Mass Dots: Nanoparticle Isotope Tags

Abstract

Compositions and methods are provided for the use of nanoparticles, which may be referred to herein as mass dots, as mass tags for probes such as antibodies, aptamers, nucleic acids, etc. in multiplexed bioassays with ICP-MS detection.

1 . A probe comprising a specific binding member for an analyte, conjugated to a mass dot, wherein the mass dot is a high-atomic mass, non-biological element of a size and uniformity sufficient to enable highly sensitive detection of very small quantities of analyte. 
     
     
         2 . The probe of  claim 1 , wherein said high-atomic mass, non-biological element is a metal with isotopic purity between about 90 and 100%. 
     
     
         3 . The probe of  claim 2 , wherein said mass dot is at least 100 metal atoms. 
     
     
         4 . The probe of  claim 2  wherein said mass dot is at least about 10 3  metal atoms. 
     
     
         5 . The probe of  claim 2 , wherein said mass dot is at least about 10 4  metal atoms. 
     
     
         6 . The probe of  claim 2 , wherein said mass dot is free of high atomic mass dopants. 
     
     
         7 . The probe of  claim 2 , wherein said mass dot is comprised of non-fluorescent nanocrystals with two or more atomic mass metals. 
     
     
         8 . The probe of  claim 2  where said mass dot is comprised of multiple high atomic mass metals at a known ratio and absolute quantity. 
     
     
         9 . The probe of  claim 2 , wherein said mass dot comprises a nanocrystal. 
     
     
         10 . The probe of  claim 2 , wherein said mass dot comprises a nanoparticle core of said metal, and a low molecular weight counter-anion. 
     
     
         11 . The probe of  claim 2 , wherein said mass dot comprises a coating selected from an amphipathic polymer, PEG, silane, siloxane, silica, or lipids. 
     
     
         12 . The probe of  claim 2 , wherein a single mass dot is conjugated to said specific binding member. 
     
     
         13 . The probe of  claim 12 , wherein not more than 10 mass dots are conjugated to said specific binding member. 
     
     
         14 . The probe of  claim 12 , wherein said specific binding member is a polypeptide. 
     
     
         15 . The probe of  claim 14 , wherein said specific binding member is an antibody. 
     
     
         16 . The probe of  claim 12 , wherein said specific binding member is a polynucleotide. 
     
     
         17 . The probe of  claim 12 , wherein said specific binding member is avidin or streptavidin. 
     
     
         18 . A method for the sensitive detection of an analyte, the method comprising:
 binding said analyte through specific binding to a probe as set forth in  claim 1 ; and detecting the presence of said mass dot.   
     
     
         19 . The method of  claim 18 , wherein said detecting is performed by ICP-MS. 
     
     
         20 . A probe comprising a specific binding member for an analyte, conjugated to a daughter assayable detector species (DADS), wherein the DADS is (1) associated with the analyte particle or (2) can be separated from the analyte particle, measured and registered to the particle they were derived from. 
     
     
         21 . The probe of  claim 20 , wherein the DADS is a metal encoded nano object with definable mass over charge ratio. 
     
     
         22 . The probe of  claim 20 , wherein the DADS is a structural unit encoded nano-object with definable mass over charge ratio. 
     
     
         23 . A method for the sensitive detection of an analyte, the method comprising:
 binding said analyte through specific binding to a probe as set forth in  claim 20 ; and detecting the presence of said probe.