关键词: DNA sequencing, base analogues, fluorescent probe

Abstract: To understand the gene-based biological processes in-depth, the single-molecule real-time sequencing has drawn increasing attention with promoted by the Human Genome Project. Herein, a set of newly designed canonical fluorescent bases (A$_{\rm y}$, tC, G$_{\rm b}$, T$_{\rm p}$) are proposed for four-color DNA sequencing. These quasi-intrinsic probes are derived from the fluorophore replacement and ring expansion on natural bases, which still keep the pyrimidine or purine underlying skeleton and Watson-Crick hydrogen bonding face to allow minimal perturbation to the native DNA duplex. More importantly, these nucleobase analogues possess red-shifted absorption and efficient photoluminescence due to the enhanced $\pi $-conjugation in character. Meanwhile, the four analogues could generate distinct emission wavelength ($\Delta \lambda \sim50$ nm) for real-time sequencing. To assess the biological employment of the proposed biosensors, the effects of base pairing and linking deoxyribose are also considered.

Key words: DNA sequencing, base analogues, fluorescent probe