Hybridization and melting behavior of Peptide Nucleic Acid (PNA) oligonucleotide chimeras conjugated to gold nanoparticles

Peptide nucleic acids (PNA) and PNA-DNA chimeras carrying thiol groups were used for surface functionalization of Au nanoparticles. Conjugation of PNA to citrate-stabilized Au nanoparticles destabilized the nanoparticles causing them to precipitate. Addition of a tail of glutamic acid to the PNA prevented destabilization of the nanoparticles but resulted in loss of interaction with complementary sequences. Importantly, PNA-DNA chimeras gave stable conjugates with Au nanoparticles. The hybridization and melting properties of complexes formed from chimera-nanoparticle conjugates and oligonucleotide-nanoparticle conjugates are described for the first time. Similar to oligonucleotide- nanoparticle conjugates, conjugates with PNA-DNA chimeras gave sharper and more-defined melting profiles than those obtained with unmodified oligonucleotides. In addition, mismatch discrimination was found to be more efficient than with unmodified oligonucleotides.