STRC Research

Dynamic reassembly of peptide RADA16 nanofiber scaffold

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What they found

RADA16-I nanofiber scaffold sonicated into 20–100 nm fragments reassembles to original length (hundreds of nm to few microns) within 2 hours; this cycles reproducibly. Key geometry data from AFM: nanofiber height 1.3–1.5 nm (single peptide thickness); individual peptide monomer ~5 nm long × 1.3 nm wide × 0.8 nm thick. Assembled fibers reach 615 ± 104 nm mean length. Hydrogel forms at 0.6–3 mM (1–5 mg/ml), >99.5% water. Storage modulus G′ ~50 Pa at full reassembly. pH 7.5, 20 mM Tris.

How this applies to h09

AFM length distribution directly supports the model’s fibril_length_nm = 1000 — fibers reach several hundred nm to low microns, so 1 μm is a plausible upper-range estimate. The 1.3–1.5 nm AFM height matches a single-peptide-layer tape, consistent with the bilayer (double-sheet) model that underlies the 4.35 peptides/nm packing estimate. No direct statement of peptides/nm, but the monomer dimensions are consistent with H-bond spacing ~0.47 nm.

Key numbers — CRITICAL GEOMETRY

  • Peptide monomer: 5 nm long × 1.3 nm wide × 0.8 nm thick
  • Nanofiber AFM height: 1.3–1.5 nm (single peptide layer)
  • Nanofiber length (intact): several hundred nm to few μm; mean ~615 ± 104 nm
  • Post-sonication fragments: 20–100 nm
  • Reassembly complete: ~2 hours
  • Hydrogel concentration: 0.6–3 mM (1–5 mg/ml)
  • G′ (storage modulus): ~50 Pa at full reassembly (1 Hz, 25°C)
  • Assembly conditions: 20 mM Tris pH 7.5, >99.5% water

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