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Ursa BioScience offers a range of Fluorescent Probes for the sizing and detection of a variety of nanoparticles and analytes. We offer Probes which function in a fluorescence intensity format (both Turn-On and Turn-Off), Probes which show colorimetric responses and Fluorescent Probes which show a wavelength ratiometric response to a particular analyte.

Our Probes are conveniently sold dry in a micro-ample and are simply reconstituted by adding water/buffer/solvent. The re-constituted concentrations are high enough to allow for 10 aliquots to be taken, where aliquot dilution into a 3 cm3 cuvette provides for an optimized concentration, ideal for nearly every fluorescence sensing and microscopy application.

Our Fluorescent Particle Sizing Probes work on the principle of fluorescence anisotropy (Steady-State and Time-Resolved) and can readily determine the size of nanoparticles ranging from less than 1 to greater than 10 nm in size. We offer a range of Probes with differing water solubilites, allowing customers to readily choose a Probe for their desired application. All the Probes can be excited from 320-380 nm, with high-quantum yield fluorescence emission ≈ 440 nm.

Our highly water soluble fluorescent Cyanide Probes readily chelate aqueous cyanide with relatively high binding constants (µM). The Probes can be used in a fluorescence intensity, excitation wavelength ratiometric (colorimetric) or fluorescence emission wavelength ratiometric manner. Optimum wavelength ratiometric wavelengths are 450/550 nm, with excitation wavelengths 325-425 nm. Our range of Cyanide Probes is ideal for customers measuring free cyanide in the range 1 – 100 µM. Our new Cyanide Orange™ Fluorescent Probe offers long wavelength-based cyanide detection, ≈ 575 nm, with the significant advantage of a "Turn-On" fluorescence response, i.e. the fluorescence intensity at 575 nm increases with increasing cyanide concentration. Ursa BioScience also offers a range of "Turn-Off" Cyanide Sensors all with differing disassociation / binding constants, Cyanide Sensing Probes which are widely applicable over different sensing dynamic ranges. While Cyanide Violet™ is readily excited at 300-350 nm, Cyanide Blue™ can be excited at 300-400 nm, and with a slightly longer wavelength emission, ≈ 460 nm, as compared to that of Cyanide Violet™, ≈ 440 nm.

Ursa offers a range of water-soluble highly sensitive Glucose Fluorescence Sensors, ideal for detecting Glucose 1-200 mM, but with particular merit below 2 mM glucose, ideal for tear glucose quantitation. We offer 6 "Turn-Off" Glucose Sensors and 2 Control Fluorescence Compounds. Our Control Fluorescence Compounds are ideal for researchers wishing to calibrate against other analytes, which may potentially influence the fluorescence properties of the parent glucose-chelating dyes, without switching wavelengths / microscope filters etc.

Ursa BioScience offers a wavelength ratiometric (both absorption and emission) pH Sensor, with a dynamic range in the pH 6-8 region, ideal for cellular and physiological pH measurements.

Amino Blue™ emits 400-700 nm.

Our highly sensitive aqueous Chloride Sensors (Saline Blue™ 1-4) are ideal for researchers wishing to study physiological or cellular chloride levels. Saline Blue™ 2-4 are progressively less water soluble than the highly water soluble Saline Blue™ respectively, with Saline Blue 4™ ideal for cellular surface chloride determination, the probes hydrophobic tail anchoring the probe within the cellular membrane.

Ursa BioScience offers a unique wavelength ratiomeric Fluoride Probe, namely Fluo-Green™ and its respective Control Compound, Fluo-Green C™. While the other halides, Cl-, Br- and I- are readily known to quench fluorescence, the fluoride ion seldom quenches fluorescence and hence its detection and quantitation is usually limited to other non-fluorescence techniques such as ion-selective electrodes. Fluo-Green™ readily chelates fluoride with a colorimetric and fluorescence emission wavelength ratiometric response. Fluo-Green™ is selective to fluoride in the presence of high concentrations of dissolved chloride and other blood analytes, such as glucose. The Stern-Volmer fluorescence quenching constants for I-, Br- and Cl- are 34, 1.4 and 1.0 M-1 respectively, making Fluo-Green™ able to detect dissolved fluoride in the presence of the other heavier atom halides.

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