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N2B27 for conventional or single cell ESC derivation is best bought ready to use from Stemcells, Inc.Home-made N2B27 using either commercially available or entirely home-made supplements (as described below) usually works equally well, however can display some batch variability.
N2B27 是干细胞生长的很好的添加剂，其配置方法和配方一直是很难把握的问题，站长在一权威文献看到独家配方，现整理如下：
1. 配制成分组成
1. Dissolve 100 mg Insulin in 4 mL of sterile 0.01 M HCl to give a 25 mg/mL stock solution by incubating overnight at 4 C.
Insulin does not dissolve well, so ensure the suspension is mixed well before aliquoting.
2. Make 100 mg/mL stock of Apo-transferrin by incubating 500 mg in 5 mL of dH2O overnight at 4 C.
3. Dissolve6 mg Progesteronein 10mLEthanoltogivea 0.6mg/mL stock.
4. Dissolve 1.6 g Putrescine in 10 mL dH2O to give a 160 mg/mL stock.
5. Dissolve 2.59 mg Sodium Selenite in 5 mL dH2O to give a 3 mM stock.
6. Dissolve 750 mg BSA in 10 mL PBS to make a stock of 75 mg/mL.
Store all stocks at 20 C.
2.100XN2 配制
Add the following stocks together: 1 mL Insulin, 1 mL Apotransferrin, 0.67 mL BSA, 33 μL Progesterone, 100 μL Putrescine,10 μL Selenite, 7.187 mL DMEM/F12.
