Diagnostics increasingly relies on biomarkers—measurable molecular signals such as proteins, peptides, nucleic acids, metabolites, or enzymatic activities—that correlate with disease presence, stage, or treatment response. To read those signals reliably in real samples (blood, saliva, urine, tissue), modern assays need a recognition element that can find the target selectively, bind strongly enough, and produce a measurable output. Alongside antibodies and nucleic acids (aptamers), peptide probes have become a powerful option because they are chemically programmable, compatible with many detection platforms, and can be engineered for stability and surface attachment. This article explains how peptide probes are developed for biomarker detection, which design strategies are most common, and what technical pitfalls matter most in real diagnostic workflows. 1) What Is a “Peptide Probe” in Diagnostics? A peptide probe is a designed short amino-acid sequence that either: Binds a biomarker (affinity peptide / targeting peptide / peptide aptamer concept), or Responds to a biomarker-related activity (for example, a protease-cleavable peptide that changes signal after enzymatic cutting), or Acts as a capture element on a surface to pull a biomarker out of complex samples for readout. Compared with antibodies, peptides are usually easier to synthesize and modify (labels, linkers, anchors),…
