溴化乙锭单叠氮化物 (EMA)

有两种简单的方法。一种是通过60°C放置20分钟热灭活细胞。第二种是将细胞放入70%乙醇。乙醇固定的细胞可以在冰箱中无限期储存直到使用，可达好几年。

1.离心细胞、使细胞沉淀并去除上清
2.固定细胞：在15mL含有细胞团的试管中加入10 mL70%冰乙醇，先开始逐滴加入后震荡，混合均匀。
3.在冰箱中储存直到使用。
4.快使用时，水洗两次且在选择的缓冲液中重悬。

•用于流式细胞仪分析的LIVE/DEAD可固定试剂盒适用于固定。这些试剂盒使用胺基反应细胞-非渗透染料对活细胞细胞表面和死细胞胞质染色——活细胞暗淡死细胞明亮。因为染料共价结合到细胞，固定后保留。不幸的是，此方法对基于成像的实验效果不好，由于所有细胞都被染色，很难通过显微镜从暗淡的活细胞中分辨出明亮的死细胞。

•Image-IT DEAD绿色活性染料（货号I10291），用于成像和高通量扫描（HCS）分析的，是一种活细胞非透过型DNA结合染料，固定且透过后可保留长达48小时。

•我们同时推出用于成像分析的LIVE/DEAD Reduced Biohazard Cell Viability试剂盒（货号L7013），其含有两种DNA结合染料，SYTO 10和Dead Red，可以有效染色且通过4%戊二醛固定后快速分析。

注：总的来说，DNA结合的染料和钙黄绿素AM不适用于固定，由于这些染料不能共价地结合到细胞组分上，因此会在固定后缓慢扩散出细胞，逐渐地将所有细胞都染色。

There are two easy options. One is to heat-inactivate the cells by placing at 60 degrees C for 20 minutes. The second is to subject the cells to 70% ethanol. Alcohol-fixed cells can be stored indefinitely in the freezer until use, potentially up to several years.

Centrifuge cells, pellet, and remove supernatant.
Fix cells: Add 10 mL ice cold 70% ETOH to a 15 mL tube containing the cell pellet, adding dropwise at first while vortexing, mix well.
Store in freezer until use.
When ready to use, wash twice and resuspend in buffer of choice.

Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.

The LIVE/DEAD Fixable kits for flow cytometry analysis are compatible with fixation. These kits use amine-reactive cell-impermeant dyes that stain the cell surface of live cells and also the cytosol of dead cells-live cells are dim and dead cells are bright. Since the dye is covalently bound to the cells, it will be retained after fixation. Unfortunately, this method does not work well for imaging-based assays, as all cells are stained and it is difficult to distinguish bright dead cells from dim live cells with a microscope. Ethidium monoazide (EMA; Cat No. E1374) is a cell impermeant nucleic acid stain that can be applied to live cultures and stains only dead cells. After incubation and washing away unbound dye, the cells can be exposed to light to photoactivate EMA to crosslink to dead cell DNA. After crosslinking to dead cell DNA, the samples may be fixed and permeabilized. Image-IT DEAD Green Viability Stain (Cat. No. I10291) for imaging and high-content screening (HCS) analysis is a live-cell impermeant DNA binding dye that is compatible with fixation and permeabilization with good retention up to 48 hours. We also have a LIVE/DEAD Reduced Biohazard Cell Viability Kit (Cat. No. L7013) for imaging and flow analysis that contains two DNA binding dyes, SYTO 10 and Dead Red, that are sufficiently retained to be analyzed soon after 4% glutaraldehyde fixation.
Note: In general, DNA-binding dyes and calcein AM are not compatible with fixation, as these dyes are not covalently bound to components of the cell and will thus slowly diffuse out of cells after fixation, gradually staining all cells as dead.

Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.