AAT Bioquest

Protonex™ Red 780, NHS ester

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Physical properties
Molecular weight853.06
Spectral properties
Excitation (nm)748
Emission (nm)769
Storage, safety and handling
H-phraseH303, H313, H333
Hazard symbolXN
Intended useResearch Use Only (RUO)
R-phraseR20, R21, R22
StorageFreeze (< -15 °C); Minimize light exposure


Molecular weight
Excitation (nm)
Emission (nm)
Protonex™ Red 780 NHS ester is an excellent building block for developing a target-specific conjugate that can be used for monitoring a pH-sensitive biological event. Protonex™ Red 780 dye works by changing its fluorescence intensity depending on the pH of the environment. Protonex™ Red 780 is minimally fluorescent at a basic pH and maximally fluorescent at an acidic pH. When Protonex™ Red 780 is bound to a receptor or an antibody on the cell surface, it is essentially non-fluorescent because the extracellular pH is neutral. However, when the receptor or antibody is internalized into the cell in response to a stimulus, it enters the endosomal pathway, where the pH is acidic. This causes Protonex™ Red 780 to become highly fluorescent and emit near-infrared light when excited by a red laser. By measuring the fluorescence intensity of Protonex™ Red 780, one can monitor the activation and trafficking of receptors or antibodies in live cells.


Common stock solution preparation

Table 1. Volume of DMSO needed to reconstitute specific mass of Protonex™ Red 780, 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 mg0.5 mg1 mg5 mg10 mg
1 mM117.225 µL586.125 µL1.172 mL5.861 mL11.723 mL
5 mM23.445 µL117.225 µL234.45 µL1.172 mL2.345 mL
10 mM11.723 µL58.613 µL117.225 µL586.125 µL1.172 mL

Molarity calculator

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Spectral properties

Excitation (nm)748
Emission (nm)769

Product Family

NameExcitation (nm)Emission (nm)
Protonex™ Red 670, NHS ester643660


View all 16 references: Citation Explorer
Functional coupling of apical Cl-/HCO3- exchange with CFTR in stimulated HCO3- secretion by guinea pig interlobular pancreatic duct.
Authors: Stewart, A K and Yamamoto, A and Nakakuki, M and Kondo, T and Alper, S L and Ishiguro, H
Journal: American journal of physiology. Gastrointestinal and liver physiology (2009): G1307-17
Hyperacidity of secreted fluid from submucosal glands in early cystic fibrosis.
Authors: Song, Yuanlin and Salinas, Danieli and Nielson, Dennis W and Verkman, A S
Journal: American journal of physiology. Cell physiology (2006): C741-9
Evidence against aquaporin-1-dependent CO2 permeability in lung and kidney.
Authors: Fang, Xiaohui and Yang, Baoxue and Matthay, Michael A and Verkman, A S
Journal: The Journal of physiology (2002): 63-9
Airway surface liquid pH in well-differentiated airway epithelial cell cultures and mouse trachea.
Authors: Jayaraman, S and Song, Y and Verkman, A S
Journal: American journal of physiology. Cell physiology (2001): C1504-11
Perfused rat intrahepatic bile ducts secrete and absorb water, solute, and ions.
Authors: Masyuk, A I and Gong, A Y and Kip, S and Burke, M J and LaRusso, N F
Journal: Gastroenterology (2000): 1672-80
Identification of PLCgamma-dependent and -independent events during fertilization of sea urchin eggs.
Authors: Carroll, D J and Albay, D T and Terasaki, M and Jaffe, L A and Foltz, K R
Journal: Developmental biology (1999): 232-47
Growing pollen tubes possess a constitutive alkaline band in the clear zone and a growth-dependent acidic tip.
Authors: Feijó, J A and Sainhas, J and Hackett, G R and Kunkel, J G and Hepler, P K
Journal: The Journal of cell biology (1999): 483-96
Luminal ATP stimulates fluid and HCO3- secretion in guinea-pig pancreatic duct.
Authors: Ishiguro, H and Naruse, S and Kitagawa, M and Hayakawa, T and Case, R M and Steward, M C
Journal: The Journal of physiology (1999): 551-8
Changes in cytosolic pH within Arabidopsis root columella cells play a key role in the early signaling pathway for root gravitropism.
Authors: Scott, A C and Allen, N S
Journal: Plant physiology (1999): 1291-8
The embryoid body as a novel in vitro assay system for antiangiogenic agents.
Authors: Wartenberg, M and Günther, J and Hescheler, J and Sauer, H
Journal: Laboratory investigation; a journal of technical methods and pathology (1998): 1301-14