Alloy metal nanoparticles for multicolor cancer diagnostics

Cancer is a multigenic complex disease where multiple gene loci contribute to the phenotype. The ability to simultaneously monitor differential expression originating from each locus results in a more accurate indicator of degree of cancerous activity than either locus alone. Metal nanoparticles have been thoroughly used as labels for in vitro identification and quantification of target sequences. We have synthesized nanoparticles with assorted noble metal compositions in an alloy format and functionalized them with thiol-modified ssDNA (nanoprobes). These nanoprobes were then used for the simultaneous specific identification of several mRNA targets involved in cancer development - one pot multicolor detection of cancer expression. The different metal composition in the alloy yield different "colors" that can be used as tags for identification of a given target. Following a non-cross-linking hybridization procedure previously developed in our group for gold nanoprobes, these multicolor nanoprobes were used for the molecular recognition of several different targets including differently spliced variants of relevant genes (e.g. gene products involved in chronic myeloid leukemia BCR, ABL, BCR-ABL fusion product). Based on the spectral signature of mixtures, before and after induced aggregation of metal nanoparticles, the correct identification could be made. Further application to differentially quantify expression of each locus in relation to another will be presented. The differences in nanoparticle stability and labeling efficiency for each metal combination composing the colloids, as well as detection capability for each nanoprobe will be discussed. Additional studies will be conducted towards allele specific expression studies.