SERS-active multi-channel fluorescent probe for NO: Guide to discriminate intracellular biothiols

Abstract

We explored a rational design and synthesis of a Raman-active small molecular fluorescent probe (S1/Int-1) to acquire multicolor fluorescence-images based on intracellular nitric oxide (NO) in cancer cells. A new UV–vis absorption band centered at λab 510 nm for S1 was appeared in the presence of NO. Similarly, with increasing concentration of NO, the emission signal centered at 527 nm increased gradually. The probe S1 reacted with NO to form benzotriazole derivative Int-1 which showed characteristic intense Raman band centered at 1440 cm-1 for NN-. Individually, GSH and Cys reacted with Int-1 to offer a pair of new fluorophore 2 and 3 with different emission band centered at λem = 482 nm and λem = 453 nm respectively. Furthermore, the non-toxic probe S1 facilitated the monitoring of intracellular NO based dual colored imaging in the green and blue channel which intern allowed differentiating the intracellular GSH and Cys levels. Moreover, its cellular “off-on-off” response in the SERS spectral mode indicates that S1 can be a noninvasive tool to detect endogenous NO, GSH/Cys. Therefore, probe (S1/Int-1) could allow us monitoring of intracellular NO formation through dual channel fluorescence imaging with synchronous discrimination of thiols.