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Aluminum Probes

Ursa BioScience offers a range of water soluble highly photostable probes (dye molecules) sensitive to aqueous aluminum ions (Al3+).

Our probes are very bright, easy to use and provide highly reproducible results.

Alumen 450™

Alumen 450™ is a unique fluorescence probe, that is highly selective for Aluminum over other dissolved cations, that can both detect and quantitate dissolved Aluminum (Al3+ ions). Alumen 450™ is a turn-on fluorescent sensor, meaning that the solution fluorescence increases as a function of the concentration of dissolved Aluminum. Alumen 450™ can readily be excited over a broad wavelength range from 280-400 nm with an extinction coefficient of 8300 ± 600 M-1 cm-1 at 318 nm. The fluorescence emission is very strong in the presence of Aluminum ions, centered at 420 nm.

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Figure 1. (A) Absorption spectra recorded for Alumen 450™ dissolved in water:ethanol mixtures (90:10 vol-%) at different concentrations. (B) Peak absorption observed at 318 nm plotted as function of concentration dye. The molar exticntion coefficent is calcuolted from the slope to (8300 ± 600) M-1 cm-1. The error accounts for weightning and dilution inaccuracies.

 

Alumen 450™ ready chelates dissolved Al3+ and subsequently shows an increase in the emission spectra for Alumen Blue™ in the presence of dissolved Al3+, i.e. it gets significantly brighter.  The probe increases its fluorescence emission > 300% in going from 0 ≈ 750 µM Al3+.  Alumen 450™ shows an almost linear response to Al3+ from 1 → 300 µM dissolved Al3+.

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Figure 2. (A) Emission spectra recorded for Alumen 450™ in the prescence of different concentrations Al3+. The exciation wavelength was 320 nm and the samples prepared in 90:10 water:ethanal (vol %) mixture.  (B) Normalized peak are, as presented in panel A, plotted as unction of concentration Al3+.

 

Figure 2  - Fluorescence emission spectra of Alumen 450 in the presence of Al3+ (Left) and the peak area Vs the concentration of dissolved Al3+ (Right).

 
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Figure 3. Contour emission graphs recorded for Alumen 450™ without (A) and in prescence (B) of 100 uM Al3+ ions in 90:10 water:ethanol (vol-%) solutions. Note the difference in the color scale.

 

Alumen 450™ is a highly selective probe for both the detection and determination of dissolved Al3+.

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Figure 4. Peak emission intensities recorded for Alumen 450™ in the presence of various metal ions at 100 mM concentrations. 

 

The fluorescence response of Alumen 450 to dissolved Al3+ is reversible, making it ideal for numerous sensing applications and for situations where the amount of dissolved Aluminum may change over time, such as inter/extra cellular, or in river/waste waters.

Figure 5 shows the fluorescence response of Alumen 450™ to dissolved Al3+, and the subsequent reversible response in the presence of EDTA, a competitive binding agent for the dissolved Al3+ ions.

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Figure 5. (A) Emission spectra recorded for a 7.94 μM water sample of Alumen 450™ with increasing concentration of Al3+ ions. The excitation wavelength was 350 nm. (B) Emission spectra recorded for Alumen 450™ with increasing concentration of EDTA (Ethylenediaminetetraacetic acid). (C) Emission spectra presented in panel A integrated and plotted as function of concentration Al3+. (D) Emission spectra presented in panel B integrated and plotted as function of concentration EDTA. The solid lines in panel C and D are regression lines without any physical meaning.

 

Alumen 450™ in Pre-Loaded Cuvettes

We offer Alumen 450™ already conveniently loaded into a box of 100 plastic cuvettes (transmission down to 285 nm). These cuvettes allow for dissolved Aluminum detection in a 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.

 

Ursa 520-R™

Ursa 520-R™ is a highly sensitive probe for dissolved Aluminum ions that can be used to  both detect and quantitate Aluminum. The probe can be excited from 300-400 nm with a ε ≈ 53 900 M-1 cm-1.

Ursa 520-R epsilon

Figure 6. (A) Absorption spectra recorded for Ursa 520-R™ at different concentrations in spectroscopic ethanol. (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 Aluminum ions to be readily and easily determined. Figure 7 shows the ratiometric plots determined for Ursa 520-R™, ranging from 1.5 to 10 equivalents of Al3+, 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 Al3+. In the presence of 10 equivalents of Al3+ ions, Ursa 520-R™ shows a triple exponential decay with time constants 246 ps (10%), 1.14 ns (11%) and 9.62 ns (79%). In the absence of dissolved Al3+ the lifetime of Ursa 520-R™ is very short.

Ursa 520-R epsilon

Figure 7. (A) Ratiometric value as function of time recorded for Ursa 520-R™ with different equivalents of Al3+ added. The calculation of the ratiometric values is described in the caption to Figure 8B. (B) Ratiometric value observed 50 minutes after mixing, plotted as function of the concentration of Al(NO3)3.

 

Ursa 520-R™ is a modestly selective probe for dissolved Al3+ as shown in Figure 8. The probe does show a response to both dissolved Fe3+ and Cu2+ and can additionally be used to sense those dissolved cations also.

Ursa 520-R epsilon

Figure 8. (A) Ratiometric responses observed for Ursa 520-R™ mixed with various metal ions dissolved in 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 Al3+ and K+. The ratiometric numerical values are calculated by dividing the emission intensity centered at 450 nm, highlighted in blue, with that observed centered at 560 nm, highlighted yellow.

 

 

 

Alumen 470™

Alumen 470™ is a highly sensitive probe for dissolved Al3+ ions that can be used to both detect and quantitate aluminum. The probe is readily excited from 310 – 410 nm, with an extinction coefficient of (53 000 ± 1 800) M-1 cm-1 at 379 nm.

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Figure 9. (A) Absorption spectra recorded for Alumen 470™ dissolved in ethanol at different concentrations. (B) Peak absorption observed at 379 nm plotted as a function of the concentration of the dye. The molar extinction coefficient is calculated from the slope to ≈ (53 000 ± 1 800) 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. 

 

Alumen 470™ is a dramatic turn-on fluorescence probe, meaning that the fluorescence of this probe gets dramatically brighter in the presence of dissolved aluminum, enabling you to determine aluminum ions in your samples with relative ease. The emission spectra of Alumen 470™ is centered at  ~500 nm giving the sample a greenish tint. In the prescence of Al3+ ions the emission spectra shifts towards 460 nm, see figure 10, giving the sample an aqua blue color. Note that the quantum yield for Alumen 470™ is very low when not complexed with Al3+ ions, which bind in a 1:1 ratio. This is demonstrated in Figure 10, where Panels A (No Aluminum) and C (20 uM Aluminum) are on the same y-axes intensity scale.

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Figure 10. (A) Contour emission graph recorded for Alumen 470™ dissolved in ethanol at ~1 μM concentration. There are no aluminum ions added to the sample. (B) Same data as presented in panel A but on a different scale, see color bar. (C) Alumen 470™ mixed with 20 equivalents Al3+ ions. The sample was left to equilibrate for 30 minutes before data were recorded. Images of the samples, i.e. cuvettes, used for these experiments can be seen in the right hand side column.

 

Alumen 470™ is a selective probe for dissolved aluminium ions, with much weaker responses observed for other dissolved ions, see figure 11.

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Figure 11. (A) Recorded emission spectra for Alumen 470™ dissolved in ethanol with various ions. The dye concentration was ~2μM and the ions added were in 20 molar excess (20x). The excitation wavelength was 380 nm. The samples were left to equilibrate for 4 hours. No ions were added to the control sample. (B) Integrated and normalized spectral area, as shown in panel A, presented in a bar chart.

 

Alumen 470™ can be used to readily quantify the amount of Al3+ in samples, using either  absorbance or fluorescence measurements. The fluorescence intensity of Alumen 470™ dramatically increases in the presence of Al3+ ions, the rate of the binding a function of the amount of Al3+ present. By recording the fluorescence intensity value at a specific time point, such as 10 mins as shown in figure 12c, a calibration plot can be simply developed.

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Figure 12. (A) Emission spectra recorded for Alumen 470™ as function of time when dissolved in ethanol with 20 equivalents of Al3+ ions added. The concentration of dye was ~1.91 μM and the excitation wavelength was 380 nm. (B) Emission band area recorded for Alumen 470™, in the prescence of different concentrations Al3+ ions, plotted as function of time. Data for the sample with 20x molar equivalents of Al3+ are shown in panel A. (C) Emission band integrated area observed 10 minutes after mixing plotted as a function of concentration of Al3+.

 

Alumen 470™ also shows dramatic changes in its absorption spectrum in the presence of aluminum ions, Figure 13. The absorbance band at 380 nm decreases, while the band at 433 nm increases, both as a function of time and also by the amount of aluminum present in the sample. Subsequently, Alumen 470™ can be used in an absorption ratiometric manner, i.e. by plotting the absorbance at 433 nm divided by the absorbance value at 380 nm, one is readily able to develop a calibration curve. Similar to the fluorescence calibration curve of figure 12c, an arbitrary time point can be used to construct the absorption-based calibration plot. Alumen 470™ is ideal for use on any spectrophotometer.

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Figure 13. (A) Absorption spectra recorded for Alumen 470™ as function of time when dissolved in ethanol with 10 equivalents of Al3+ ions added. The concentration of dye was ~2.7 μM and the excitation wavelength was 380 nm. (B) Ratiometric absorption graph, i.e. absorbance observed at 433 nm divided by absorption observed at 380 nm. Panel C and D shows the same data, but recorded on a sample with 80 molar excess Al3+ ions. Note that an isosbestic point is centered at 400 nm.

 

Alumen 470™ can also be readily used for FLIM (Fluorescence Lifetime Imaging Microscopy), and is particularly attractive due to its much longer lifetime in the presence of aluminum ions. The photophysics of Alumen 470™ is described by a multiexponential decay function as shown below in Figure 14.

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Figure 14. (A) Time-resolved decay recorded in the magic angle format for Alumen 470™ dissolved in ethanol with 20 equivalents of Al3+ ions added. The excitation wavelength was 400 nm and the emission collected at 460 nm using a monochromator. The technique used to record data is the Time-Correlated Single Photon Counting (TCSPC) method. The data fits well to a 3-exponential decay function as supported by inspecting the weighted reiduals and the reduced chisquare value. The fitted decay constans and their contribution to the intensity are 0.51 ns (-5.7 %), 2.0 ns (45.7 %), and 2.3 ns (60 %). Note that the shortest decy constant represents a rise time. (B) Contour emissin graph recorded for the sample used for the TCSPC experiment with the excitation and the data collection regions indicated.

 

 

For current pricing of Alumen 470™, please visit our online store.

 

alumen 450

Alumen 450™ dissolved in 90:10 water:ethanol (vol-%) with 100 μM Al3+ added to the left cuvette.

 

Al Blue cuvettes 2

Selectivity of Alumen 450™ for Al3+ ions, (front center cuvette), Vs other ions shown in Figure 4. All ions were 100 µM concentration, Alumen 450™ was 5 µM.

 

Alumen Blue box of 100 prepacked cuvettes.

Alumen 450™ is available in prepacked cuvettes. See on-line store for more information.

 

Ursa BioScience also offers Aluminum standards supplied in six vial kits, containing approximately 7.5 ml of precisely specified Al3+ concentrations. These standards offers the user a fast, reproducible, and cost effective technique to record calibration data. Our standards can be stored on the bench top, at room temperature, with the vial cap tightly closed.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 Cuvettes showing AlNO3 on UV light box

The left cuvette shows a sample of 11.0 μM Ursa 520-R™ dissolved in 90:10 EtOH:H20 and placed on an UV-Lightbox. The contour emission spectra recorded for this sample is shown in panel A below. The cuvette to the right shows the same sample, but after 5 equivalents Al3+ were added. The contour emission graph is shown in Panel B below.

 

Ursa 520-R™ ContourPlot

Contour plots recorded for Ursa 520-R™ at 11.0 μM concentration witout (panel A) and with (panel B) 5 equivalents Al3+. The corresponing samples, i.e. the cuvettes, are shown in the image on top of this column.

 

Ursa520-R with Al

Time-dependent absorption spectra (0-60 min) recorded for Ursa 520-R™ at 3.0 μM concentration mixed 15 equivalents Al(NO3)3. The arrows indicate the spectral trend with time. Panel A and B shows the same data but on different scales.

Ursa 520-R with aluminium

Ratiometric curves constructed for Ursa 520-R™, with different concentrations of Al(NO3)3 as indicated, by dividing absorbance value observed at 255 nm by that observed at 370 nm.

 

 

 

 

 

 

 

Mg 510

Cuvettes containing ~1 μM Alumen 470™ dissolved in ethanol. The cuvettes are placed on an UV light box and illuminated from below at 365 nm. The cuvette on the right contains an additional 20 uM Al3+, which is approximately 20x. Corresponding contour graphs can bee seen in Figure 10.

 

Ursa standard prodcut vial

Alumen 470™ is supplied dry in a prepacked vial for easy reconstitution. Visit our Online Store for current pricing. A short video shows our reconstitution procedure.