Enhanced detection levels in a semi-automated sandwich hybridisation assay using a peptide nucleic acid (PNA) signal probe

A peptide nucleic acid (PNA) signal probe was tested as a replacement for a typical DNA oligonucleotide-based signal probe in a semi-automated sandwich hybridisation assay designed to detect the harmful phytoplankton species Alexandrium tamarense. The PNA probe yielded consistently higher fluorescent signal intensities than the DNA-based signal probes without any loss of specificity. A combination of species-specific DNA-based capture probes and more generic PNA signal probes are suggested as an optimal configuration for semi-automated sandwich hybridisation assays, designed to detect harmful algal species. The DNA-based probe provides a cost-effective means of capturing RNA from different species, whereas the more expensive PNA signal probe provides enhanced signal intensity compared with traditional DNA probes. Configuring the PNA signal probe to bind multiple species can facilitate the development of new assays and reduce the per-assay cost of using PNA probes.