Cucurbit[7]uril-Tetramethylrhodamine Conjugate for Direct Sensing and Cellular Imaging (original) (raw)
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Solubilization of Pyridone-Based Fluorescent Tag by Complexation in Cucurbit[7]uril
ACS Omega
Aimed at further exploring the hosting properties of cucurbit[7]uril (CB7), we have exploited the spectroscopic and photophysical properties of a known fluorescent label as the guest molecule, namely, 3-cyano-6-(2-thienyl)-4-trifluoromethyl pyridine (TFP), in neat solvents. The formation of an inclusion host−guest complex with CB7 was checked by UV−vis absorption spectroscopy, and the value of binding constant (9.7 × 10 5 M −1) was extracted from the spectrophotometric data. The modulation of keto−enol equilibrium in TFP by the local environment is governed by the interplay between dimerization through intermolecular hydrogen bonding between individual solute molecules, favoring the enol form, and intermolecular hydrogen bonding between TFP and the surrounding solvents, favoring the keto form. Time-resolved fluorescence results established that the macromolecular CB7 host stabilizes preferentially the neutral enol form over the keto form of TFP. Unprecedentedly, our results reveal a linear dependence of the amplitudes of the extracted decay-associated spectra from the time-resolved fluorescence spectra of TFP on the sum of polarity/polarizability and hydrogen bonding parameters of the local environment, confirming that TFP at micromolar concentration in the CB7 complexes is experiencing a methanol-like environment. The results rationalized the 42-fold enhancement in the solubility of TFP in water media by complexation in CB7.
The journal of physical chemistry. B, 2014
Supramolecular interaction between an intramolecular charge transfer (ICT) probe, N,N-dimethylaminonaphthyl-(acrylo)-nitrile (DMANAN), and two well-recognized macrocyclic hosts, cucurbit[7]uril (CB7) and β-cyclodextrin (β-CD), has been studied in aqueous medium by absorption, emission, time-resolved measurements, and (1)H NMR spectroscopic methods. The changes in the profiles of the fluorescence spectra illustrate significant modifications in fluorescence intensity, decay time, and quantum yield upon confinement of probe within the hydrophobic cavity of the hosts. Using the Benesi-Hildebrand relationship, the stoichiometric ratio as well as the binding constant of the host-guest complexation has been estimated. The stable inclusion complexes of the probe with different hosts have been supported by DFT and ONIOM based quantum chemical calculations. These methods of measurement establish that the acceptor group of the probe resides inside the hydrophobic cavity of the macrocycle. The ...
A Visible–Near‐Infrared Light‐Responsive Host–Guest Pair with Nanomolar Affinity in Water
Chemistry – A European Journal, 2019
The discovery of stimuli-responsive high affinity hostguest pairs with potential applications under biological relevant conditions is a challenging goal. Herein we report a high-affinity 1:1 complex formed between cucurbit[8]uril and a water soluble photochromic diarylethene derivative. We found that confining the open isomer within the cavity of the receptor induces a red-shift in the absorption spectrum and leads to an enhancement of the photocyclization quantum yield from Φ = 0.04 to Φ = 0.32. This improvement in the photochemical performance enables quantitative photocyclization with visible light that together with the near-infrared light induced ring-opening reaction and the 100-fold selectivity for the closed isomer confirms this as an outstanding light-responsive affinity pair.
RSC Advances, 2013
A new turn-on Cu 2+ fluorescent sensor (CST) having a trehalose moiety, which confers a relatively large solubility in water, has been synthesized. The chemosensor is therefore suitable for studies in aqueous solution. Full potentiometric and UV-vis characterization evidence that at physiological pH CST forms with Cu 2+ a species with a 1 : 1 stoichiometry allowing for a straightforward correlation between CST response and copper(II) concentration. The presence of the trehalose unit does not negatively affect the selectivity of CST for Cu 2+ over a series of metal ions of interest as proven by fluorescence measurements. The novel chemosensor, tested in differentiated neuroblastoma SH-SY5Y cells, is able to detect Cu 2+ in the extracellular region, as well as to track copper transfer processes upon cell stimulation induced by cellular depolarization. ; Fax: +39 051 20 9 9456; Tel: +39 051 20 9 9481 † Electronic supplementary information (ESI) available: NMR spectra, species distribution diagram of the proton complexes of CST, UV-vis of CST, inuence of the pH on the uorescence emission of CST and uorescence response of CST to some selected anions. See
Chemistry-a European Journal, 2007
The blue fluorescence of acridizinium bromide (ADZ+) and the green fluorescence of 9-aminoacridizinium bromide (AADZ+) in aqueous solutions can be almost entirely switched off upon the double inclusion of these guests in the cavity of cucurbit[8]uril (CB[8]) owing to the formation of a nonfluorescent, noncovalent dimer complex, and then fluorescence can be effectively restored by adding cucurbit[7]uril (CB[7]) to the complex because it competitively extracts the fluorophores out of the CB[8] cavity.
Here we report the synthesis of nanoparticles based on a conjugated oligomer which is synthesized through Heckcoupling of divinylfluorene and dibromobenzothiodiazole monomers. These water dispersible nanoparticles emit in the region of red tailing to the near-infrared region of the spectrum with high fluorescent quantum yield and brightness. The nanoparticles were found to be stable in water for a prolonged time without forming any aggregates and could carry camptothecin, an anticancer drug with high loading efficiency. MTT cell viability studies performed with breast cancer cell lines showed that halfmaximal inhibitory concentration (IC50) values of nanoparticles for MCF7 and MDA-MB-231 were 44.7 μM and 24.8 μM, respectively. In order to further decrease the cytotoxicity and increase the stability of nanoparticles, amine groups were disguised by capping with cucurbit[7]uril (CB7). Drug release studies showed that drugs were released at low pH (at 5.0) faster than physiological pH (7.4) confirming the pH-responsive nature of the nanoparticles. On the other hand, CB7-capped drug-loaded nanoparticles regulated the release rate by providing slower release at pH 7.4 than the nanoparticles in the absence of CB7s. IC50 values for camptothecin in the presence of nanoparticles with or without CB7 were significantly reduced in MCF7 and MDAMB-231 cells.
Supramolecular Chemistry, 2017
A FRET-based chemosensor L containing donor phenanthroline and acceptor fluorescein moiety was designed, synthesised and characterised for the ratiometric fluorescent detection of Cu 2+ in organoaqueous solution. Probe L showed high selectivity and excellent sensitivity towards Cu 2+ ions by exhibiting both colorimetric and fluorometric changes due to opening of the spirolactum ring of fluorescein upon complexation with Cu 2+. In presence of Cu 2+ ions, probe L formed L-Cu 2+ complex in 1:1 stoichiometric fashion which is established on the basis of Job's plot and mass spectroscopy. We also performed DFT computational studies to know the binding nature and coordination feature of the complex. Furthermore, fluorescence imaging studies revealed that probe L was cell permeable and could be used to detect intracellular Cu 2+ in living cells.