Label-Free High-Throughput Optical Technique for Detecting Biomolecular Interactions

Abstract

Methods and compositions are provided for detecting biomolecular interactions. The use of labels is not required and the methods can be performed in a high-throughput manner. The invention also provides optical devices useful as narrow band filters.

1 . A method of detecting the binding of one or more specific binding substances to their respective binding partners comprising:
 (a) applying one or more binding partners to a biosensor comprising: (i) a linear grating layer having a depth and a period comprised of a material having a high refractive index; (ii) a low refractive index material layer that supports the linear grating layer; and (iii) one or more specific binding substances immobilized on the surface of the linear grating layer opposite of the low refractive index material layer; wherein, when the biosensor is illuminated a resonant grating effect is produced on a transmitted radiation spectrum, and wherein the depth and the period of the linear grating layer are less than the wavelength of the resonant grating effect;   (b) illuminating the biosensor with light; and   (c) detecting a minimum in the spectrum of transmitted wavelength of light from the biosensor;   
     wherein, if the one or more specific binding substances have bound to their respective binding partners, then the minimum in the spectrum of transmitted wavelength of light is shifted. 
   
   
       2 . The method of  claim 1 , wherein the one or more specific binding substances and their binding partners are detection label-free. 
   
   
       3 . The method of  claim 1 , wherein the one or more binding partners comprise one or more tags comprising biotin, succinimidyl-6-[a-methyl-a-(2-pyridyl-dithio) toluamido] hexanoate (SMPT), dimethylpimelimidate (DMP), or histidine. 
   
   
       4 . The method of  claim 3 , wherein the one or more tags are reacted with streptavidin, horseradish peroxidase, or streptavidin coated nanoparticles, before the step of illuminating the biosensor with light. 
   
   
       5 . The method of  claim 1 , wherein the low refractive index material layer comprises glass, plastic, or epoxy. 
   
   
       6 . The method of  claim 1 , wherein the linear grating layer is comprised of zinc sulfide, titanium dioxide, indium tin oxide, tantalum oxide, or silicon nitride. 
   
   
       7 . The method of  claim 1 , wherein the one or more specific binding substances are arranged in an array of distinct locations on the linear grating layer. 
   
   
       8 . The method of  claim 1 , wherein the amount of the one or more binding partners is determined. 
   
   
       9 . The method of  claim 1 , wherein the biosensor is illuminated from its top surface or from its bottom surface. 
   
   
       10 . A detection system comprising:
 (a) a biosensor comprising (i) a linear grating layer having a depth and a period comprised of a material having a high refractive index; (ii) a low refractive index material layer that supports the linear grating layer; and (iii) one or more specific binding substances immobilized on the surface of the linear grating layer opposite of the low refractive index material layer; wherein, when the biosensor is illuminated a resonant grating effect is produced on a transmitted radiation spectrum, and wherein the depth and the period of the linear grating layer is less than the wavelength of the resonant grating effect;   (b) a light source that directs light to the biosensor; and   (c) a detector that detects light transmitted through the biosensor.   
   
   
       11 . The detection system of  claim 10 , wherein the low refractive index material layer comprises glass, plastic, or epoxy. 
   
   
       12 . The detection system of  claim 10 , wherein the linear grating layer is comprised of zinc sulfide, titanium dioxide, indium tin oxide, tantalum oxide, or silicon nitride. 
   
   
       13 . The detection system of  claim 10 , wherein the one or more specific binding substances are arranged in an array of distinct locations on the linear grating layer. 
   
   
       14 . The detection system of  claim 10 , wherein the amount of the one or more binding partners is determined. 
   
   
       15 . The detection of  claim 10 , wherein the light source illuminates the biosensor from its top surface or from its bottom surface.