Chlorophosphonazo III 

Chlorophosphonazo III is a cell membrane-permeable contrast agent and spectrophotometric reagent. Chlorophosphonazo III forms stable 1:1 complexes with intracellular calcium, magnesium, uranium, titanium, zirconium, thorium, scandium, equivalent actinides and protactinium. Chlorophosphonazo III generates photoacoustic signals correlated with Ca²⁺ concentrations, which is applicable for imaging 3D tumor cell cultures and tumor spheroids. Chlorophosphonazo III exhibits no cytotoxicity, can be used for spectrophotometric detection of target ions, and the absorbance of its complexes remains stable for up to one week within the pH range of 2.2 to 7.0^[1][2].

Chlorophosphonazo III (150 μM) forms a stable complex with Ca²⁺. The absorbance of this complex increases linearly in a wavelength-dependent manner with elevated Ca²⁺ concentration, which is particularly pronounced at 627 nm, rendering it suitable for photoacoustic Ca²⁺ imaging^[1].
Chlorophosphonazo III (50-5000 μM; 30 min) is cell membrane-permeable and exhibits no cytotoxicity against Neuro2A cells at concentrations up to 1000 μM^[1].
Chlorophosphonazo III (100-150 μM) generates PA signals that are linearly correlated with Ca²⁺ concentration, among which 150 μM CPZ III provides a more predictable correlation than 100 μM; an 8 MHz US transducer enables optimal detection of these PA signals to achieve accurate Ca²⁺ quantitative analysis^[1].
Chlorophosphonazo III (100-150 μM; 60 min) enables real-time, depth-resolved imaging of spatiotemporal Ca²⁺ dynamics in 3D Neuro2A tumor spheroids, revealing delayed Ca²⁺ responses and greater endoplasmic reticulum Ca²⁺ release in hypoxic core regions compared with normoxic edge regions^[1].
Chlorophosphonazo III (0.2 nM-0.2 μM; 10 min-1 week) forms stable 1:1 complexes with Ca²⁺ and Mg²⁺, enabling highly sensitive spectrophotometric determination of these metals (with a detection limit as low as 0.1 μg per 25 mL when using a 5-cm cuvette at pH 7.0) with good precision; specifically, Ca²⁺ can be selectively determined at pH 2.2, while the additivity of absorbance allows simultaneous quantification of both metals at pH 7.0^[2].

MedChemExpress (MCE) has not independently confirmed the accuracy of these methods. They are for reference only.

757.36

C₂₂H₁₆Cl₂N₄O₁₄P₂S₂

1914-99-4

Solid

Brown to black

O=P(O)(C1=CC(Cl)=CC=C1/N=N/C2=C(C3=C(C=C2S(=O)(O)=O)C=C(S(=O)(O)=O)C(/N=N/C4=CC=C(C=C4P(O)(O)=O)Cl)=C3O)O)O

Room temperature in continental US; may vary elsewhere.

* Please refer to the solubility information to select the appropriate solvent. Once prepared, please aliquot and store the solution to prevent product inactivation from repeated freeze-thaw cycles.
Storage method and period of stock solution: -80°C, 6 months; -20°C, 1 month. When stored at -80°C, please use it within 6 months. When stored at -20°C, please use it within 1 month.

• [1]. Liu WW, et al. Functional photoacoustic calcium imaging using chlorophosphonazo III in a 3D tumor cell culture. Biomed Opt Express. 2021;12(2):1154-1166. Published 2021 Feb 1.

  [2]. Ferguson J W, et al. Simultaneous spectrophotometric determination of calcium and magnesium with chlorophosphonazo III. Analytical Chemistry, 1964, 36(4): 796-799.