TY - JOUR
T1 - Effect of Cationic Surfactant Micelles on Hydroxyapatite Nanocrystal Formation
T2 - An Investigation into the Inorganic-Organic Interfacial Interactions
AU - Shiba, Kota
AU - Motozuka, Satoshi
AU - Yamaguchi, Tadashi
AU - Ogawa, Nobuhiro
AU - Otsuka, Yuichi
AU - Ohnuma, Kiyoshi
AU - Kataoka, Takuya
AU - Tagaya, Motohiro
N1 - Funding Information:
This work was partially supported by a Grant-in-Aid for Young Scientists (A) (Grant No. 26709052) from MEXT/JSPS KAKENHI and was partially supported by Izumi Science and Technology Foundation (Grant No. H26-J-028). Collaterally, this research was also supported by the World Premier International Research Center Initiative on Materials Nanoarchitectonics (WPI-MANA) and was partially supported by a Grant-in-Aid for Young Scientists (B) (Grant No. 26870836) from MEXT/JSPS KAKENHI and Kazuchika Okura Memorial Foundation.
Publisher Copyright:
© 2016 American Chemical Society.
PY - 2016/3/2
Y1 - 2016/3/2
N2 - To clarify hydroxyapatite (HAp) nanocrystal formation based on the interfacial interactions with organic molecules is important for controlling the dispersion states/shapes of HAp and understanding the biomineralization mechanism. In this study, the effects of cetyltrimethylammonium bromide (CTAB) micelles on the HAp nanocrystal formation process were investigated through both the morphosynthesis technique and the molecular orbital calculations. The HAp nanocrystals synthesized in the presence of CTAB exhibited a controlled rod-like shape and subsequently grew up by a thermal treatment to be larger-sized nanocrystals at a well-dispersed state. It was also found that the CTAB micelles strained and disordered at the higher temperature effectively induced heterogeneous nucleation to initiate the nucleation/growth processes. In contrast, HAp nanocrystals synthesized without CTAB exhibited irregular-shaped and aggregated nanocrystals, which are due to dominantly occurring homogeneous nucleation. According to the molecular orbital calculations, the cationic N atom of the CTAB molecule strongly interacted with the Ca ion in the a-plane as well as the hydroxyl/phosphate groups in the c-plane of HAp via ionic/covalent bonding (e.g., only ionic bonding at the closer interfacial distance at 1.0 Å), leading to effective nucleation on the micelle surfaces. Therefore, a possible reason for the rod-like and well-dispersed nanocrystal formation is due to the heterogeneous nuclei formation/growth on the N atoms of CTAB micelles and subsequent fusion growth among the CTAB micelle-directed inorganic-organic complexes in the confined spaces. The present results will be applicable for designing tailored HAp morphologies based on inorganic-organic hybrid interaction systems.
AB - To clarify hydroxyapatite (HAp) nanocrystal formation based on the interfacial interactions with organic molecules is important for controlling the dispersion states/shapes of HAp and understanding the biomineralization mechanism. In this study, the effects of cetyltrimethylammonium bromide (CTAB) micelles on the HAp nanocrystal formation process were investigated through both the morphosynthesis technique and the molecular orbital calculations. The HAp nanocrystals synthesized in the presence of CTAB exhibited a controlled rod-like shape and subsequently grew up by a thermal treatment to be larger-sized nanocrystals at a well-dispersed state. It was also found that the CTAB micelles strained and disordered at the higher temperature effectively induced heterogeneous nucleation to initiate the nucleation/growth processes. In contrast, HAp nanocrystals synthesized without CTAB exhibited irregular-shaped and aggregated nanocrystals, which are due to dominantly occurring homogeneous nucleation. According to the molecular orbital calculations, the cationic N atom of the CTAB molecule strongly interacted with the Ca ion in the a-plane as well as the hydroxyl/phosphate groups in the c-plane of HAp via ionic/covalent bonding (e.g., only ionic bonding at the closer interfacial distance at 1.0 Å), leading to effective nucleation on the micelle surfaces. Therefore, a possible reason for the rod-like and well-dispersed nanocrystal formation is due to the heterogeneous nuclei formation/growth on the N atoms of CTAB micelles and subsequent fusion growth among the CTAB micelle-directed inorganic-organic complexes in the confined spaces. The present results will be applicable for designing tailored HAp morphologies based on inorganic-organic hybrid interaction systems.
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U2 - 10.1021/acs.cgd.5b01599
DO - 10.1021/acs.cgd.5b01599
M3 - Article
AN - SCOPUS:84960157787
VL - 16
SP - 1463
EP - 1471
JO - Crystal Growth and Design
JF - Crystal Growth and Design
SN - 1528-7483
IS - 3
ER -