KINETICS OF ENGINEERED PEPTIDES AND POLYMERIC PEPTIDE-MIMICS THAT BIOMINERALIZE NANOMATERIALS FROM THE ATOM UP

Scott K. Stanley, Matthew L. Becker, Eric K. Lin, Wen-li Wu

 

In biomineralization processes, peptides mediate reduction and clustering of inorganic ions to build nanomaterials with well-defined shape, size, and composition.  This precise control exerted by peptides has been linked to specific amino acid sequence.  This poster presents a fundamental kinetic study for the short engineered peptide AYSSGAPPMPPF that builds monodisperse <10 nm Au nanocrystals from Au(III) ions at very low relative peptide concentrations, at room temperature, and in water at neutral pH.  Our data show that (i) peptides actually inhibit nucleation and growth of nanocrystals, (ii) the biological buffer HEPES plays a key, active chemical role as the reducing agent, and (iii) HAuCl4 accelerates kinetics.  We use a kinetic scaling analysis to propose rate laws for nucleation and growth and extract observed rate constants to quantify the kinetics of peptide mediated nanocrystal biomineralization.  We also compare peptide kinetics to kinetics for citrate and various polymer ligands and show that peptides belong to a unique kinetic class of non-reducing inhibitor ligands. Our data show that peptides regulate the surface-reaction-limited growth of nanocrystals, which explains that inhibition is solely due to strong surface binding of peptides and not diffusion limited or steric effects.  Finally, based on observed nucleation and growth regimes and theory, we propose that a full shell of ≈ 60 AYSSGAPPMPPF peptides lying flat on the surface (as opposed to end-on) is required to control size and shape of the growing nanocrystal.

Corresponding Author: Scott K. Stanley (nonmember), mentor: Wen-li Wu (member)

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Category: Materials.