Multiple use of blotted polyvinylidene difluoride membranes immunostained with nitro blue tetrazolium

A simple procedure for reusing polyvinylidene difluoride membranes with bound proteins reacted with antibodies and developed by the nitro blue tetrazolium method (M. S. Blake, K. H. Johnston, G. J. Russell-Jones, and E. C. Gotschlich (1984) Anal. Biochem. 136, 175-179) is described. The blue diformazan precipitate produced by the reduction of the nitro blue tetrazolium salt was dissolved by soaking the membrane in dichloro- or trichloromethane for 10-60 min at room temperature. After equilibration in methanol and then in distilled water the first and second antibodies were removed by incubating the membrane in 0.2 M glycine-HCl buffer, pH 2.2, for 90 min at room temperature. These cleaned membranes could be successively reused with different monoclonal antibodies or preimmune serum up to 21 times. The intensity of the spots or electroblotted bands and their specific reaction pattern with different monoclonal antibodies remained unchanged, and no background was observed when the membranes were reacted with preimmune serum. This procedure makes it possible to reuse membranes freshly developed or stored for long periods without loss of resolution.