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It is believed that HSO3− and SO32− play important roles in several physiological processes. However, probes with two-photon absorption to detect HSO3− or SO32− in living cells are still limited. Herein, a series of novel indolium derivatives (L1–L4) with an A–π–A′ structure was designed and synthesized as ratiometric probes to detect HSO3−/SO32−in vitro. L3 and L4 display a colorimetric and ratiometric fluorescence dual response to HSO3−/SO32− with a very fast (∼15 s) and high specificity, as well as low detection limits (∼22 nM). Furthermore, their detection is also carried out by using a two-photon excited fluorescence method. A nucleophilic addition reaction is proposed for the sensing mechanism, which is supported by MS, 1H NMR, and density functional theory (DFT) investigations. Importantly, L3 was successfully used for detecting intrinsically generated intracellular HSO3−/SO32− in cancerous cells under one- and two-photon excited fluorescence imaging. [ABSTRACT FROM AUTHOR]

Imaging of RNA in living cells is a potential tool to understand intracellular RNA function. Therefore, an effective two-photon fluorescent probe with a reasonable two-photon action cross-section to label RNA is now urgently required. In this work, a series of novel two-photon absorbing terpyridine ZnX2 (X = Cl, Br, I) complexes have been designed and an effective RNA imaging probe has been obtained. The results revealed that OTP-ZnCl2 possesses large Stokes shift and two-photon action cross-section. Furthermore, live cell imaging experiments indicated that OTP-ZnCl2 could stain nucleoli in living cells by binding with nucleoli RNA. The mechanism of selective nucleoli staining of OTP-ZnCl2 was studied systematically via both experiments and molecular modeling calculations. Due to its low cytotoxicity, good membrane permeability and counterstain compatibility with the commercial fluorescent nucleic acid dye Hoechst 33342, as well as its ability to label RNA in living cells, OTP-ZnCl2 is a promising candidate for the detection of nucleic acid in living cells. [ABSTRACT FROM AUTHOR]

It is believed that HSO 3 - and SO 3 2- play important roles in several physiological processes. However, probes with two-photon absorption to detect HSO 3 - or SO 3 2- in living cells are still limited. Herein, a series of novel indolium derivatives (L1-L4) with an A-π-A' structure was designed and synthesized as ratiometric probes to detect HSO 3 - /SO 3 2- in vitro. L3 and L4 display a colorimetric and ratiometric fluorescence dual response to HSO 3 - /SO 3 2- with a very fast (∼15 s) and high specificity, as well as low detection limits (∼22 nM). Furthermore, their detection is also carried out by using a two-photon excited fluorescence method. A nucleophilic addition reaction is proposed for the sensing mechanism, which is supported by MS, 1 H NMR, and density functional theory (DFT) investigations. Importantly, L3 was successfully used for detecting intrinsically generated intracellular HSO 3 - /SO 3 2- in cancerous cells under one- and two-photon excited fluorescence imaging.

Imaging of RNA in living cells is a potential tool to understand intracellular RNA function. Therefore, an effective two-photon fluorescent probe with a reasonable two-photon action cross-section to label RNA is now urgently required. In this work, a series of novel two-photon absorbing terpyridine ZnX 2 (X = Cl, Br, I) complexes have been designed and an effective RNA imaging probe has been obtained. The results revealed that OTP-ZnCl 2 possesses large Stokes shift and two-photon action cross-section. Furthermore, live cell imaging experiments indicated that OTP-ZnCl 2 could stain nucleoli in living cells by binding with nucleoli RNA. The mechanism of selective nucleoli staining of OTP-ZnCl 2 was studied systematically via both experiments and molecular modeling calculations. Due to its low cytotoxicity, good membrane permeability and counterstain compatibility with the commercial fluorescent nucleic acid dye Hoechst 33342, as well as its ability to label RNA in living cells, OTP-ZnCl 2 is a promising candidate for the detection of nucleic acid in living cells.

A specific series of D-π-A (1A-3A) and D-π-A (1B-3B) structural chromophores with various electron donors and π-conjugated bridges were designed, synthesized, and fully characterized. Their crystal structures were determined by single crystal X-ray diffraction analysis. The one/two-photon absorption properties of the chromophores have been successfully tuned by using different electron donors and π-bridges. Interestingly, it was found that chromophore 3B shows quite weak fluorescence in pure DMSO, while a significant AIE (aggregation-induced emission) effect is observed in water-DMSO (v/v 90%) mixtures with a sharp increase in fluorescence intensity of about 11 times. Furthermore, chromophore 3B shows strong two-photon excited fluorescence (TPEF) and has a large 2PA action cross-section (394 GM). The results of live-cell imaging experiments show that 3B can be effectively used as a bio-imaging probe in two-photon fluorescence microscopy towards HepG2 cells in vitro. The TPEF images of 3B not only exhibit cellular cytosol uptake but also exhibit actin regulatory protein uptake which are different from OPEF images.