Biomimetic nanoparticles with polynucleotide and PEG mixed-monolayers enhance calcium phosphate mineralization
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Biomineralization of hydroxyapatite (Ca10(PO4)6(OH)2) is of significant importance in biomedical applications such as bone and dental repair, and biomimetic control of mineral formation may lead to more effective restorative procedures. Gold nanoparticles are functional scaffolds on which to assemble multi-component monolayers capable of mimicking protein activity in the templated synthesis of calcium phosphate. The goal of this research was to explore nanoparticle templates with mixed-monolayers of uncharged polar polyethylene glycol (PEG) molecules and highly charged polynucleotide and amino acid molecules in their ability to influence mineralization rates and mineral particle size and morphology. This research demonstrates through time-resolved optical density and dynamic light scattering measurements that the combination of tiopronin, PEG, and DNA presented on a nanoparticle surface decreases nanoparticle aggregation from 59 to 21 nm solvated radius, increases mineralization kinetics from 1.5 × 10−3 to 3.1 × 10−3 OD/min, and decreases mineral particle size from 685 to 442 nm average radius. FT-IR and TEM data demonstrate that mineralized material, while initially amorphous, transforms to a semi-crystalline material when guided by template interactions. This demonstrates that surface-tailored monolayer protected cluster scaffolds are successful and controllable mineralization templates with further potential for biomedical applications involving calcium phosphate and other biomaterials.
KeywordsBiomimetic Mineralization Bionanotechnology Functional coatings Gold nanoparticles
A. E. Gerdon would like to thank Emmanuel College for funding and support; P. March for access to spectroscopy instrumentation; H. C. Margolis, F. B. Wiedemann-Bidlack, and S.-Y. Kwak at the Forsyth Institute, Cambridge, MA, for helpful discussion and access to microscopy instrumentation; and numerous dedicated and talented undergraduate students, including V. Perrone, T. Cicuto, G. Conklin, S. Ngourn, and H. Butts for their contributions.
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