•A new rhodamine B derivatized chemosensor (L1) was synthesized and characterized.•The interactions of L1 with amino acids and metal ions were studied.•L1 exhibited a highly sensitive and selective fluorescence response toward GSH.•The detection limit of GSH by L1 was 0.219 μM.•L1 can be used as a fluorescent probe for the detection of GSH in living cells.A novel rhodamine B spirolactam derivative bearing an N-[4-(carbonyl)phenyl] maleimide moiety (L1) was designed, synthesized and structurally characterized to develop a chemosensor. The interactions of L1 with amino acids and metal ions were studied by UV–vis absorption and fluorescence spectroscopy. L1 exhibited a highly sensitive and selective turn-on fluorescence response toward glutathione (GSH) over other biological species in EtOH/HEPES (3:2, v/v, 0.1 mM, pH 7.34) solution. The detection limit of GSH by L1 was 0.219 μM. Intracellular imaging applications demonstrated that L1 can be used as a fluorescent probe for the detection of GSH in HepG-2 and HUVEC cells.

•A novel fluorescent probe that utilizes fluorescein and rhodamine B derivatives as chromophores was synthesized.•Studies indicate that the fluorescence intensity of TRDM-F can be mainly determined by the fluorescein group.•The chemosensor of TRDM-F had excellent selectivity and sensitivity for Cys.•Cell studies demonstrated that TRDM-F can be used as a fluorescent probe for the detection of Cys in Hela cells.A new fluorescent probe (TRDM-F) based on a molecular chain of open-loop maleic anhydride, rhodamine B and fluorescein was designed, synthesized and evaluated to develop a chemosensor. Photochemical studies show that fluorescence properties of TRDM-F are dominated by fluorescein group in the pH range of 2–10. UV–vis absorption and fluorescence spectroscopic studies further display a high selectivity towards Cys over GSH/Hcy and other amino acids and a high sensitivity towards Cys (0.088–270 μM) with 95-fold fluorescence enhancement in a HEPES buffer solution (10 mM, pH = 7.4) containing 20% MeCN at room temperature. We further demonstrated that the proposed method was satisfactorily applied to the discrimination of Cys in living Hela cells with low cell toxicity.Download high-res image (143KB)Download full-size image

•A new furfuran-based rhodamine B fluorescent probe (RBFF) was designed and synthesized.•RBFF exhibits a highly sensitive and selective “turn-on” fluorescent response to Fe3+ and “turn-off” response to B4O72−.•The detection limit of RBFF for Fe3+ was calculated to be 0.025 μM.•Cell studies demonstrated that RBFF can serve as a biological fluorescence probe for the detection of Fe3+ in HeLa cells.A new furfuran-based rhodamine B fluorescent probe (RBFF) has been designed and synthesized, and its sensing behavior towards various metal ions was evaluated via UV–vis and fluorescence spectroscopic techniques. RBFF exhibits a highly sensitive and selective “turn-on” fluorescent response toward Fe3+ ion and a fluorescence “turn-off” response when added B4O72− to the RBFF-Fe3+ in the EtOH/H2O solution (1:1, v/v, HEPES, 1 mM, pH 7.20). The detection limit of RBFF for Fe3+ was calculated to be 0.025 μM. The fluorescence microscopy experiment suggested that RBFF could also be served as a biological fluorescence probe for the detection of Fe3+ in human cervical carcinoma cells (HeLa).Download high-res image (96KB)Download full-size image

A new fluorescein derivative, namely, (E)-2-(((1H-pyrrol-2-yl) methylene)amino)-3′,6′-dihydroxyspiro[isoindoline-1,9′-xanthen]-3-one (FLPY), was designed, synthesized, and structurally characterized to develop a chemosensor. The interactions of FLPY with different metal ions have been studied over UV–vis absorption spectra and fluorescent spectra. The results show that FLPY exhibits high sensitivity and selectivity toward Cu2+ among many other metal cations in a DMSO/HEPES (3:1, v/v, 1 mM, pH 7.2) solution. The binding association constant (Ka) of FLPY for Cu2+ based on a 1:1 stoichiometry was estimated to be 1.29 × 104 M−1 in the solution. The detection limit of Cu2+ by FLPY was further determined to be 0.296 μM.A new selective fluorescent chemical sensor for Cu2+ based on a Pyrrole moiety and a Fluorescein conjugate, was designed, synthesized, and structurally characterized.

•A new Rhodamine B derivative based on a maleimide moiety was designed and synthesized for the development of a fluorescent chemical sensor for glutathione (GSH).•UV–vis absorption and fluorescence spectroscopic studies show that Probe-M exhibited a high selectivity and sensitivity towards GSH among many other amino acids in an EtOH/HEPES (3:2; v/v; 600 μM, pH 7.36) solution.•The 1:2 coordination mode was proposed on the basis of Job’s plot and High resolution Mass spectrometry results.•Fluorescence cell studies of Probe-M in both Hepg2 cells and Huvec cells further demonstrated that the Probe-M could be served as a potential fluorescent probe to detect GSH in living cells.A new rhodamine B-based fluorescent probe (Probe-M), namely N-(2-(3′,6′-bis(diethylamino)-3-oxospiro[isoindoline-1,9′-xanthen]-2-yl)ethyl)-3,5-bis(2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl) benzamide, was designed and synthesized to develop a fluorescent sensor for glutathione (GSH). Probe-M displayed excellent selectivity and sensitivity for GSH over many other amino acids in an EtOH/HEPES buffer solution. The application of GSH in cellular imaging experiments indicated that the probe has appreciable cell permeability and is highly responsive to changes in the GSH level. As a result, Probe M can serve as a fluorescent probe for detecting GSH in living cells.A novel rhodamine B-based fluorescent sensor (Probe-M) for glutathione (GSH) was designed and synthesized. Probe-M displays an excellent selectivity and sensitivity for GSH over many other amino acids in an EtOH/HEPES buffer solution.

•A novel sensitive and selective nanocomposite sensor for Doxorubicin based on Graphene Oxide and fluorescent [2]Rotaxane is developed.•The quencher properties of GO are analyzed by UV–vis and fluorescence spectra.•Fluorescence recovery can be observed after the addition of DOX.•The results of the fluorescence analysis demonstrate that the RhBPy-GO sensor exhibits high sensitivity and selectivity toward DOX alone among many other antibiotics.Graphene oxide (GO) displays advantageous characteristics as a quencher due to its excellent quenching capacity toward organic fluorescent molecules. In this paper, GO is used as a quencher of RhBPy [2]rotaxane based on the mechanism of fluorescence resonance energy transfer (FRET), and a GO-based fluorescent probe that allows rapid, sensitive and selective detection of doxorubicin (DOX) in a MeOH/H2O solution is reported. The results show that the efficient fluorescence quenching that occurs between GO and RhBPy [2]rotaxane is due to their strong noncovalent interactions via energy transfer, leading to very weak emission in the absence of DOX, while a strong red fluorescence is observed upon the addition of DOX into the RhBPy-GO solution. As a consequence, it is possible to employ the RhBPy-GO platform in DOX detection with high sensitivity and selectivity by monitoring changes in the fluorescence intensity of the MeOH/H2O (3:2, v: v) solution.A novel sensitive and selective nanocomposite sensor for Doxorubicin based on Graphene Oxide and fluorescent [2]Rotaxane is developed. The results show high sensitivity and selectivity toward DOX among many other antibiotics in the MeOH/H2O (3:2, v:v) solution.

A novel Rhodamine B-derivatized host [2]rotaxane, containing a dibenzyl-24-crown-8 (DB24C8) ring as the wheel and a pyrene as another fluorophore blocking group, was designed, synthesized and structurally characterized. A comparison of the 1H NMR spectra of RhBPy [2]rotaxane with those of 2 and DB24C8, nuclear Overhauser effect spectroscopy (NOESY), mass spectrometry and fluorescence spectroscopy confirmed the interlocked nature of RhBPy [2]rotaxane. The temperature dependence of the rotaxane studied by 1H NMR spectroscopy further demonstrated that RhBPy [2]rotaxane can be applied as a molecular switch. RhBPy [2]rotaxane has also been demonstrated to be an efficient transport agent for delivering the cancer drug doxorubicin (DOX) into tumor cells. Indeed, DOX delivered by RhBPy [2]rotaxane could effectively inhibit tumor cell growth.

A new Rhodamine B derivative (RBDPA), namely, N1-(2-(3′,6′-bis(diethylamino)-3-oxospiro[isoindoline-1,9′-xanthen]-2-yl)ethyl)-N4,N4-bis(pyridin-2-ylmethyl)succinamide, was designed, synthesized and structurally characterized to develop a chemosensor. The studies show that RBDPA exhibits high sensitivity and selectivity toward Al3+ among many other metal cations in an ethanol/H2O (1:1, v/v, pH = 7.2, HEPES buffer, 0.1 mM) solution. Fluorescence microscopy experiments further demonstrate that RBDPA can be used as a fluorescent probe to detect Al3+ in living cells.

Over the past few decades, bistable [2]rotaxanes have been extensively studied because of their applications in molecular switches. In this paper, a rotaxane molecule containing a dibenzo-24-crown-8 ring and Rhodamine B units was synthesized and characterized by 1H NMR and HRMS. The Rhodamine B component allows the fluorophore fluorescence to be manipulated in alternate modes by varying the pH of the solution under irradiation. Because of the easy regulation and high sensitivity of the changes in fluorophore fluorescence, Rhodamine B [2]rotaxane can be used as a molecular switch, with different pH values as the input and changes in the fluorescence intensity as the output signals.

A new fluorescent chemosensor based on a Rhodamine B and pyrrole conjugate (RBPY) has been designed and synthesized. UV–vis absorption and fluorescence spectroscopic studies show that RBPY exhibits a high selectivity and sensitivity toward Fe3+ among many other metal cations in a MeOH/H2O solution (3:2, v/v, pH 7.10, HEPES buffer, 0.1 mM) by forming a 1:1 complex with Fe3+. Furthermore, results reveal that the formation of the RBPY–Fe3+ complex is fully reversible in the presence of sulfide anions and could also be used as an efficient sensor for S2−. Importantly, fluorescence microscopy experiments further demonstrated that RBPY can be utilized as a fluorescent probe for the detection of Fe3+ in human liver (L-02) cells.A new fluorescent chemosensor, RBPY, was synthesized. Studies show that RBPY exhibits a high selectivity and sensitivity toward Fe3+ in a MeOH/H2O (3:2, v/v, pH 7.10, HEPES buffer, 0.1 mM) solution. Fluorescence microscopy experiments demonstrated that RBPY can be used as a fluorescent probe for the detection of Fe3+ in living cells.

The synthesis and characterization of a novel Rhodamine B [2]rotaxane is described. This species contains dibenzyl-24-crown-8 (DB24C8) as a wheel, which is threaded onto a sec-ammonium-containing axle. The axle has a Rhodamine B unit and a 2,2-diphenylethanamine unit as two bulky terminal stoppers to prevent unthreading.

A novel Rhodamine B-derivatized host [2]rotaxane, containing a dibenzyl-24-crown-8 (DB24C8) ring as the wheel and a pyrene as another fluorophore blocking group, was designed, synthesized and structurally characterized. A comparison of the 1H NMR spectra of RhBPy [2]rotaxane with those of 2 and DB24C8, nuclear Overhauser effect spectroscopy (NOESY), mass spectrometry and fluorescence spectroscopy confirmed the interlocked nature of RhBPy [2]rotaxane. The temperature dependence of the rotaxane studied by 1H NMR spectroscopy further demonstrated that RhBPy [2]rotaxane can be applied as a molecular switch. RhBPy [2]rotaxane has also been demonstrated to be an efficient transport agent for delivering the cancer drug doxorubicin (DOX) into tumor cells. Indeed, DOX delivered by RhBPy [2]rotaxane could effectively inhibit tumor cell growth.