FITC-Dextran 4 (FD4)   FITC标记葡聚糖（4 kDa）

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产品标签

FITC-Dextran FITC标记葡聚糖；FD4；FD10；FD40；FD70；TRITC-dextran 罗丹明标记葡聚糖；TD10；TD40；TD70；microcirculation 微循环研究；Cell permeability 细胞渗透性研究； CAS NO：60842-46-8

产品信息

产品描述

FITC标记葡聚糖（FITC-Dextran）是以天然葡聚糖B512F限制水解和分级纯化制备的不同分子量葡聚糖为底物，经荧光素标记所得的合成探针。荧光素基团通过一个稳定的硫代氨甲酰键连接到葡聚糖上（见附录图1. FITC-Dextran分子片段的结构特征），此标记步骤不会引起任何的葡聚糖降解。FITC-Dextran内每个葡萄糖单位含0.002~0.008 mol FITC，这一低水平的替换确保葡聚糖最小的结构变化，这一特性对渗透性研究来说是最基本需求。

FITC标记葡聚糖（FITC-Dextran）广泛用于微循环和细胞通透性研究，通过荧光显微测定法来检测。还可用于植物细胞壁多孔性和毛细血管通透性研究。血浆蛋白不会结合FITC-Dextran。

FITC标记葡聚糖（FITC-Dextran）用于心血管、微循环、灌注、细胞单层和细胞膜渗透性研究，作为一种荧光流动示踪化合物，来支持对血流、膜损伤、血管引流和肾清除等过程的测定。小分子量的FITC-Dextran也能用来测定比如内吞。FITC-Dextran40（FD40）可能用于研究细胞内吞行为。也可能用于研究内皮单细胞层孔隙度和细胞层内顶端到基底膜的运动。

本品是对平均分子量约4kDa葡聚糖进行标记的荧光素衍生物，即异硫氰酸荧光素葡聚糖4（fluorescein isothiocyanate dextran 4, FITC-dextran, FD4），以冻干粉形式提供，易溶于水，最大激发和发射波长分别为493和520nm。

产品特性

1）CAS NO：60842-46-8
2）化学名：Dextran(3´,6´dihydroxy-3-oxospiro(isobenzofuran-1(3H),9´-[9H]xanthen]-5(or 6)-yl)carbamothioate
, average Mw of approximately 4,000
3）同义名：Fluorescein isothiocyanate-dextran 4; Fluoresceinyl thiocarbamoyl-dextran 4;
4）分子量：average Mw 3,000-5,000
5）置换率：0.001~0.008 mol FITC/glucose unit
6）外观：浅黄色至暗黄色至暗橘色粉末
7）溶解性：易溶于水或盐溶液，也溶于DMSO，甲酰胺和某些其他极性有机溶剂，不溶于更低的脂肪醇、丙酮、氯仿和二甲基甲酰胺（DMF）
8）光谱特性：Ex/Em=493/520nm【由于荧光素基团的电荷状态依赖于缓冲液的pH和离子强度，因此荧光强度也会因这些参数的变化而变化。pH＞8观察到最大荧光强度。生理缓冲液能显著影响荧光强度，或得到增加或受到抑制。】

保存与运输方法

保存：室温避光短期保存，2-8℃避光长期保存，保持密封干燥，至少3年稳定。 

运输：室温运输。

产品稳定性

综合各种溶液体系和温度下FITC-Dextrans的稳定性测定，总的来说，体内外FITC-Dextrans的稳定性非常优秀。仅当pH＞9和上升温度内荧光素可能存在水解的风险。兔血浆、肌肉匀浆液、肝脏匀浆液和尿液内的FITC-Dextrans在37℃，至少3天内保持稳定，分子量不会发生变化，且未发现荧光素基团的释放。6%三氯乙酸内FITC-Dextrans室温稳定保存3天。【文献来源：P. Kurtzhals, C. Larsen and M. Johansen, High performance size-exclusion chromatographic procedure for the determination of fluoresceinyl isothiocyanate dextrans of various molecular masses in biological media. J Chromatogr, 491(1989), 117-127.】

硫代氨甲酰键的水解产生4-或5-氨基荧光素，能立即被HPLC定量检测到。未发表的研究数据显示，将高压处理的FITC-Dextran 70溶液置于8-50℃长达5个月，发现仅在50℃情况下可能观察到微量（1%）的自由氨基荧光素含量增加。单独进行高压处理会引起2.7%的自由氨基荧光素产生。

其他的未发表研究显示，FITC-Dextran在pH4溶液35℃内能稳定保存高达1年。而在pH4，80℃内硫代氨甲酰键稳定30min，可能观察到葡聚糖的降解。pH9，35℃内存放一个月以上会发生一定量（24%）的荧光衰减。

一些研究证明，FITC-Dextrans在持续性实验（1-6天）的体内稳定性。【文献来源：N. Thorball, FITC-dextran tracers in microcirculatory and permeability studies using combined fluorescence Stereo Microscopy, Fluorescence Stereo-microscopy and electron microscopy, Histochemistry, 71(1981), 209-233.】

注意事项

1. FITC-Dextrans易溶于水或盐溶液，可根据实际使用浓度配制适当浓度的母液。

2. FITC-Dextrans溶液高压灭菌可能导致少量氨基荧光素的释放，若需要无菌，建议用过滤的方法来除菌。

3. 为了您的安全和健康，请穿实验服并戴一次性手套操作。

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附录

图1. FITC-Dextran分子片段的结构特征

— —Written/Edited by V. Shallan【版权归MKBio懋康所有】

      上海懋康生物科技有限公司是一家涉足于生命科学和生物技术领域研究的试剂、仪器和实验室消耗品与实验服务工作，主要从事细胞生物学、植物学、分子生物学、免疫学、生物化学、蛋白组学。生物制药与诊断试剂研发生产等领域。 本公司秉承“以人为本，以诚为信、合同守信”的经营理念。坚持"品质保障"的原则为广大客户提供优质产品。

引用文献：

[1] Yan, Z., Niu, L., Wang, S. et al. Intestinal Piezo1 aggravates intestinal barrier dysfunction during sepsis by mediating Ca²⁺ influx. J Transl Med 22, 332 (2024). https://doi.org/10.1186/s12967-024-05076-z 

4 kDa FITC-dextran was obtained from Maokang Biotechnology (Shanghai, China).

Intestinal barrier permeability analysis

After 24 h of CLP modeling, the mice underwent a three-hour fast. To ensure sterility, a gavage needle was autoclaved, and then 150 µl of 80 mg per milliliter four-kilodalton FITC dextran in sterile water was administered via gavage. Serum samples (0.1 ml) were collected four hours after oral gavage, diluted five-fold, and measured using an H4 microplate reader with fluorescence read at an excitation of 485 nm and an emission of 528 nm.

[2] Gu Y, Dong Z, Gu Y, Gao Y, Li D, Zhang Y, Zhang X. Paeoniae radix alba improved intestinal mucosal microcirculation disturbance by regulating lncRNA MALAT1/HIF-1α pathway in the treatment of ulcerative colitis. Phytomedicine. 2024 Dec;135:156037. doi: 10.1016/j.phymed.2024.156037. Epub 2024 Sep 12. PMID: 39303508.

Intestinal permeability analysis Examination of intestinal permeability by oral 4 kDa FITC-dextran (Shanghai Maokang Biotechnology Co., Ltd, Shanghai, China).

[3]Tang, Z., Zhu, Y., Hu, X. et al. Improving Intestinal Barrier Function in Sepsis by Partially Hydrolysed Guar Gum via the Suppression of the NF-κB/MLCK Pathway. Mol Biotechnol (2024). https://doi.org/10.1007/s12033-024-01180-z

Briefly, the rats were given fluorescein isothiocyanate-conjugated dextran (0.5 mL, 22 mg/mL
of FITC-dextran 4 (FD-4, Shanghai Maokang Biotechnology Co., Ltd., Shanghai, China) 

[4]Zheng X, Cao Z, Wang M, Yuan R, Han Y, Li A, Wang X. Betulinic Acid Reduces Intestinal Inflammation and Enhances Intestinal Tight Junctions by Modulating the PPAR-γ/NF-κB Signaling Pathway in Intestinal Cells and Organoids. Nutrients. 2025 Jun 20;17(13):2052. doi: 10.3390/nu17132052. PMID: 40647158; PMCID: PMC12251175.

FITC-dextran 4 was obtained from Maokangbio (Shanghai, China). 

2.6. Paracellular Permeability Assay

The use of FITC-dextran 4 allowed for an evaluation of paracellular permeability. After the monolayers had been gently rinsed with PBS, 1 mg/mL of FITC-dextran 4 was added to the apical compartment, and the basolateral chamber’s media were replaced with PBS. After incubation for 6 h, 100 µL of basolateral PBS was transferred to a black opaque 96-well plate. Next, the fluorescence intensity was measured using a multi-mode microplate reader at an excitation/emission wavelength of 493/520 nm. A fluorescence value of 100% was considered to have been achieved in the control cells.

[5]  Zhang J, Liu J, Zhang H, Liu B, Li L, Li Y, Pei J, Lin Q, Chen Q, Lin J. Lymph node-targeted delivery of Lonicera japonica thunb. polysaccharides for enhancing antitumor immunotherapy. Mater Today Bio. 2025 Feb 4;31:101559. doi: 10.1016/j.mtbio.2025.101559. PMID: 40026631; PMCID: PMC11871467.

2.12. Uptake ability

To confirm the maturation of BMDCs, cells were stimulated as mentioned above, and co-cultured with FITC-dextran (1 mg/mL, 40,000 Da, Shanghai Maokang Biotechnology Co., China) for 1 h and ended by cold 2 % FBS. Finally, stained cells were analyzed by LSRFortessa (BD, USA) and analyzed by Flowjo.

[6] Yang Liu et al. Preparation and characterization of Arctium lappa L. polysaccharide-Zn(II) complex and evaluation of its immune activity.  Food Chemistry Advances. Volume 5, December 2024, 100784

The fluorescein isothiocyanate (FITC)-dextran was from Shanghai Maokang Biotechnology Co., Ltd. (Shanghai, China). 

2.6.6. Determination of FITC-dextran uptake by DCs

The DCs were collected and incubated at 1 × 10⁶ cells/mL in 12-well plates on day 7. Then, these cells were stimulated for 48 h with RPMI-1640 medium (negative control group), LPS (2 μg/mL), ALP (30 μg/mL), and ALP-Zn (30 μg/mL) respectively. After the culture with ALP, ALP-Zn or LPS for 48 h, DCs were collected and then hatched with 100 μL FITC-dextran (1 mg/mL, 40,000 Da) and 5 % CO₂ for 1 h at 37 °C. The reaction was ended by cold PBS including 2 % FBS. Then the cells were washed by PBS and hatched with PE-conjugated anti-mouse CD11c for 30 min at 4 °C in the dark. After being thoroughly washed, the double-stained DCs were analyzed by BD LSRFortessa flow cytometer.

[7] Li Y, Xu J, Gao Z, Chen H. Cyclic Strain and Macrophage-Mediated Transport Govern Micron-Sized PM₂.₅ Translocation across the Air-Blood Barrier. Adv Sci (Weinh). 2026 Jan;13(3):e11955. doi: 10.1002/advs.202511955. Epub 2025 Oct 29. PMID: 41160810; PMCID: PMC12806473.

1 mg mL⁻¹ FITC-dextran (4 kDa, both from Maokang Biotechnology, Shanghai, China) was added to the apical chamber.

[8] Bai, T., Li, M., Liu, Y. et al. The promotion action of AURKA on post-ischemic angiogenesis in diabetes-related limb ischemia. Mol Med 29, 39 (2023). https://doi.org/10.1186/s10020-023-00635-4

Cell permeabilization assay

Cell suspension (200 μL) with a density of 5 × 10⁴ cells/mL was added to the upper compartment of the Transwell chambers, and the lower compartment was filled with culture medium. After the establishment of confluent monolayers of cells, the medium was discarded and the washing procedures were repeated twice using PBS. A total of 100 μL fluorescein isothiocyanate (FITC)-labeled dextran (FITC-dextran, 1 mg/mL, Maokang Biotechnology, Shanghai, China) was added to the upper compartment, and 500 μL phosphate buffer saline (PBS) solution was added to the lower compartment. The cell permeability was assessed by measuring the fluorescence intensity of FITC-dextran from the upper compartment to the lower compartment.

[9]Guo, Y., Li, Y., Shi, M. et al. Human umbilical cord mesenchymal stromal cell-derived exosomes alleviate antibiotic-induced intestinal barrier damage by regulating autophagy via the S100G/mTOR signaling pathway. Cell Mol Biol Lett 30, 139 (2025). https://doi.org/10.1186/s11658-025-00810-x

Intestinal permeability assay

After 12 h of fasting, mice were administered fluorescein isothiocyanate-dextran (FITC-D, 4 kDa, Shanghai Mao-Kang Biotechnology Co., Ltd.) by gavage for intestinal permeability assessment [21]. Each mouse received 60 mg/100 g of FD4, and they were euthanized by cervical dislocation after 2 h. The peritoneal cavity was opened to expose the colon, and the total fluorescence intensity was measured using a live animal imaging system (IVIS Spectrum, Revvity, USA). Data are expressed as mean ± standard deviation (SD) (n = 3 per group).

[10]  Liu X, Xi C, Li W, Su H, Yang H, Bai Z, Tian Y, Song S. Moringa oleifera Leaves Protein Enhances Intestinal Permeability by Activating TLR4 Upstream Signaling and Disrupting Tight Junctions. Int J Mol Sci. 2023 Nov 16;24(22):16425. doi: 10.3390/ijms242216425. PMID: 38003615; PMCID: PMC10671199.

Fluorescein isothiocyanate (FITC)-labeled dextran 4 kDa and 70 kDa were purchased from Shanghai Mao Kang Biotechnology Co. (Shanghai, China).