Angew. Chem. Int. Ed.http://doi.org/fz5db8 (2012)

Credit: © 2012 WILEY

The early diagnosis of cancer — for example, the identification of intracellular gene expression abnormalities — is critical to increase survival rates. Multiple tumour-related messenger RNAs (mRNAs) are often present at initial disease stages but methods so far have focused on single mRNA detection. Now, Bo Tang and colleagues report nanoprobes that can simultaneously detect three intracellular tumour-related mRNAs in living cells. The nanoprobes consist of gold nanoparticles functionalized with oligonucleotides hybridized to three reporter sequences with different dye molecules attached. The dyes' fluorescence is quenched in this configuration; however, in the presence of the three tumour-related mRNAs the recognition sequences present on the oligonucleotides hybridize with the mRNA targets and the dye-containing sequences are released, producing fluorescence signals. The nanoprobe can detect the presence of the three target mRNAs in human breast and liver cancer cells, and can discriminate between cancer cells and normal cells. The fluorescence intensity of the signals correlates with the concentration of the mRNA targets, and drug-induced changes in gene expression levels within cancer cells can be detected.