Strand-displacement amplification reduces structure-induced PCR bias and preserves structurally diverse aptamers during SELEX.

Strand-displacement SELEX (SD-SELEX) preserves G-quadruplex–containing aptamers during thrombin selection, achieving 37-fold greater structural preservation than Taq-SELEX over 11 rounds.

• Why it matters: Secondary structures can skew PCR amplification during SELEX, risking loss of structurally diverse candidates—especially G-quadruplexes that are hardest to amplify fairly.
• What they did: SD-SELEX used a polymerase with strong 5'→3' strand-displacement activity and was compared with Taq polymerase in thrombin SELEX, with structural preservation and reproducibility assessed across 11 rounds plus high-throughput sequencing.
• The result: SD-SELEX maintained G4 motif representation and enriched the known 15-mer thrombin-binding aptamer through round 8, then shifted to newly found G4 variants, while Taq-SELEX depleted these sequences and yielded weaker-binding candidates.

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