Polyaspartic Acid Concentration Controls the Rate of Calcium Phosphate Nanorod Formation in High Concentration Systems

Journal Article · Tue Aug 22 00:00:00 EDT 2017 · Biomacromolecules

DOI:https://doi.org/10.1021/acs.biomac.7b00772· OSTI ID:1408130

Krogstad, Daniel V.  ^[1]; Wang, Dongbo ^[2]; Lin-Gibson, Sheng ^[2]

---

1. National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States); Univ. of Illinois at Urbana-Champaign, IL (United States)
2. National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States)

Polyelectrolytes are known to greatly affect calcium phosphate (CaP) mineralization. The reaction kinetics as well as the CaP phase, morphology and aggregation state depend on the relative concentrations of the polyelectrolyte and the inorganic ions in a complex, nonlinear manner. This study examines the structural evolution and kinetics of polyaspartic acid (pAsp) directed CaP mineralization at high concentrations of polyelectrolytes, calcium, and total phosphate (19–30 mg/mL pAsp, 50–100 mM Ca²⁺, Ca/P = 2). Using a novel combination of characterization techniques including cryogenic transmission electron microscopy (cryo-TEM), spectrophotometry, X-ray total scattering pair distribution function analysis, and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), it was determined that the CaP mineralization occurred over four transition steps. The steps include the formation of aggregates of pAsp stabilized CaP spherical nanoparticles (sNP), crystallization of sNP, oriented attachment of the sNP into nanorods, and further crystallization of the nanorods. The intermediate aggregate sizes and the reaction kinetics were found to be highly polymer concentration dependent while the sizes of the particles were not concentration dependent. Furthermore, this study demonstrates the complex role of pAsp in controlling the mechanism as well as the kinetics of CaP mineralization.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• Grant/Contract Number: AC02-06CH11357
• OSTI ID: 1408130
• Journal Information: Biomacromolecules, Vol. 18, Issue 10; ISSN 1525-7797
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
mineralization
nanoparticles
phosphates
phase transitions
nanorods
calcium phosphate
polyaspartic acid
biomineralization
oriented attachment