The invention concerns a water soluble vinyl membrane-polymer protein amphiphilic complex, characterised in that said vinyl polymer corresponds to formula (I) in which: R1 is a group: COO⊖ M+ M+ being an alkaline cation, COOR7, R7 being a sugar radical; polyoxyalkylene, polyoxyethylene; N-pyrrolidonyl; phenyl sulphonate; CONR8R9, R8 and R9 identical or different being hydrogen atom, a sugar radical, polyoxyalkylene, in particular polyoxyethylene, a zwitterion radical; R4, R5, R6 identical or different are hydrogen atom, or methyl radical; R2 is a COOR12 or CONR13R14 radical, R12 being a linear or branched alkyl or alkylene radical; R13, R14 identical or different have one of the meanings of R12, and moreover one of the two can correspond to hydrogen atom; R3 is a COOR15 or CONR16R17 radical; R15 being a (C1-C5) alkyl radical; R16, R17 having one if the meanings of R15 and moreover one of the two can correspond to hydrogen atom; x, y, z correspond to the respective percentages of units. The complex is applicable for producing reagent and diagnosis kits.