Particles for detecting intracellular targets
Methods describing the use of nanoparticles modified with binding moieties are provided.
1. A method of determining the intracellular concentration of a target polypeptide or small molecule comprising the step of contacting the target polypeptide or small molecule with a nanoparticle under conditions that allow association of the target polypeptide or small molecule with the nanoparticle, said nanoparticle comprising a binding moiety aptamer specific for said target polypeptide or small molecule, said binding moiety aptamer labeled with a marker, wherein the association of the target polypeptide or small molecule and the nanoparticle results in detectable change in the marker, wherein the change in the marker is proportional to the intracellular concentration of said target polypeptide or small molecule,
said binding moiety aptamer is a single-stranded polynucleotide covalently attached to said nanoparticle and said marker is a fluorescent label attached to a polynucleotide hybridized to said binding moiety aptamer, wherein said polynucleotide hybridized to said binding moiety aptamer is not attached to a nanoparticle and wherein association of said binding moiety aptamer with said target polypeptide or small molecule releases said hybridized polynucleotide and said marker is detectable after release.
2. The method of claim 1 wherein the binding moiety aptamer is DNA.
3. The method of claim 1 wherein the binding moiety aptamer is RNA.
4. The method of claim 1 wherein said nanoparticle comprises a multiplicity of binding moiety aptamers.
5. The method of claim 4 wherein the binding moiety aptamers specifically associate with one target polypeptide or small molecule.
6. The method of claim 4 wherein the binding moiety aptamers specifically associate with more than one target polypeptide or small molecule.
7. The method of claim 1 wherein the small molecule is adenosine triphosphate (ATP).
8. The method of claim 1 wherein the nanoparticle is a metal.
9. The method of claim 8 wherein the metal is gold, silver, copper, or platinum.
10. The method of claim 9 wherein the metal is gold.
11. A method of determining the intracellular concentration of a target polynucleotide comprising the step of contacting the target polynucleotide with a gold nanoparticle under conditions that allow association of the target polynucleotide with the gold nanoparticle, said nanoparticle comprising a binding moiety polynucleotide specific for said target polynucleotide, said binding moiety polynucleotide labeled with a marker, wherein the association of the target polynucleotide and the nanoparticle results in detectable change in the marker, wherein the change in the marker is proportional to the intracellular concentration of said target polynucleotide, said binding moiety polynucleotide is covalently attached to said gold nanoparticle and said marker is a fluorescent label attached to a polynucleotide hybridized to said binding moiety polynucleotide, wherein said polynucleotide hybridized to said binding moiety polynucleotide is not attached to a nanoparticle and wherein association of said binding moiety polynucleotide with said target polynucleotide releases said hybridized polynucleotide and said marker is detectable after release.
12. The method of claim 11 wherein said nanoparticle comprises a multiplicity of binding moieties.
13. The method of claim 12 wherein the binding moieties specifically associate with one target molecule.
14. The method of claim 12 wherein the binding moieties specifically associate with more than one target molecule.