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临界点干燥(CPD)是目前公认的制备SEM生物试样较为理想的干燥方法。然而,即便是最严谨的操作,经CPD处理的试样仍有13-49％不等的收缩率。深入研究表明,其收缩过程可以分为四个阶段:a)置换阶段(20℃左右); b)升温阶段;c)降压阶段;d)回复到大气压阶段。收缩程度依次为a>c>b>d。为了避免升温、升压产生的收缩效应,我们参照Boyde工作,在HCP-II型临界点干燥器上,运用准饱和CO_2干燥法(QSCD)制备二种肿瘤细胞的SEM试样,镜下观察效果不亚于DPD法,且收缩率亦较CPD小。QSCD操作安领如下:1.样品室预冷至—10℃,边进边微放CO_2,持续3～5分钟,CO_2最后注入量占样品室的80—90％;2.样品室升温至18℃左右,停留5分钟后缓慢放气,放气过程压力维持在
Critical Point Drying (CPD) is a well-accepted drying method for the preparation of SEM biological samples. However, CPD-treated samples still have 13-49% shrinkage, even for the most rigorous operations. Further studies show that the shrinkage process can be divided into four stages: a) the replacement stage (about 20 ℃); b) the warming stage; c) the depressurization stage; and d) the return to the atmospheric pressure stage. Shrinkage followed by a> c> b> d. In order to avoid the shrinkage effect caused by heating and pressurizing, we refer to Boyde’s work to prepare SEM samples of two kinds of tumor cells on HCP-II critical point dryer by using quasi-saturated CO 2 drying method (QSCD) As much as the DPD method, and the contraction rate is also smaller than the CPD. QSCD operating collar as follows: 1. The sample chamber precooled to -10 ℃, the edge of the micro-release CO_2 for 3 to 5 minutes, CO_2 final injection volume accounted for 80-90% of the sample room; 2. The sample chamber was warmed to 18 ℃ or so, stay for 5 minutes after the slow deflation, deflation process pressure is maintained at