A mixture of various variants of exposed peptides (called a library) may be screened for variants with desired properties like binding to a target protein. Within our studies, we have obtained a specific peptide as a selective receptor for human cardiac troponin T (TnT). We tried to measure the strength of the interaction between phage-exposed peptide and TnT via ELISA. However, we found a gap in the literature devoted to studying the interactions between ligands and polyvalent receptors, especially discussing their mathematical and physicochemical basis.