STIRRER FOR BIOCHEMICAL REACTIONS

Abstract: A stirrer for biochemical reactions comprising a magnetically permeable vessel for containing a solution of biochemically reacting substances, at least one magnetic bead placed in the vessel, and a magnetic device which is installed outside the vessel and generates an oscillating magnetic field acting on the bead. The stirrer is advantageous for stirring the solution of without direct contact.

Description: Background of the Invention: Field of the Invention: The present invention relates to an apparatus for biochemical reactions, and more particularly to an apparatus which permits adequate agitation of solutions that undergo biochemical reactions. Following description is made with reference to an apparatus for immunological reactions by which the present invention can be most appropriately practised. In the immunological reactions, either the antigen or the antibody is marked with a convenient label (for example, a fluorescent or radioactive material or an enzyme) and the immunological reaction is utilized to form a complex of the antigen and the antibody. The labelled antibody allows the determination of the amount of the object antigen or antibody. For the reaction to proceed adequately, to increase the accuracy and precision of estimation, to carry out the process more rapidly, and to enhance the efficiency of operations, the procedure of stirring is preferable as in most chemical reactions. However, in biochemical reactions such as immunological reaction where a small volume of sample, say from several hundreds microliters to several tens of milliliters, is commonly employed, difficulties are often met in agitating the solution. A stirrer with blades cannot be used practically and, if the stirring means is brought into contact with the solution, the estimation may bring about loss in accuracy probably due to "carry over". Stirring by oscillating the vessel itself cannot be expected to be effective and loss of the solution by spattering may occur. Stirring by ultrasonic waves as non-contact stirring may cause the reacting substances to be destroyed and therefore is not universally applicable. GB-A-1 500 127 discloses stirring of a solution using a magnetic metal substrate in the course of which no internal stir bars are necessary. As disclosed in column 1, line 35, the stirring is effected by a rotating magnetic field. The rotating magnetic field transmits a rotary impulse to the magnetic metal substrates which thereby can agitate a solution. Summary of the Invention: To solve the above-mentioned problems, an object of the present invention is to provide an apparatus by means of which a solution containing biochemically reactive substances is stirred efficiently without direct contact. Another object of this invention is to provide a versatile stirring apparatus which does not adversely affect the reacting substances involved. Detailed Description of the Invention: The stirrer for biochemical reactions provided by the present invention which has been made to attain the aims mentioned above comprises: at least one vessel formed of magnetically permeable material for containing a solution of a biochemically reactive substance; at least one magnetic bead positionable in each said at least one vessel; means for generating an oscillating magnetic field in each said at least one vessel for oscillating said at least one bead, said generating means comprising a bar having pieces of magnet implanted thereon and positioned relative to said at least one vessel so as to magnetically affect said at least one bead in said at least one vessel, and drive means for oscillating said bar, whereby said at least one bead is oscillated. The magnetically permeable vessel used in the invention may be in the form of a cup, a plate having a number of concavities where reactions take place, a column or any other suitable form, and can be made of a magnetically permeable material such as glass or resins. The magnetic bead to be placed in the vessel may include a magnet as such, magnetic powders conglomerated by a resin binder, a bead which is surface coated by a suitable material and others. The dimensions depend on the size and shape of the vessel, but generally a diameter of 0.5 - 10 mm is preferred. One to several beads may be used for the purpose. Further, it is preferred for immunological reaction to fix an antibody on the surface of the magnetic beads, so as to form an insoluble carrier of the antibody. The magnetic device is intended to move the magnetic beads to oscillate (in an alternating or a circular movement) themselves in the vessel with a predetermined frequency, and the oscillation may be performed at a low frequency ranging from 10 to 120 per min. as considered from the aim of the stirring. The oscillating field provided by the magnetic device may be produced by a coil in which an alternating current flows and by a movement (alternating or circular) of a permanent magnet. In considering the heating effect, the use of a permanent magnet, is preferred. The biochemical reactions to which the stirrer of this invention can be used with merit include immunological, enzymatic and agglutination reactions. But the invention is not particularly restricted to any of the cited examples. Brief Description of the Drawings: Fig. 1 is a drawing showing the constitutional outline of the stirrer of the present invention. Fig. 2(a) is a cross-section of the magnetic device and Fig. 2(b) is a plan of the magnetic bars. Detailed Description of the Preferred Embodiments: The present invention will be described referring to the accompanying drawings. Fig. 1 is a graphical representation showing the constitutional outline of the stirring apparatus, where 1 is a test plate on which a plurality (5 × 6) of circular openings 2, each to incorporate a test cup 13, are provided. As shown in Fig. 2, the test plate is made of an aluminium plate 3, aluminium being a magnetically permeable substance, on the upper surface of which is intimately attached a thin plate of a resin 4 to suppress the dissipation of heat. The lamination structure of 5, 8 and 9 forms a setting stage for the test plate 1 (or serves as a carrying stage when combined with a suitable transportation means), where 5 is an upper cover plate, 8 is a magnetic device, and 9 is a thermostat. The magnetic device 8 is composed of a spacer 7 which has along the surface a number of longitudinal ditches 7a parallel to each other and magnetic bars 6 which are placed in the ditches of 7a one by one. The magnetic bars 6 are capable of moving in the longitudinal direction and their one ends are consolidated outside of the spacer 7 and the whole can be moved back and forth with a definite amplitude in the longitudinal direction by the action of an eccentric cam mechanism 10 and a driving motor 11. On the upper side (facing to the upper cover plate 5) of the magnetic bars 6, a number of circular pieces of magnet 12 are fixed alternatively as indicated in Fig. 2(b), and they apply a magnetic field on the magnetic beads 14 in the test cups 13. In this configuration described above, the magnetic beads 14 in the test cups 13 are influenced by the oscillating magnetic field, as the magnetic bar 6 moves back and forth, to move in the solution, and hence non-contact agitation is realized. In this example, pieces of magnet 12 are arranged in two rows and the pitch in each row is nearly equal to the diameter of the test cups, so that the magnetic beads undergo an elliptic motion. The above-mentioned stirrer for biochemical reactions according to the present invention permits an effective stirring of a solution to be realized in a relatively small vessel in a non-contact manner and an excellency lies in that the degree of agitation can be varied by simply adjusting the magnetic device. Thus, a large usefulness is expected by using the apparatus according to the present invention. Since the performance is made by use of the magnetic device which is placed close to the vessels, any operation to be made to the vessels when necessary, for instance, placing a sample solution in a vessel and conducting an optical measurement, is possible without difficulty.

Claims: A stirrer for biochemical reactions, comprising: at least one vessel formed of magnetically permeable material for containing a solution of a biochemically reactive substance; at least one magnetic bead positionable in each said at least one vessel; means for generating an oscillating magnetic field in each said at least one vessel for oscillating said at least one bead, said generating means comprising a bar having pieces of magnet implanted thereon and positioned relative to said at least one vessel so as to magnetically affect said at least one bead in said at least one vessel, and drive means for oscillating said bar, whereby said at least one bead is oscillated. The stirrer of claim 1 including an antibody fixed on said at least one bead, whereby said at least one bead comprises an insoluble carrier of said antibody. The stirrer of claim 1 or 2 including means for supporting a plurality of said vessels, wherein said bar comprises a plurality of commonly connected bar portions, each of said bar portions extending beneath at least one of said vessels supported by said supporting means.

Inventors: HIGO, YUJI
Applicants: TOSOH CORPORATION
Application year: 1986
Main classification: G01N33
IPC codes: G01N35, C12M1, B01F11, B01F13, G01N1