
Liposomes are extensively used to study the interaction of proteins, peptides and other molecules with the surface of a lipid membrane. One of the parameters that affects this interaction is the charge of the liposomal membrane. Liposomes are always made in aqueous environment and they are sized to the desired size in liquid state using various methods such as high-pressure extrusion through nano sized pore track etch membranes. Liposome without water is meaningless. In rare occasions, liposomes are freeze dried and proliposomes are formed in the presence of a lyoprotectant such as trehalose. Using a lyoprotectant is necessary in order to maintain the size of the liposomes after rehydration.
Phosphatidylserine (PS) is a negatively charged molecule. The amount of the negative zeta potential in the liposomes depends on the molar percentage of the phosphatidylserine (PS) in the formulation. Anionic Lyophosome™-Phosphatidylserine (PS) catalog contains products made from 0.5 up to 90 percent DOPS with various amount of negative zeta potentials. The matrix lipid, DOPC, that is used in the formulations does not significantly contribute to the charge of the liposomes. Anionic liposomes are used in blood complement studies and various types of in vitro studies.
Lyophosome™ product catalog is composed of a large selection of freeze-dried liposomes with various types of lipids and wide range of zeta potentials and different properties. Lyophosome™ products should be used by scientists who understand liposome formulation and have the proper equipment to check the size, separate non-encapsulated drugs and do the proper assays. Freeze-dried liposomes cannot be used blindly.
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现在国内最差也是用3代试剂,有些地方会用4代试剂。
4代试剂(检查抗原+抗体)——窗口期为4周。因为抗原于3-4周达到复制的峰值,此时通过4代试剂检查,如果感染了HIV,抗原/抗体至少有一个为阳性,如果都是阴就排除了。
3代试剂(只查抗体)——窗口期为6周。
以上为理论分析+临床经验的结果,可以说是99.9%的准确度。
但是目前FDA、CDC和试剂生产商统一达成的共识,也就是针对普通人,最保守的窗口期是3个月。无论什么试剂,3个月都100%排除。
复习了很多文献在测定方法里面均提到了CV
例如:
Theintra-assaycoefficientofvariationfortheassaywas4-6%.
Theanalyticcoefficientofvariationwas10.2%
问题是:
我是否可以直接使用说明书里的CV值?
如果不可以,我该如何操作进行计算
DAS-ELISA试剂盒中抗体有包被抗体和酶标抗体,这两种抗体是一种抗体,前者没有酶标,后者用酶进行了标记。
NCM-ELISA一般有一抗和二抗,这两种抗体不一样,前者(一抗)一般是鼠抗体或兔抗体,没有酶标,相对应的二抗一般是羊抗鼠或羊抗兔抗体,用酶进行标记。也有用马大规模备抗体的。
TDS-ELISA是三抗体ELISA,第三级的抗体是将信号级联放大。
以上三种是比较常见的,还有其他一些试剂盒,可参考免疫学的内容。
首先要什么有什么的,你得好好考虑一下。
2、看生产地址
根本没有生产地址,我们知道做实验做产品需要很多的仪器、试剂、耗材,没有人相信一间简单的屋子可以生产各种样的试剂盒。
3、看产品包装
没有任何的生产地址、联系方式等信息,这种产品有问题了连个投诉的地方都没有。
4、看公司网站
有些打着国外原装旗号,整个公司网站为英文页面,实际注册IP地址在中国。如果写着国外的地址,让你国外的朋友实地去看一下!
5、做交叉验证
拿对方提供的几个种类的试剂盒,把里面的关键组份相互替换做做实验,如果交叉严重,只能说明是一种原料生产的试剂盒贴了不同的标签。
6、看价格
价格低得离谱,却打着进口大公司原料分装,核算成本,这种低得离谱的价格是连原料都买不起的。
需要的仪器有:酶标仪、恒温箱、枪、枪头、烧杯、滤纸.当然有自动洗板机最好.