TopBanner

Cart empty

User Account

 

Non-Conjugatable Viscosity Probes

We offer a unique range of organic Viscosity Probes (Molecular Rotors), ideal for microscopy, such as the spatial imaging of microviscosity within individual domains within live cells, as well as for a great many other applications in the Life and Physical Sciences. [1-5]

Ursa BioScience's approach is based upon the detection of fluorescence from unique fluorescent molecules, termed Molecular Rotors, which show a strong fluorescence response in both lifetime and emission spectra to the viscosity of the surrounding environment.

We offer a range of highly photostable probes with different excitation regions and emission wavelengths, coupled with large dynamic sensing ranges (the fluorescence Vs viscosity response), as well as with differing water solubility, probes specifically developed to tailor for your every viscosity need.

All our probes are sold prepacked and dry and are simply reconstituted by adding 50 µL of solvent.

Viscous Blue 1™

Viscous Blue 1™ is a water soluble probe, which can readily be excited from 300-420 nm, the absorbance spectra very similar in both Methanol and Glycerol.

Viscous Blue 1

Figure 1. (A) Absorption spectra recorded for Viscous Blue 1™ dissolved in methanol (solid line) and in glycerol (dotted line). (B) Fluorescence contour plot recorded for Viscous Blue 1™ dissolved in glycerol at +5 C (+41 F).

 

Viscous Blue 1™ has an emission spectra centered around 430 nm, the intensity of which is dependent on viscosity, over a broad range of viscosity.

figure 2

Figure 2. (A) Emission spectra recorded for Viscous Blue 1™ in glycerol at different temperatures. The excitation wavelength was 320 nm. (B) Peak fluorescence intensity observed for Viscous Blue 1™ at different temperatures plotted as function of glycerol viscosity.

 

The mean fluorescence lifetime observed for Viscous Blue 1™ is temperature dependent.

Viscous Blue 1™

Figure 3. Time-resolved fluorescence decays recorded for Viscous Blue 1™ dissolved in glycerol at different temperatures. The excitation wavelength was 311 nm and the emission observed through a monochromator centered at 440 nm. Note that the instrumental response function (irf), recorded from a scattering solution, also is shown in black. The data can be analyzed in terms of a bi-exponential decay model with recovered parameters shown in the table.

 

Viscous Blue 2™

Similar to Viscous Blue 1™, Viscous Blue 2™ can readily be excited from 300-420 nm, has an emission centered around 430 nm and shows a viscosity dependent emission spectra.

Viscous Blue 2™

Figure 4. (A) Absorbance spectra recorded for Viscous Blue 2™ dissolved in methanol. (B) Contour emission plot recorded for Viscous Blue 2™ dissolved in glycerol.

 

Viscous Blue 2™ shows a viscosity sensitive fluorescence intensity and can be used to probe viscosity over a broad dynamic range.

Viscous Blue 2™

Figure 5. (A) Fluorescence emission spectra recorded for Viscous Blue 2™ dissolved in glycerol at different temperatures. (B) Peak fluorescence intensity observed in panel A plotted as function of glycerol viscosity.

 

The mean fluorescence lifetime observed for Viscous Blue 2™ is temperature dependent.

Viscous Blue 2™

Figure 6. Time-resolved decays recorded for Viscous Blue 2™ dissolved in glycerol at different temperatures. The excitation wavelength was 311 nm and the emission observed through a monochromator centered at 440 nm. Note that the instrumental response function (irf), recorded from a scattering solution, also is shown in black. The data can be analyzed in terms of a mono-exponential decay model with recovered parameters shown in the table.

 

Viscous Blue 420™

Viscous Blue 420™ is a water soluble probe which can readily be excited in the range 250-400 nm, with λmax Abs ≈ 330 nm in Methanol and a blue emission band centered at ≈ 420 nm (glycerol). At 20 C the lifetime is bi-exponential (in glycerol), 0.899 ns (56%), and 1.70 ns (44%), with a mean lifetime of 1.13 ns. At 50 C the lifetimes are much shorter, 0.492 ns (82.7%) and 1.16 ns (17.3%), with a mean lifetime of 0.547 ns. Viscous Blue 420™ has a viscosity dependent emission centered at 420 nm, the intensity of which is dependent on viscosity, over a broad range of viscosity.

Viscous Blue 420™

Figure 7. (A) Absorbance spectra recorded for Viscous Blue 420™ dissolved in methanol. (B) Contour emission graph recorded for Viscous Blue 420™ dissolved in glycerol.

 

Viscous Blue 420™ has an emission spectra centered around 420 nm, the intensity of which is dependent on viscosity, over a broad range of viscosity.

Viscous Blue 420™

Figure 8. (A) Emission spectra recorded for Viscous Blue 420™ dissolved in glycerol at different temperatures. The excitation wavelength was 320 nm. (B) Peak fluorescence intensity plotted as function of glycerol viscosity.

 

Viscous Green 1™

Viscous Green 1™ is modestly water soluble.  It can be readily excited at 350-450 nm with an emission centred in the green around 520 nm.

Viscous Green 1™

Figure 9. (A) Absorbance spectra recorded for Viscous Green 1™ dissolved in methanol (black solid line), glycerol (red dotted), and in water (blue dash-dot-dot). (B) Fluorescence emissioon contour graph recorded for Viscous Green 1™ dissolved in glycerol.

 

Viscous Green 1™ has an emission spectra centered around 510 nm, the intensity of which is dependent on viscosity, over a broad range of viscosity.

Viscous Green 1™

Figure 10. (A) Emission spectra recorded for Viscous Green 1™ dissolved in glycerol at different temperatures. The excitation wavelength was 350 nm. (B) Peak fluorescence intensity as seen in panel A plotted as function of glycerol viscosity.

 

The mean fluorescence lifetime observed for Viscous Green 1™ is temperature dependent.

Viscous Green 1™

Figure 11. Time-resolved decays recorded for Viscous Green 1™ dissolved in glycerol at different temperatures. The excitation wavelength was 311 nm and the emission observed through a monochromator centered at 500 nm. The data can be analyzed in terms of a bi-exponential decay model with recovered parameters shown in the table.

 

Viscous Green 2™

Viscous Green 2™ is sparsely water soluble, with better solubility in glycerol. It can be readily excited from 300-450 nm, with an emission centred around 420 nm.

Absorbance and emission contour graph recorded for Viscous Green

Figure 12. (A) Absorbance spectra recorded for Viscous Green 2™ dissolved in water, methanol, glycerol and in dichloromethane. (B) Contour emission graph recorded for Viscous Green 2™ dissolved in glycerol at room  temperature.

 

The fluorescence intensity observed for Viscous Green 2™ correlates with the viscosity over a broad dynamic range. The fluorophore can also be used to characterize aggregation state of lipophilic molecules, e.g. micelle formation of CTAB in water.

Figure 13. (A) Emission spectra recorded for Viscous Green 2™ in glycerol at different temperatures. The excitation wavelength was 320 nm. (B) Peak fluorescence intensity observed for Viscous Green 2™ at different temperatures plotted as function of glycerol viscosity. (C) Fluorescence spectra recorded for Viscous Green 2™ dissolved in water with different concentrations of CTAB. The exciation wavelength was 320 nm. (D) Integrated fluorescence intensity (400 nm -550 nm) plotted as function of CTAB concentration. The formation of micelles at ~ 1 mM can clearly be seen.

 

DCVJ (9-(Dicyanovinyl) Julolidine

Ursa BioScience also offers the classic DCVJ viscosity probe, which is belongs to a common class of molecular rotors based on Twisted Intramolecular Charge Transfer (TICT) states. The accessibility of the dark non-emissive TICT state is typically responsible for the non-radiative decay pathways in a rotor, which can be altered via viscosity, giving rise to the viscosity dependence observed [2]. Ursa BioScience Viscosity probes have a much greater fluorescence Vs Viscosity dynamic sensing range as compared to DCVJ.

figure 3

Figure 14. Comparison of the viscosity response observed for Viscous Blue 1™, Viscous Blue 2™, and DCVJ dissolved in glycerol at different temperatures. Panel A and B shows the same data but on different scales. Note that the peak emission intensities are normalized, i.e. divided by the peak intensity observed for the the highest viscosity sample.

 

DCVJ is readily soluble in water/MeOH and can be excited at ~455 nm with an emission at 500 nm. The fluorescence emission of DCVJ is dependent on environmental / solution viscosity, as well as by binding to proteins / membranes. DCVJ is also known by the names (4-(Dicyanovinyl)Julolidine), as well as 9-(2,2-Dicyanovinyl)Julolidine.

DCVJ (9-(Dicyanovinyl) Julolidine

Figure 15. (A) Absorbance spectra recorded for DCVJ dissolved in methanol. (B) Contour emission graph recorded for DCVJ dissolved in glycerol.

 
JD glycerol temp response

Figure 16. (A) Emission spectra recorded for DCVJ dissolved in glycerol at different temperatures. The excitation wavelength was 450 nm. (B) Peak emission intensity observed in panel A plotted as function of glycerol viscosity.

 

The mean fluorescence lifetime observed for DCVJ is temperature dependent.

JD fluorescence lifetimes

Figure 17. Time-resolved fluorescence decays recorded for DCVJ dissolved in glycerol at different temperatures. Note that the instrument response function (irf) recorded from a scattering solution also is shown. The excitation wavelength was 444 nm and the emission observed through a monochromator centered at 500 nm. The table summarizes parameters obtained by fitting the data to biexponential or monoexponential decay models. Here f1 and f2 indicates the fractional contribution to the intensity with decay times τ1 and τ2, respectively. The average decay time, <τ>, is also shown. The quality of the fit is indicated by the reduced chi-squre value, χ2,that should be close to 1 for a good fit.

 

Viscous UV™

Viscous UV™ is a water soluble probe which can readily be excited over a broad wavelength range, 280-360 nm, with a broad emission centered ≈ 385 nm (in glycerol).

Viscous UV™

Figure 18. (A) Absorbance spectra recorded for Viscous UV dissolved in methanol. (B) Contour emission spectra recorded for Viscous UV dissolved in glycerol at 20 C.

 

The emission of Viscous UV™ is dependent on solution viscosity and therefore also on the temperature dependence of viscosity.

Viscous UV™

Figure 19. (A) Emission spectra recorded for Viscous UV dissolved in glycerol at different temperatures. The excitation wavelength was 320 nm. (B) Peak emission intensity, as recorded in panel A, plotted as function of glycerol viscosity.

 

At 20 C the lifetime of Viscous UV™ is Bi-exponential 0.80 ns (86 %) and 1.7 ns (14%) with a mean lifetime of 0.86 ns. At 50 C the lifetimes are shorter, 0.43 ns (95 %) and 1.6 ns (5 %) with a mean lifetime of 0.45 ns.

Viscous UV™

Figure 20. Time-resolved fluorescence decays recorded for Viscous UV™ dissolved in glycerol at different temperatures.  Note that the instrument response function (irf) recorded from a scattering solution also is shown The excitation wavelength was 311 nm and the emission observed through a monochromator centered at 400 nm. The table summarizes parameters obtained by fitting the data to a bi-exponential decay model. Here f1 and f2 indicates the fractional contribution to the intensity with decay times τ1 and τ2, respectively. The average decay time, <τ>, is also shown. The quality of the fit is indicated by the reduced chi-squre value, χ2,that should be close to 1 for a good fit.

 

Viscous UV™ can readily be used to study micelle / lipid formation, in addition to solution or cellular viscosity measurements. Figure 20, shows Viscous UV™ in water at different concentrations of CTAB (0 to 2.5 mM). The excitation wavelength was 320 nm. The integrated fluorescence spectra plotted as a function of CTAB concentration shows a steep increase at ≈ 1 mM CTAB, indicating micellular formation and the location of the viscosity probe in the hydrocarbon region of the micelle. Similarly, this can also be seen for DCVJ (9-(Dicyanovinyl) Julolidine.

TICT 8 DCVJ - [CTAB for www]

Figure 21. (A) Fluorescence spectra recorded for Viscous UV™ at different concentrations of CTAB. The excitation wavelength was 320 nm. (B) Integrated fluorescence spectra as shown in panel A plotted against concentration CTAB. Note the steep increase in intensity around 1 mM CTAB, indicating the formation of micelles. (C) Fluorescence spectra recorded for DCVJ (9-(Dicyanovinyl) Julolidine dissolved in water in the presence of CTAB at different concentrations. (D) Integrated fluorescence spectra  shown in panel C plotted against concentration CTAB. The formation of micelles is clearly seen around 1 mM CTAB concentration.

 

Viscous Aqua™

Viscous Aqua™ is a highly water soluble probe, soluble in a variety of polar media, such as methanol, glycerol etc. Viscous Aqua™ shows both an emission and lifetime dependence on solution / cellular viscosity (and subsequently the temperature effect on viscosity), coupled with good photostability, makes it ideal for your imaging applications. Viscous Aqua™ can readily be excited from 360-460 nm, with an emission centered ~495 nm. The emission is typically more pronounced in the more viscous the media and shows a linear response over the 1-200 cP viscosity range.

The fluorescence lifetime of Viscous Aqua™ is also viscosity dependent, making it ideal for FLIM (Fluorescence Lifetime) type viscosity imaging.

 

Viscous Aqua

Figure 22. (A) Absorbance spectra recorded for Viscous Aqua™ dissolved in water an in methanol. Note that the water absorbance spectra is red shifted about 10 nm. (B) Contour emission graph recorded for Viscous Aqua™ dissolved in glycerol at +20 C.

 
Aqua

Figure 23. (A) Emission spectra recorded for Viscous Aqua™ dissolved in gluycerol at different temperatures. The excitation wavelength was 400 nm. (B) Peak intensity plotted as function of glycerol viscosity.

 
Aqua

Figure 24. Time resolved decays recorded for Viscous Aqua™ dissolved in glycerol at different temperatures. The excitation wavelength was 400 nm and the emission recorded through a monochromator centered at 480 nm. Note that the instrument response function, irf, also is shown. The table summarize results obtained by fitting the time-resolved data to a bi-exponential decay model.

 

Dual VpH™

Dual VpH™ is a unique water soluble probe which is both pH and Viscosity sensitive.

Aqua

Figure 25. (A) Absorbance spectra recorded for Dual VpH™ dissolved in neat solvents, ethanol (blude solid line), glycerol (black dotted line), and in water (red dash dotted line). (B) Absorbance spectra recorded for Dual VpH™ in 50:50 glycerol : methanol mixtures (w/w) at different pH as indicated.

 

Dual VpH™ can be excited from 300-400 nm in solvents such as Ethanol, Water, Glycerol, Figure 25 A. At lower pH’s there is a bathochromic shift in the absorption spectrum, as compared to higher pH’s, Figure 25 B. The quantum yield of the Dual VpH™ is low in non-viscous media and also at low pH, but increases as the viscosity increases. The advantage of Dual VpH™ is that the background intensity from aqueous media is very low, as compared to say a higher intracellular viscosity, where the emission would be more pronounced.

Dual_VpH_contour_plot

Figure 26. Excitation-Emission intensity Map (EEM) recorded for Dual VpH™ dissolved in glycerol at + 0 °C (32 °F).

 

Figure 26 shows the excitation-Emission intensity map for Dual VpH™ dissolved in glycerol at 0 °C (32 °F) with the emission centered around 400 nm.

Aqua

Figure 27. (A) Emission spectra recorded for Dual VpH™ dissolved in neat glycerol at different temperatures. The excitation wavelength was 330 nm. (B) Peak area plotted as function of glycerol viscosity.

 

As with all our viscosity probes, the emission intensity increases as the viscosity also increases. This is shown in Figure 27, for Dual VpH™ in glycerol as a function of temperature.

 

Viscous Red™

Unlike Ursa’s other viscosity probes, Viscous Red™ is predominantly more soluble in media such as cyclohexane, ethyl acetate and ethanol, making it ideal for your non-polar viscosity sensing needs.

Viscous Red absorption and emission spectra in different solvents

Figure 28. (A) Absorption spectra recorded for Viscous Red™ dissolved in (1) cyclohexane, (2) ethanol, and (3) ethyl acetate. (B) Normalized emission spectra, excitation at 400 nm, recorded for Viscous Red™ in solvents presented in panel A.

 

Figure 28 shows the absorption and emission of Viscous Red™ in several solvents. In cyclohexane, Viscous Red™ can be excited from 380-500 nm, but in slightly more polar solvents, the probe can be excited out to 530 nm. Similarly, the emission spectra, see Figures 28 B and 29, are solvent polarity dependent, the emission in cyclohexane centered at ~500 nm, while in ethyl acetate, the emission is significantly red shifted, ~650 nm.

Contour emission graphs recorded for Viscous Red™ dissolved in cyclohexane and in ethanol.

Figure 29. Contour emission graphs recorded for Viscous Red™ dissolved in (A) cyclohexane and (B) in ethanol.

 

Viscous Red™ is readily soluble in many oils. Figure 30 A shows the absorption of Viscous Red™ in a commercial vacuum pump oil, the excitation-emission matrix shown in Figure 30 B, after subtraction of the oils weak background luminescence.

Absorption and contour graph for emission from Viscous Red™ when dissolved in a commercial vacuum oil.

Figure 30. (A) Absorbance spectra recorded for Viscous Red™ dissolved in a comercial vacuum oil. (B) Contour emission graphs recorded for sample as shown in panel A. The data has been corrected for a background emission form the oil.

 

Similar to Ursa’s other Viscosity probes, Viscous Red™ shows a viscosity dependence on its emission spectrum, and subsequently on the temperature dependence on viscosity, Figure 31.

Temperature dependent emission recorded from Viscous red when dissolved in a commercial vacuum oil.

Figure 31. (A) Emission spectra recorded for Viscous Red™ at different temperatures when dissolved in a commercial vacuum oil. The excitation wavelength was 400 nm. (B) Integrated emission spectra as presented in panel A plotted as function of the viscosity of the oil measured in an independent experiment.

 

The lifetime of Viscous Red™ is also viscosity dependent, making it ideal for FLIM, Fluorescence Lifetime Imaging Microscopy of non-polar materials, such as plastics.

Viscous Red time resolved decays.

Figure 32. (A) Fluorescence lifetime decays recorded for Viscous Red™ dissolved in a commercial vacuum oil at different temperatures. Note that the instrumental response function also is shown, as recorded from a scattering solution. The excitation wavelength was 400 nm and the excitation and emission polarizers set to vertical and magic angle, respectively.(B) results of fitting recorded decay data to a bi-exponential decay model.

 

References

[1] Kuimova, M.K., Mapping viscosity in cells using molecular rotors. Physical Chemistry Chemical Physics, 2012. 14(37): p. 12671-12686.

[2] Haidekker, M.A. and E.A. Theodorakis, Molecular rotors - fluorescent biosensors for viscosity and flow. Organic & Biomolecular Chemistry, 2007. 5(11): p. 1669-1678.

[3] Kuimova, M.K., et al., Imaging intracellular viscosity of a single cell during photoinduced cell death. Nature Chemistry, 2009. 1(1): p. 69-73.

[4] Kuimova, M.K., et al., Molecular rotor measures viscosity of live cells via fluorescence lifetime imaging. Journal of the American Chemical Society, 2008. 130(21): p. 6672-+.

[5] Levitt, J.A., et al., Membrane-Bound Molecular Rotors Measure Viscosity in Live Cells via Fluorescence Lifetime Imaging. Journal of Physical Chemistry C, 2009. 113(27): p. 11634-11642.

 

 

 

 

 

ViscousRed 1

Viscous Red™ is a highly viscosity sensitive probe, with a polarity sensitive emission, from the green to the red. Viscous Red™ is ideal for FLIM.

 

Viscous Green 2

Comparision of Viscous Green 1™ in different solvents.

 

DCVJ

Chemical structure of the classic DCVJ (9-(Dicyanovinyl) Julolidine viscosity probe.