title: A unique type of pyrrole-based cyanine fluorophores with turn-on and ratiometric fluorescence signals at different pH regions for sensing pH in enzymes and living cells.
abstract: The development of new functional fluorescent dyes has attracted great attention. Herein we have described a novel strategy to design a unique type of cyanine dyes by attaching two indolium moieties at the α-positions of the pyrrole core. The new type of cyanine dyes is named as PyCy fluorophores. Importantly, PyCy dyes can exhibit an exceptional feature, fluorescence turn-on response at pH varying from acidic to near-neutral conditions, and a ratiometric fluorescence response at pH varying from near-neutral to basic conditions. By taking advantage of the fluorescence turn-on response of PyCy2 at pH varying from acidic to near-neutral conditions and emission properties of PyCy2, we have demonstrated that a small-molecule fluorescent probe can image pH variations in living cells. Furthermore, we have demonstrated that PyCy2 can sense real-time pH changes under alkaline conditions induced by enzymes based on the ratiometric fluorescence response of PyCy2 at pH varying from near-neutral to basic conditions. We expect that the new design strategy for PyCy fluorophores may prompt the development of a wide variety of cyanine derivatives with desirable properties.
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University , Changsha, Hunan 410082, P. R. China.
authors.forename: Longwei
authors.initials: L
authors.lastname: He
authors.forename: Weiying
authors.initials: W
authors.lastname: Lin
authors.forename: Qiuyan
authors.initials: Q
authors.lastname: Xu
authors.forename: Haipeng
authors.initials: H
authors.lastname: Wei
mesh_terms: D002232:Carbocyanines / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000138:chemical synthesis*; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing; D011758:Pyrroles / Q000737:chemistry*; D013050:Spectrometry, Fluorescence / Q000379:methods*
chemical_list: D002232:Carbocyanines; D005456:Fluorescent Dyes; D011758:Pyrroles
keywords: cyanine dyes; fluorescence imaging; pH probe; pyrrole; ratiometric; turn-on