This book spans diverse aspects of modified nucleic acids, from chemical synthesis and spectroscopy to in vivo applications, and highlights studies on chemical modifications of the backbone and nucleobases. Topics discussed include fluorescent pyrimidine and purine analogs, enzymatic approaches to the preparation of modified nucleic acids, emission and electron paramagnetic resonance (EPR) spectroscopy for studying nucleic acid structure and dynamics, non-covalent binding of low- and high-MW ligands to nucleic acids and the design of unnatural base pairs. This unique book addresses new developments and is designed for graduate level and professional research purposes.