WesternBlot时*常用的两种膜是硝酸纤维素膜（nitrocellulose，NC膜）和PVDF膜（又称Positively chargednylon）（Polyvinylidene fluoride，聚偏二氟乙烯膜）。
这两种膜各自有什么特点？我们的实验中该选择哪一种呢？来看下面的文字。（摘自《Making and usingAntibodies》）
A study of the performance of nitrocellulose,mixed ester, nylon, and covalent-binding PVDF memberanes afterpassive protein adsorption and also after electrotransfer was donewith several different proteins labeled with 125Iodine.The membranes exhibited different binding capacities in passiveadsorption tests with labeled bovine serum albumin. The PVDF showedthe least, and the regenerated cellulose and nylon membranes showedthe most protein binding. Nitrocellulose and mixed ester membraneswere midway between. In tests measuring protein retention, PVDFretained the most bound protein when washed with detergents or 5%skimmed milk. All the membranes showed virtually the samebinding capacity as measured by autoradiography when tested underelectrotransfer conditions with Towbin's buffer. In passiveadsorption tests, the membranes wxhibited a broad range ofcapacities but gave similar results in electrotransfer tests. Thesedifferences were ascribed to active migration of protein into themembrane matrix instead of simple diffusion and the increasedhydrophobicity of Towbin's transfer buffer because of the inclusionof methanol.
上面这段文字指出在被动扩散转移蛋白时，几种膜之间结合蛋白的能力差别明显；但是当使用转膜仪转移蛋白时，各种膜之间的差别就很小了。
The choice of membrane used for Western Blot ismore critical if the blotted protein must maintain its nativeconformation for detection by the antibody. For example, acomparison using a guanosine triphosphate(GTP)-overlay assay showedthat the activity of a bovine GTP-binding protein was barelydetectable after transfer to hydrophobic PVDF membranes but wasclearly detected after transfer to nitrocellulose. Western blotanalysis showed the GTP-binding protein to be present on both PVDFand nitrocellulose membranes, with slightly more detected on thePVDF membranes. The authors speculated that the poor performance ofPVDF in the GTP-overlay assay may have been due to an inability ofGTP-binding protein, thus immobilized, to renature correctly.Therefore, nitrocellulose might be preferred for a Western blotprocedure, in which detection requires that the transferred proteinregain its native conformation after transfer, such as when theblotting agent recognized three dimensional structure; for example,an antigenic epitope consisting of noncontiguous residues.
由此可见，如果你的抗原表位需要维持其三维结构才能被抗体识别，就应该优先选择NC膜。
另外，Abcam网站上技术资料中的建议是：
Two types of membranes are available:nitrocellulose and PVDF. The choice is personal and both work verywell. PVDF membranes require careful pre-treatment: cut themembrane to the appropriate size then soak it in methanol for 1-2min. Incubate in ice cold transfer buffer for 5 minutes. The gelneeds to equilibrate for 3-5 minutes in ice cold transfer buffer.Failure to do so will cause shrinking while transferring, and adistorted pattern of transfer.
Methanol is only necessary if usingnitrocellulose. If using PVDF, methanol can be removed from thetransfer buffer altogether, and is only needed to activate thePVDF before assembling the gel/membrane sandwich.可见，使用PVDF膜时，一定要先用无水甲醇预处理，再在transferbuffer中平衡好才可以使用（PVDF膜用甲醇泡的目的是为了活化PVDF膜上面的正电基团，使它更容易跟带负电的蛋白质结合）。经过预处理的PVDF膜在转膜时，可以使用不含甲醇的transferbuffer。而使用NC膜时，有的需要用无水甲醇处理，有的则不必，直接用transferbuffer平衡好就可以了。（注：我使用的是Pall公司的NC膜，不需要无水甲醇处理，其他公司的不是很清楚，*好参考产品说明）
提醒使用PVDF膜的朋友们注意两点：
1. Because of thehigh number of protein-binding sites in the activated nylon,the backgrouds are normally considerably worse, but carefulblocking will eliminate many of these problems.
2. Chicken antibodies tend tobind PVDF and other nylon-based membranes, leading to highbackgroud. Switching to a nitrocellulose membrane should helpreduce background staining.
通过上面的分析，基本可以得出结论，NC膜比PVDF膜更通用一些。尽管NC膜能满足绝大多数情况下的要求，大家在使用NC膜时也要注意到NC膜的不足之处。
Nitrocellulose is the most commonly used, and itor more recently developed derivatives are highly recommended.However, nitrocellulose does have certain disadvantages. Theproteins are not covalently bound, and nitrocellulose can bebrittle, especially when dry. With appropriate care, however, itwill fit most applications.
下面这段话来自互联网，仅供参考。
硝酸纤维素膜：硝酸纤维素膜是蛋白印迹实验的标准固相支持物。在低离子转移缓冲液的环境下，大多数带负电荷的蛋白质会与硝酸纤维素膜发生疏水作用而高亲和力的结合在一起，虽然这其中的机制还不是十分清楚，但由于硝酸纤维素膜的这个特性，而且易于封闭非特异性结合，从而得到了广泛的应用。在非离子型的去污剂作用下，结合的蛋白还可以被洗脱下来。根据被转移的蛋白分子量大小，要选择不同孔径的硝酸纤维素膜。因为随着膜孔径的不断减小，膜对低分子量蛋白的结合就越牢固。但是膜孔径如果小于0.1mm，蛋白的转移就很难进行了。因此，我们通常用0.45μm和0.2μm两种规格的硝酸纤维素膜。大于20kD的蛋白就可以用0.45μm的膜，小于20kD的蛋白就要用0.2μm的膜了，如果用0.45μm的膜就会发生“Blowthrough”的现象。从膜的质地上来看，*重要的指标就是单位面积上能够结合的蛋白的量。硝酸纤维素膜的结合能力主要与膜的硝酸纤维素的纯度有关，市场上有些硝酸纤维素膜通常会还有大量的醋酸纤维素，因而降低了蛋白的结合量。如果采用的是100%纯度的硝酸纤维素，保证了*大的蛋白结合量，可达80-150μg/cm2。由于100%的纯度，因而也大大减少了非特异性的结合，降低杂交背景，无需高严谨度的洗脱步骤。其次，膜的强度和韧性也是需要考虑的因素。常规的硝酸纤维素膜比较脆，漂洗一两次就会破损，不能反复使用。
PVDF转移膜：PVDF是一种高强度、耐腐蚀的物质，通常是用来制造水管的。PVDF膜可以结合蛋白质，而且可以分离小片段的蛋白质，*初是将它用于蛋白质的序列测定，因为硝酸纤维素膜在Edman试剂中会降解，所以就寻找了PDVF作为替代品，虽然PDVF膜结合蛋白的效率没有硝酸纤维素膜高，但由于它的稳定、耐腐蚀使它成为蛋白测序理想的用品，一直沿用至今。PVDF膜与硝酸纤维素膜一样，可以进行各种染色和化学发光检测，也有很广的适用范围。这种PVDF膜，灵敏度、分辨率和蛋白亲和力在精细工艺下比常规的膜都要高，非常适合于低分子量蛋白的检测。但PVDF膜在使用之前必需用纯甲醇进行浸泡饱和1-5秒钟。
----------转载自lunar sea