IR-820 (New Indocyanine Green) is a near-infrared dye with improved stability, good color rendering, and excellent fluorescence penetration. It serves as an infrared blood pool contrast agent for detecting and quantifying diseased tissue in live animals, with maximal excitation (Ex) and emission (Em) of 710 and 820 nm, respectively.

Instructions:
I. Solution preparation
1. Stock solution: Prepare 1–10 mM stock solution, dissolve in sterile water or DMSO, and adjust the concentration according to experimental needs.
2. Working concentration: Dilute the stock solution to 10–50 µM (in vitro) or 0.5–1 mg/kg (in vivo) according to the experimental objectives.
Notes:
Powder: It is recommended to store in a dry environment away from light, and the temperature is controlled at -20°C or lower.
Solution: It can be stored at 4°C for short-term storage, and it needs to be aliquoted and kept away from light for long-term storage, and stored at -20°C to avoid repeated freezing and thawing.
II. Bioimaging experiment
IR820 is commonly used in near-infrared fluorescence imaging (NIRF) and is suitable for in vivo or in vitro imaging studies.
Experimental steps:
In vitro experiment: Directly add IR820 working solution to the cell culture system and incubate for 30–60 minutes.
In vivo experiment: Dilute IR820 and inject it into the experimental animal through the tail vein.
The signal is detected by near-infrared imaging equipment during imaging.
III. Photothermal/photodynamic therapy
IR820 has photothermal and photosensitivity properties and can be used for photothermal therapy or photodynamic therapy of tumors.
Illumination conditions: Use 808 nm laser irradiation, and the light intensity and time are optimized according to the experiment (such as 1–2 W/cm², 5–10 minutes).
Concentration reference: Dilute IR820 to 5–20 µM (in vitro) or 0.5–2 mg/kg (in vivo) according to the treatment goal.
IV. Fluorescence detection parameters
Excitation wavelength: about 700–800 nm
Emission wavelength: about 820–850 nm
Precautions
Light-avoiding operation: IR820 is sensitive to light, and strong light should be avoided during the operation.
Fresh preparation: It is recommended to prepare it before use to prevent degradation of the dissolving solution.
Control: A blank group and a control group should be set up in the experiment to ensure reliable data.

The above information is based on published literature. Experimental procedures should be appropriately modified to meet specific research demands.

DMSO: 4.5 mg/mL (5.3 mM), Sonication and heating to 60℃ are recommended.