Electrochemical assays

Abstract

Disclosed is a component for a device for detecting the presence of an analyte of interest in a sample, the component comprising an electrically conducting solid support having immobilised thereon a chemical moiety, said chemical moiety comprising an electroactive portion with an electrochemical property capable of being directly modulated in a detectable manner by the binding thereto of a binding partner having a specific binding activity for the electroactive portion, together with apparatus comprising the component, and a method of detecting the presence of an analyte of interest.

1 . A component for a device for detecting the presence of an analyte of interest in a sample, the component comprising an electrically conducting solid support having immobilised thereon a chemical moiety, said chemical moiety comprising an electroactive portion with an electrochemical property capable of being directly modulated in a detectable manner by the binding thereto of a binding partner having a specific binding activity for the electroactive portion.  
     
     
         2 . A component according to  claim 1 , wherein the electrically conducting solid support comprises gold, platinum, metal oxide, carbon/graphite, silicon or silicate.  
     
     
         3 . A component according to  claim 1  or  2 , wherein the modulation of the electrochemical property involves oxidation or reduction of the chemical moiety.  
     
     
         4 . A component according to any one of claims  1 ,  2  or  3 , wherein the electroactive portion comprises an immunogen or a hapten, and the binding partner comprises an immunoglobulin or an effective antigen-binding portion thereof with binding specificity for the electroactive portion.  
     
     
         5 . A component according to any one of the preceding claims, wherein the chemical moiety comprises an organic, moderately hydrophobic entity.  
     
     
         6 . A component according to any one of the preceding claims, wherein the chemical moiety comprises a conjugated system of delocalized electrons.  
     
     
         7 . A component according to any one of the preceding claims, wherein the chemical moiety comprises an organometallic compound or a heteroaromatic compound.  
     
     
         8 . A component according to any one of the preceding claims, wherein the chemical moiety comprises a monomer, dimer or polymer comprising one or more of the following: carbazoles, ferrocenes, pyrroles, furans, and thiophenes.  
     
     
         9 . A component according to any one of the preceding claims, wherein the electroactive portion of the chemical moiety is separated from the electrically conducting solid support by a pendant chain portion.  
     
     
         10 . A component according to  claim 9 , wherein the pendant chain portion comprises a conjugated system of delocalised electrons, to facilitate transport of electrons between the electroactive portion and the electrically conducting solid support.  
     
     
         11 . A component according to  claim 9 , wherein the pendant chain portion is alkyl, alkenyl, or substituted alkyl or alkenyl.  
     
     
         12 . A component according to  claim 11 , wherein the chain portion conforms to the general formula (—CH 2 —) n , where n is an integer from 3 to 14, preferably from 5 to 12, inclusive.  
     
     
         13 . A component according to any one of the preceding claims, wherein the chemical moiety is a molecule which can form a self-assembling monolayer on the electrically conducting solid support.  
     
     
         14 . An assay device for detecting the presence of an analyte of interest, comprising a component in accordance with any one of the preceding claims.  
     
     
         15 . An assay device according to  claim 14 , further comprising one or more of the following: sample receiving means for accepting a sample under test; a binding partner having specific binding activity for the electroactive portion of the chemical moiety; detection means for detecting a modulation in an electrochemical property of the electroactive portion of the chemical moiety; data processing means for processing data output from the detection means; and data display means for displaying the assay result.  
     
     
         16 . An assay device according to  claim 14  or  15 , comprising a binding partner releasably immobilised on a solid support, said binding partner having specific binding activity for the electroactive portion of the chemical moiety, and being released from the solid support in the presence of the analyte of interest.  
     
     
         17 . A component for use in a device according to  claim 14 , said component comprising a solid support having releasably immobilised thereon a binding partner having specific binding activity for an electroactive portion of chemical moiety, the binding partner being released from the solid support in the presence of the analyte of interest, and wherein binding of the binding partner to the electroactive portion directly modulates an electrochemical property of the electroactive portion in a detectable manner.  
     
     
         18 . A method of detecting the presence of an analyte of interest in a sample, the method comprising the steps of: providing an electrically conducting solid support having immobilised thereon a chemical moiety having an electroactive portion with an electrochemical property capable of being modulated in a detectable manner directly by the binding thereto of a binding partner having specific binding activity for the electroactive portion; and causing the binding partner to contact the electroactive portion of the chemical moiety as a result of the presence in the sample of the analyte of interest.  
     
     
         19 . A method according to  claim 18 , comprising use of a component according to any one of claims  1 - 13 , or an assay device according to any one of claims  14 ,  15  or  16 .  
     
     
         20 . A method according to  claim 18  or  19 , wherein the binding partner is present as a binding entity and comprises a first specific binding activity for the electroactive portion of the chemical moiety, and a different, second specific binding activity.  
     
     
         21 . A method according to any one of claims  18 ,  19  or  20 , wherein the binding partner comprises a bispecific antibody or bispecific antigen-binding immunoglobulin portion.  
     
     
         22 . A chemical moiety, comprising an electroactive portion, having the structure shown in FIG. 13 wherein R 1  and R 2  are, indepenently, H; OH; C 1 -C 14  alkyl, aryl, alkenyl or alkoxy (all optionally substituted); halide; amide; or amine; and further wherein the heteroaromatic ring structure may be optionally substituted at one or more positions with alkyl, aryl, alkenyl, or alkoxy groups (all themselves optionally substituted), acid groups (organic or inorganic), halide, amide or amine.  
     
     
         23 . A chemical moiety according to  claim 22 , wherein R 1  is alkyl, preferably ethyl, propyl or butyl.  
     
     
         24 . A chemical moiety according to  claim 22  or  23 , wherein R 2  is C 1 -C 12  alkyl, preferably C 4 -C 8  alkyl.  
     
     
         25 . A chemical moiety according to any one of claims  22 ,  23  or  24 , wherein R 1  or R 2  is substituted so as to comprise a terminally positioned reactive substituent thiol, carboxyl, amide, amine, halide, aldehyde, ketone, epoxide, or succinimide group, or other protein coupling agent which facilitates coupling of the moiety to other entities.  
     
     
         26 . A molecule having specific binding activity for a chemical moiety in accordance with any one of claims  22 - 25 .  
     
     
         27 . A molecule according to  claim 26 , comprising an immunoglobulin molecule or an effective portion thereof.  
     
     
         28 . A molecule according to  claim 26  or  27 , comprising at least one further specific binding activity, which further specific binding activity is for an analyte of interest of for an antibody directed against an analyte of interest.