Specific binding method and composition

Claim 2

A composition for determining a ligand in a sample, which composition comprises: (a) a binding partner for said ligand; (b) a detection system which has at least two components; (c) a selectively accessible vesicle having a surface incorporated ligand or ligand analog and a first component of said detection system therein; (d) a substance which modifies vesicle accessibility in response to binding of surface-incorporated ligand or ligand analog and the binding partner; and (e) at least one additional component of said detection system which is reactive with said first component to produce a detectable response; and (f) at least one surfactant which does not modify vesicle accessibility.

Claim 3

A composition according to claim 1, wherein the vesicle is comprised of a lipid membrane, and wherein the lipid membrane preferably comprises a phospholipid, or incorporates a sterol, or includes an ampiphile to which the ligand or ligand analog is bound.

Claim 4

A composition according to claim 1 or 2, wherein the surfactant is (i) a polyoxyethylene polymer having at least about 23 ethylene oxide monomer units, and preferably comprises a C $ -C 17 hydrophobic group, and is for example polyoxyethylene lauryl ether, or (ii) a nonyl phenoxy polyethoxyethanol having at least 30 ethylene oxide monomer units, or (iii) an octyl phenoxy polyethoxy ethanol having at least 30 ethylene oxide monomer units.

Claim 5

A composition according to claim 1, wherein the surfactant has the formula: where b is at least 15 and a plus c is from about 11 to 73, preferably 11, 18, 34, 41, 46, 49, 51 or 73; or the surfactant has the formula: where b is at least 5 and a plus c is from about 30 to 113, preferably from 50 to 75.

Claim 6

A composition according to claim 1,2,3 or 4, wherein the said components (a) to (e) are, respectively: (a) an antibody to said ligand; (b) a liposome having ligand or ligand analog bound to its surface and B-galactosidase therein; (c) complement; (d) a substrate for said B-galactosidase; (e) a substance which is detectably altered by the interaction of the B-galactosidase and its substrate.

Claim 7

A specific binding assasy method for determining a ligand in a sample, which method comprises: reacting said sample with a composition as defined in any of claims 1 to 5, and observing any detectable response so-produced.

Claim 8

A specific binding assay for determining a ligand in a sample, which method comprises: (i) reacting said sample with a part of a composition as defined in any of claims 1 to 5, said part comprising (a) the binding partner for said ligand, (b) the second component of the detection system and (f) at least one said surfactant which does not modify vesicle accessibility; and (ii) then reacting the reaction mixture of (i) with a second part of the composition which second part comprises (c) the selectively acccessible vesicle having a surface incorporated with a ligand or ligand analog and, within said vesicle, a first component of said detection system which is reactive with said second component to produce a detectable response, (d) a substance which modifies vesicle accessibility in response to binding of surface-incorporated ligand or ligand analog and the binding partner, and (f) at least one surfactant which does not modify vesicle accessibility; and (iii) observing any detectable response so-produced.

Claim 9

An assay according to claim 7, wherein step (i) comprises reacting the sample with a first part of the composition comprising (a) antibody to said ligand, (b) components of said detection system comprising an enzyme substrate and a substance which is detectably altered by the ineraction of the substrate with an enzyme therefor and (f) at least one surfactant which does not modify vesicle accessibility; and step (ii) comprises reacting the reaction mixture from step (i) with a second part comprising (b) a liposome having a surface incorporated with ligand or ligand analog and, within said liposome, an enzyme which is reactive with said substrate to so alter said detectably alterable substance, (c) complement and (f) at least one surfactant which does not modify vesicle accessibility.

Claim 12

A specific binding assay method for detecting a ligand in selected liquid segments of a stream of an alternating sequence of gas and liquid segments flowing in a single conduit having a single inlet and sequential first, second and third sections, which method comprises: (a) introducing into said single inlet a first liquid segment of a sample suspected to contain said ligand and a first reagent comprising (i) a binding partner for said ligand, (ii) a second component of a detection system having a first and second component and (iii) at least one surfactant which does not modify vesicle accessibility; (b) introducing into said single inlet a first air segment which is occlusive in said single inlet and said first conduit section; (c) introducing into said single inlet a second liquid segment of a second reagent comprising (iv) a selectively accessible vesicle having a surface incorporated with ligand or ligand analog and, within said vesicle, a first component of a detection system which is reactive with said second component to produce a detectable response, (v) a substance which modifies vesicle accessibility in response to binding of surface-incorporated ligand or ligand analog and the binding partner, and (vi) at least one surfactant which does not modify vesicle accessibility; (d) introducing into said single inlet a second air segment which is occlusive in said inlet and said first conduit section; (e) maintaining said segments separate while in said probe and first conduit sections; (f) passing said segments which had been maintained separate in said first conduit section into a second conduit section having a diameter sufficiently greater than that of said first conduit section to render said first gas segment non-occlusive in said second section; (g) combining said first and second liquid segments in said second conduit section; (h) coalescing said first and second gas segments in said second conduit section; (i) maintaining said combined liquid segment separate from other liquid segments by occluding said second and third conduit sections with said coalesced gas segment; (j) completely mixing said combined liquid segments in said third conduit section; (k) analyzing said completely mixed combined liquid segment for said detectable response while it is passing through said third conduit section; and wherein the said surfactants are preferably as defined in claim 3 or 4.