Synthesis of symmetrical thiol-adenosine conjugate and 5' thiol-RNA preparation by efficient one-step transcription.

A symmetrical transcription initiator containing two adenosines and conjugated thiol functionality (ThioAMP dimer) is chemically synthesized. Transcription in the presence of ThioAMP dimer under the T7 Φ2.5 promoter yields 5' thiol-labeled RNA (5' HS-RNA) with up to 90% labeling efficiency, depending on the concentration ratio of ThioAMP dimer to ATP. The resulting 5' HS-RNA may be used directly or after thiopropyl Separose 6B affinity column purification. Biotinylation of 5' HS-RNA and formation of gold nanoparticle-RNA nanoplexes are demonstrated.