Detection of Individual p53-Autoantibodies by Using Quenched Peptide-Based Molecular Probes

Single‐molecule spectroscopy for cancer diagnostics: Short dye‐labeled peptide epitopes derived from human p53 show strong fluorescence quenching owing to efficient electron transfer from a tryptophan residue to the fluorophore (1, see picture). The specific recognition of the peptide epitope by the antibody induces a change in the conformation which is accompanied by a strong increase in fluorescence intensity. The fluorescing antibody–peptide complex can be detected at the single‐molecule level even in slightly diluted serum samples by using confocal fluorescence microscopy.