Enzyme detection and measurement

2 A unitary single use analytic device for detecting an enzyme selected from a first class and/or an enzyme selected from a second class in a liquid at a suitable temperature, said device comprising a support structure for manual manipulation, a first composition and a second composition each associated with the support structure, the first composition being selectively responsive to an enzyme of the first class and the second composition being responsive to an enzyme of the second class, each responding in such a way as to cause a change in appearance of the device indicative of the presence of an enzyme of a respective class and wherein the change in appearance of the device is due to digestion of a layer of a composition associated with said support structure to reveal an underlying stratum which is of a different appearance from the layer digested.

3 A device according to claim 2 wherein the underlying stratum revealed is the support structure or a coating on the support structure.

4 A device according to claim 2 or 3 wherein a composition associated with said substrate is opaque or translucent.

5 A device according to claim 4 wherein a composition associated with said substrate contains a finely divided solid dispersion.

6 A device according to claim 5 wherein the dispersion is barium sulphate.

7 A device according to claim 2 wherein a change in appearance of the device is due to digestion of a surface layer of an associated composition whereby a substance captive in or on the surface layer which differs in appearance from an underlying stratum of the composition is released.

8 A device according to claim 7 wherein the captive substance is an ink or pigment applied to a surface of the composition

9 A device according to claim 2 wherein a composition associated with said substrate contains a solid dispersion of which at least a surface layer portion is coloured differently from the remainder.

10 A device according to claim 9 wherein the surface layer is coloured by application of an ink or dye to a surface of the composition

11 A device according to any one of claims 1 or 2 wherein a change in appearance is due to a reaction between a component of an associated composition of the device and an enzyme in the liquid to produce a product of different appearance either directly or via one or more mediators.

12 A device according to any one of the preceding claims wherein the time from insertion of a predetermined portion of the device in the liquid until a predetermined change, if any, in appearance is observed is indicative of the activity of the detected enzyme at the liquid temperature.

13 A device according to any one of claims 1 to 11 wherein the appearance of the device changes with time after immersion of a predetermined portion of the device in a liquid containing an enzyme at a suitable temperature and wherein the appearance after a predetermined time is indicative of the activity of the detected enzyme at that temperature.

14 A device according to any one of the preceding claims wherein an associated composition is protease digestible.

15 A device according to any one of the preceding claims wherein an associated composition is cellulase digestible.

16 A device according to any one of the preceding claims wherein an associated composition is lipase digestible.

17 A device according to any one of the preceding claims wherein an associated composition is amylase digestible.

18 A device according to any one of the preceding claims wherein an associated composition is oxidase digestible.

19 A device according to any one of the preceding claims wherein an associated composition forms a layer of uniform thickness and is selectively digested in a predetermined time by an appropriate enzyme of predetermined activity.

20 A device according to any one of claims 1 to 18 wherein an associated composition forms a layer of progressively increasing thickness and is selectively digested in a predetermined time by an appropriate enzyme of predetermined activity whereby the thickness digested in a predetermined time is indicative of the activity of the enzyme

21 A device according to any one of claims 1 to 18 wherein the associated composition is a layer increasing in thickness in steps of predetermined thickness each of which is selectively digested in a predetermined time according to the step thickness by an appropriate enzyme of predetermined activity whereby the number of steps digested in a predetermined time is indicative of the activity of the enzyme.

22 A device according to any one of the preceding claims wherein the support structure is formed from a plastic sheet or film

23 A method for estimating the activity of an enzyme in a liquid at a suitable temperature comprising the steps of inserting a test strip into the liquid, the test strip comprising a support structure, a composition associated with the support structure, the composition being responsive to the enzyme in such a way as to cause a change in appearance of the test strip,

• and measuring the time taken from the moment of insertion until a predetermined change in appearance of the test strip is observed;
• and wherein the composition is an enzyme digestible composition and wherein the change in appearance of the test strip results from a change in appearance at the surface of the composition.

24 A method according to claim 23 wherein the change in appearance of the test strip results from digestion from the strip of the composition to reveal the support structure underlying the composition.

25 A method according to claim 23 wherein the change in appearance is a change in transparency of the test strip,

26 A method according to claim any one of claims 23-25 wherein the liquid is maintained at a predetermined temperature

27 A method according to anyone of claims 23 to 26 wherein the test strip comprises a plurality of compositions on the support structure, each selectively digestible by an enzyme of a respective class, and the time taken for each composition to change in appearance is measured.

28 A method of estimating the activity of an enzyme comprising the steps of inserting a test strip into a liquid containing the enzyme, the test strip comprising a support structure coated with one or more layers of increasing predetermined thickness of a composition digestible by the enzyme at a predetermined activity in a predetermined time, and visually distinguishable from the support structure, and noting the thickness the composition digested in a predetermined time

A kit including a device according to any one of claims 1 to 19 and an indicator of the appearance of a predetermined change, if any, in appearance of the device

A device substantially as herein described with reference to any one of the examples, excluding any comparative examples.

A method of estimating the activity of an enzyme substantially as herein described with reference to any one of the examples, excluding any comparative examples.

A kit substantially as herein described with reference to any one of the examples.