Methods and compositions for biosensing

Abstract

In one aspect, methods of sensing are described herein. In some embodiments, such a method comprises disposing a population of luminescent species in a test sample, exposing the test sample to electromagnetic radiation having a wavelength corresponding to an excitation wavelength of the luminescent species, detecting light emitted by the luminescent species within a detection region of the test sample, and correlating the light emitted by the luminescent species within the detection region to a presence or absence of an analyte within the test sample. The luminescent species, in a non-aggregated state, exhibits luminescence blinking and, in an aggregated state, does not exhibit luminescence blinking. Additionally, correlating the light emitted by the luminescent species to the presence or absence of the analyte comprises determining whether the light emitted by the luminescent species within the detection region is blinking luminescence or non-blinking luminescence.

1 . A sensing composition, the composition comprising:
 a population of individual luminescent species;   wherein the luminescent species, in a non-aggregated state, exhibits luminescence blinking and, in an aggregated state, do not exhibit luminescence blinking; and   wherein the individual luminescent species are operable to transition from the non-aggregated state to the aggregated state in the presence of an analyte.   
     
     
         2 . The composition of  claim 1 , wherein the individual luminescent species comprise colloidal quantum dots. 
     
     
         3 . The composition of  claim 2 , wherein the colloidal quantum dots exhibit a size distribution having a standard deviation of 5-15 percent. 
     
     
         4 . The composition of  claim 2 , wherein the colloidal quantum dots exhibit a size distribution having a standard deviation of 5-10 percent. 
     
     
         5 . The composition of  claim 2 , wherein the colloidal quantum dots comprise a ligand shell. 
     
     
         6 . The composition of  claim 5 , wherein ligands of the ligand shell are bonded to surfaces of the quantum dots via covalent bonds. 
     
     
         7 . The composition of  claim 5 , wherein ligands of the ligand shell are bonded to surfaces of the quantum dots via non-covalent bonds. 
     
     
         8 . The composition of  claim 5 , wherein ligands of the ligand shell include 4 to 50 carbon atoms. 
     
     
         9 . The composition of  claim 2 , wherein the colloidal quantum dots comprise one or more surface binding sites operable to interact with a coupling moiety of an analyte binding species. 
     
     
         10 . The composition of  claim 9 , wherein the binding sites comprises streptavidin. 
     
     
         11 . The composition of  claim 9 , wherein the analyte binding species comprises a nucleic acid. 
     
     
         12 . The composition of  claim 2 , wherein the quantum dots are formed of a Group II-VI semiconductor material. 
     
     
         13 . The composition of  claim 2 , wherein the quantum dots are formed of a Group III-V semiconductor material. 
     
     
         14 . The composition of  claim 12 , wherein the quantum dots further comprise a metal dopant. 
     
     
         15 . The composition of  claim 14 , wherein the metal dopant is light emitting. 
     
     
         16 . The composition of  claim 2 , wherein the quantum dots have a core/shell architecture. 
     
     
         17 . The composition of  claim 16 , wherein the quantum dots have a Type I electronic structure. 
     
     
         18 . The composition of  claim 16 , wherein the quantum dots have a Type II electronic structure. 
     
     
         19 . The composition of  claim 2 , wherein the quantum dots have an emission in the range of 350 nm to 650 nm. 
     
     
         20 . The composition of  claim 19 , wherein the quantum dots have a quantum yield of 30-50 percent.