One of the most important discoveries in the 20th century is that DNA and RNA are not only materials for genetic information storage and transfer, but also enzymes for a variety of biological reactions. Since metal ions play essential roles in the structure and function of catalytic DNA/RNA, the study and application of these new metalloenzymes has become a new frontier in bioinorganic chemistry. While different classes of metal-specific proteins have been studied, including a comprehensive understanding of their sequence, structural, and functional features specific to each metal ions, similar information about metal-specific DNA/RNA is not available. Using in vitro selection methods, we have been able to obtain new DNAzymes from a large DNA library of up to 1015 different sequences that are specific to a metal ion of choice, with high specificity.1 We have also carried out both biochemical and biophysical studies of these DNAzymes in order to elucidate features responsible for the selective binding of metal ions by the DNAzymes.2 Because of the high selectivity, these DNAzymes have been converted into fluorescent, colorimetric, electrochemical sensors and magnetic resonance imaging agents for detection of metal ions with high sensitivity (down to 11 ppt limit of detection) and selectivity (up to millions of fold of selectivity).3 Recently, these DNAzymes have been delivered into cells through conjugation with gold nanoparticles4 or cationic peptides.5 Together with photo-caged DNAzymes,5 these methods allow detection and imaging of a wide variety of metal ions in living cells with high spatial and temporal resolution. 1. a) J. Liu et al., Proc. Natl. Acad. Sci. USA 104, 2056–2061 (2007); b) Y. Xiang and Y. Lu Inorg. Chem. 53, 1925–1942 (2014). 2. a) H.-K. Kim et al. Nature Chem. Biol. 3, 763-768 (2007); b) T. Lan and Y. Lu, in Interplay between Metal Ions and Nucleic Acids", Metal Ions in Life Sciences, Vol. 10, A. Sigel, H. Sigel, R. K. O. Sigel, eds.; Springer Netherlands; pp. 217-248 (2012). 3. J. Liu, Z. Cao, Y. Lu, Chem. Rev. 109, 1948–1998 (2009). 4. P. Wu, et al. J. Am. Chem. Soc. 135, 5254-5257 (2013) 5. K. Hwang, Angew. Chem. Inter. Ed. (in press: DOI: 10.1002/anie.201408333)

In vitro selection and characterization of metallo-DNAzymes and their delivery into cells for sensing and imaging applications

249th National Meeting (2015)

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