Fluorescent nucleosides with ‘on–off’ switching function, pH-responsive fluorescent uridine derivatives

We synthesized various pH-responsive fluorescent deoxyuridine derivatives (1a–g). These fluorescent nucleosides exhibited distinctive fluorescence at 470–600 nm in aqueous solvents containing methanol only at acidic to neutral pH values. In particular, 1f exhibited strong fluorescence only at pH range of 3.1–7.2 with a pKa of 6.1. Such pH-sensitive fluorescent nucleosides can be used as ‘on–off’ fluorescence switch for monitoring pH change in biological systems, particularly for cancer cell detection.

Graphical abstractStructures of fluorescent pH responsive nucleosides.Figure optionsDownload full-size imageDownload as PowerPoint slide