Spectroscopic Characterization of i-motif Forming c-myc Derived Sequences Double-Labeled with Pyrene

In current studies we use the oligonucleotides based on c-myc sequence: CCC CAC CCT CCC CAC CCT CCC C (cmyc22) and CCC CAC CCT CCC CAC CCT CCC CA (cmyc22A) functionalized by pyrene moieties at both termini. Results of the circular dichroism (CD), UV absorption melting experiments, and steady-state fluorescence measurements of pyrene-modified i-motifs as well as their unlabeled precursors are presented and discussed here. The pyrene labels have a remarkable influence on i-motif stability which was deduced from CD spectra and confirmed by UV melting experiments. Both probes emit fluorescence band of pyrene monomer with intensity decreasing upon pH lowering. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s10895-013-1184-z) contains supplementary material, which is available to authorized users

Steady-State Fluorescence and Lifetime Emission Study of pH-Sensitive Probes Based on i-motif Forming Oligonucleotides Single and Double Labeled with Pyrene

Cytosine-rich nucleic acids undergo pH-stimulated structural transitions leading to formation of an i-motif architecture at an acidic pH. Thus, i-motifs are good foundation for designing simple pH-sensitive fluorescent probes. We report here steady-state and time-resolved fluorescence studies of pyrene-labeled probes based on RET sequence: C4GC4GC4GC4TA (RET21), AC4GC4GC4GC4TA (RET21A) and C4GC4GC4GC4T (RET20). Comparative studies with single- and double-labeled i-motif probes were carried out. For each probe, we have measured fluorescence spectra and decays for emission wavelength of 390 nm over a wide range of pH (from 4.0 to 8.0). Effect of the oligonucleotide sequence and the number of pyrene labels on the spectral characteristics of probes were discussed

pH-Sensing fluorescence oligonucleotide probes based on an i-motif scaffold: a review

Fluorescent i-motif based sensors as promising tools for cellular pH-sensing and bioimaging.</p