Qi Qingkai, Chi Weijie, Li Yuanyuan, Qiao Qinglong, Chen Jie, Miao Lu, Zhang Yi, Li Jin, Ji Wei, Xu Tao, Liu Xiaogang, Yoon Juyoung, Xu Zhaochao
CAS Key Laboratory of Separation Science for Analytical Chemistry , Dalian Institute of Chemical Physics , Chinese Academy of Sciences , Dalian 116023 , China . Email:
Singapore University of Technology and Design , 8 Somapah Road , Singapore 487372 , Singapore . Email:
Chem Sci. 2019 Apr 4;10(18):4914-4922. doi: 10.1039/c9sc01284b. eCollection 2019 May 14.
Rhodamine spirolactam based photoswitches have been extensively applied in super-resolution single-molecule localization microscopy (SMLM). However, the ring-opening reactions of spirolactams are cross-sensitive to acid, limiting their photoswitch use to neutral pH conditions. In addition, the ring-closing reactions of spirolactams are environment-sensitive and slow (up to hours), virtually making rhodamine spirolactams caged fluorescent dyes instead of reversible photoswitches in SMLM. Herein, by introducing hydrogen bonds to stabilize spirolactams, we report a series of acid-resistant rhodamine spirolactams with accelerated ring-closing reactions from fluorescent xanthyliums to non-fluorescent spirolactams, endowing them with good photoswitchable properties even in acidic environments. By further substitution of 6-phenylethynyl naphthalimide on the spirolactam, we shifted the photoactivation wavelength into the visible region (>400 nm). Subsequently, we have successfully applied these dyes in labeling and imaging the cell surface of at pH 4.5 using SMLM.
基于罗丹明螺内酰胺的光开关已广泛应用于超分辨率单分子定位显微镜（SMLM）。然而，螺内酰胺的开环反应对酸具有交叉敏感性，这限制了它们在中性pH条件下的光开关应用。此外，螺内酰胺的闭环反应对环境敏感且缓慢（长达数小时），实际上使得罗丹明螺内酰胺在SMLM中成为笼形荧光染料而非可逆光开关。在此，通过引入氢键来稳定螺内酰胺，我们报道了一系列耐酸的罗丹明螺内酰胺，其从荧光呫吨盐到非荧光螺内酰胺的闭环反应加速，即使在酸性环境中也赋予它们良好的光开关性能。通过在螺内酰胺上进一步取代6-苯乙炔基萘二甲酰亚胺，我们将光激活波长转移到可见光区域（>400 nm）。随后，我们成功地使用SMLM将这些染料应用于在pH 4.5下对细胞表面进行标记和成像。
