Clarification of immunoblots on polyvinylidene difluoride (PVDF) membranes for transmission densitometry

The opacity of polyvinylidene difluoride (PVDF) transfer membrane can be reduced by infiltration with liquid. A mixture of 9:1 v/v ethylene glycol/glycerol gives complete transparency; clarification by this mixture is stable due to the low volatility of the components and is reversed by washing in water without loss of band intensity. The mixture is easy to apply to the membrane and being water soluble, non-corrosive and relatively non-toxic, is convenient to use. Clarification and densitometric analysis of stained immunoblots of PVDF membranes is at least as effective as that previously described for nitrocellulose, but the greater ease of use of the new mixture makes PVDF the membrane of choice for transmission densitometry. Using a blot onto PVDF of monoclonal IgG probed with anti-mouse antibody, laser transmission densitometry revealed that the stained peak area was related to loading in a linear fashion over a 60-fold range on a single blot.