near the preparation loading chamber 217 and connected to the preparation duct 215 or directly to the injection ducts 218. Thus, the oil may be conveniently added via such an inlet well.
Finally, after loading and possible sealing the wells 33 and disconnection of the external pumping units 214, 220, the body 200 is inserted in a thermal cycler (not shown) for subsequent RT-PCR analysis based upon detection of fluorescence thanks to the transparency of the material of the body 200.
In this embodiment, the first communication duct 303 extends partially within the discharge chamber 20 and is here provided with a discharge hole 303a facing the bottom base of the discharge chamber 20. The portion of the first communication duct 303 within the discharge chamber 20 is provided, at its own terminal section, with a first partial diaphragm 303b. The first partial diaphragm 303b is arranged transverse to the longitudinal direction of the first communication duct 303, and obstructs the terminal section only partially, forming a ball-suction hole 303e and a stop for the mobile ball 303c.
The ball-suction hole 303e and the discharge hole 303a have a smaller cross-section than the overall dimensions of the ball 303c so that the latter cannot exit the first communication duct 303 through them.
The first communication duct 303 is moreover provided with a second partial diaphragm 303d arranged upstream of the discharge hole 303a, on a section transverse to the longitudinal direction of the first communication duct 303. The second partial diaphragm 303d obstructs the section only partially, forming a connection opening 303f and defining a stop for the mobile ball 303c.
The cross-section of the first communication duct 303 and the diameter of the mobile ball 303c are chosen so as to enable rolling of the mobile ball 303c within the first communication duct 303, at least in the stretch comprised between the first and second diaphragms 303b, 303d.
In the embodiment in
The third communication duct 311 has a third partial diaphragm 311c at its terminal section. The third partial diaphragm 311c is arranged transversely to the longitudinal direction of the third communication duct 311, only partially obstructs its terminal section, forming the further ball suction hole 311e, and forms a stop for the further ball 311a. The further ball suction hole 311e has a surface smaller than the overall dimensions of the further mobile ball 311a.
The connection hole 311d (formed both in the third communication duct 311 and the underlying partial diaphragm 310c) faces the bottom base of the suction chamber 10 and has a cross-section smaller than the overall dimensions of the further mobile ball 311a. The connection hole 311d fluidically connects the preparation conveying chamber 10f and the third communication duct 311.
The third communication duct 311 has a fourth partial diaphragm 311b arranged on a section transverse to the longitudinal direction of the third communication duct 311 and obstructing the section only partially, forming a further connection opening 311f and defining a stop for the further mobile ball 311a. The cross-section of the third communication duct 311 and the diameter of the ball 311a are chosen so as to enable rolling of the further mobile ball 311a within the third communication duct 311.
Operation of the device 3000 of
At the same time, the negative pressure in the discharge chamber 20 propagates to the third communication duct 311, causing movement of the further ball 311a towards the third partial diaphragm 311b (dashed line position).
Here, the further ball 311a totally obstructs the further connection opening 311f, similarly to closing the second hydraulic valve 28 of
In a dual way, in the steps of eluent liquid injection 108, elution 109, and well loading 110 of
Consequently, fluidic connection is obtained between the third communication duct 311 and the suction chamber 10, corresponding to opening the second hydraulic valve 28 of
At the same time, the negative pressure in the suction chamber 10 causes displacement of the ball 303c towards the second partial diaphragm 303d (position of the mobile ball 303c represented with a solid line), obstructing the further connection opening 303f, in a way similar to closing the first hydraulic valve 27 in
As is evident to a person skilled in the art, the hydraulic valves 27 and 28 of
The apparatus 4000 is further provided with means for optical detecting the presence or absence of the fluid within the fluidic circuit, here formed by a first laser source 408 and a corresponding first sensing photodiode 412, and by a second laser source 409 and a corresponding second sensing photodiode 413. The first laser source 408 and the first sensing photodiode 412 are positioned so as to intercept the first communication duct 3 in a transverse direction (
The electronic device 401 is connected to and controls the electric actuators 404 and 405, the laser sources 408 and 409, the sensing photodiodes 412 and 413, and the injection module 414.
A software may be loaded into the memory 441 and may be executed by the processing unit 431 so as to actuate the electric actuators 404, 405, the first and second laser sources 408, 409, the first and second sensing photodiodes 412 and 413, and the injection module 414 in order to carry out the steps of the method of
In particular, temporal scanning of the steps of the method of
As is evident to a person skilled in the art, the apparatus 4000 may comprise, instead of the device 1000, the device 2000 or 3000 of
The described solutions present numerous advantages. In fact, they can be integrated with expert systems that can be used not only in the specialist field but also in the doctor's surgery or at home (in the case of self-diagnosis).
Moreover, by performing the operations of adsorption, washing, and elution within a single body, closed to the external environment and thus not subject to contamination, these devices are able to ensure a high degree of purity of the prepared sample, thus increasing the diagnostic reliability. In addition, the execution of the operations in sequence within a same device enables reduction of the analysis times.
The device can operate also on reduced volumes of sample and thus of reagents, thus reducing the costs of analysis and increasing the yield. In fact, treatment of the liquids within a same filtering compartment enables reduction of the leakages typical of known kits, no longer requiring transfer of the intermediate product to different test tubes or Eppendorf® tubes.
The proposed solutions meet the requirement of purity, understood both as presence in solution of the considered nucleic acid and as absence of contaminating substances, which, binding to or interfering with the reagents in solution, could modify the results of the subsequent experiment (PCR, RT-PCR, sequencing, restriction digestion, etc.).
Furthermore, the described device eliminates the risks of contamination of the external environment, since the steps of adsorption, washing, and elution, as well as subsequent analysis are carried out within the same device.
The described devices can be pre-arranged so as to be operated in a semiautomatic or automatic way using appropriate machinery, as explained above.
In the solution of
In the solution of
Numerous modifications and variations may be made to the device and the method described herein, all of which fall within the scope of the attached claims.
For example, in the solution of
The fluid movement means may be implemented in a different way, as elements internal or external to the body 1; for example, in the solution of
In
According to a variant, the first and second hydraulic valves 27, 28 of the device 1000 of
In
In
In the embodiment of
Number | Date | Country | Kind |
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TO2012A0320 | Apr 2012 | IT | national |
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Number | Date | Country | |
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20130273548 A1 | Oct 2013 | US |