Chemical apparatus and process disinfecting – deodorizing – preser – Analyzer – structured indicator – or manipulative laboratory... – Means for analyzing liquid or solid sample
Reexamination Certificate
2000-05-26
2003-11-25
Warden, Jill (Department: 1743)
Chemical apparatus and process disinfecting, deodorizing, preser
Analyzer, structured indicator, or manipulative laboratory...
Means for analyzing liquid or solid sample
C422S051000, C422S051000, C422S082080, C422S082090, C422S091000, C422S105000, C436S164000, C436S165000, C436S172000
Reexamination Certificate
active
06652809
ABSTRACT:
This invention relates to a novel apparatus for performing photometric assays, especially biochemical photometric assays.
Conventionally photometric assays are performed in microtitre plates comprising 96, 384, 864 or even 1536 wells (8×12, 16×24, 24×36 and 32×48, respectively). The geometry of such plates has become standardised in order to enable photometric readings based on the principles of absorbance, fluorescence, luminescence, phosphorescence or scattering to be made by a plate reading machine on all the wells within a standard format. Such assay systems suffer from the disadvantage that the volume of sample required can be relatively large and the concentration of the substance to be assayed relatively high which increases costs. Furthermore, as assay volumes decrease, systems which do not provide for covering or sealing become increasingly prone to evaporation.
There remains a desire to miniaturise photometric assay systems to make possible the assaying of samples of smaller volume while retaining sensitivity and adequate signal-to-noise.
We have now invented an apparatus which permits the performance of photometric assays at high density and low volume with significantly greater sensitivity than has been possible hitherto and with significantly lessened problem of evaporation. Other advantages of our apparatus, such as reduced interference between signals from samples will become apparent from the foregoing.
Thus, according to the invention we provide an apparatus for the performance of photometric assays comprising:
1. A housing;
2. A plurality of translucent capillaries each being sealed at one end;
3. Means to provide each capillary with photonic isolation from a neighbouring capillary; and
4. Optical instrumentation and circuitry adapted to read a photonic response or event in each capillary.
The housing may be manufactured of any rigid material, such as plastics (e.g. perspex) or metal (e.g. steel, aluminium). The housing will serve to retain the capillaries in the desired orientation for reading by the optical instrumentation and circuitry.
Preferably the plurality of translucent capillaries will be arranged in a regular orientation. For example they may be arranged in the housing in arrays of 8×12, 16×24, 32×48, 64×96 (especially when this conforms to the conventional microplate format) or any other desired geometrical arrangement.
Alternatively (although this is not preferred) they may be close packed, in which case they will preferably be close packed into a regular shape, such as a square, rectangle, hexagon or circle. The close packed arrangement may then be retained in the housing.
Capillaries will generally be of circular section, typically having internal and external dimensions in the range 0.1-4 mm e.g. 0.8 mm and 1.0 mm respectively. Capillaries will have a length in the range 1-50 mm e.g. 10 mm.
Capillaries may also have internal and external geometries other than circular. For example, a hexagonal outer section might be an advantageous geometry for close packing.
Preferably, when the capillaries are arranged in arrays, the means to provide each capillary with photonic isolation from a neighbouring capillary is provided when the part of the housing retaining the capillaries comprises a support block in which is manufactured holes, ideally in a regular arrangement, each hole capable of receiving and retaining a single capillary.
The material of manufacture of the housing should not contribute a significant background signal for the assay method used and should not permit transmission of signal from one capillary to the next (“cross-talk”) to any significant extent.
Preferably the support block will be manufactured of a light impervious, e.g. a plastics material, such as perspex or high density polypropylene or polytetrafluoroethylene material which may be coloured black. The entire housing may be manufactured of the same material.
For fluorescence applications, the support block will preferably be impervious to light at the emission wavelength even if it is not impervious to light at the excitation wavelength.
For fluorescence applications, the material of manufacture of the support block will preferably have low intrinsic fluorescence.
Capillaries may be arranged in the support block in a density of typically 1-10,000/cm
2
. Capillaries arranged in arrays of 96, 384 and 1536 will generally be arranged with a separation of 9, 4.5 and 2.25 mm respectively.
The end of the capillary retaining or intending to retain the sample may protrude beyond or be held within the support block. Preferably it will protrude beyond the support block.
We prefer the end of the capillary to be sealed to form a fused bulb.
When the capillaries are close packed the means to provide each capillary with photonic isolation from a neighbouring capillary may be provided by coating each capillary with a light impervious material. Alternatively they may be provided with a coating which is highly internally reflective such as a silver or aluminium coating.
Generally the coating will be a plastics coating. The coating should be sufficiently thick and dense and the material will have properties suitable for the application. For fluorescence applications it will preferably have low intrinsic fluorescence. Frequently the coating will be of a black plastics material.
It is also envisaged that capillaries coated with a light impervious material may be retained in a housing comprising a support block which need not be made of a light impervious material.
In an alternative embodiment, when the capillaries are arranged in arrays the means to provide each capillary with photonic isolation from a neighbouring capillary may comprise an air space. The capillaries will nevertheless be connected through the housing in order to retain them in the desired orientation although these connections will be such that no significant cross-talk occurs.
In one refinement of this embodiment, the capillaries may be considered to be retained in a support block in the sense that the support block rigidly retains them in a fixed orientation, save that the part of the capillary containing or intended to contain a liquid sample is not retained within the support block but is surrounded by air space.
The means for providing each capillary with photonic isolation from a neighbouring capillary may also comprise an air space together with a capillary coating of light impervious material.
Performance of an assay will involve dispensing liquid into one or more capillaries. This may be performed manually but will preferably be performed by an automated system.
Frequently it will be necessary to dispense a sample to be assayed of smaller volume and an assay reagent of larger volume but it may also be necessary to dispense a sample of larger volume. In any event the liquid to be dispensed in the capillary may be dispensed in one or more aliquots which may range in volume from small (nanoliter to picoliter range) to large (microliter range).
Each aliquot may be administered by standard contact dispensing methods, e.g. syringe needle, pipette tip or transfer pin. A sample may be administered to the bottom of the capillary using a microinjection needle but will preferably be administered towards the top of the capillary and encouraged to the bottom of the capillary, e.g. by vibration, taking advantage of surface coatings or geometrical features, by use of pressure differentials or, preferably, by centrifugation.
Centrifugation has the further advantage that it enhances sample mixing.
Centrifugation may be performed using conventional apparatus, e.g. a conventional microplate centrifuge. The shape of the housing may be adapted to assist centrifugation.
Apparatus (e.g. 96, 384 or 1536 multi-channel dispensers) may be used which enables a number of arranged aliquots to be dispensed simultaneously.
Aliquots may also be dispensed by non-contact dispensing, e.g. using piezoelectric or solenoid valve dispenser. This method is more suitable for dispensing smaller volumes (nanoliter to
Comley John Charles William
Lang Li Qun
Legge Coulton Heath
Glaxo Research and Development Limited
Handy Dwayne K
Nixon & Vanderhye PC
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