湖南星科科学仪器有限公司
2012/4/18 15:15:02离心技术是利用物体高速旋转时产生强大的离心力,使置于旋转体中的悬浮颗粒发生沉降或漂浮,从而使某些颗粒达到浓缩或与其他颗粒分离之目的。这里的悬浮颗粒往往是指制成悬浮状态的细胞、细胞器、病毒和生物大分子等。离心机转子高速旋转时,当悬浮颗粒密度大于周围介质密度时,颗粒离开轴心方向移动,发生沉降;如果颗粒密度低于周围介质的密度时,则颗粒朝向轴心方向移动而发生漂浮。常用的离心机有多种类型,一般低速离心机的zui高转速不超过6000rpm,高速离心机在25000rpm以下,超速离心机的zui高速度达30000rpm以上。
Centrifugation techniques is to condense certain granule or to separate one granule from the other using a powerful centrifugal force which is generated by high speed revolving item. During the centrifugation process, granules in the rotating object either settles or floats. What worth mentioning is that the granule hereby refers to cell, organelle, virus and large biological molecule in suspension. While the centrifuge rotor is high speed revolving, the granule would depart the axis to settle if the granule density is higher than that of the ambient medium, and it would get closer to the axis to float if its density is lower than that of the ambient medium.
根据离心原理,可设计多种离心方法,常见下列三大类型:
Several centrifugation methods are designed based on the centrifugal principle, and following are the most commonly used three types.
1.差速离心法。通过逐步增加相对离心力,使一个非均相混合液内形状不同的大小颗粒分步沉淀。
the differential centrifugation. It is to centrifugate different shape granules in uneven mixture step by step through gradually increase the centrifugation power.
2.密度梯度离心法。离心前,实验室离心机的离心管内先装入分离介质(如蔗糖、甘油等),使形成连续的或不连续的密度梯度介质,然后加入样品进行离心,具体又可分为:
1)速度区带离心法。离心前,离心管内先装入蔗糖、甘油、CsCl、Percoll等密度梯度介质,待分离样品铺在梯度液的顶部,离心管底部或梯度层中间,同梯度液一起离心,利用各颗粒在梯度液中沉降速度或漂浮速度的不同,使具有不同沉降速度的颗粒处于不同密度的梯度层内,达到彼此分离的目的。本法可分离各种细胞、病毒、染色体、脂蛋白、DNA和RNA等生物样品。
2)预制梯度等密度离心法。要求在离心前预先配制管底浓而管顶稀的密度梯度介质,常用介质有蔗糖、CsCl、Cs2SO4等,待分离样品一般铺在梯度液顶上,如需挟在梯度液中间或管底部,则需调节样品液密度。离心后,不同密度的样品颗粒到达与自身密度相等的梯度层,即达到等密度的位置而获得分离。
No.2 the density gradient centrifugation. Before centrifuging, fill the tube with centrifugation medium such as sugar or glycerol so as to form continuous or un-continuous density gradient medium, and then put in the sample item to centrifugate. The density gradient centrifugation is then subdivided into speed zone centrifugation, preparative gradient even-density centrifugation and auto form gradient even-density centrifugation.
3)自成梯度等密度离心法。某些密度介质经过离心后会自成梯度,例Percoll,可迅速形成梯度,CsCl、Cs2SO4和三碘甲酰葡萄糖胺经长时间离心后也可产生稳定的梯度。需要离心分离的样品可和梯度介质先均匀混合,离心开始后,梯度介质由于离心力的作用逐渐形成管底浓而管顶稀的密度梯度,与此同时,可以带动原来混合的样品颗粒也发生重新分布,到达与其自身密度相等的梯度层里,即达到等密度的位置而获得分离。
No. 3 the sedimentation equilibrium centrifugation. It is to centrifugate based on the sample granules' buoyant density difference. The medium primarily used shares the same density of that of the sample and the medium forms density gradient during centrifuging, granules either setting or floating to a proper position in the mixture.
3.沉降平衡离心法。根据被分离物质的浮力密度差别进行分离,所用的介质起始密度约等于被分离物质的密度,介质在离心过程中形成密度梯度,被分离物质沉降或上浮到达与之密度相等的介质区域中停留并形成区带。
There are several different centrifuge types. Generally speaking, the max rev of low speed centrifuge won't pass 6000rpm, the max rev of high speed centrifuge won't pass 25000 rpm and the max rev of super speed centrifuge is over 30,000 rpm.
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