Optical polarization of selectively functionalized cadmium selenide nanorods and potential for application in selective detection of oligonucleotides

A nucleic acid biosensing strategy that involves immobilization of oligonucleotide probes onto CdSe nanorods (NRs) is being investigated. Experiments have demonstrated presence of polarization memory in solutions of randomly oriented NRs. This can be related to the mismatch between dielectric constants of NRs and solvent, as well as to anisotropy of optical matrix elements. Selective functionalization of both apexes of CdSe NRs with gold nanoparticles was achieved. This derivatization was selected to allow for preferential immobilization of NRs on a surface. Preliminary work to conduct sandwich-type assay with two oligonucleotide probes complementary to a target sequence was initiated. The proposed design is based on orientation of bioconjugated NRs and the subsequent changes of emission polarization as a result of the hybridization. This biosensor technology may provide a sensitive and selective method for rapid and reliable detection of oligonucleotides in a strategy that does not rely on labeling of probes and targets.