SeTau Lifetime Labels

Fluorescent labels with long fluorescence lifetimes

			Excitation Light Sources												Characteristics						Characteristics
Product Number (Specs Sheet)	Product Name (Product Info)	Target Group	380	405	436	488	532	594	635	650	680	700	750	780	Medium	λ abs [nm]	ε [M –1 cm–1]	λ em [nm]	QY [%]	FLT [ns]	Medium	λ abs [nm]	ε [M–1 cm–1]	λ em [nm]	QY [%]	FLT [ns]	Buy
K1-204 K1-204	SeTau-380-NHS SeTau-380-NHS	NH2	•	•											Water	270	23,800	480	56	32.5	BSA, D/P=1	383	23,800	468	44	30.6
K7-547 K7-547	SeTau-405-NHS SeTau-405-NHS	NH2	•	•											PB 7.4	405	13,800	518	80	9.3	IgG, D/P=8	405	13,800	518	19	8.4
K7-567 K7-567	SeTau-405-Azide SeTau-405-Azide	triple-CC	•	•											PB 7.4	405	13,800	518	80	9.3	EtOH	391	15,000	498	55	8.5
K7-545 K7-545	SeTau-425-NHS SeTau-425-NHS	NH2	•	•	•										PB 7.4	425	4,200	545	39	26.2	BSA, D/P=1	427	4,200	528	16	26.2
K9-4119 K9-4119	SeTau-665-NHS SeTau-665-NHS	NH2								•	•	•			PB 7.4	664	160,000	712	53	3.1	IgG, D/P=1.5	662		716	46
K9-4142 K9-4142	SeTau-647-di-NHS SeTau-647-di-NHS	NH2							•	•					PB 7.4	650	200,000	694	65	3.2	IgG, D/P=0.5	649	200,000	691	58	3.2
K9-4148 K9-4148	SeTau-647-Maleimide SeTau-647-Maleimide	SH							•	•					PB 7.4	648	200,000	692	45	3.2	PB 7.4	648	200,000	692	45	3.2
K9-4149 K9-4149	SeTau-647-NHS SeTau-647-NHS	NH2							•	•					PB 7.4	649	200,000	695	61	3.2	IgG, D/P=1	648	200,000	694	59	3.3
K9-4169 K9-4169	SeTau-670-NHS SeTau-670-NHS	NH2							•	•	•				PB 7.4	673	275,000	694	36	1.6	IgG D/P = 4	672		693	14	1.75
K7-548 K7-548	SeTau-405-Maleimide SeTau-405-Maleimide	SH	•	•											PB 7.4	405	13,800	518	51	9.1	EtOH	391	15,000	498	32	8.5
K7-544 K7-544	SeTau-425-Maleimide SeTau-425-Maleimide	SH	•	•	•										PB 7.4	425	4,200	545	39	26.2	PB 7.4	425	4,200	545	39	26.2
K9-4179 K9-4179	SeTau-680-NHS SeTau-680-NHS	NH2							•	•	•				PB 7.4	683	295,000	705	58	2.9	IgG D/P=1	682		703	47	3.1

 

Short-Wavelength SeTau Lifetime Dyes

These labels with longer lifetimes in the range between 9 and 32 ns are excitable in the UV or blue region and are well-suited as polarization probes for the measurement of high MW analytes (small proteins) or for lifetime-based applications. They exhibit long lifetimes that are not environment sensitive.

SeTau-380-NHS is a reactive dye with a with a large Stokes’ shift of 210 nm and a fluorescence lifetime of 32.5 ns in water. Exc./Em. max: 270/480 nm.

SeTau-405-NHS is a dye with a fluorescence lifetime of 9 ns in PB7.4 that is well suited for excitation with the blue 404 nm diode laser. Because of its large Stokes’ shift of more than 110 nm, the quenching tendency upon labeling to proteins is very low. Importantly the longer lifetime of 9 ns in aqueous media is making it also a valuable label for studying of protein hydrodynamics (fluorescence polarization measurements). It is a good alternative for Pacific Orange to be used with Pacific Blue in flow cytometry applications. Compatible with the Fluorescein emission filter. Exc./Em. max: 405/518 nm.

SeTau-425-NHS with a fluorescence lifetime of 26 ns in PB7.4 was used to measure high-molecular-weight analytes such as BSA directly in an FP assay (more under Fluorescence Polarization). Importantly the FLT of these labels does not change upon covalent attachment to proteins or other analytes. For more information we refer you to Lifetime Applications.
 

 

Long-Wavelength SeTau Lifetime Dyes

While the fluorescence lifetime (FLT) of organic dyes is a reporting strategy for molecular imaging and recently even for flow cytometry, fluorescent dyes emitting in the NIR have very short lifetimes in the range between 0.5 to 1.5 ns. Importantly, longer lifetimes of NIR dyes (in the order of 3 ns) were only measured in presence of BSA or in organic solvents. In addition most of these dyes are neither soluble in aqueous media nor can be conjugated to biomolecules and therefor are not suitable as labels [28].

SETA BioMedicals has developed several reactive, ionic, water-soluble squaraine rotaxanes with emission in the NIR region that have «longer» fluorescent lifetimes ~ 3 ns (see below), making them in particular suitable as labels for lifetime-based imaging applications in the red and NIR wavelength region.

The NIR squaraine rotaxane dye SeTau-680 has a lifetime of 2.9 ns in PB7.4, while the fluorescent lifetimes of comparable, conventional NIR labels e.g. Alexa 680 or Alexa 700 are in the order of 1 - 1.2 ns.

SeTau-647-maleimide with a lifetime of 3.2 ns in PB7.4 has been successfully used in the studies of the mechanism of muscle contractions using FCS, specifically fluorescence lifetime correlation spectroscopy (FLCS), fluorescence lifetime and time-resolved fluorescence polarizations methods [27].

SeTau 680-NHS  (Φ = 0.58, ε = 215,000 and Φ. ε = 124,700) with a similar absorption and emission as Alexa 680 is twice as bright as Alexa 680 (Φ = 0.36,  ε = 183,000 and Φ. ε = 65,880) and exhibits a lower quenching tendency when labeled to biomolecules. Exc./Em. max of IgG-conjugates: 682/703 nm. Its lifetime is 2.9 ns in PB7.4.

SeTau-665-NHS is a hydrophilic, mono-reactive squaraine rotaxane label for biomolecules. It is very bright (Φ = 0.53,  ε = 161,000 and Φ. ε = 83,330) with a large Stokes' shift of 48 nm and a similar emission as Alexa 700 (Φ = 0.25,  ε = 205,000 and Φ. ε = 51,250) but SeTau-665 is a factor of ~ 1.6 times brighter. It is optimally excited with a 665 nm diode laser. This dye also holds the record for 2PECSs of fluorescent labels with >8500 GM at 900 nm. Lifetime: 3.2 ns in PB7.4. Exc./Em. max of IgG-conjugates: 665/712 nm.

SeTau-647-NHS is a hydrophilic, mono-reactive squaraine rotaxane label for biomolecules. Compared to Cy5 (Φ = 0.27,  ε = 250,000 and Φ. ε = 67,500) or Alexa 647 (Φ = 0.33,  ε = 239,000 and Φ. ε = 78,870) it is an extremely bright label (Φ = 0.53,  ε = 200,000 and Φ. ε = 106,000) with a large Stokes' shift of 46 nm. It is a highly ozone- and photostable dye that is optimally excited with the 647 nm spectral line of the Krypton-Argon laser. Its lifetime is 3.2 ns in PB7.4. Exc./Em. max for conjugates: 649/695 nm. 

 

Additional dyes for lifetime applications can be found here.