A low affinity nanoparticle based fluorescent ratiometric probe for the determination of Zn(ii) concentrations in living cells (original) (raw)
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.