Patent Publication Number: US-11638917-B2

Title: Rotary platform for cell lysing and purification and method of use

Description:
FIELD OF THE DISCLOSURE 
     The disclosure herein relates generally to the field of cell lysing, purification, and elution. More particularly, the present disclosure relates to a rotary, multi-well tray having particular utility in the field of cell lysis, purification, and elution in molecular diagnostics. 
     BACKGROUND 
     In typical cell lysis and purification systems, magnetic beads used to capture desired sample components such as DNA and RNA are kept in one well or some other processing space while unwanted sample fluid is removed from the well and wash and other buffers are added to the well by a pipetting system. During the fluid removal process, the magnetic beads are captured and retained by an external magnet. When another fluid is reintroduced into the well, the beads are typically released from the influence of the magnet to enable turbulent mixing. 
     An alternative approach as practiced in the prior art is to move the magnetic beads, and associated target components, from well to well to carry out a sequence of washing steps prior to elution. This may be carried out, for example, through use of a magnet disposed within a disposable cover and inserting the combination directly into the well containing the magnetic beads. Once the beads have been transferred to a new well, the combined magnet and disposable cover may be retracted, or the magnet may be retracted from the disposable cover. Agitation is preferably employed to enhance washing and elution. The use of heat for sample processing may further complicate such prior art approaches. 
     Innovations directed at streamlining automated cell lysis and purification, minimizing the number of consumables, and simplifying the application of external factors such as agitation and heat would be highly desirable. 
     SUMMARY 
     In order to overcome the complexity of the prior art systems and processes for cell lysis, purification, and elution, the present disclosure provides for the transport of magnetic beads having associated therewith nucleic acids or other cell components of interest along a unique pathway within a substantially circular consumable tray. The tray is rotated about a central axis and a magnet, an agitator such as ultrasonic actuator, and a heater are provided external to the consumable tray. 
     The circular tray may contain one or more sequences of wells to support one or more discrete and unique sample preparation sequences. This allows for ultrasonic assisted lysing, washing, and magnetic bead manipulation via external magnet attraction rather than through the use of one or more pipette heads and associated disposable pipetting tips. Multiple trays may be integrated into a single system, thereby allowing for the asynchronous operation of each tray. This provides an improvement in flexibility, parallelism, and equipment redundancy in sample processing. 
     Each tray provides at least one sequence of interconnected wells. In an embodiment illustrated below, two sequences of wells per tray are provided on opposite tray sides. Each well within a sequence is connected to at least one other well by a channel therebetween. An external magnet may be disposed in proximity to an exterior surface of the fluid wells and the channel. This magnet is held stationary, next to the tray, where magnetic beads are gathered into a cluster adjacent the well or channel exterior wall. Manipulation of the tray in rotation and elevation results in the magnetic bead cluster transitioning between the interior of one well, up to a channel, and into an adjacent well. Changes in rotational and elevational position are implemented by an actuator on which the tray is suspended. Once the magnetic particles enter the next fluidic well, the magnet is retracted and the particles are able to be resuspended into the fluid through mixing. 
     Mixing can be performed in a variety of ways. A direct approach is to rotate the tray back and forth about the central axis of symmetry through selective actuation of the actuator upon which the tray is suspended. This agitation in combination with well geometry enables fluids and magnetic beads inside a well to move about and mix up the liquids and solid particles. 
     Another method of mixing includes the use of an external agitating apparatus. Positioned external to the tray in a manner similar to the external magnet, the well containing magnetic beads may be rotationally positioned in front of the agitator through rotational actuation of the actuator. The agitator may then be extended forward and into contact with the target well. Mechanical agitation may then be implemented. The agitation may be ultrasonic, for example. Upon completion of agitation, the agitator may be retracted to avoid mechanical interference with the subsequent rotational or elevational movement of the tray. 
     Other methods of agitation may include mixing bars or stirring rods disposed within selected wells, vibration of the entire tray, orbital mixing, and sonication. 
     In addition, a system implementing the presently disclosed lysis and sample preparation disposable tray and a method of use may further include a heater normally disposed beneath the tray, except when the tray is lowered by the actuator to a height where one well, aligned with the heater, is lowered into the heater for a desired temporal period. Such heating may be an adjunct to the cell lysis process, elution, or any other step. 
     Magnetic beads are contained within the disposable tray the entire time, thus eliminating any dripping or contamination such as may occur with bead transfer or fluid pipetting. Obviating the use of external resources for inserting a magnet in a disposable sleeve or for pipetting thus makes the presently disclosed process more time efficient. The need for disposable sample tips is obviated. Multiple well sequences on one tray enable the simultaneous processing of multiple samples. Bulk loading of liquids such as lysis, wash, and elution buffers and of magnetic beads prior to processing reduces test duration. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Illustrative embodiments of the disclosed technology are described in detail below with reference to the attached drawing figures, which are incorporated by reference herein and wherein: 
         FIG.  1    is a perspective view of a rotary platform having plural well sequences each interconnected by a respective channel according to the present disclosure; 
         FIG.  2    is a top view of the rotary platform of  FIG.  1   ; 
         FIG.  3    is front elevation view of the rotary platform of  FIG.  1   ; 
         FIG.  4    is a rear elevation view of the rotary platform of  FIG.  1   ; 
         FIG.  5    is a right side elevation view of the rotary platform of  FIG.  1   ; 
         FIG.  6    is a left side elevation view of the rotary platform of  FIG.  1   ; 
         FIG.  7    is a bottom view of the rotary platform of  FIG.  1   ; 
         FIG.  8    is a bottom perspective view of the rotary platform of  FIG.  1   ; 
         FIG.  9    is a system for cell lysing and purification incorporating the rotary platform of  FIG.  1    according to the present disclosure; and 
         FIG.  10    is a flowchart of a presently disclosed process for cell lysis, purification, and elution employing the system of  FIG.  9   . 
     
    
    
     DETAILED DESCRIPTION 
     Disclosed herein is a rotary platform for cell lysing, sample purification, and elution. Use of the platform enables simplified movement of magnetic particles or beads and associated sample fragments such as nucleic acids through a multi-stage cell lysis and purification protocol without the requirement for external pipetting systems and associated pipetting tips. 
     A rotary tray having at least one sequence of processing wells distributed along a periphery thereof is mounted for selective rotation and elevation relative to an extendable and retractable magnet. The magnet enables selective attraction of magnetic beads into a cluster within a well. Coordinated movement of the tray in rotation and elevation enables the magnetic bead cluster to be moved from well to well without the use of a pipetting system or associated disposable tips and while the magnet remains stationary. The system may also include an extendable and retractable agitator for selective agitation of the contents of a well, such as for purposes of washing. In addition, a heater may be located beneath the tray and offset from an axis of symmetry of the tray such that a well may be aligned above the heater, the tray lowered, and the aligned well received within the heater for a desired period of heating, such as for lysing or elution. 
     With regard to  FIG.  1   , a rotary platform  100  for cell lysing, purification, and elution is shown. The platform comprises a substantially circular tray  102  having an upper surface  104  and an opposite lower surface  106  ( FIG.  7   ), the upper and lower surfaces defining a thickness therebetween. A vertical axis of symmetry  110  passes through the center of the tray, orthogonal to the upper and lower surfaces thereof. The tray outer extent is defined by an outer radial edge  112 . The tray further includes a rotor mating interface  140  ( FIGS.  2  and  7   ) coaxial with the axis of symmetry for mechanically mating to an actuator  302  via a rotor  304  configured to selectively rotate and adjust the elevation of the tray, as will be discussed subsequently. 
     Disposed in conjunction with the tray  102  is at least one sequence  120  each comprising plural wells  122 . In the figures, there are two such sequences per tray, symmetrically distributed about the axis of symmetry  110 . As can be seen in  FIG.  1   , each well has an outer surface that extends from the lower surface  106  of the tray about a periphery of the tray in an arc equidistant from the axis of symmetry. The outer surface as illustrated is frustoconical and extends substantially orthogonal to the tray lower surface, narrowing as the well extends distal from the tray. 
     Each well  122  has an interior volume  124  and an associated opening  126  in the tray upper surface  104 . The opening of each well extends into the respective interior volume. Each opening is substantially circular and coplanar with the tray upper surface  104 , except where it is intersected by a channel  130  of the respective well sequence  120 . 
     The channel  130  is formed in the tray upper surface  104 . The channel connects each adjacent pair of wells  122  within a sequence  120  of wells. Thus, as there are two sequences of wells in the presently illustrated embodiment, there are two channels, one for each sequence. 
     The depth of each channel  130  is less than the thickness of the tray  102  between the upper  104  and lower  106  surfaces. Intermediate each pair of wells, the channel has inner walls  132  and an outer wall  134 . The inner and outer walls intersect the openings  126  of the adjacent wells. 
     All points on the inner walls  132  have the same radial distance from the tray  102  axis of symmetry  110 . This radial distance is the same as the radial distance between the axis of symmetry and the center point of each circular opening  126  associated with each well  122 . Similarly, all points on the outer wall  134  have the same radial distance from the axis of symmetry. The outer wall radial distance is greater than that of the inner walls. The radial distance from the axis of symmetry for points on the outer wall is the same as the maximum radial distance from the axis of symmetry to each well opening  126 . Each channel  130  also includes a floor surface  136  that is substantially parallel to and intermediate the upper  104  and lower  106  surfaces of the tray  102 . 
     The rotary platform  100  as described in the foregoing may be used in a system  300  for cell lysing, purification, and elution. As seen in  FIG.  9   , in addition to the previously described platform, the system includes an actuator  302  having a rotor  304 . The actuator enables the selective rotation and adjustment in elevation of the platform. Specifically, the rotor  304  is configured to mate with a tray  102  mating interface  140  ( FIGS.  2  and  7   ) that is coaxial with the tray axis of symmetry  110 . The actuator, under control of a controller as known to one skilled in the art, is capable of selectively rotating the tray and adjusting its height. 
     The system  300  also includes a magnetic member  306  adapted to selectively extend and retract a magnet  308  with respect to a first position adjacent the tray  102  in a horizontal plane. In addition, an agitating member  310  is adapted to selectively extend and retract an agitating tip (also referred to herein as an agitator)  312  with respect to a second position adjacent the tray  102  in a horizontal plane. The agitating member is also capable of imparting agitating motion in the agitating tip. The magnetic member and the agitating member may also be under control of the same or distinct programmable controllers. In the illustrated embodiment, the first and second positions are separated by 180 degrees about the tray. 
     The system may further comprise a heater  316  disposed beneath the tray  102  and, in particular, offset from the tray  102  axis of symmetry  110  the same distance as the wells  122 . 
     Thus, through coordinated movement of the rotary platform  100 , the actuator  302 , magnetic member  306 , agitating member  310 , and heater  316 , a method of lysing, purifying, and eluting a sample may be carried out. This method is described with respect to  FIG.  10   . 
     Lysis buffer is disposed  202  in a first well  122  of a sequence of wells  120 , wash buffer is disposed in one or more second wells, and elution buffer is disposed in a third well. Ideally, a bulk liquid loader (not illustrated) may be used for this purpose in order to expedite the testing method. 
     A quantity of fluid sample may then be disposed  204  into the first well  122 , previously loaded with lysis buffer, through the use of a pipetting system (not illustrated). The actuator  302  is then activated to align  206  the first well with the agitating member. The agitating tip  312  is extended  208  laterally towards the first well, and the agitating tip agitates the first well exterior surface. Such agitation may, for example, by ultrasonic. After agitation, the agitating tip is retracted. 
     Next, the tray  102  is again rotated  210  by the actuator  302  via the rotor  304  to align the first well  122  with the heater  316 . The tray is lowered  212  through adjustment in tray height via the actuator, by which the first well is lowered into the heater. A desired temperature or temperature profile is applied to the well for a desired temporal period. The tray is the elevated by the actuator. 
     Magnetic beads are then disposed  214  within the first well  122 , and the tray  102  is rotated  216  by the actuator  304  to align the target well with the magnetic member  306 . The magnet  308  is extended by the magnetic member to a position proximate the target well, allowing magnetic beads to cluster on the well inner wall near the magnet. 
     With the magnet remaining extended, the actuator  302  lowers  218  the tray. Since the cluster of magnetic beads is held in vertical position by the magnet, the cluster is effectively dragged into the channel  130  as the tray descends. Next, the actuator rotates  220  the tray  102  thereby moving the relative location of the cluster through the channel into the upper extent of the second well  122 . The actuator then raises  222  the tray, thereby positioning the cluster into the lower extent of the second well. The magnetic member  306  then retracts  224  the magnet  308 , releasing the cluster of magnetic beads from the well side wall. 
     To enhance the dispersion of the magnetic beads, with sample components of interest attached thereto, the tray is again rotated  226  about the axis of symmetry  110  by the actuator  302  to align the target well  122  with the agitating member  310 . The agitating tip  312  is extended  228  and the well is agitated, following which the agitating tip is retracted. 
     Optionally, the tray  102  is once again rotated  230  to the heater  316 , the tray is lowered  232 , disposing the target well into the heater, the well is heated as desired, and the tray is elevated. 
     The cycle of clustering the magnetic beads, moving them from one well into the channel and into the next well, retracting the magnet, agitating the well contents, and optionally heating the well contents may be repeated  234  for each subsequent second well having wash buffer therein. 
     Once the last wash iteration has been completed, the actuator  302  aligns  236  the target second well having magnetic beads with sample components associated therewith with the magnetic member  306 , and the magnet  308  is extended into proximity with the target well. The tray  102  is lowered  238  by the actuator  302 , thereby moving the cluster up the well wall to the channel  130 . The tray is again rotated  240  to move the cluster through the channel to the third well, which is the elution well. The tray is raised  242  to locate the cluster at a lower extent of the respective well, and the magnet is retracted  244 . The magnetic beads are again dispersed by rotating  246  the tray to align the target well with the agitating member  310 , which extends  248  the agitating tip  312  to the well, agitates the contents thereof, then retracts the agitating tip. 
     The tray is again rotated  250  to align the target well with the magnetic member  306  and the magnet  308  is extended to attract the magnetic beads from which the components of interest have been released by the elution buffer and agitation. The eluate is then aspirated  252 . While not illustrated, the method may further include rotating the target well to the heater for incubation after agitation and prior to attracting the magnetic beads and removing the eluate. 
     The tray  102  may then be removed from the mating interface  140  and transferred to a waste receptacle, following which a new tray may be provided. 
     The foregoing description has been directed to particular embodiments. However, other variations and modifications may be made to the described embodiments, with the attainment of some or all of their advantages. It will be further appreciated by those of ordinary skill in the art that modifications to the above-described systems and methods may be made without departing from the concepts disclosed herein. Accordingly, the invention should not be viewed as limited by the disclosed embodiments. Furthermore, various features of the described embodiments may be used without the corresponding use of other features. Thus, this description should be read as merely illustrative of various principles, and not in limitation of the invention. 
     Many changes in the details, materials, and arrangement of parts and steps, herein described and illustrated, can be made by those skilled in the art in light of teachings contained hereinabove. It will be understood that certain features and sub-combinations are of utility and may be employed without reference to other features and sub combinations and are contemplated within the scope of the claims. Accordingly, it will be understood that the following claims are not to be limited to the embodiments disclosed herein and can include practices other than those specifically described, and are to be interpreted as broadly as allowed under the law. Additionally, not all steps listed in the various figures need be carried out in the specific order described.