in its simplest sense , the invention provides methods where nucleic acid - templated reactions are enhanced by catalysts that are directly incorporated in the reaction system . although the design of a catalyst ( for example , a diamine catalyst ) to act in a concerted fashion upon two otherwise unreactive moieties to rapidly catalyze a high yield of product is very attractive , there are some potential disadvantages for this system . first , a millimolar concentration of the catalyst may be needed for efficient hemicyanine formation . this high concentration might not be compatible with or could even be toxic to some biological systems . however , high catalyst concentration may be required for establishing and maintaining a schiff &# 39 ; s base under aqueous conditions throughout the initial reaction sequence in order to localize the catalyst at the reaction site . second , the reaction rate may not be fast enough for a “ point - of - care ” device ( as the reaction may take 1 to 2 hours for completion ). without wishing to be bound by theory , it is believed that , in the case of diamine catalysts , the slow reaction kinetics is due , in part , to the hydrophilic catalyst &# 39 ; s slow diffusion rate to the hydrophobic core of dna site and cannot be dramatically improved by just optimizing the catalyst &# 39 ; s structure . although increasing the catalyst &# 39 ; s concentration increases its diffusion rate , high catalyst concentration destabilizes the indolinium compound and is also toxic for most biological systems . increasing hydrophobicity of the catalyst decreases its water solubility . third , catalyst has to be added separately to the reaction mixture and this increases the complexity of the system . in order to simplify the above system while taking advantages of the catalytic enhancement and minimize the disadvantages , we describe here “ all - in - one ” designs where catalysts are built into template dnas and / or reactant dna strands . such “ all - in - one ” designs allow the possibility of synthesis of bioactive compounds and / or reporter compounds in living systems where the introduction of an excess of catalyst are difficult or toxic . since catalyst , reactants and dna are all in one catalyzed dpc reaction system , there is no catalyst accessibility issue for the dpc reactants and the reaction rate can increase dramatically . the increased reaction rate benefits reactive reactants such as indolinium compound and minimizes their possible decomposition due to the prolonged reaction time . the elimination of high concentration of catalyst additives also help stabilize the reactant , thus the product yield is increased . these combined effects enable a more sensitive and convenient bioassay for the biological detection than the previous method . the choice of catalytic moiety for use in the present invention is of course dependent upon the nature of the reactive groups and in particular the type of chemical reaction desired between those reactive groups . in one embodiment , the first reactive group is an aldehyde and the second reactive group is an active hydrogen component . in this embodiment , the catalytic moiety is selected from a secondary amine , a primary amine , a bifunctional amine - acid catalyst or a diamine . secondary amines useful as catalytic moieties in this invention include , but are not limited to pyrrolidines such as 1 -( 2 - pyrrolindinylmethyl )- pyrrolidine , piperidines , a nornicotines , prolines , or analogs thereof . primary amines useful as catalytic moieties in this invention include , but are not limited to 1 -( ethylpyrrolidin - 2 - yl ) methanamine , 2 - aminomethylpyrrolidine , valine or a peptide having fewer than 3 amino acid units , or an amino acid of the general formula ( i ): wherein r 1 is hydrogen or c 1 - c 6 straight or branched alkyl ; and r 2 is c 1 - c 6 straight or branched alkyl . bifunctional amine - acid catalysts useful as catalytic moieties in this invention include , but are not limited to pyrrolidine / acoh . diamine catalysts useful as catalytic moieties in this invention include , but are not limited to a compound of the general formula ( ii ): wherein each r is independently selected from hydrogen or c 1 - c 6 straight or branched alkyl . in one embodiment , each r is independently selected from hydrogen or c 1 - c 6 straight alkyl . specific examples of diamine catalysts include n 1 , n 1 - dimethylethane - 1 , 2 - diamine , n 1 , n 1 - dimethylpropane - 1 , 3 - diamine , n 2 , n 2 - dimethylpropane - 1 , 2 - diamine , ethylenediamine , n 1 , n 1 - diethylethylene - 1 , 2 - diamine (“ dmeda ”), propane - 1 , 2 - diamine , 1 -( 2 - aminoethyl )- piperidine , or an analog thereof , for example . in one specific embodiment , the catalytic moiety is dmeda . the reactive groups utilized in this invention react with one another in the presence of the catalytic moiety that is covalently attached to one of the oligonucleotides to produce a product (“ reaction product ”). in one embodiment the reaction product is a polymethine dye . in one embodiment , the reaction product is a hemicyanine dye . it is understood that the reaction product can be a peptide or a small molecule . although not to be bound by a particular mechanistic theory , a possible mechanism for hemicyanine formation is illustrated in fig6 . for the purpose of illustration , the catalyst in fig6 is dimethylethane diamine ( dmeda ). the proposed mechanism involves the n1 - nitrogen atom reacting with the aldehyde to faun a schiff &# 39 ; s base which brings the catalyst into proximity with the indolinium compound . the lone pair electrons on the n1 ′- nitrogen atom extract a proton from the methyl group of the indolinium compound converting it to the somewhat stabilized methyleneindoline . the proton on the n1 ′- nitrogen atom is subsequently transferred to the n1 - nitrogen atom of the schiff &# 39 ; s base due to its higher pka . a contributing resonance structure increases the electrophilicity of the imine carbon and makes it susceptible to attack by nucleophiles . as a result , the methyleneindoline then reacts with the protonated imine to form a neutral intermediate which upon intramolecular proton abstraction by n1 ′- nitrogen atom eliminates the catalyst to form the stable hemicyanine product . although most of the proposed steps are in equilibrium , the extended conjugation of the hemicyanine product essentially drives the reaction to completion . addition of nacnbh 3 to dpc reaction mixtures provided direct evidence for the schiff &# 39 ; s base intermediate , as lc - ms analysis has provided quantitative formation of the reduced schiff &# 39 ; s base ( secondary amine formation ) for dmeda . in some embodiments , the methods described herein are used to detect and / or quantify a biological target , which can include , for example , a protein , peptide , nucleic acid , or carbohydrate . exemplary proteins include , for example , a receptor , ligand , hormone , enzyme , or immunoglobulin . the biological target can be a multimeric protein , for example , a homodimeric protein , a heterodimeric protein , or a fusion protein . exemplary multimeric proteins that can be detected and or quantified , include , for example , erbb protein family homo - and heterodimers ( e . g ., erbb2 ( her2 ) homodimers , erbb1 ( egfr ) homodimers , egfr / erbb2 heterodimers , etc ), vegf receptor homo - and heterodimers , vegf dimmers , pdgf dimmers , tyrosine kinase receptor complexes , tnf / tnfr complexes , cadherin complexes , catenin complexes , igfr complexes , insulin receptor complexes , receptor / receptor ligand complexes ( e . g ., epo / epo receptor ), nf - kb / ikb complexes , t - cell antigen complexes , integrin protein complexes , fkbp protein complexes , p53 protein complexes , bcl family protein complexes , myc / max complexes , cyclin protein complexes , intracellular protein kinase complexes , caspase protein complexes , autoantibody - antigen complexes , and secreted protein complexes ( e . g ., amyloid protein complexes . the methods of this invention are particularly useful in the detection and / or quantification of erbb protein family homodimers or heterodimers . exemplary fusion proteins that can be detected and / or quantified , include , for example , bcr - abl ; npm - alk ; and certain alk containing fusion proteins . exemplary post - translational modifications that can be detected and / or quantified , include , for example , phosphorylated proteins ( e . g ., phosphorylated stat proteins ); glycosylated proteins ; and farnesylated proteins ( e . g ., ras ). under certain circumstances , the formation of a reaction product requires the use of two probe components that associate with one another to produce a reaction product by dpc that can be detected directly or indirectly . it is understood that individual probe components do not contain a reaction product , but are capable of associating with a complimentary probe component to produce a reaction product by dpc . it is understood that in the methods of detecting a biological target , the first probe component and the second probe component ( and the third probe component in certain embodiments ) can each be a single molecule . for example , in the first and second probe components , the binding moiety can be covalently bound to the oligonucleotide sequence and the oligonucleotide sequence covalently bound to the reactive group . alternatively , the first probe component and the second probe component ( and the third probe component ) can comprise two or more pieces that non - covalently associate with one another to produce a functional probe component . the “ target binding component ” comprises a zipcode oligonucleotide sequence covalently associated with the binding moiety . the “ reporter component ” comprises an anti - zipcode oligonucleotide sequence that is complementary or substantially complementary to the zipcode oligonucleotide sequence covalently bound to the oligonucleotide sequence of the probe component which itself is covalently bound to the reactive group . the catalytic moiety may be bound to either the target binding component or the reporter component . preferably , the catalytic moiety is bound to the reporter component . the construction of various zipcode and anti - zipcode oligonucleotides for use in the probe components of this invention is known in the art ( see , for example , co - owned international patent application publication nos . wo 2008 / 054600 and wo 2006 / 128138 ). depending upon the biological target and assay format , the first and second ( and third , if present ) binding moieties may bind to different locations on the biological target ( e . g ., different nucleotide sequences , different amino acid sequences , different epitopes , etc .). a variety of binding moieties , for example , antibodies , affibodies , adnectins , ligands , receptors , aptamers , nucleic acids , carbohydrates , lipids , small molecules and other binding molecules known in the art can be used in the practice of the invention depending upon the nature of the biological target . depending upon the target , the binding moieties used in each of the individual first , second ( and third ) probe components can be the same or different . in certain embodiments , the reaction product is directly detected because it generates a signal . in this embodiment detection may involve the use of an instrument to detect the level of signal being emitted by the reaction product ( e . g , in the case of a fluorescent , chemiluminescent , or colorimetric molecule ). in other embodiments the reaction product itself does not generate a signal and must be detected indirectly through the use of an added agent that both specifically associates with the reaction product and generates a signal . for example , the reaction product may be an antigen that is detected by the addition of a specific antibody that is labeled and the bound antibody is then detected . in certain aspects of this embodiment , the indirect detection of the reaction product results in an amplification of the signal , thus increasing the sensitivity of detection . when an added agent is necessary for detection of the reaction product , that agent interacts preferentially with the reaction products versus the reactive groups . in one aspect of this embodiment , the reaction product is detected using a labeled antibody that either binds directly to the reaction product or binds to a second antibody that binds to the reaction product ( e . g ., in an elisa assay ). other examples of reaction products include a product that : catalyzes a reaction that creates an optical label ; inhibits a reaction that creates an optical label ; is a fluorescence quencher ; is a fluorescent energy transfer molecule ; creates a raman label ; creates an electrochemiluminescent label ( i . e . ruthenium bipyridyl ); produces an electron spin label molecule ; is a ligand ; is an enzyme activator ; or is an enzyme substrate . the choice of reactive groups for use in the present invention is based upon the following criteria : a ) the reactive groups should not react with one another in the absence of the catalyst ; b ) the reactive groups should produce a product when they react in the presence of the catalyst , where the product can be detected ( either directly or indirectly ); and c ) neither individual reactive group should be detectable by the method used to detect the detectable product . there are several methods that may be employed to conjugate a catalyst into a dna strand . for example , in design a ( fig1 ), a catalyst and one of the reactants are linked to a bifurcated dna while the other reactant is linked to a complementary dna ( end - of - helix , or e - architecture ) or a dna that is complementary to a common template that hydrogen - bond ( h - bond ) to both dna reactants ( middle - of - helix , or m - architecture ). phosphoramidite containing two orthogonal functional groups can be incorporated into the 5 ′ end of the dna for linking the catalyst and the reactant . extra linkers can be added between the dna and the catalyst . in design b ( fig2 ), catalyst and reactant are linked sequentially to a dna . the sequence of these two molecules relating to the dna can be switched . depending on which molecule is linked to the dna first , the molecule should have two orthogonal functional groups . in design c ( fig3 , the catalyst and reactant can be one molecule , which means one part of the molecule can be used as a catalyst and while another part as a reactant . in this case , a molecule containing the functionalities of both a catalyst and a reactant will be synthesized first before linking it to the dna . in design d ( fig4 ), catalyst can be linked directly to a dna template in a m - architecture . a side chain of the nucleobase can be modified to contain a functional group for linking the catalyst . some of those nucleobase phosphoramidites can be purchased commercially ; e . g . amino - modifier c6 dt , carboxy - dt ( glen research ). in design e ( fig5 ), catalyst is linked to a third dna strand that can form a triplex with reactant / template strand through hoogsteen or reversed hoogsteen hydrogen bonds . in this case , a long stretch of homopurine or homopyridine dna ( over 10 bases ) is preferred . in one embodiment , the methods described herein can be used to detect the formation of a egfr / erbb2 heterodimer in a sample of interest . an exemplary system is described in fig7 , which shows two probe components , a first probe component denoted 10 that binds to egfr and a second probe component denoted 100 that binds to erbb2 . both probe components are two piece ligand reporter assemblies as described , for example , in u . s . patent application ser . no . 12 / 176 , 798 , filed jul . 21 , 2008 , the contents of which are incorporated by reference herein . egfr probe component 10 comprises a target binding component 20 and reporter component 30 . target binding component 20 comprises a first binding moiety 22 , for example , an antibody , that specifically binds egfr linked ( either by a covalent bond or through a linker 24 ) to zipcode 26 . reporter component 30 comprises antizipcode 32 ( which is an oligonucleotide sequence complementary to zip code 26 ) linked ( either by a covalent bond or through a linker 34 ) to a first oligonucleotide 36 , which is linked directly or through a linker to ( i ) a catalyst 38 ( for example , a dmeda catalyst as shown ) and ( ii ) an aldehyde containing reactive group 40 . in probe component 10 , the target binding component 20 is non - covalently associated with reporter component 30 via hybridization of zipcode 26 and antizipcode 32 to produce a functional probe component . erbb2 probe component 100 comprises a target binding component 120 and reporter component 130 . target binding component 120 comprises a first binding moiety 122 , for example , an antibody , that specifically binds erbb2 linked ( either by a covalent bond or through a linker 124 ) to zipcode 126 . reporter component 130 comprises antizipcode 132 ( which is an oligonucleotide sequence complementary to zipcode 126 ) linked ( either by a covalent bond or through a linker 134 ) to a second oligonucleotide 136 , which is linked directly or through a linker to an indolinium containing reactive group 138 . in probe component 100 , the target binding component 120 is non - covalently associated with reporter component 130 by hybridization of zipcode 126 and antizipcode 132 to produce a functional probe component . if erbb2 and egfr have formed a heterodimer , probe components 10 and 100 are brought into proximity with one another . thereafter , the first oligonucleotide 36 of first probe component 10 hybridizes with second oligonucleotide 136 of second probe component 100 to bring the first reactive group 40 into reactive proximity with the second reactive group 138 , which react with one another to produce reaction product 140 , which as shown is a hemicyanine . as shown in fig7 , catalyst 38 is covalently attached to the first oligonucleotide 36 and catalyzes the production of product 140 from reactive groups 40 and 138 . it is understood , however , that a catalyst can be included in probe component 100 rather than in probe component 10 as shown . furthermore , it is understood that the catalyst can be associated with components other than the first oligonucleotide 36 of probe component 10 or the second oligonucleotide 136 of probe component 100 . the presence of reaction product 140 ( a fluorophore ) is indicative of the presence and / or amount of a egfr - erbb2 heterodimer in the sample . the following examples contain important additional information , exemplification and guidance that can be adapted to the practice of this invention in its various embodiments and equivalents thereof . practice of the invention will be more fully understood from these following examples , which are presented herein for illustrative purpose only , and should not be construed as limiting in anyway . the term , “ dna - programmed chemistry ” or “ dpc ”, as used herein , refers to nucleic acid - templated chemistry , for example , nucleic acid sequence specific control of chemical reactants to yield specific products accomplished by ( 1 ) providing one or more templates , which have associated reactive group ( s ); ( 2 ) contacting one or more transfer groups ( reagents ) having an anti - codon ( e . g ., complementary sequence with one or more templates ) and reactive group ( s ) under conditions to allow for hybridization to the templates and ( 3 ) reaction of the reactive groups to yield products . for example , in a one - step nucleic acid - templated reaction , hybridization of a “ template ” and a “ complementary ” oligonucleotide bring together reactive groups followed by a chemical reaction that results in the desired product . structures of the reactants and products need not be related to those of the nucleic acids comprising the template and transfer group oligonucleotides . see , e . g ., u . s . pat . nos . 7 , 070 , 928 b1 and 7 , 223 , 545 and european patent no . 1 , 423 , 400 b1 by liu et al . ; u . s . patent publication no . 2004 / 0180412 ( u . s . ser . no . 10 / 643 , 752 ; aug . 19 , 2003 ) by liu et al ., by liu et al . ; gartner , et al ., 2004 , science , vol . 305 , pp . 1601 - 1605 ; doyon , et al ., 2003 , jacs , vol . 125 , pp . 12372 - 12373 , all of which are expressly incorporated herein by reference in their entireties . see , also , “ turn over probes and use thereof ” by coull et al ., international patent application publication no . wo07 / 008 , 276a2 , filed on may 3 , 2006 ; “ biodetection by nucleic acid - templated chemistry ” by coull et al ., pct / us06 / 20834 , wo06 / 128138a2 , filed may 26 , 2006 . the terms , “ nucleic acid ”, “ oligonucleotide ” ( sometimes simply referred to as “ dna ” or “ oligo ”) or “ polynucleotide ,” as used herein , each refer to a polymer of nucleotides . the polymer may include , without limitation , natural nucleosides ( i . e ., adenosine , thymidine , guanosine , cytidine , uridine , deoxyadenosine , deoxythymidine , deoxyguanosine , and deoxycytidine ), nucleoside analogs ( e . g ., 2 - aminoadenosine , 2 - thiothymidine , inosine , pyrrolo - pyrimidine , 3 - methyl adenosine , 5 - methylcytidine , c5 - bromouridine , c5 - fluorouridine , c5 - iodouridine , c5 - propynyl - uridine , c5 - propynyl - cytidine , c5 - methylcytidine , 7 - deazaadenosine , 7 - deazaguanosine , 8 - oxoadenosine , 8 - oxoguanosine , o ( 6 )- methylguanine , and 2 - thiocytidine ), chemically modified bases , biologically modified bases ( e . g ., methylated bases ), intercalated bases , modified sugars ( e . g ., 2 ′- fluororibose , ribose , 2 ′- deoxyribose , arabinose , and hexose ), or modified phosphate groups ( e . g ., phosphorothioates and 5 ′- n - phosphoramidite linkages ). nucleic acids and oligonucleotides may also include other polymers of bases having a modified backbone , such as a locked nucleic acid ( lna ), a peptide nucleic acid ( pna ), a threose nucleic acid ( tna ). the term “ detectable reagent ” as used herein refers to a reagent that produces a signal that can be observed or quantified by visual observation or through the use of a machine that detects the signal ( e . g ., a spectrophotometer , a fluorometer , a scintillation counter , a microscope , etc .) the term “ small molecule ,” as used herein , refers to an organic compound either synthesized in the laboratory or found in nature having a molecular weight less than 5 , 000 grams per mole , optionally less than 2 , 000 grams per mole , and optionally less than 1 , 000 grams per mole . throughout the description , where compositions are described as having , including , or comprising specific components , or where processes are described as having , including , or comprising specific process steps , it is contemplated that compositions of the present invention also consist essentially of , or consist of , the recited components , and that the processes of the present invention also consist essentially of , or consist of , the recited processing steps . further , it should be understood that the order of steps or order for performing certain actions are immaterial so long as the invention remains operable . moreover , two or more steps or actions may be conducted simultaneously . examples 1 - 3 below illustrate designs a , b , and c , and it is contemplated that designs d and e can be carried out by incorporating the catalysts in a fashion similar to that used to incorporate the reactants . preparation of an aldehyde and diamine linked dna for hemicyanine dpc ( design a ) a synthetic sequence for preparing a compound of design a ( i . e ., a reactant and catalyst linked bifurcated dna ) is provided in fig8 . the synthetic route begins by synthesizing the dna on a controlled pore glass ( cpg ) following standard phosphoramidite chemistry . then , an asymmetric doubler phosphoramidite ( based on a dendrimer structure ) is introduced . this doubler contains a hydroxyl group protected by an acid - sensitive dimethoxytrityl ( dmt ) group and an amino group protected by a base - sensitive fluorenylmethoxycarbonyl ( fmoc ) group . upon removing the dmt group using mild acidic conditions ( acetic acid ), the doubler reacts with the catalyst phosphoramidite . base - induced cleavage of the dna from cpg also cleaves the fmoc group , and the resulting amino group then reacts with aldehyde n - hydroxylsuccimide ( nhs ) ester to form the desired compound for hemicyanine dpc . preparation of an aldehyde and diamine linked dna for hemicyanine dpc ( design b ) a synthetic sequence for preparing a compound of design b ( i . e ., where a reactant and a catalyst are linked to a dna sequentially ) is provided in fig9 . the sequence begins by coupling dna to a phenyl aldehyde compound that includes an nhs ester and dmt - protected amino functional groups . this reaction is typically carried out in solution . after dmt cleavage , the dna reacts with a diamine nhs ester to form the desired compound for hemicyanine dpc . preparation of an aldehyde / diamine linked dna for hemicyanine dpc ( design c ) a synthetic sequence for preparing a compound of design c ( i . e ., a dna strand bearing a chemical fragment comprising both a catalyst and a reactant ) is provided in fig1 . the sequence involves coupling an activated ester to an amino group of the dna using amide bond - forming conditions . synthesis of a dna conjugated quaternary salt bearing active hydrogen component ( indolinium - dna ) general experimental procedures : 2 , 3 , 3 - trimethylindolenine is commercially available . the acid functionality is introduced to the indoline ring through n - quaternization . synthesis of compound 1 : to 5 - bromovaleric acid ( 2 . 435 g , 13 . 45 mmole ) was added 2 , 3 , 3 - trimethylindolenine ( 2 . 141 g , 13 . 45 mmole ). the reaction mixture was heated with rigorous stirring at 110 ° c . overnight . the dark red sticky oil obtained was transferred to a gregar extractor and extracted with etoac overnight . a light red solid was obtained . the solid was redissolved in 30 ml of meoh . meoh was removed under reduced pressure and the remaining residue was treated with 10 ml of etoac . a brownish solid was precipitated out and filtrated . the solid was washed with 2 × 50 ml of acetone and 2 × 100 ml of etoac . a total 1 . 590 g of light brownish solid was obtained ( 35 % yield ). 1 h nmr ( dmso ) δ ppm : 7 . 98 ( m , 1h ), 7 . 84 ( m , 1h ), 7 . 61 ( m , 2h ), 4 . 49 ( t , 2h ), 2 . 84 ( s , 3h ), 2 . 30 ( t , 2h ), 1 . 84 ( m , 2h ), 1 . 63 ( m , 2h ), 1 . 53 ( s , 6h ). maldi - ms ( positive mode ): 260 . 2419 . synthesis of compound 2 : compound 1 ( 0 . 1 g , 0 . 294 mmole ), n - hydroxy succimide ( 0 . 068 g , 0 . 588 mmole ) and n , n ′- dicyclohexylcarbodiimide ( dcc ) ( 0 . 085 g , 0 . 411 mmole ) were dissolved in 1 . 5 ml of dimethyl formamide ( dmf ). the reaction mixture was stirred at 37 ° c . for 1 hr . the precipitated dicyclohexylurea ( dcu ) was removed by filtration , and the filtrate was treated with 15 ml of ether . a light orange solid was washed three times with 10 ml of ether and dried under vacuum for several hours . the solid obtained was used directly for the next reaction . maldi - ms ( positive mode ): 357 . 1590 . labeling dna with indolinium compound : to a 1 . 5 ml of centrifugation vial containing 20 nmole of dna was added 41 . 6 μl of 0 . 1 m sodium phosphate buffer ( napi ), ph 7 . 8 , 41 . 6 μl of compound 2 in n - methyl 2 - pyrrolidone ( nmp ) ( 96 mm ) and 41 . 6 μl of nmp . the vial was placed in a shaker and shaken for 2 hr at 25 ° c . the reaction mixture was desalted by gel filtration using sephadex g - 25 and then purified by reversed - phase c8 column . indolinium_antizip5 : 22 % yield . lc - ms ( negative mode ): calcd for c 309 h 402 n 108 o 179 p 29 ( monoisotopic ): 1877 . 1797 [ m - 6h ] − 5 ; found : 1877 . 3717 [ m - 6h ] 5 − . synthesis of compound 3 : to a 1 . 5 ml of centrifugation vial containing 20 nmole of dna was added 41 . 6 μl of 0 . 1 m sodium phosphate buffer ( napi ), ph 7 . 8 , 41 . 6 μl of aldehyde nhs - ester ( compound 1 ) in n - methyl 2 - pyrrolidone ( nmp ) ( 96 mm ) and 41 . 6 μl of nmp . the vial was placed in a shaker and shaken for 2 hours at 25 ° c . the reaction mixture was desalted by gel filtration using sephadex g - 25 and then purified by reversed - phase c8 column . the dna conjugate ( compound 3 ) is dried by lyophilization . synthesis of dna - aldehyde - diamine : the dried dna is treated with 1 ml of 4 : 1 acetic acid / water at 4 ° c . for 1 hour . the solvent is removed by speed vacuum . the dna is then dissolved in 41 . 6 μl of 0 . 1 m sodium phosphate buffer ( napi ), ph 7 . 8 , 41 . 6 μl of diamine nhs - ester ( compound 2 ) in n - methyl 2 - pyrrolidone ( nmp ) ( 96 mm ) and 41 . 64 of nmp . the vial was placed in a shaker and shaken for 2 hours at 25 ° c . the reaction mixture was desalted by gel filtration using sephadex g - 25 and then purified by reversed - phase c8 column . the dna - aldehyde - diamine conjugate is dried by lyophilization . the dried dna is treated with 1 ml of 4 : 1 acetic acid / water at 4 ° c . for 1 hour . the solvent is removed by speed vacuum . the residue is dissolved in 1 ml of 2m teaa solution and purified by reversed - phase c8 column . the dna is dried by lyophilization . zip - coded architecture for dpc - based detection of an erbb ( egfr - erbb2 ) heterodimer in cells compounds described herein ( for example , the indolinium - dna conjugate described in example 4 and the dna - conjugated aldehyde containing a diamine catalyst described in example 5 ) can also be used to detect and quantify receptor dimers using a dmeda - catalyst to facilitate hemicyanine formation . dpc is used to generate a fluorescent hemicyanine signal that depends upon the presence of receptor dimers and effectively discriminates them from constituent monomers . the optimal design for the binder and reporter oligonucleotides may be achieved by taking into consideration the size and geometry of the binder and the size and geometry of the binding sites of the target . for example , longer or shorter spacer arms may be used to optimally span the distance between binding sites on the target and avoid steric hindrance due to the binders themselves . a synthetic sequence for preparing zip - coded oligonucleotides is shown in fig1 . a zip - coded oligonucleotide designed to hybridize to the aldehyde - dmeda reporter molecule is prepared by reacting an activated indolinium compound with a dna strand having a 5 ′- amino group . the zip - coded oligonucleotide designed to hybridize to the indolinium reporter molecule is prepared by reacting a dna strand having a 3 ′- amino group with a compound containing the catalyst and aldehyde ( or protected aldehyde ). synthesis of the conjugates between oligonucleotides and anti - egfr or anti - erbb2 antibody can be performed based on known procedures , such as those described by solulink biosciences ( san diego , calif . ; see www . solulink . com ). for example , conjugation of an antibody and oligonucleotides can be carried out by first modifying the primary amino groups of the antibody with succinimidyl 2 - hydrazinonicotinate acetone hydrazone to incorporate an acetone hydrazone onto the antibody . then , the primary amino groups of the oligonucleotides are separately activated with succinimidyl 4 - formylbenzoate . the two activated molecules then are mixed in the desired ratio ( such as 6 : 1 ) and reacted at a mildly acidic ph to form a stable hydrazone linkage . additional description of synthetic procedures can be found at www . solulink . com . two conjugates can be prepared according to this technology : one conjugate containing the zip code to anneal to the dmeda - aldehyde - containing reporter oligonucleotide , and the other containing the zip code to anneal to the indolinium - containing reporter oligonucleotide . antibody - oligonucleotide conjugates prepared according to the above procedures may be further purified by gel chromatography , such as on a 1 . 6 × 60 cm column of superdex s - 200 ( amersham biosciences ) in pbs buffer ( 0 . 01 m potassium phosphate , ph 7 . 4 - 0 . 138 m sodium chloride ). the main antibody peak , eluting at about 0 . 6 times the column volume , is collected and a later eluting peak of contaminating non - conjugated oligonucleotide may be discarded . the fractions containing the antibody conjugate may be concentrated by reversed dialysis with a pierce ( rockford , ill .) 30 k molecular weight cut - off slide - a - lyzer using pierce concentrating solution . protein content can then be determined using a bio - rad micro bca reagent kit , and oligonucleotide content determined using sybr gold dna binding dye ( molecular probes ( eugene , oreg .). purification of the above conjugates according to this procedure provides a conjugate having an average of approximately 3 oligonucleotides per protein molecule . the two antibody - oligo conjugates with their reporter ( see fig7 and the discussion relating thereto ) are first assembled separately in a volume of 10 μl . each assembly contained 0 . 5 μm ( 5 picomoles ) of antibody - oligonucleotide conjugate and 0 . 15 μm of ( 15 pmoles ) of complementary reporter oligonucleotide in 0 . 05 m tris / hcl ph 8 - 0 . 01 m magnesium chloride . each is incubated for at least 15 minutes at 4 ° c . before use in the detection reaction mixture . egf - activated a431 cells are washed by centrifugation three times in phosphate buffered saline (“ pbs ”; sigma chemical company ). 50 , 000 cells are introduced into each well of a hi - bind plate in pbs and allowed to settle overnight at 4 ° c . the immobilized cells are washed three times with pbs . wells are blocked with blocking solution ( pbs - t + 1 mg / ml bovine serum albumin + 0 . 1 mg / ml rabbit igg ) for 1 hr at room temperature , then washed three times with pbs plus tween - 20 (“ pbs - t ”; sigma chemical company ), once with water and dried at room temperature . wells then are incubated with equal amounts of anti - egfr ( labvision ) conjugated to the amino terminus zip2 ( anti - egfr - zip2 ; 0 to 15 pmoles ) and anti - erbb2 ( labvision ) conjugated to amino terminus of zip5 ( anti - erbb2 - zip5 ; 0 to 15 pmoles ) for one hour and washed 3 times with pbs - t ( fig1 ). samples are incubated in the wells of a 96 - well microplate in a fluorimeter at 25 ° c . for up to 4 hours . fluorescence can be monitored at various times with excitation at 535 nm and emission at 580 nm . alternatively , fluorescence detection of erbb dimers on a431 cells may be performed by facs analysis . cells are treated with egf as described above , fixed in 3 % formaldehyde for 30 min at 4 ° c ., blocked , and incubated with dpc detection reagents as described . in this approach , the drying step would not be necessary . controls may be used , such as : a ) samples incubated without anti - egfr conjugates ; b ) samples incubated without aldehyde - dmeda or indolinium conjugates ; and c ) samples incubated without both anti - egfr / erbb2 conjugates aldehyde or indolinium conjugates . the entire disclosure of each of the publications and patent documents referred to herein is incorporated by reference in its entirety for all purposes to the same extent as if each individual publication or patent document were so individually denoted . the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof . the foregoing embodiments are therefore to be considered in all respects illustrative rather than limiting on the invention described herein . scope of the invention is thus indicated by the appended claims rather than by the foregoing description , and all changes that come within the meaning and range of equivalency of the claims are intended to be embraced therein .