WO2002038808A2 - Slide or chip hybridisation unit - Google Patents

Abstract

A hybridisation unit (10) is provided with a chassis (11) supporting a sample block (12) on which a plurality of microscope slides or biochips (14) can be placed. A vibratory unit (16) is fixed to the chassis (11) and is coupled to the block (12) to impart vibration to the block (12) and therethrough to the samples. This vibration assists in mixing of samples and thus better hybridisation.

Description

SLIDE HYBRIDISATION UNIT

The present invention relates to a hybridisation unit for the incubation of biological samples immobilised on solid surfaces. The invention is intended for use with, but not restricted to, biochips (the binding of DNA or other molecule to an immobilised molecule or group of molecules) and the technique of in situ hybridisation. Many biological applications involve incubation of solid materials (such as glass, silicon, plastics materials and so on) onto which are chemically coupled or otherwise attached biological materials for assay. These biological materials may consist of tissue samples attached to glass, such as for in situ analysis of nucleic acids, proteins and other bio-molecules, or may be discrete patches of defined molecules (biochips) to which a variety of ligands may be hybridised. In these applications it is required that, following a variety of preparative steps, the solution to be tested is applied to the solid support holding the attached molecules or tissue. Hybridisation of biological samples is generally carried out between 25 and 75 degrees centigrade, for periods ranging from several minutes to days. This is then followed by washing and other procedures, after which assessment of binding is made.

Several attempts have been made to make the processing of such materials more effective and convenient, a requirement which has become more pronounced with the popularisation of biochips for analysis of nucleic acids. Hybridisation of biochips requires stringent control of hybridisation conditions such that variation between chips in the same experiment, and between chips in independently performed experiments is minimised. Additionally it has become convenient to perform hybridisation on a relatively large number of chips in a single batch as the requirement for sample throughput has increased. Several published documents describe methods for hybridisation of microscope slides and biochips. In the simplest versions of these, a simple chamber may be formed in which the biochip or biochips are held. The chamber may then be placed in an oven or water-bath for the hybridisation period. Other approaches seek to automate some or all of the hybridisation and wash protocols (see US-A-5,654,200, US-A-6,238,910).

The simpler hybridisation devices suffer in that they are cumbersome to use and, importantly, the solution which is applied to the surface for hybridisation is not actively moved. There is concern among users of biochips that where the is no active fluid movement, the molecules in solution being subjected only to random "Nan der Naals" forces, there may be local depletion of molecules in particular areas of the solution. Systems which seek to automate all or part of the hybridisation process often attempt to provide means to actively move the sample solution. This may be achieved by use of pumps such as those operated via solenoid or piezo mechanisms. However, such systems tend to be unreliable and inconsistent due to the complexities involved in using biological materials which tend to be highly variable in terms of purity and other qualities, along with precision-engineered components.

The present invention seeks to provide improved sample hybridisation. According to an aspect of the present invention, there is provided a hybridisation unit as specified in claim 1. According to another aspect of the present invention, there is provided a method of hybridising a sample as specified in claim 8.

The present invention can provide improved hybridisation by ensuring sample mixing. Additionally, where active mixing of the solution can be achieved, the molecules in solution are more mobile and will therefore more rapidly find their target site, hence hybridisation can be completed in less time.

Embodiments of the present invention are described below, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a schematic diagram of an embodiment of hybridisation unit; and Figure 2 shows in schematic form a preferred embodiment of transformer for the unit of Figure 1.

The described embodiment seeks to provide a convenient means to perform carefully controlled hybridisation of up to 20 slides. The slides may be microscope slides. In addition to creating an environment in which the slides are incubated at very close to the same temperature to one another, the hybridisation unit is capable of increasing movement of fluid on the chip by introducing controlled vibration of the block carrying the slides. Referring to Figure 1, there is shown in schematic form an embodiment of slide hybridisation unit 10. The unit 10 is provided with a chassis 11, which may be part of the main casing of the unit 10. Located on the chassis 11 is a slide support block 12 which is substantially of known type and typically is heatable for sample processing. The top surface of the block 12 can accommodate a plurality of slides 14 holding samples to be tested. Again, the slides 14 are of known type. The structure of the block will depend upon how the samples to be tested are held and many variations are possible, these being known to the skilled person.

The unit 10 will also be provided the other components typical of a hybridisation unit. As can be seen in Figure 1, the block 12 is spaced from the chassis 11, there being provided a rubber gasket 13 which supports the sides of the block 12.

Coupled to the chassis 11 is a vibration unit 16 which also abuts the block 12, in this example supporting the centre of the lock 12. The vibration unit 16 imparts vibration to the block 12 and therethrough to the slides 14 and the samples being tested. This vibration is intended to ensure proper mixing of samples and hence better hybridisation.

The vibration unit 16 can be fixed to the chassis 11 in any suitable manner, such as by gluing, screws, by suitable profiling of the top side of the chassis 11 and so on. The unit 16 may simply abut the block 12 or may be fixed thereto in any suitable manner.

Referring to Figure 2, in the preferred embodiment of the invention, the vibration unit 16 used to introduce vibration into the block 12 is provided by a modified transformer 18. However, it will be evident to the skilled person from the teachings herein that many different means could be used to impart controlled vibration to the block 12.

The transformer 18 is provided with a transformer coil 20 which includes an AC input line 22 and an AC output line 24. The casing 26 which supports the coil 20 is provided with an upper wall 28 which is hinged to the remainder of the casing 26 by hinge 30. The other end of this wall 28 rests on the remainder of the casing 26 through an insulating support 32. The base of the casing 26 will typically be fixed to the chassis 11 and the hinged wall 28 will abut or be fixed to the block 12.

In the modified transformer 18, shown in outline in Figure 2, the magnetic field created by input AC current in line 20 maintains conformation of the transformer. Where the current is zero (at crossover of the positive to negative portion of the AC curve) no magnetic field exists and the hinged wall 28 moves away from the body of the transformer creating a gap at the insulator 32. The movement is thereby controlled by the wavelength of the AC current, with the frequency of movement related to the number of times per second that the current is zero. The hinged wall 28 of the transformer 18 is held in close contact with the block 12 and thus the vibration of the block 12 is controlled via control of the AC current. The embodiment of Figure 2 will provide an upward and downward movement of the hinged wall 28 and thus of the block 12. However, other vibratory motions can be provided, depending upon preferences. For example a side-to-side vibration can be provided by modification of the arrangement shown in Figures 1 and 2. One modification is to locate the transformer 18 at 90° to the orientation shown in Figure 2 and to place the wall 28 (which would then lie "vertically") against the side of the block 12. A more elegant embodiment alters the orientation of the coil 20 and allows the wall 28 to slide relative to the remainder of the casing 26 (rather than being hinged) and to vibrate in sideways motion upon application of an electric current to the coil 20, thereby imparting a vibratory motion to the block 12 and to the slides 14.

The unit is capable of some control of humidity, meaning that in general use, the hybridisation fluid should be sealed in contact with the surface of the chip (slide) to avoid drying. This may be achieved by enclosing the unit 10 in a sealed environment where humidity and other environmental conditions can be controlled. This can ensure that a humid environment is maintained to prevent drying out of samples on slides, while having the benefit of uniform temperature and vibrational movement of the hybridisation block 12. Similarly, the block 12 is capable of accepting a completely sealed container into which slides 14, held in close contact with the block can be washed via addition of up to 300 ml of a bulk washing solution. The block 12 can be heated via a standard heating element (not shown), but equally temperature may be controlled by other means such as Peltier elements. Controlled heating and cooling in this embodiment can provide the additional means of fluid movement via rapid modulation of temperature. Such temperature alterations can provide convection currents through the fluid, thereby stimulating movement of molecules in solution.

Although the described embodiments provide for a vibratory action on the slides 14 via the block 12, other versions are contemplated. For example, in applications where the slides or other sample holders are provided with a cover film of member, this cover could be vibrated by an equivalent vibration unit provided above the block 12, which the block 12 having a conventional structure. Similarly, vibration of the samples could be provided by imparting relative movement between the cover and the slide, such as by keeping one still and vibrating the other. Although the preferred embodiments have been described with reference to sample slides, as described above, they are applicable to any type of sample holder, such as biochips and so on.

The system can also be set up to impart vibration in a plurality of direction, such as upward/downward and side-by-side by an appropriate combination of vibration units or by suitable gearing or cam arrangements.

Claims

1. A hybridisation unit for performing hybridisation of samples including means to impart vibratory motion to samples during hybridisation.

2. A unit according to claim 1, including a sample holding block, the vibration means being operable to vibrate the sample holding block.

3. A unit according to claim 2, wherein the block is designed to hold a plurality of sample slides or biochips.

4. A unit according to claim 2 or 3, wherein the sample holding lock includes heating means for heating samples.

5. A unit according to any preceding claim, including a chassis member, the vibration means being fixed to the chassis.

6. A unit according to any preceding claim, wherein the vibration unit is operable to impart vibration in an upward and downward direction, in a side-by-side direction or in a combination of the two.

7. A unit according to any preceding claim, wherein the unit provides a sealed chamber for providing controlled humidity within the chamber.

8. A method of hybridising samples including the step of imparting vibratory motion to said samples during hybridisation.

9. A method according to claim 8, wherein vibration is imparted to sample holding block.

10. A method according to claim 8 or 9, wherein vibration is imparted vibration in an upward and downward direction, in a side-by-side direction or in a combination of the two.

11. A method according to any one of claims 8 to 10, including the step of providing controlled humidity to the samples.