Microbead-Based Heterodimer Assay for Amplification-Free Detection of Single-Stranded DNA

MBHA enables amplification-free detection of single-stranded DNA, reaching a lowest target concentration of 166 fM above the blank-derived detection threshold.

• Why it matters: Rare nucleic-acid targets are hard to detect without amplification because specific recognition must be distinguished from nonspecific bead interactions.
• What they did: Two spectrally distinct microbead populations with partially double-stranded probes were used for two-site target bridging, with heterotypic bead pairs classified by fluorescence identity and interparticle distance.
• The result: A sequence-scrambled non-target stayed below threshold, 166 fM detection persisted with 1 uM non-target DNA (~six-million-fold molar excess), and probe redesign detected a 60-nucleotide SARS-CoV-2 ORF1ab-derived target.