Optimized adhesin fragments and corresponding nanoparticles

A method of preparing a contrast agent for medical use comprising the steps of:

• providing an adhesin comprising an amino acid sequence selected from the group consisting of the following sequences,
• DraE SEQ ID NO:
• 1
• wherein said adhesin has one or more of the following mutations and is deleted N-terminally by up to 18 amino acids and/or C-terminally by up to 10 amino acids:
• T7 (N, F, C, S, V, R, A, I, L, Y);
• E17 (S, P, K, G, D, R, N, H, Q);
• R22 (T, A, S, N, K);
• D25 (S, G, N, A, T, K, R, H, Q, M);
• T27 (K, R, L, V, Y, P, N, O);
• V28 (W, F);
• A29 (K, R, S, E, Q, F, G, L, H, P, N, T, W);
• T31 (G, D, S, N);
• Q34 (D, G, S, N, L, V, T, A);
• D37N;
• A38 (S, T, L);
• A39 (Q, S, D, M, G, F);
• I41 (V);
• Q47 (T, N, C, S, G, A, P);
• D52 (G, N, S, C, P, Q, Y, H, K, R, T);
• N84 (D, S, H);
• R86V;
• T88 (M, L);
• T95 (L, M, Y, F, C, W, Q, N, E, S, I, H);
• F100 (Y, V);
• V105 (S, A, T, R, M, V, P, N, E, Q, G, K, H);
• I111 (C, V, H, Y, T, M, F) I114 (V, L, A, C);
• Y115 (T, W, E, V);
• V116 (A, S, L);
• G118 (P, S),
• combining the adhesin with a suitable carrier for use as a contrast agent in medical treatment.