title: Polypeptide folding-mediated tuning of the optical and structural properties of gold nanoparticle assemblies.
abstract: Responsive hybrid nanomaterials with well-defined properties are of significant interest for the development of biosensors with additional applications in tissue engineering and drug delivery. Here, we present a detailed characterization using UV-vis spectroscopy and small angle X-ray scattering of a hybrid material comprised of polypeptide-decorated gold nanoparticles with highly controllable assembly properties. The assembly is triggered by a folding-dependent bridging of the particles mediated by the heteroassociation of immobilized helix-loop-helix polypeptides and a complementary nonlinear polypeptide present in solution. The polypeptides are de novo designed to associate and fold into a heterotrimeric complex comprised of two disulfide-linked four-helix bundles. The particles form structured assemblies with a highly defined interparticle gap (4.8±0.4 nm) that correlates to the size of the folded polypeptides. Transitions in particle aggregation dynamics, mass-fractal dimensions and ordering, as a function of particle size and the concentration of the bridging polypeptide, are observed; these have significant effects on the optical properties of the assemblies. The assembly and ordering of the particles are highly complex processes that are affected by a large number of variables including the number of polypeptides bridging the particles and the particle mobility within the aggregates. A fundamental understanding of these processes is of paramount interest for the development of novel hybrid nanomaterials with tunable structural and optical properties and for the optimization of nanoparticle-based colorimetric biodetection strategies.
authors: Department of Materials, Institute for Biomedical Engineering, Imperial College London, Exhibition Road, SW7 2AZ London, United Kingdom.
authors: Daniel
authors: D
authors: Aili
authors: Piotr
authors: P
authors: Gryko
authors: Borja
authors: B
authors: Sepulveda
authors: John A G
authors: JA
authors: Dick
authors: Nigel
authors: N
authors: Kirby
authors: Richard
authors: R
authors: Heenan
authors: Lars
authors: L
authors: Baltzer
authors: Bo
authors: B
authors: Liedberg
authors: Mary P
authors: MP
authors: Ryan
authors: Molly M
authors: MM
authors: Stevens
mesh_terms: D006046:Gold / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*; D017510:Protein Folding; D053838:Scattering, Small Angle; D013056:Spectrophotometry, Ultraviolet; D014961:X-Ray Diffraction
chemical_list: D010455:Peptides; D006046:Gold