Displacement assay for detection of small molecules

Abstract

Complex of an anti-cocaine aptamer and the dye diethylthiotricarbocyanine behaves as a calorimetric sensor with attenuation in absorbance at 760 nm for cocaine in the concentration range of 2-5000 μM. Mechanistic studies indicate an intermolecular displacement of the dye as the mechanism of action of the sensor. As the dye is insoluble in buffer, cocaine binding can be detected as displaced dye precipitates and supernatant decolorizes.

1 - 69 . (canceled)  
     
     
         70 . A method of identifying a dye which can be displaced from a dye-receptor complex by an analyte comprising: 
 a) providing a dye-receptor complex wherein the receptor is a nucleic acid and the dye is bound to the nucleic acid and wherein the dye-receptor complex is capable of binding to the analyte;    b) exposing the dye-receptor complex to the analyte; and    c) detecting any dye released after the analyte binds to the dye-receptor complex,    wherein detection of dye being released in step c) indicates that the dye can be used in the receptor-dye complex.    
     
     
         71 . The method of claim  1 , wherein attachment of the dye to the receptor comprises a covalent bond.  
     
     
         72 . The method of claim  1 , wherein attachment of the dye to the receptor comprises a non-covalent bond.  
     
     
         73 . The method of claim  1 , wherein absorbance of the dye is attenuated when the dye is released.  
     
     
         74 . The method of claim  1 , wherein absorbance of the dye is enhanced when the dye is released.  
     
     
         75 . The method of claim  1 , wherein absorbance wavelength of the dye is modified when the dye is released.  
     
     
         76 . The method of claim  1 , wherein the released dye is insoluble in solution.  
     
     
         77 . The method of claim  1 , wherein the released dye is detected with a visual indicator.  
     
     
         78 . The method of claim  1 , wherein the released dye precipitates.  
     
     
         79 . The method of claim  1 , wherein the dye has a fluorescence property which is changed when the dye is released.