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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希望知道如何购买的朋友告诉一下，谢谢。
一般来说，试剂盒曲线上的最小浓度是比较准确的，低于这个值因为与曲线是个“S"型结构有关，所以结果是有偏差的，是一种估算。再加上实验误差，所以达不到理想的效果。建议选择试剂盒时，应该看曲线上最小的浓度值，而不是试剂盒上写的灵敏度。
虽然酶活性调节ELISA方法的灵敏度目前并不十分理想，但在酶活性放大ELISA中，检测的灵敏度远比RIA高。根据质量作用定律。即免疫反应所形成的免疫复合物量与反应物浓度成正比。推测所检测的待测物分子数为1。已知1个摩尔浓度含6.02×1023个分子，那么理论推测酶活性放大ELISA方法的最低检测限可达1.7×10-24mol/L。虽然在实际应用中由于反应条件和试剂纯度以及仪器精度等因素的影响，往往达不到这个水平(大于104个分子)，但表明ELISA在灵敏度方面的改进潜力是很大的。
