Overview

The lifetime-sensitive Seta labels Seta-633-NHS or Seta-670-NHS exhibit shorter fluorescence lifetimes (FLTs) in aqueous media or when labeled to low molecular weight analytes (drugs or small ligands) but increased brightness and up to ten-times longer FLTs when bound to proteins or oligonucleotides and are unique tracers for FLT-based assays.

The table below provides data of the expected changes in lifetime for selected FLT dyes. It is important to note that the observed lifetime change of a fluorescently labeled ligand will strongly depend on the nature and size of the biomolecule it binds to:

All of these environment-sensitive FLT labels are excitable with a 633, 635 or 647 nm laser source and Square-660 and Seta-670 can also be excited with a 405 nm laser.

Squaraine Rotaxanes:

The long-wavelength squaraine-rotaxane series is a new, next generation class of dyes that combines high quantum yields (up to 60%) and high extinction coefficients in the order of 150,000 – 200,000 M ^–1 cm ^–1 . These dyes were developed by SETA BioMedicals in order to overcome some of the shortcomings of conventional dyes such as low brightness in aquous solutions, low stability against oxygen species and low photostability.

 

Squaraine rotaxanes are available in reactive, water-soluble formats as carboxy, NHS ester and maleimides but also as hydrophobic probes for imaging applications. More importantly, these rotaxanes are currently considered the best 2P probes and labels on the market combining high sensitivity and extremely high 2PA cross-sections of up to 10,000 GM!

They also have excellent properties as fluorescent detection reagents for DNA and protein microarrays.

Reactive Lifetime-Labels:

The SeTau lifetime labels have lifetimes in the range between 32 and 9 ns. These dyes are excitable in the UV or blue region and are also useful as polarization probes for the measurement of high MW analytes (small proteins).

 

SeTau-425-NHS for example was used to measure a high molecular-weight analyte such as BSA directly in an FP assay. Importantly the FLTs of these labels do not change upon labeling or binding to proteins or analytes as they are not environment sensitive.

Square Dyes:

The Square dyes are more hydrophobic in nature and thus they exhibit a strong environment sensitive behavior and are therefore very suitable to trace binding between a labeled, low-molecular-weight analyte and a larger biomolecules. These dyes are suitable for use with either intensity or lifetime as the read out mode.

More detailed information about specific probes and labels in this series e.g. Square-655 (protein-sensitive fluorescent probe), Square-650-pH-NHS (pH-sensitive label), Square-670-Carboxy (fluorescent probe), and Square-660-NHS or Square-680-NHS (lifetime-sensitive fluorescent labels) are provided in the Applications Section.

Zy Dyes:

The water-soluble Zy dye NHS esters and maleimides are structurally identical with the reactive Cy^TM dyes (Cy3, Cy5, Cy5.5 and Cy7) of GE Healthcare and are sold at very competitive prices! Please contact us for price quotations on other derivatives or bulk orders.

Fluorescent Probes:

YOSeta-1 is a cell-impermeant fluorescent dye used for staining of double-stranded DNA (same dye as YOYO1). The unbound YOSeta-1 dye has a very low fluorescence quantum yield but the QY increases several thousand times upon binding to double-stranded DNA (see specs sheet ). The probe is available as a 1 mM solution in DMSO.

Other probes are suitable for the measurement of changes in lipid bilayer hydration of cells, measurement of cholesterol in biological fluids, or are used for proteins analysis . Square probes are probably one of the most sensitive dyes for the quantitative analysis of proteins.

Our new type of extremely photostable and bright squaraine rotaxane probes for cellular imaging are based on the long-wavelength SeTau dye series.

The pH-sensitive probe Square-650-pH is the only probe of its kind which shows lifetime sensitive responses in the physiological pH range.

Our pH-sensitive dyes with a pKa in the alkaline pH range are also available in reactive form for labeling to carrier molecules.

 

Phycobiliproteins and Tandem-Conjugates:

Phycobiliproteins hold the record for the largest number of photons emitted before bleaching – they are one of the most sensitive fluorescent reporters known. SETA BioMedicals offers lyophilized versions including new, bright and highly photostable tandems of APC and PE with Seta dyes for use in flow cytometry and other immuofluorescence applications: Seta-APC-705, Seta-APC-780, Seta-PE-670, Seta-PE-775 and Seta-PerCP-680.

 

 

 

Fluorescence Standards:

Fluorescence lifetime (FLT) standards are used to calibrate or test the performance of time- and frequency-domain instrumentation for luminescence lifetime measurements while fluorescence polarization (FP) standards help to calibrate or test fluorescence instrumentation for polarization measurements. Please visit the relevant links for more information.

Characteristics of Fluorescence Lifetime (FLT) Standards

Dyes for Beads:

The extremely bright fluorescent classification dyes for encoding of microspheres (beads) are used in High-Throughput Screening (HTS) and Multiplexed Analysis Systems.

Non-fluorescent Quenchers:

Non-fluorescent quencher molecules for FRET applications , both reactive and non-reactive versions are also available.