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Iron (Fe3+) Probes

Ursa BioScience offers a range of highly photostable probes (fluorescent dye molecules) sensitive to Iron (Fe3+) ions. Our probes are very bright (highly fluorescent), easy to use and provide highly reproducible results. Our probes can be used in an Absorption (colorimetric) or Fluorescence manner. Our probes do not react with iron like other approaches for Iron detection, but more simply, Fe3+ readily binds, causing dramatic changes / shifts in the absorption spectrum or in fluorescence intensity. Our probes are offered in our standard vial format, ideal for nearly all analysis formats such as in a cuvette or in microscopy; in a 96-well kit, and pre-loaded into a box of 100 cuvettes for quick, easy and convenient Iron analysis. A reconstitution and use data sheet is provided with each probe.

Ferrum 430™

Ferrum 430™ is a unique fluorescence probe, that is selective for Iron (Fe3+) over other dissolved cations, that can both detect and quantitate dissolved Iron (Fe3+ ions). Ferrum 430™ is not influenced by Fe2+ ions, enabling the two forms of Iron to be readily distinguished by this remarkable fluorescent probe.

figure 1

Figure 1. (A) Absorption spectra recorded for Ferrum 430™ dissolved in ethanol at different concentrations. (B) Peak absorption observed at 386 nm plotted as a function of the concentration of dye. The molar extinction coefficient is calculated from the slope to be ≈ (23 000 ± 3 000) M-1 cm-1. The error accounts for weighing and dilution inaccuracies. Note that the error specified in the graph is the regression error only. 

 

Ferrum 430™ can be used in both an absorption or fluorescent manner to either detect or quantitate Fe3+ concentrations. Ferrum 430™ readily chelates (binds) iron (Fe3+) in a 1:1 ratio, as a function of time, but is not influenced by Fe2+ ions.

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Figure 2. (A) Absorption spectra recorded for Ferrum 430, one spectra recorded every 5 mins for a total of 60 minutes, when mixed with 5 equivalents of FeCl3. The concentration dye is (3.65 +/- 0.41) uM in a 90:10 ethanol:water mixture (by volume). The arrows indicate the trend in the absorption spectra with time. (B) Same experiment as presented in panel A but with FeCl2. Note that all spectra overlay. 

 

Ferrum 430™ is a turn-on fluorescent sensor, meaning that the solution fluorescence increases as a function of the concentration of dissolved Iron and as a function of time. Ferrum 430™ can readily be excited over a broad wavelength range from 280-400 nm with an extinction coefficient of 23 000 ± 3 000 M-1 cm-1 at 386 nm. The fluorescence emission is very strong in the presence of Fe3+ ions, centered at ˜430 nm.

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Figure 3. (A) Emission spectra recorded for Ferrum 430 at different times after mixing with 5 equivalents of FeCl3. The concentration of dye is (3.65 +/- 0.41) uM and the solvent mixture is composed of 90:10 Ethanol:H2O by volume. Data recorded at room temperature. The excitation wavelength was 355 nm. (B) Integrated and normalized spectra, i.e. the area under spectra presented in panel A normalized, and plotted as function of time after mixing. Note that a limiting value, a plateau value, is reached after about 60 minutes. (C) Limiting values observed for Ferrum 430 when mixed with different concentrations FeCl3. The mol ratio [FeCl3]/[Ferrum 430] is given on the lower x-axis and the concentration of FeCl3 is given on the upper x-axis. The concentration of dye was kept fixed at (3.65 +/- 0.41) uM.

 

Ferrum 430™ can be used to readily quantitate the amount of Fe3+ in a sample by using a given time point to record the emission intensity or alternatively by using the equilibrium fluorescence intensities to record the calibration curve. For concentration greater than 50 µM (10 equivalents of Iron to dye), the equilibrium is achieved in less than 8 minutes.

Ferrum 430™ is a selective probe for both the detection and determination of Fe3+ ions.

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Figure 4. Emission peak intensities, I, observed for Ferrum 430 in the presence of the same concentrations of various ions. The data has been normalized against a sample containing no ions with intensity I0.

 

Ferrum 430™ in Pre-Loaded Cuvettes

We offer Ferrum 430™ already conveniently loaded into a box of 100 plastic cuvettes (transmission down to 285 nm). These cuvettes allow for dissolved Fe3+ detection in either an absorption or fluorescence based format. With these convenient pre-loaded cuvettes, there is no reconstitution procedure necessary, simply add 3 ml (3cm3) of your sample to each cuvette and measure, it’s that simple.

Go to the online store for a price for this kit.

Ferrum 430™ in a 96-well Format (For Absorption)

We offer Ferrum 430™ in a convenient 96-well kit format. A clear bottom 96-well plate and a vial are supplied, allowing up to 96 Fe3+ measurements to be undertaken in an absorption- based manner.

Go to the online store for the price of this kit.

Ferrum 430™ in a 96-well Format (For Fluorescence)

We offer Ferrum 430™ in a convenient 96-well kit format. A black 96-well plate and a vial are supplied, allowing up to 96 Fe3+ measurements to be undertaken in a fluorescence-based manner.

Go to the online store for the price of this kit.

 

Ursa 520-R™

Ursa 520-R™ is a highly sensitive probe for dissolved Iron (III) that can be used to  both detect and quantitate Iron (III). The probe can be excited from 300-400 nm with a ε ≈ 53900 M-1 cm-1.

Ursa 520-R epsilon

Figure 5. (A) Absorption spectra recorded for Ursa 520-R™ dissolved in spectraoscopic ethanol at different concentrations. (B) Peak absorbance at 370 nm plotted as a function of the concentration of dye. The molar extinction coefficient is calculated from the slope (gradient) to be (53 900 ± 800) M-1cm-1. The error includes contributions from weighing and dilution inaccuracies.

 

Ursa 520-R™ is a fluorescence ratiometric probe, meaning that the fluorescence intensity at 450 nm, divided by that at 560 nm, enables the concentration of Fe3+ to be readily and easily determined. Figure 6 shows the ratiometric plots determined for Ursa 520-R™, ranging from 1.0 to 10 equivalents of Fe3+, with a dye concentration of  ≈3.68 µM. Panel B shows the ratiometric response recorded at 50 minutes after the addition of different concentrations of Fe3+.

Ursa 520-R Ratiometric response with Fe3+

Figure 6. (A) Ratiometric values observed as function of time for Ursa 520-R™ dissolved in a 90:10 EtOH:H2O (by volume) mixture with different equivalents of Fe3+ added. The concentration of dye in the samples were kept fixed at 3.68 μM and the concentration of Fe3+ is specified in the legend,  e.g. data labelled 2.5x was recorded for a sample with Fe3+ concentration equla to 9.2 μM. The calculation of the ratiometric values is described in the caption to Figure 7B. (B) Ratiometric value observed 50 minutes after mixing, plotted as function of the concentration of FeCl3.

 

Ursa 520-R™ is a modestly selective probe for dissolved Fe3+ as shown in Figure 7. The probe does show a response to both dissolved Al3+ and Cu2+ and can additionally be used to sense those dissolved cations also. See response to Al3+.

Slectivity FeCl3 Ursa 520-R

Figure 7. (A) Ratiometric responses observed for Ursa 520-R™ mixed with various metal ions when dissolved in a mixture of 90:10 EtOH:H2O by volume. The concentration of dye is 5.52 uM and the metal ions are added in 5 molar equivalents. The samples were left to equilibrate for 90 min. (B) Typical emission spectra recorded for  Ursa 520-R™ mixed with metal ions here exemplified by Fe3+ and K+. The excitation wavelength was set to 350 nm. The ratiometric numerical values are calculated by dividing the emission intensity centred at 450 nm, highlighted in blue, with that observed centred at 560 nm, highlighted yellow.

 

Ferrum 560™

Ferrum 560™ is a unique fluorescence probe, that is selective for Iron (Fe3+) over other dissolved cations, that can both detect and quantitate dissolved Iron (Fe3+ ions). Ferrum 560™ is not influenced by Fe2+ ions, enabling the two forms of Iron to be readily distinguished. Unlike Ferrum 430™, this probe is a turn-off fluorescent probe, meaning that the fluorescence gets weaker with an increased Iron (iii) concentration. Most remarkably, this iron sensitive probe shows an ≈ 220 nm Stokes shifted fluorescence emission maximum, as compared to the absorption maximum at ≈ 340 nm, making this probe ideal for your imaging applications. Subsequently, Ferrum 560™ can readily be used with our 400DLP microscope dichroic filter.

Figure 8. Comparison of the absorbance spectra recorded for Ferrum 560™ dissolved in water or in ethanol. Panels (A) and (B) show the same data but on different scales.

 

Ferrum 560™ can readily be excited from 300 – 400 nm, with an absorption maximum at ≈ 340 nm, ε ≈ 6 250 mol-1, L, cm-1, in EtOH.

Figure 9. Absorption spectra recorded for Ferrum 560™ dissolved in neat water and in neat water with various ions added, as indicated by the legends. Panels (A) and (B) shows the same data but on different scales.

 

Ferrum 560™ readily chelates Iron (iii) in the ground state, but not Iron (ii).

Figure 10. Contour emission graphs recorded for Ferrum 560™ dissolved in EtOH without (A) and with (B) 100 uM FeCl3. After the addition of Fe3+ the sample was left to equilibrate for 30 min.

 

The fluorescence emission of Ferrum 560™ is centered at around 520 nm in Ethanol, and ≈ 560 nm in water solutions. The fluorescence emission is readily diminished in the presence of Fe3+ ions in solution, but not by other dissolved cations. The probe responds very rapidly towards iron (iii), allowing almost instantansous read-out of your samples iron concentration, particularly useful for either living or dynamic systems where the concentration of iron (iii) can change over time.

Figure 11. (A) Emission spectra recorded at different times for Ferrum 560™ dissolved in water with 100 μM FeCl3 added. The excitation wavelength was 325 nm. (B) Peak intensity at 560 nm plotted as function of  time. Note that the first spectra, indicated at -5 minutes, was recorded BEFORE the addition of FeCl3. Thus, the reaction is instantaneous.

 

Ferrum 560™ is highly selective for Iron (iii), with other dissolved cations showing little to no response on the fluorescence emission.

Figure 12. Normalized emission intensity recorded for Ferrum 560™ at 560 nm when mixed with various ions in water. The concentration the dye is identical between the samples. The concentration of each ion is 60 μM.

 

Ferrum 560™ can also be readily used for FLIM (Fluorescence Lifetime Imaging Microscopy), due to the drop (reduction) in fluorescence lifetime in the presence of Iron (iii). The photophysics of Ferrum 560™ is described by a single monoexponential decay function, allowing the relative ease of data fitting and analysis.

Figure 13. Time-resolved decays recorded for Ferrum 560™ dissolved in water. The excitation wavelength was 310 nm and the emission collected at 560 nm. Panel (A) shows data for the dye dissolved in neat water and panel (B) with FeCl3 added at a concentration of 60 μM. The data fits well to a single exponential model with decay constants (A) 2.52 ns and (B) 2.40 ns.

 

For current pricing of Ferrum 560™, please visit our online store.

Ferrum 560™ in Pre-Loaded Cuvettes

We offer Ferrum 560™ already conveniently loaded into a box of 100 plastic cuvettes (transmission down to 285 nm). These cuvettes allow for dissolved Fe3+ detection in either an absorption or fluorescence based format. With these convenient pre-loaded cuvettes, there is no reconstitution procedure necessary, simply add 3 ml (3cm3) of your sample to each cuvette and measure, it’s that simple.

Go to the online store for a price for this kit.

Ferrum 560™ in a 96-well Format (For Fluorescence)

We offer Ferrum 560™ in a convenient 96-well kit format. A black 96-well plate and a vial are supplied, allowing up to 96 Fe3+ measurements to be undertaken in a fluorescence-based manner. Go to the online store for the price of this kit.

 

 

 

 

Ferrum 430

Selectivity of Ferrum 430™ towards Iron (III) over Iron (II)

 

Ursa standard prodcut vialFerrum 430™ is supplied dry in a prepacked vial for easy reconstitution. Visit our Online Store for current pricing.

 

 

 

Contour plot recorded for Ferrum 430

Excitation-Emission matrices recorded for Ferrum 430 dissolved in 10:90 water:ethanol mixture (by volume) at room temperature. The concentration of dye is (3.65 +/- 0.41) µM. The upper panel shows data recorded before FeCl3 was added and the lower panel after FeCl3 was added. 

 

BlueCuvette

Ferrum 430™ in pre-loaded cuvettes, simply add 3 ml of your sample and measure.  Visit our Online Store for current pricing.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Ursa 520-R™ ContourPlot

Contour plots recorded for Ursa 520-R™ at 11.0 μM concentration without (panel A) and with (panel B) 5 equivalents Fe3+.

 

Ursa 520-R Fe 3 abs

Time-dependent absorption spectra (0-60 min) recorded for Ursa 520-R™ at 3.0 μM concentration mixed with 5 equivalents of FeCl3. The arrows indicate the spectral trend with time. Panel A and B shows the same data but on different scales.

Ursa 520-R Fe 3 ratiometric

Ratiometric curves constructed for Ursa 520-R™, with different concentrations of FeCl3 as indicated, by dividing the absorbance value observed at 253 nm by that observed at 370 nm.

 

 

 

Ferrum 560 cuvettes

Photograph illustrating the selectivity between Fe3+ and Fe2+ions offered by Ferrum 560™. Cuvettes containg equal concentrations of Fe2+ or Fe3+ ions dissolved in water and mixed with Ferrum 560™ are placed on an UV light box and illuminated from below at 365 nm.

 

Ursa standard prodcut vialFerrum 560™ is supplied dry in a prepacked vial for easy reconstitution. Visit our Online Store for current pricing. A short video shows our reconstitution procedure.

 

Ferrum 560 cuvettes

Ferrum 560™ is available in prepacked cuvettes. See on-line store for more information.