title: Biomineralization and size control of stable calcium phosphate core-protein shell nanoparticles: potential for vaccine applications.
abstract: Calcium phosphate (CaP) polymorphs are nontoxic, biocompatible and hold promise in applications ranging from hard tissue regeneration to drug delivery and vaccine design. Yet, simple and robust routes for the synthesis of protein-coated CaP nanoparticles in the sub-100 nm size range remain elusive. Here, we used cell surface display to identify disulfide-constrained CaP binding peptides that, when inserted within the active site loop of Escherichia coli thioredoxin 1 (TrxA), readily and reproducibly drive the production of nanoparticles that are 50-70 nm in hydrodynamic diameter and consist of an approximately 25 nm amorphous calcium phosphate (ACP) core stabilized by the protein shell. Like bone and enamel proteins implicated in biological apatite formation, peptides supporting nanoparticle production were acidic. They also required presentation in a loop for high-affinity ACP binding as elimination of the disulfide bridge caused a nearly 3-fold increase in hydrodynamic diameters. When compared to a commercial aluminum phosphate adjuvant, the small core-shell assemblies led to a 3-fold increase in mice anti-TrxA titers 3 weeks postinjection, suggesting that they might be useful vehicles for adjuvanted antigen delivery to dendritic cells.
authors.affiliation: Department of Chemical Engineering, University of Washington, Seattle, Washington 98195, USA.
authors.forename: David
authors.initials: D
authors.lastname: Chiu
authors.forename: Weibin
authors.initials: W
authors.lastname: Zhou
authors.forename: Sathana
authors.initials: S
authors.lastname: Kitayaporn
authors.forename: Daniel T
authors.initials: DT
authors.lastname: Schwartz
authors.forename: Kaja
authors.initials: K
authors.lastname: Murali-Krishna
authors.forename: Terrance J
authors.initials: TJ
authors.lastname: Kavanagh
authors.forename: François
authors.initials: F
authors.lastname: Baneyx
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002130:Calcium Phosphates / Q000737:chemistry*; D017931:DNA Primers; D004926:Escherichia coli / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D008969:Molecular Sequence Data; D053758:Nanoparticles; D011506:Proteins / Q000737:chemistry*; D017386:Sequence Homology, Amino Acid; D014612:Vaccines / Q000008:administration & dosage*
chemical_list: D002130:Calcium Phosphates; D017931:DNA Primers; D011506:Proteins; D014612:Vaccines; C020243:calcium phosphate