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Copper (II) Probes

Ursa BioScience offers a range of water soluble highly photostable probes (dye molecules, also called fluorophores) sensitive to aqueous Copper (II) ions, (Cu2+).

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

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 copper analysis. A reconstitution and use data sheet is provided with each probe.

Ursa 520-R™

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

Ursa 520-R epsilon

Figure 1. (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 Copper ions to be readily and easily determined. Figure 2 shows the ratiometric plots determined for Ursa 520-R™, ranging from 1.0 to 5.0 equivalents of Cu2+, 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 Cu2+. In the presence of 10 equivalents of Cu2+ 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 Cu2+ the lifetime of Ursa 520-R™ is very short.

Ursa 520-R™ Ratiometric plot

Figure 2. (A) Ratiometric value as function of time recorded for Ursa 520-R™ with different equivalents of Cu2+ added. The calculation of the ratiometric values is described in the caption to Figure 3B. (B) Ratiometric value observed 50 minutes after mixing, plotted as function of the concentration of CuCl2.


Ursa 520-R™ is a modestly selective probe for dissolved Cu2+ as shown in Figure 3. The probe does show a response to both dissolved Fe3+ and Al3+ and can additionally be used to sense those dissolved cations also.

Ursa 520-R selectivity towards various ions

Figure 3. (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 Cu2+ 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.


For current pricing information please visit our on-line store.


 CuCl2 tn

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 CuCl2 were added. The contour emission graph is shown in Panel B below.


Ursa 520-R™ ContourPlot CuCl2

Contour plots recorded for Ursa 520-R™ at 11.0 μM concentration without (panel A) and with (panel B) 5 equivalents Cu2+. The samples, i.e. the cuvettes, are shown in the image on top of the column.


 Ursa standard prodcut vial

Ursa 520-R™ is supplied dry in a prepacked vial for easy reconstitution. Visit our Online Store for current pricing.