Cy7 DiC18 does not target a specific biological receptor or enzyme; instead, it functions as a lipophilic tracer that partitions into lipid bilayers. Its primary "target" is the cellular membrane or lipid-containing structures such as liposomes and lipoproteins. The dye's NIR fluorescence properties make it suitable for in vivo imaging applications where deep tissue penetration is required.

Labeling cells, organelles, toners, viruses, and lipoproteins with henna dyes is a common practice. The dialkylphoenix dye DiA (4-Di-16-ASP), which is used to designate membranes and other focal structures, is one of the long-chain henna cyanines, along with DiO (DiOC18 (3)), DiI (DiIC18 (3)), DiD (DiIC18 (5)), and DiR. Comparing DiIC16 (3) to DiI (C18), the alkyl substituent (C16) is shorter. They exhibit brief excited-state depletion in pyramid settings, environment-dependent fluorophores, and extraordinarily high extinction factors. While they are oil-forming and have poor fluorescence in water, when they are attached to lipophilic biomolecules or integrated into membranes, they become moderately photostable and highly fluorescent. Their optical characteristics render them perfect for the staining of cell plasma membranes. These dyes diffuse laterally within the plasma membrane after cells are identified, staining the entire cell [1 DiO, DiI, DiD, and DiR exhibit distinct green, orange, red, and red fluorescence, respectively, making it easier to image live cells in multiple colors and perform flow cytometry analysis. You can utilize normal FITC and TRITC filters with DiO and DiI, respectively. Because they often show extremely low cytotoxicity, DiI and its analogs are the most widely employed among them. Furthermore, lipoproteins like LDL and HDL are frequently measured using DiI. Another often used tool for determination is the lipophilic radical dye DiA. Protocol general 1. Get Di staining solution ready. The Metatracer [2]. Compile stock solutions in dimethylformamide (DMF), dimethylformamide (DMSO), or ethanol DMSO. The concentration of the stock solutions should range from 1 to 5 mM. To act as Di's solvent, DMF b. Aliquot the stock solution and store it in the freezer at a minimum of -20°C. An aliquot of any leftover solution is advised. Don't freeze and thaw again. The solution has a six-month shelf life. B. To create a working solution, mix the stock solution with a suitable buffer, like serum-free medium, HBSS, or PBS, ranging from 1 to 5 μM. Storing the sink for longer than a day is not advised. Note: Two is the working solution's final concentration. Cells suspended a. For three to five minutes, centrifuge at 1000 g at 4°C. Once the Di working solution has been added, wait one to thirty minutes. D. Rinse twice with PBS for five minutes each time, then centrifuge three to four times at 400 g and 4°C. Discard the supernatant. D. Wash for five minutes each time, twice, using PBS. E. After resuspending the cells in PBS or serum-free cells, examine them using a microscope or flow cytometry. 3. cells that adhere a. B. After removing the coverslip from the culture medium, aspirate any extra cells. an. Once the cells are well covered, add 100 μL of the working solution, shake gently, and let the cells purify for five to thirty minutes. Apply culture medium twice, allowing each wash to last five minutes. Observe using flow cytometry or fluorescence microscopy.
In vitro, Cy7 DiC18 is used to label cells for tracking migration, distribution, and homing in various experimental settings. The dye exhibits strong NIR fluorescence with excitation and emission in the deep-red/near-infrared region, enabling minimal background autofluorescence from biological samples. It is soluble in organic solvents such as DMSO (≥19.8 mg/mL) and ethanol (≥29.35 mg/mL) but is insoluble in water, requiring appropriate formulation for aqueous biological applications.

In vivo, Cy7 DiC18 enables non-invasive imaging of cell trafficking, tumor localization, and biodistribution in small animal models. The NIR fluorescence allows for deep tissue imaging with reduced scattering and absorption compared to visible light. It has been used to track the homing of labeled cells to target tissues, providing valuable information for cell-based therapy research. The dye's lipophilic nature ensures stable membrane integration for extended tracking periods.

In vitro enzyme/receptor binding assays are not applicable for Cy7 DiC18 as it is a fluorescent tracer rather than a pharmacological agent targeting specific enzymes or receptors. However, its membrane insertion properties can be characterized using liposome partitioning assays. In such assays, the dye is incubated with lipid vesicles at various concentrations, and fluorescence intensity is measured to determine membrane affinity and insertion efficiency.

For in vitro cell labeling experiments, cells are incubated with Cy7 DiC18 at concentrations typically ranging from 1-10 μM in serum-free medium for 15-30 minutes at 37°C. After incubation, cells are washed thoroughly with PBS to remove unbound dye. Labeled cells can then be analyzed by flow cytometry or fluorescence microscopy using NIR excitation/emission filters. The dye exhibits stable membrane incorporation and low cytotoxicity at recommended concentrations.

For in vivo animal experiments, Cy7 DiC18-labeled cells (typically 1-5 × 10⁶ cells) are administered via intravenous, subcutaneous, or intraperitoneal injection into mice or rats. Alternatively, the dye can be injected directly as a liposomal formulation. Animals are then imaged using an NIR fluorescence imaging system at various time points post-injection (e.g., 0, 24, 48, 72 hours) to track cell migration and biodistribution. Ex vivo organ imaging can be performed to confirm tissue localization.

As a lipophilic dye, Cy7 DiC18 displays high stability in lipid membranes and prolonged retention in labeled cells. Its pharmacokinetic properties are determined by the carrier or labeled cells rather than the dye itself. When administered as a free dye, it rapidly associates with serum lipoproteins and distributes to lipid-rich tissues. The dye is metabolically stable and can persist in labeled cells for several days to weeks.

Cy7 DiC18 is generally considered to have low cytotoxicity at concentrations used for cell labeling (typically 1-10 μM). However, like other carbocyanine dyes, it may exhibit toxicity at higher concentrations or with prolonged exposure. The dye is not intended for human therapeutic use and is classified as a research-grade reagent. Standard laboratory safety practices should be followed when handling the compound.

[1]. Multicolor "DiOlistic" labeling of the nervous system using lipophilic dye combinations. Neuron. 2000 Aug;27(2):219-25.

[2]. Applied electric fields accelerate the diffusion rate and increase the diffusion distance of DiI in fixed tissue. J Neurosci Methods. 2005 Jan 30;141(1):155-63.

DiIC18(7) dye is an organic iodide salt used as a fluorescent dye. It contains a diIC18(7)(1+) group and is functionally similar to C7-indocyanine.
Cy7 DiC18 is a research-use only compound and has not been approved for clinical or therapeutic applications. It is widely available from various chemical suppliers for research purposes. The compound is also referred to as DiR (1,1-dioctadecyl-3,3,3,3-tetramethylindotricarbocyanine iodide). Its molecular formula is C₆₃H₁₀₁IN₂ and molecular weight is approximately 1013.4 g/mol. Storage recommendations typically include protection from light and storage at -20°C for long-term stability.

C63H101IN2

1013.3939

1012.7

100068-60-8

25195411

Brown to reddish brown solid powder

0

2

38

66

1260

0

CCCCCCCCCCCCCCCCCCN\1C2=CC=CC=C2C(/C1=C\C=C\C=C\C=C\C3=[N+](C4=CC=CC=C4C3(C)C)CCCCCCCCCCCCCCCCCC)(C)C.[I-]

JLIOTPLALDYAEH-UHFFFAOYSA-M

InChI=1S/C63H101N2.HI/c1-7-9-11-13-15-17-19-21-23-25-27-29-31-33-38-46-54-64-58-50-44-42-48-56(58)62(3,4)60(64)52-40-36-35-37-41-53-61-63(5,6)57-49-43-45-51-59(57)65(61)55-47-39-34-32-30-28-26-24-22-20-18-16-14-12-10-8-2;/h35-37,40-45,48-53H,7-34,38-39,46-47,54-55H2,1-6H3;1H/q+1;/p-1

(2E)-2-[(2E,4E,6E)-7-(3,3-dimethyl-1-octadecylindol-1-ium-2-yl)hepta-2,4,6-trienylidene]-3,3-dimethyl-1-octadecylindole;iodide

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment (e.g. under nitrogen), avoid exposure to moisture and light.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO : ~25 mg/mL (~24.67 mM)

Solubility in Formulation 1: ≥ 2.08 mg/mL (2.05 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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 (Please use freshly prepared in vivo formulations for optimal results.)