Particles for detecting intracellular targets

A method of determining the intracellular concentration of a target polynucleotide comprising the step of contacting the target polynucleotide with a nanoparticle under conditions that allow association of the target polynucleotide with the 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 detectable marker is proportional to the intracellular concentration of said target polynucleotide, said binding moiety polynucleotide is covalently attached to said nanoparticle and said marker is a label attached to a polynucleotide hybridized to said binding moiety polynucleotide, wherein association of said binding moiety polynucleotide with said target polynucleotide releases said hybridized polynucleotide and said marker is detectable after release.