The best TnT binders were isolated via ELISA screening (Fig. ). As a negative control, wildtype M13 phage was used. Selected clones provide higher signals for TnT-containing wells than for BSA (negative control). It is worth mentioning that both TnT-and BSA-precoated wells were blocked with the same 0.1% BSA solution, so BSA was present in each well in significant excess. Nevertheless, the presence of TnT causes a noticeable increase of signal, which may suggest a higher affinity of clones to TnT than BSA. Signals from wells that do not contain phages (blank sample) and wild-type phage, which does not expose any peptide, are at least 2 to 5 times lower than signals from the analysed clones. This result confirms the impact of the displayed peptide on phage behaviour against TnT and BSA. The significant drawback of this experiment is the inequality of concentrations of different clones because although all solutions were about 10 10 pfu/ml, the exact value of the pre-exponential factor differed. Nevertheless, a comparison of the signal of each clone for TnT and BSA reveals a difference.