Selectivity advancement through chemical structure engineering: Long-term intracellular DNA recognition, chromosomal staining and micronuclei detection

- Molecular probe with rational functionality for selective DNA recognition over RNA.
- The probe showed high photostability, negligible cytotoxicity and phototoxicity.
- Nuclear specificity was established through efficient metaphase chromosomal staining.
- Fluorescence based cell-proliferation and micronuclei detection using the developed probe.
- Appreciable optical response in the presence of DNA (ϕ = 0.23, B = 7000 M−1 cm−1).

Simultaneous integration of the most desired properties such as high photostability, negligible cytotoxicity and phototoxicity, good brightness, large Stokes shift and high selectivity toward DNA over RNA into a single DNA stain has always been challenging. Despite several efforts, the practical development of such DNA stain has been rare. In this context, probes (RD1-RD8) were synthesized and the worth of crescent geometry toward DNA selectivity of RD2 was established through careful structure-interaction relationship studies. Probe RD2 displayed admirable selectivity toward dsDNA with noticeable fluorescence enhancement (ϕ = 0.23). Molecular simulation was performed to comment on its stable conformation and optical changes observed due to electronic distribution in the presence of DNA. The excited state dynamics and binding mechanism were evaluated through fluorescence life-time and anisotropy measurements in the presence and absence of DNA. Further, the cell studies demonstrated its quick membrane permeability, extremely low cytotoxicity and potential toward specific nuclear staining with high contrast. Moreover, the negligible photoinduced cellular deterioration and high photostability under continuous laser scanning shed light on its long-term applicability for cellular investigations. Finally, the utility of RD2 in fluorescence based detection of cell-proliferation and micronuclei reflected its encouraging potential as a bioprobe for cellular imaging.

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