A low affinity nanoparticle based fluorescent ratiometric probe for the determination of Zn(ii) concentrations in living cells (original) (raw)
ICPBCZin: A red emitting ratiometric fluorescent indicator with nanomolar affinity for Zn 2+ ions
Cell Calcium, 2008
A new fluorescent Zn2+ indicator, namely, ICPBCZin was synthesized and the spectral profile of its free and Zn2+ bound forms was studied. The newly synthesized zinc indicator incorporates as chromophore the chromeno [3′,2′:3,4]pyrido[1,2a] [1,3]benzimidazole moiety and belongs to the dicarboxylate-type of zinc probes. The compound is excited with visible light, exhibits high selectivity for zinc in the presence of calcium and other common biological ions, and its Zn2+ dissociation constant is 4.0 nM. Fluorescence spectra studies of ICPBCZin indicated a clear shift in its emission wavelength maxima upon Zn2+ binding, as it belongs to the class of Photoinduced Charge Transfer (PCT) indicators, along with changes in fluorescence intensity that enable the compound to be used as a ratiometric, visible-excitable Zn2+ probe.
Tetrahedron, 2013
Herein the synthesis and characterization of new, lipophilic highly Zn 2þ-selective fluorescent probes are reported. High affinity for zinc (K d 1.1e8.0 nM) over other biologically relevant metals and mixtures of metals was observed. Excitation at 360 nm afforded an emission spectrum with maximum at 530 nm for the zinc bound complex. The linear relationship between fluorescence intensity and zinc concentration indicates that FZnA-probes can be used for quantification. The probes have been synthesized in 28e45% overall yield and the feasibility for further functionalization with biologically relevant side chains has been demonstrated. In vitro studies using PC12 cells and 10 mM of one of the novel probes (FZnA-Ada) visualized endogenous labile Zn 2þ after 45 min incubation time.
Intracellular imaging of zinc ion in living cells by fluorescein based organic nanoparticles
Sensors and Actuators B: Chemical, 2018
Novel fluorescein based nano probe (FBNPs) was designed and synthesized Selective fluorescence enhancement of FBNPs by Zn 2+ ion Fluorescence enhancement is an account for chelation of FBNPs and Zn 2+ in 1:1 stoichiometry. Lower detection limit for Zn 2+ = 0.0011 µg/mL in an aqueous medium. FBNPs exhibits excellent hydrophilicity, biocompatibility, and non-toxicity for intracellular detection of Zn 2+ in MDA-MB-231 breast cancer cell line.
Measuring zinc in living cells
Cell Calcium, 2002
New fluorescent indicators with nanomolar to micromolar affinities for Zn 2+ have been synthesized in wavelengths from UV to the far red. The UV light-excited indicators are ratiometric. The visible wavelength indicators are non-ratiometric and exhibit large and pH-independent fluorescence increases with increasing zinc concentrations, with little to no sensitivity to physiologically relevant Ca 2+ concentrations. Experiments in neuronal and non-neuronal cell cultures show the new indicators to retain their sensitivity to and selectivity for zinc after conversion to cell-permeable forms.
Detecting Zn(II) Ions in Live Cells with Near-Infrared Fluorescent Probes
Molecules, 2019
Two near-infrared fluorescent probes (A and B) containing hemicyanine structures appended to dipicolylamine (DPA), and a dipicolylamine derivative where one pyridine was substituted with pyrazine, respectively, were synthesized and tested for the identification of Zn(II) ions in live cells. In both probes, an acetyl group is attached to the phenolic oxygen atom of the hemicyanine platform to decrease the probe fluorescence background. Probe A displays sensitive fluorescence responses and binds preferentially to Zn(II) ions over other metal ions such as Cd2+ ions with a low detection limit of 0.45 nM. In contrast, the emission spectra of probe B is not significantly affected if Zn(II) ions are added. Probe A possesses excellent membrane permeability and low cytotoxicity, allowing for sensitive imaging of both exogenously supplemented Zn(II) ions in live cells, and endogenously releases Zn(II) ions in cells after treatment of 2,2-dithiodipyridine.
Molecules, 2022
Zinc is an essential trace element involved in many biological activities; however, its functions are not fully understood. To elucidate the role of endogenous labile Zn2+, we developed a novel ratiometric fluorescence probe, 5-(4-methoxyphenyl)-4-(methylsulfanyl)-[2,2′-bipyridin]-6-amine (6 (rBpyZ)) based on the 6-amino-2,2′-bipyridine scaffold, which acts as both the chelating agent for Zn2+ and the fluorescent moiety. The methoxy group acted as an electron donor, enabling the intramolecular charge transfer state of 6 (rBpyZ), and a ratiometric fluorescence response consisting of a decrease at the emission wavelength of 438 nm and a corresponding increase at the emission wavelength of 465 nm was observed. The ratiometric probe 6 (rBpyZ) exhibited a nanomolar-level dissociation constant (Kd = 0.77 nM), a large Stokes shift (139 nm), and an excellent detection limit (0.10 nM) under physiological conditions. Moreover, fluorescence imaging using A549 human lung adenocarcinoma cells re...
A selective and sensitive fluorescence probe for imaging endogenous zinc in living cells
Tetrahedron, 2013
ABSTRACT A carboxamidoquinoline-based fluorescent Zn2+ probe 1 containing N/S/S heteroatoms as a receptor was designed and readily synthesized, which was featured by the Zn2+-induced red-shift of emission (45 nm) based on internal charge transfer (ICT) in an aqueous HEPES buffer (pH=7.4). Moreover, spectroscopic studies indicated that the composition of the complex 1-Zn2+ was 1:1, which was also confirmed by X-ray crystallography. In addition, 1H NMR titration experiment suggested that probe 1 transformed from the amide tautomer to imidic acid tautomer after binding with Zn2+. The binding of zinc with 1 was easily reversed by addition of N,N,N′,N′-tetrakis(2-picolyl)ethylenediamine (TPEN) or EDTA. Furthermore, probe 1 was successfully applied to image both exogenous and endogenous zinc in living HeLa cells.
ACS Chemical Biology, 2014
Small-molecule fluorescent sensors are versatile agents for detecting mobile zinc in biology. Capitalizing on the abundance of validated mobile zinc probes, we devised a strategy for repurposing existing intensity-based sensors for quantitative applications. Using solid-phase peptide synthesis, we conjugated a zinc-sensitive Zinpyr-1 derivative and a zinc-insensitive 7-hydroxycoumarin derivative onto opposite ends of a rigid P 9 K peptide scaffold to create HcZ9, a ratiometric fluorescent probe for mobile zinc. A plate reader-based assay using HcZ9 was developed, the accuracy of which is comparable to that of atomic absorption spectroscopy. We investigated zinc accumulation in prostatic cells and zinc levels in human seminal fluid. When normal and tumorigenic cells are bathed in zinc-enriched media, cellular mobile zinc is buffered and changes slightly, but total zinc levels increase significantly. Quantification of mobile and total zinc levels in human seminal plasma revealed that the two are positively correlated with a Pearson's coefficient of 0.73.
Analytical and Bioanalytical Chemistry, 2007
Potassium hydrotris(N-tert-butyl-2-thioimidazolyl)borate [KTt t-Bu ] and potassium hydrotris(3-tert-butyl-5-isopropyl-l-pyrazolyl)borate [KTp t-Bu,i-Pr ] have been synthesized and evaluated as ionophores for preparation of a poly(vinyl chloride) (PVC) membrane sensor for Zn(II) ions. The effect of different plasticizers, viz. benzyl acetate (BA), dioctyl phthalate (DOP), dibutyl phthalate (DBP), tributyl phosphate (TBP), and o-nitrophenyl octyl ether (o-NPOE), and the anion excluders sodium tetraphenylborate (NaTPB), potassium tetrakis(p-chlorophenyl)borate (KTpClPB), and oleic acid (OA) were studied to improve the performance of the membrane sensor. The best performance was obtained from a sensor with a of [KTt t-Bu ] membrane of composition (mg): [KTt t-Bu ] (15), PVC (150), DBP (275), and NaTPB (4). This sensor had a Nernstian response (slope, 29.4±0.2 mV decade of activity) for Zn 2+ ions over a wide concentration range (1.4×10 −7 to 1.0× 10 −1 mol L −1) with a limit of detection of 9.5×10 −8 mol L −1. It had a relatively fast response time (12 s) and could be used for 3 months without substantial change of the potential. The membrane sensor had very good selectivity for Zn 2+ ions over a wide variety of other cations and could be used in a working pH range of 3.5-7.8. The sensor was also found to work satisfactorily in partially non-aqueous media and could be successfully used for estimation of zinc at trace levels in biological and environmental samples.
Chemosensors
This study aims to introduce a fluorescence-based chemosensing method for Zn2+ in aqueous suspensions and untreated surface waters, conditions which generally hinder the application of conventional optochemical sensing platforms. A macrocyclic fluoroionophore was covalently bonded to a silica-coated magnetic nanoparticle and applied according to a predetermined protocol for analyzing trace amounts of Zn2+ under rarely investigated conditions. Utilizing the reversible complexation of the immobilized fluoroionophore, rapid regeneration was carried out via simple acidification after the magnetic-assisted solid-phase extraction of the particles. Forming inclusion complexes with Zn2+ with the receptor units of the particles leads to a significant enhancement in fluorescence intensity at 370 nm, above the detection limit of 5 ppb, with a dynamic linear range of quantification of 15–3000 ppb in a pH range of 5.5–7.5. Practical applicability was confirmed by analyzing untreated river water ...
This paper describes the activity of a Schiff base ligand, derived from pyridoxal, as a promising fluorescence probe for biologically important Zn(II) ion sensing. A physiologically compatible pyridoxal based chemosensor PydDmen was synthesized and evaluated for its fluorescent response towards metal ions. Chemosensor PydDmen exhibits a selective turn-on type response in the presence of Zn 2+ in ethanol– water mixture. The addition of EDTA quenches the fluorescence of receptor PydDmen-Zn 2+ , making the chemosensor PydDmen reversible. The response is specific for Zn(II) ions, and remains almost unaffected by the presence of alkali and alkaline earth metals but is suppressed to varying degrees by transition metal ions. The selectivity mechanism of PydDmen for Zn 2+ is the combined effects of proton transfer between the prevailing tautomeric forms, C]N isomerization and CHEF. The DFT optimized structure of the complex is compatible with elemental analysis, mass spectrometry, FT-IR, electronic and NMR spectra. The experimental and theoretical support in terms of NMR spectroscopy and DFT are provided to establish the existence of Zn 2+ induced transformation of PydDmen to a 3-pyridone tautomeric form.
Rationally Designed Probe for Reversible Sensing of Zinc and Application in Cells
ACS Omega
Biologically compatible fluorescent ion sensors, particularly those that are reversible, represent a key tool for answering a range of fundamental biological questions. We report a rationally designed probe with a 6′-fluoro spiropyran scaffold (5) for the reversible sensing of zinc (Zn 2+) in cells. The 6′-fluoro substituent overcomes several limitations normally associated with spiropyran-based sensors to provide an improved signal-tobackground ratio and faster photoswitching times in aqueous solution. In vitro studies were performed with 5 and the 6′-nitro analogues (6) in HEK 293 and endothelial cells. The new spiropyran (5) can detect exogenous Zn 2+ inside both cell types and without affecting the proliferation of endothelial cells. Studies were also performed on dying HEK 293 cells, with results demonstrating the ability of the key compound to detect endogenous Zn 2+ efflux from cells undergoing apoptosis. Biocompatibility and photoswitching of 5 were demonstrated within endothelial cells but not with 6, suggesting the future applicability of sensor 5 to study intracellular Zn 2+ efflux in these systems.
The Analyst, 2013
A new "naked-eye" and ratiometric fluorescent zinc sensor (TAQ) of carboxamidoquinoline with 2-chloro-N-(quinol-8-yl)-acetamide as a receptor was designed and synthesized. The sensor TAQ shows good water solubility and high selectivity for sensing; about a 15-fold increase in fluorescence quantum yield and a 100 nm red-shift of fluorescence emission upon binding Zn 2+ in aqueous HEPES buffer solution are observed. The human lung cancer cell line (A549) activity is also demonstrated.