Biosensor Using Whispering Gallery Modes in Microspheres

Abstract

A biosensor for detecting the presence of a target analyte is disclosed. The biosensor is formed from microspheroidal particles which have had a binding partner for the target analyte immobilized on their surfaces. The binding partners may be nucleotides; peptides, proteins, enzymes, antibodies and so on. When the analyte binds to its partner, the whispering gallery mode (WGM) profiles of the microspheroidal particles change such that the profile peaks undergo a red-or blue-shift. The immobilised binding partners may include fluorophores and the like so that they emit fluorescence, phosphorescence, incandescence and the like. These fluorophores may take the form of a nanocrystal or quantum dot.

1 . A method of detecting an analyte, said method comprising contacting at least one set of microspheroidal particles with a sample putatively comprising said analyte, wherein each particle within a set of microspheroidal particles comprises an optically detectable label and an immobilized putative binding partner of said analyte wherein each particle set has a defined Whispering Gallery Mode (WGM) profile, wherein binding of said analyte to said immobilized binding partner results in a change in said WGM profile indicated by a spectral shift in the optically detectable label of said at least one set of microspheroidal particles which is indicative of the presence of said analyte. 
     
     
         2 . The method of  claim 1 , wherein the optically detectable label is a flurochrome. 
     
     
         3 . The method of  claim 2 , wherein each microspheroidal set of particles is labled with a different flurochrome. 
     
     
         4 . The method of  claim 1 , wherein each microspheroidal set is labeled with a different immobilized putative binding partner of said analyte. 
     
     
         5 . The method of  claim 1 , wherein each microspheroidal set of particles is a different size. 
     
     
         6 . The method of  claim 1 , wherein each microspheroidal set of particles have two or more of:
 a. a different optically detectable label;   b. a different size; and/or   c. a different immobilized binding partner of an analyte.   
     
     
         7 . The method of  claim 1  wherein said microspheroidal particle comprises a material selected from the group consisting of silica, latex, titania, tin dioxide, yttria, alumina, and other binary metal oxides, perovskites and other piezoelectric metal oxides, sucrose, agarose and other polymers. 
     
     
         8 . The method of  claim 7 , wherein said particle comprises silica. 
     
     
         9 . The method of  claim 1  wherein said particle is a substantially spherical or spheroidal particle. 
     
     
         10 . The method of  claim 5  wherein said particle comprises a diameter of about 300 nm to about 30 μm. 
     
     
         11 . The method of  claim 1  wherein said optically detectable label is a molecule, atom or ion which emits fluorescence. 
     
     
         12 . The method of  claim 1  wherein said optically detectable label is a molecule, atom or ion which emits phosphorescence. 
     
     
         13 . The method of  claim 1  wherein said optically detectable label is a molecule, atom or ion which emits incandescence. 
     
     
         14 . The method of  claim 1  wherein said optically detectable label is detectable in any one or more of the ultraviolet, visible, near infrared (NIR) and/or infrared (IR) wavelength ranges. 
     
     
         15 . The method of  claim 11  wherein said optically detectable label is detectable in the visible wavelength range. 
     
     
         16 . The method of  claim 1  wherein said optically detectable label comprises a label selected from the group consisting of a fluorophore, a semiconductor particle, a phosphor particle, a doped particle, a nanocrystal and a quantum dot. 
     
     
         17 . The method of  claim 16  wherein said optically detectable label is a fluorophore. 
     
     
         18 . The method of  claim 16  wherein said optically detectable label is a quantum dot. 
     
     
         19 . The method of  claim 1 , wherein said immobilized binding particle comprises a nucleic acid molecule. 
     
     
         20 . The method of  claim 19  wherein said nucleic acid molecule comprises DNA. 
     
     
         21 . The method of  claim 19  wherein said nucleic acid molecule comprises RNA. 
     
     
         22 . The method of  claim 1 , wherein said immobilized binding particle comprises a peptide, polypeptide or protein. 
     
     
         23 . The method of  claim 22 , wherein said peptide, polypeptide or protein is an enzyme. 
     
     
         24 . The method of  claim 22 , wherein said peptide, polypeptide or protein is an antibody. 
     
     
         25 . The method of  claim 1 , wherein said immobilized binding particle comprises a carbohydrate molecule. 
     
     
         26 . The method of  claim 25 , wherein said carbohydrate is a glycosaminoglycan molecule. 
     
     
         27 . The method of  claim 1  wherein the modulation of said WGM profile comprises a red-shift of one or more peaks in said profile. 
     
     
         28 . The method of  claim 1  wherein the modulation of said WGM profile comprises a blue-shift of one or more peaks in the profile. 
     
     
         29 . The method of  claim 27  wherein the red-shift comprises a wavelength change of said peak or peaks of between 1 and 100 nm. 
     
     
         30 . The method of  claim 29  wherein the red-shift comprises a wavelength change of said peak or peaks of between 1 and 20 nm. 
     
     
         31 . The method of  claim 1  wherein the modulation of said WGM profile comprises the appearance of one or more peaks in one or more of said WGM profile. 
     
     
         32 . The method of  claim 1  wherein the modulation of said WGM profile comprises the disappearance of one or more peaks in one or more of said WGM profile. 
     
     
         33 . The method of  claim 1  wherein the WGM profile is determined by using a confocal microscope in conjunction with a spectrometer 
     
     
         34 . The method of  claim 1  wherein the WGM profile is determined using ann array scanner in conjunction with a spectrometer. 
     
     
         35 . The method of  claim 1  wherein the WGM profile is determined by a device which measures light from individual particles in conjunction with a spectrometer 
     
     
         36 . The method of  claim 35 , wherein the device in a flow cytometer. 
     
     
         37 . An analyte detected by the method of  claim 1 . 
     
     
         38 . The method of  claim 28  wherein the blue-shift comprises a wavelength change of said peak or peaks of between 1 and 100 nm. 
     
     
         39 . The method of  claim 38  wherein the blue-shift comprises a wavelength change of said peak or peaks of between 1 and 20 nm.