Innovative Tools for Molecular and Cell Biology

Innovative Tools for Molecular and Cell Biology


AcidiFluor™ ORANGE

pH Probe for Acidic-Organelle Imaging

Goryo Intro

AcidiFluor™ ORANGE Fluorescence Spectra

Fluorescence Spectra of AcidiFluor™ Orange as a Function of pH
Fluorescence spectra of AcidiFluor™ Orange were measured in phosphate buffer at pH 5.0 or pH 7.4, respectively. pH 5.0 corresponds to the conditions in acidic organelles, and pH 7.4 corresponds to physiological conditions in the cytoplasm. Fluorescence intensity of AcidiFluor™ Orange at pH 5.0 is 50-fold higher than at pH 7.4.

AcidiFluor™ ORANGE Multicolor Imaging

Multicolor Imaging
HeLa cells expressing GFP in mitochondria were multiple stained with AcidiFluor™ ORANGE and Hoechst 33342. Lysosomes were stained orange with AcidiFluor™ ORANGE, nuclei were stained blue with Hoechst 33342 and mitochondria were stained green with GFP.

AcidiFluor™ ORANGE Photostability

AcidiFluor™ ORANGE Photobleaching

Compared to Other Dyes for Lysosome Imaging AcidiFluor™ ORANGE is Highly Resistant to Photobleaching
Samples were continuously illuminated for 180 seconds and viewed on a confocal microscope. Unlike LysoTracker® Green DND-26 and LysoTracker® Red DND-99 which discolored significantly, fluorescence of AcidiFluor™ ORANGE remained. LysoSensor™ Green DND-189 was not suitable for continuous observation because fluorescence leaked into cytoplasm during excitation light irradiation.


  • pH-sensitve fluorescent probe
  • Great photostability
  • High sensitivity even after conjugation with proteins
  • For studying endocytosis or phagocytosis


  • AcidiFluor™ ORANGE is a fluorescent probe that exhibits increasing fluorescence as the pH of its surroundings becomes more acidic. This probe can be used for staining acidic organelles such as lysosomes, late endosomes, and secretory granules. Its excellent selectivity enables the detection of acidic environments. Particularly at pH 5.0 – which corresponds to pH conditions of acidic organelles – fluorescence intensity is 50-fold higher compared to fluorescence intensity at physiological pH (7.4). AcidiFluor™ ORANGE is highly resistent to bleaching. As it emits orange fluorescence after excitation, multicolor imaging is possible. For instance, a combination with blue fluorescence (CFP, Hoechst, etc.), green fluorescence (GFP, fluorescein, etc.) and near-infrared fluorescence is possible. AcidiFluor™ ORANGE is suitable for detecting acidic organelles, observing granules release, studying endocytosis/exocytosis, and much more.

Fluorescence Characteristics of AcidiFluor™ ORANGE

λabs 535 nm
λfl 560 nm
pKa 5.1

High Brightness and High S/N Ratio

Suitable for Multicolor Imaging

Great Photostability


  • For shipping and storage information please click on Order#.
Order# Description Amount Price Data Sheet
GC301 AcidiFluor™ORANGE 10 μg×20 635,00 PDF
GC3011 AcidiFluor™ORANGE 10 μg×10 355,00 PDF
GC302 AcidiFluor™ORANGE-NHS 1 mg 797,00 PDF
GC303 AcidiFluor™ORANGE-NHS 5 samples 497,00 PDF
GC304 AcidiFluor™ORANGELabeling Kit 5 samples 697,00 PDF
GC305 AcidiFluor™ORANGE-Zymosan A 1 mg 497,00 PDF
GC306 AcidiFluor™ORANGE-Dextran 10k 1 mg 697,00 PDF
GC3071 PDF
GC3081 PDF
GC309 AcidiFluor™ORANGE-Transferrin 1 mg 597,00 PDF
  • All prices are in EURO excl. VAT and shipping. Only available in Europe.


  • Kitakaze K. et al.: Protease-resistant modified human ß-hexosaminidase B ameliorates symptoms in GM2 gangliosidosis model.
    J Clin Invest., 126(5): 1691-703 (2016) Pubmed
  • Hayashi A. et al.: High affinity receptor labeling based on basic leucine zipper domain peptides conjugated with pH-sensitive fluorescent dye: Visualization of AMPA-type glutamate receptor endocytosis in living neurons.
    Neuropharmacology Volume 100, 66-75 (2016) Pubmed
  • Masayuki I. et al.: High-throughput screening system to identify small molecules that induce internalization and degradation of HER2.
    ACS Chem Biol 9(10): 2237-41 (2014) Pubmed
  • Watanabe R. et al.: Arrayed lipid bilayer chambers allow single-molecule analysis of membrane transporter activity.
    Nat Commun. 24;5: 4519 (2014) Pubmed
  • Asanuma D. et al.: Acidic-pH-activatable fluorescence probes for visualizing exocytosis dynamics.
    Angew Chem Int Ed Engl. 53(24): 6085-9. (2014) Pubmed


  • GORYO Fluorescent Probes Catalog (PDF)