QXY21 NHS ester [equivalent to QSY-21 NHS ester]

QXY21 is the same molecule to QSY-21 acid (ThermoFisher). QSY-21 has a broad and intense absorption at ~661 nm maxima with no detectable fluorescence, making it useful as an acceptor in fluorescence resonance energy transfer (FRET) applications. It is a common long-wavelength quencher to best pair with Cy5, Alexa Fluor 647, iFluor 647 or other spectrally similar fluorescent dyes.

Calculators

Common stock solution preparation

Table 1. Volume of DMSO needed to reconstitute specific mass of QXY21 NHS ester [equivalent to QSY-21 NHS ester] to given concentration. Note that volume is only for preparing stock solution. Refer to sample experimental protocol for appropriate experimental/physiological buffers.

	0.1 mg	0.5 mg	1 mg	5 mg	10 mg
1 mM	111.995 µL	559.973 µL	1.12 mL	5.6 mL	11.199 mL
5 mM	22.399 µL	111.995 µL	223.989 µL	1.12 mL	2.24 mL
10 mM	11.199 µL	55.997 µL	111.995 µL	559.973 µL	1.12 mL

Molarity calculator

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Mass (Calculate)		Molecular weight		Volume (Calculate)		Concentration (Calculate)		Moles
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Spectrum

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Product family

Name	Excitation (nm)	Emission (nm)	Extinction coefficient (cm ^-1 M ^-1)	Quantum yield	Correction Factor (260 nm)	Correction Factor (280 nm)
XFD488 NHS Ester Same Structure to Alexa Fluor™ 488 NHS Ester	499	520	71000	0.92¹	0.30	0.11
XFD350 NHS Ester Same Structure to Alexa Fluor™ 350 NHS Ester	343	441	19000	-	0.25	0.19
XFD532 NHS Ester Same Structure to Alexa Fluor™ 532 NHS Ester	534	553	81000	0.61¹	0.24	0.09
XFD594 NHS Ester Same Structure to Alexa Fluor™ 594 NHS Ester	590	618	90000	0.66¹	0.43	0.56
XFD555 NHS Ester Same Structure to Alexa Fluor™ 555 NHS Ester	553	568	150000	0.1¹	0.08	0.08
XFD647 NHS Ester Same Structure to Alexa Fluor™ 647 NHS Ester	650	671	239000	0.33¹	0.00	0.03
XFD680 NHS Ester Same Structure to Alexa Fluor™ 680 NHS Ester	681	704	184000	0.36¹	0.00	0.05
XFD700 NHS Ester Same Structure to Alexa Fluor™ 700 NHS Ester	696	719	192000	0.25¹	0.00	0.07
XFD750 NHS Ester Same Structure to Alexa Fluor™ 750 NHS Ester	752	776	240000	0.12¹	0.00	0.04
Cy5DIGE NHS ester	651	670	250000¹	0.27¹, 0.4²	0.02	0.03
Cy2DIGE NHS ester	492	508	150000	0.120	0.08	0.15
Cy3DIGE NHS ester	555	569	150000¹	0.15¹	0.07	0.073
XFD546 NHS Ester Same Structure to Alexa Fluor™ 546 NHS Ester	561	572	112000	0.79¹	0.21	0.12
XFD568 NHS Ester Same Structure to Alexa Fluor™ 568 NHS Ester	579	603	91300	0.69¹	0.45	0.46
XFD514 NHS Ester Same Structure to Alexa Fluor™ 514 NHS Ester	518	543	80000	-	0.31	0.18
QXY7 NHS ester [equivalent to QSY-7 NHS ester]	-	-	90000¹	-	-	0.22
Cy3B NHS ester	560	571	120000¹	0.58¹	0.048	0.069
XFD405 NHS Ester [equivalent to Alexa Fluor™ 405 NHS Ester]	401	421	35,000	-	0.23	0.70
CypHer5E NHS Ester	643	660	-	-	-	-
CypHer7E NHS Ester	748	769	-	-	-	-
XFD660 NHS Ester [equivalent to Alexa Fluor® 660 NHS Ester]	663	691	132000	-	0.00	0.10
XFD430 NHS ester	432	540	15,000	-	-	0.28
Show More (13)

Citations

View all 12 citations: Citation Explorer

A Sensitive Near-Infrared Fluorescent Sensor for Mitochondrial Hydrogen Sulfide
Authors: Ji, A., Fan, Y., Ren, W., Zhang, S., Ai, H. W.
Journal: ACS Sens (2018): 992-997

Imaging intracellular quantum dots: fluorescence microscopy and transmission electron microscopy
Authors: Szymanski, C. J., Yi, H., Liu, J. L., Wright, E. R., Payne, C. K.
Journal: Methods Mol Biol (2013): 21-33

Reversible off-on fluorescence probe for hypoxia and imaging of hypoxia-normoxia cycles in live cells
Authors: Takahashi, S., Piao, W., Matsumura, Y., Komatsu, T., Ueno, T., Terai, T., Kamachi, T., Kohno, M., Nagano, T., Hanaoka, K.
Journal: J Am Chem Soc (2012): 19588-91

Family of enhanced photoacoustic imaging agents for high-sensitivity and multiplexing studies in living mice
Authors: de la Zerda, A., Bodapati, S., Teed, R., May, S. Y., Tabakman, S. M., Liu, Z., Khuri-Yakub, B. T., Chen, X., Dai, H., Gambhir, S. S.
Journal: ACS Nano (2012): 4694-701

Visualizing mechanical tension across membrane receptors with a fluorescent sensor
Authors: Stabley, D. R., Jurchenko, C., Marshall, S. S., Salaita, K. S.
Journal: Nat Methods (2011): 64-7

References

View all 1 references: Citation Explorer

Synthesis and characterization of a small, membrane-permeant, caspase-activatable far-red fluorescent peptide for imaging apoptosis
Authors: Bullok K, Piwnica-Worms D.
Journal: J Med Chem (2005): 5404

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Physical properties

Molecular weight	892.90
Solvent	DMSO

Spectral properties

Absorbance (nm)	660
Correction Factor (280 nm)	0.32
Extinction coefficient (cm ^-1 M ^-1)	89000¹

Storage, safety and handling

H-phrase	H303, H313, H333
Hazard symbol	XN
Intended use	Research Use Only (RUO)
R-phrase	R20, R21, R22
Storage	Freeze (< -15 °C); Minimize light exposure
UNSPSC	12352200