Peptide Nucleic Acid Origami for Cancer Diagnostics

Liquid biopsy offers a minimally invasive approach to cancer detection and monitoring, but the analysis of rare, fragmented tumor-derived nucleic acids remains challenging because of their low abundance and interference from wild-type sequences. Peptide nucleic acids (PNAs), with their high-affinity hybridization, nuclease resistance, and single-base mismatch discrimination, provide a promising molecular recognition strategy for cancer diagnostics. This review critically examines PNA-based biosensors, PNA-containing nanostructures and emerging PNA-origami-inspired architectures for precision oncology. Unlike recent reviews that discuss only PNA chemistry, utilized in biosensing the individual biomarkers and DNA-origami technologies, this review uniquely focuses on PNA-origami nanoarchitectures for cancer diagnostics in nanoscale-level detection. It critically examines how the chemical modification, programmable nanoscale arrangement, and spatial arrangement of probes and reporters may enable multiplexed detection of cancer-associated mutations, DNA methylation signatures, gene-fusion junctions and circulating microRNAs in liquid-biopsy samples. Optical, plasmonic, colorimetric, electrochemical, and nanopore-based detection strategies are discussed alongside established PNA-clamping and biosensing approaches. Emphasis is placed on analytical performance, structural characterization, matrix compatibility, reproducibility, scalability, and benchmarking against digital PCR, next-generation sequencing, and CRISPR-based diagnostics. Key translation barriers include scalable production, reproducible assembly, matrix compatibility, analytical benchmarking and validation using patient-derived specimens. Currently, PNA origami should be considered a preclinical, origami-inspired design framework for spatially organized and multiplexed cancer biomarker detection, rather than a clinically implemented diagnostic technology.